Skip to main content
NCBI home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2019 Jun 1.
Published in final edited form as: Hypertension. 2018 May 7;71(6):1117–1125. doi: 10.1161/HYPERTENSIONAHA.117.10764

Renal-specific silencing of TNF unmasks salt-dependent increases in blood pressure via an NKCC2A-dependent mechanism

Shoujin Hao 1, Mary Hao 1, Nicholas R Ferreri 1
PMCID: PMC6027635  NIHMSID: NIHMS954434  PMID: 29735631

Abstract

We tested the hypothesis that tumor necrosis factor-alpha (TNF) produced within the kidney and acting on the renal tubular system is part of a regulatory mechanism that attenuates increases in blood pressure in response to high salt intake. Intrarenal administration of a lentivirus construct, which specifically silenced TNF in the kidney, did not affect baseline blood pressure. However, blood pressure increased significantly 1 day after mice with intrarenal silencing of TNF ingested 1% NaCl in the drinking water. The increase in blood pressure, which was continuously observed for 11 days, promptly returned to baseline levels when mice were switched from 1% NaCl to tap water. Silencing of renal TNF also increased Na+-K+-2Cl− cotransporter (NKCC2) phosphorylation and induced a selective increase in NKCC2 isoform A mRNA accumulation in both the cortical and medullary TAL that was neither associated with a compensatory decrease of NKCC2F in the medulla nor NKCC2B in the cortex. The NaCl-mediated increases in blood pressure were completely absent when NKCC2A, using a lentivirus construct that did not alter expression of NKCC2F or NKCC2B, and TNF were concomitantly silenced in the kidney. Moreover, the decrease in urine volume and NaCl excretion induced by renal TNF silencing was abolished when NKCC2A was concurrently silenced, suggesting that this isoform contributes to the transition from a salt-resistant to salt-sensitive phenotype. Collectively, the data are the first to demonstrate a role for TNF produced by the kidney in the modulation of sodium homeostasis and blood pressure regulation.

Keywords: TNF, salt-dependent hypertension, kidney, thick ascending limb, cytokines

INTRODUCTION

While tumor necrosis factor-alpha (TNF) is best known for its pro-inflammatory actions, this cytokine also exhibits immunomodulatory effects and regulates diverse functions in kidney, lung, and colon where active Na+ transport is important for fluid clearance1–4. Indeed, clinical use of anti-TNF drugs has exposed fundamental effects of this cytokine that preclude their use in congestive heart failure and systemic lupus erythematosus1, 5–7. Micropuncture and whole animal studies first identified cytokines as regulators of renal function, however the molecular mechanisms that underlie these effects remain unclear8–12. Moreover, although TNF is produced by proximal tubule (PT), medullary thick ascending limb of Henle’s loop (mTAL), collecting duct (CD), podocytes and mesangial cells, the intrinsic effects of endogenous TNF formed within the kidney are understudied13–17.

The TAL plays an important role in the maintenance of blood pressure and has been linked to the development of salt-sensitive hypertension18, 19. We previously showed that the TAL produces TNF, and global deletion of this cytokine selectively increases expression of the Na+-K+-2Cl− cotransporter (NKCC2) isoform A along the TAL14, 20. Moreover, TNF produced by cultured mTAL cells acts in an autocrine manner to inhibit in vitro correlates of Na+ reabsorption and exogenous administration of recombinant TNF to mice elicits a natriuretic response2, 21, 22. We also showed that addition of 1% NaCl to the drinking water induces NFAT5-dependent TNF production by the mTAL, and increases the levels of this cytokine in urine but not plasma23, 24. Importantly, production of TNF by the kidney in response to increased NaCl intake was not associated with an increase in blood pressure and was observed in the absence of an inflammatory response. These data are consistent with the notion that elevated renal levels of TNF are not always detrimental25.

TNF has important pro-hypertensive effects in experimental models of hypertension associated with inflammation and involving recruitment of T cells and macrophages, which contribute to end-organ damage in the kidney, however, TNF per se does not increase blood pressure when administered to normal rats, mice, or humans26–34. Moreover, randomized clinical trials have shown that anti-TNF therapy is associated with hypertension in patients with rheumatoid arthritis, suggesting that more precise mechanistic studies are needed to understand the effects of TNF on blood pressure regulation35. Recent elegant studies suggest that in vivo effects of TNF are dictated by the cellular sources that produce this cytokine36, 37. The present study defines the intrinsic effects of endogenous TNF, produced in the kidney under normotensive and non-inflammatory conditions and demonstrates that TNF is part of an adaptive pathway that limits NKCC2A activity and attenuates increases in blood pressure in response to high NaCl intake.

Methods

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Mice

Male C57BL/6J mice were maintained on a diet containing 0.4% NaCl and tap water or 1% NaCl in the drinking water ad libitum. All protocols were approved by the New York Medical College IACUC committee and conducted in accordance with National Institutes of Health (NIH) Guide for the Care and Use of Laboratory Animals.

Preparation and in vivo administration of lentivirus targeting vectors

Constructs were generated using standard cloning procedures as previously described24, 38, 39; see online supplement.

Preparation of renal tissues and mTAL cells

Isolation of renal tissues were performed as previously described24, 38, 39; see online supplement.

Blood pressure measurements

Blood pressure was determined by tail cuff plethysmography and radiotelemetry; see online supplement.

Quantitative RT-PCR analysis

Isolation of total RNA, amplification of cDNA fragments, and quantitative RT-PCR analysis were performed as previously described24, 38, 39; see online supplement.

Western blot analysis

Analysis of total and phospho-NKCC2 expression was performed as previously described20; see online supplement.

TNF ELISA

Determination of TNF levels in plasma and urine was performed as previously described40; see online supplement.

Metabolic cage experiments

Mice placed in metabolic cages were used for studies to evaluate the effects of renal TNF silencing on sodium and chloride excretion; see online supplement.

Statistical Analysis

Data are expressed as mean ± SE; GraphPad Prism 4 was used to analyze data sets. One-way ANOVA (followed by Tukey or Dunnett post hoc test) was used for comparisons among groups, and an unpaired Students t test was used to compare data between 2 groups, with the aid of Sigma Plot software. Radiotelemetry data were analyzed by repeated-measures ANOVA. A P value of <0.05 was considered statistically significant.

RESULTS

Validation of intrarenal lentivirus silencing of TNF

A lentivirus strategy was developed to silence TNF production in the kidney by constructing an shRNA that targeted exon 4 of the TNF gene (U6-TNF-ex4) (Figure 1A). The ability of this construct to reduce TNF mRNA levels was verified in primary cultures of mouse mTAL cells in which both basal and stimulated (NaCl; 400 mosmol/kg H2O) levels of TNF mRNA were inhibited (Figure 1B). For in vivo silencing of TNF, purified U6-TNF-ex4 or control lentivirus (U6) was injected directly into each kidney as described24, 39. Three days later qRT-PCR analysis showed that TNF mRNA was markedly reduced in kidney but not spleen or liver, major extra-renal sites of TNF expression (Figures 1C–E). Intrarenal injection of lentivirus did not produce renal damage as previously described39. Collectively, the data show that the U6-TNF-ex4 construct silences TNF in the kidney and does not escape into the circulation to inhibit TNF production at other sites.

Figure 1. Lentivirus silencing of TNF in vitro and in vivo.

Figure 1

Open in a new tab

(A) Schematic of the vector used to construct the shTNF lentivirus that targeted exon 4 of the TNF gene. (B) Mouse mTAL cells were exposed for 4 hr to hypertonic NaCl (400 mOsmol/kg H2O) in the absence and presence of shTNF and TNF mRNA was assessed by qRT-PCR. (C–E) Renal, splenic, and liver TNF mRNA was determined after intrarenal injection of either control (U6) or TNF-silencing (U6-TNF-ex4) lentivirus (n=6).

Effects of renal-specific TNF silencing on blood pressure, NKCC2A mRNA accumulation, and NKCC2 phosphorylation

Mice were provided 1% NaCl in the drinking water to study the intrinsic effects of TNF produced within the kidney on blood pressure regulation under normal and high salt conditions. This approach circumvented the pro-hypertensive effects of TNF observed in models of Ang II-induced hypertension26, 30, 31, 33 and increases TNF levels in urine but not plasma, signifying renal rather than systemic TNF production24. Baseline SBP was similar in mice ingesting tap water and a normal salt diet (NSD) that were given U6 or U6-TNF-ex4 (Figure 2A). However, silencing TNF increased SBP when mice were switched to 1% NaCl for 3 days compared with mice injected with U6 control (Figure 2A). As global deletion of TNF increases NKCC2A mRNA accumulation20, we determined if this effect was dependent on TNF produced within the kidney. Indeed, a selective increase in outer medullary NKCC2A mRNA levels was observed in mice injected with U6-TNF-ex4 and given 1% NaCl (Figures 2B and C). Isoform-specific antibodies are not available, and while total NKCC2 expression did not change an increase in phospho-NKCC2 expression was observed in mice in which TNF was silenced (Figure 2D–E). Collectively, the data indicate that the selective increase in NKCC2A mRNA abundance and phospho-NKCC2 (pNKCC2) levels, in response to high salt intake in the absence of renal TNF, occurs concomitantly with an increase in SBP.

Figure 2. Effects of TNF silencing on blood pressure and NKCC2 isoforms.

Figure 2

Open in a new tab

(A) Mice were pretreated with control (U6) or TNF silencing (U6-TNF-ex4) lentivirus for 4 days and were then given either tap water or 1% NaCl for 3 days. Systolic blood pressure was measured daily by tail-cuff plethsymography (n=4). (B and C) Total RNA was isolated from outer medulla and qRT-PCR was performed to determine the effects of TNF silencing on NKCC2A and NKCC2F (n=4). (D and E) Analysis of total and phospho-NKCC2 expression by Western blot (n=6).

Renal silencing of TNF/characteristics of NaCl-induced increases in blood pressure

Injection of control or TNF silencing lentivirus had no effect on baseline blood pressure in mice ingesting a standard diet and tap water from day −2 to day 0 (Figure 3A). However, an increase in blood pressure was observed 1 day after mice began drinking 1% NaCl, an effect that was sustained for 5 days (Figure 3A). Additional studies showed that blood pressure remained elevated for 11 days while mice were drinking 1% NaCl and that blood pressure rapidly returned to baseline when mice were switched to tap water (days 12–16; p<0.05), and increased and remained elevated when they were switched back to 1% NaCl (days 17–21; p<0.05) (Figure 3B). A parallel study using radiotelemetry was performed to acquire data over 3 consecutive weeks during which time mice were subjected to a sequence of normal, high, and normal NaCl intake periods (Figure 3C). The rapid, sustained, and reversible increase in MAP detected by radiotelemetry supports the concept that TNF produced in the kidney is part of an adaptive mechanism that attenuates increases in blood pressure in normotensive mice ingesting high NaCl. Indeed, urinary levels of TNF were diminished in mice treated with intrarenal U6-TNF-ex4 while plasma levels of TNF remained unchanged (Figures 3D–E). Overall, these data indicate that in mice ingesting 1% NaCl, silencing TNF in the kidney results in elevated blood pressure responses that are rapid, reversible, and sustained until mice are once again given tap water to drink.

Figure 3. Features of blood pressure changes induced by renal silencing of TNF.

Figure 3

Open in a new tab

(A) Baseline blood pressure was established in mice injected with U6 or U6-TNF-ex4. Mice were then switched from tap water to 1% NaCl in the drinking water for 5 days (n=4; *=p<0.05). (B) Summation of blood pressure values from mice that ingested a sequence of 1% NaCl, tap water, and 1% NaCl for the indicated days (n=4); p<0.05 is for comparison of 1% NaCl vs tap water in U6-TNF-ex4-treated mice. (C) Daily averages of blood pressure assessed by radiotelemetry in mice injected with U6 or U6-TNF-ex4 and given either tap water or 1% NaCl (n=6); (D and E) TNF levels in urine and plasma were determined in mice given 1% NaCl for 3 days after treatment with control or silencing vectors (n=6).

Silencing NKCC2A reverses the increase in blood pressure in shTNF mice

The extent to which the increase in NKCC2A contributed to the salt-induced increase in MAP following silencing of renal TNF was determined by concomitantly silencing NKCC2A in the kidney. We previously designed constructs that specifically silence NKCC2 isoforms38. Accordingly, MAP was determined in mice that received intrarenal injections of either TNF silencing lentivirus (U6-TNF-ex4) alone, or a mixture of U6-TNF-ex4 and U6-N2A-ex4 to silence NKCC2A. MAP was similar in both groups of mice that ingested tap water for 3 days (Figure 4A). However, the high-salt induced increase in MAP observed in mice injected with U6-TNF-ex4 was completely absent in mice when NKCC2A was silenced (Figure 4A). Similarly MAP, averaged over 7 days of high NaCl intake, was lower in mice that received both U6-TNF-ex4 and U6-N2A-ex4 compared to mice in which only TNF was silenced (Figure 4B). These data indicate that the elevated expression of NKCC2A, in mice lacking TNF in the kidney, contributes to the increase in MAP in mice ingesting high NaCl.

Figure 4. Renal silencing of NKCC2A prevents NaCl-induced increases in MAP induced by knockdown of TNF in the kidney.

Figure 4

Open in a new tab

(A) Mice were implanted with radiotelemetry probes and injected with either U6-TNF-ex4 or a combination of U6-TNF-ex4 and U6-N2A-ex4 to concomitantly silence NKCC2A. MAP was determined in mice given tap water and then 1% NaCl (n=6). (B) Summation of MAP for mice given 1% NaCl.

Effects of renal TNF silencing on NKCC2 isoform expression

Since silencing NKCC2A abolished the NaCl-dependent increase in blood pressure observed in the absence of renal TNF, we determined the effects of silencing TNF and NKCC2A concomitantly in the kidney on NKCC2 isoform expression. In these experiments, tissue was obtained after mice were injected with empty lentivirus (U6), U6-TNF-ex4, or a mixture of U6-TNF-ex4 and U6-N2A-ex4 for 3 days then given 1% NaCl for an additional 1 day. The data show that NKCC2A mRNA expression was significantly increased in both medulla and cortex from mice with TNF silencing compared with the control group (U6) in response to high NaCl (Figure 5A and C). In contrast, neither knockdown of TNF nor NKCC2A affected NKCC2F or NKCC2B mRNA levels (Figure 5 B and D). The data also confirm that injection of U6-N2A-ex4 specifically decreases NKCC2A mRNA abundance in renal cortex and medulla.

Figure 5. Analysis of NKCC2 isoforms.

Figure 5

Open in a new tab

qRT-PCR was performed for NKCC2A and NKCC2F on total RNA obtained from medulla (A and B), and NKCC2A and NKCC2B in cortex (C and D) of mice that were injected with U6, U6-TNF-ex4, or a combination of U6-TNF-ex4 and U6-N2A-ex4 and given 1% NaCl for 7 days (n=6).

Effects of renal TNF and NKCC2A silencing on electrolyte excretion

The contributions of NKCC2A and TNF to electrolyte and urine excretion were determined using mice that were placed in metabolic cages and received intrarenal injections of control (U6), U6-TNF-ex4, or a mixture of U6-TNF-ex4 and U6-N2A-ex4. Three days after silencing, mice were switched from tap water to 1% NaCl in the drinking water and urine was collected for 24 hr. Renal silencing of TNF elicited a decrease in urine volume, sodium, and chloride excretion (Figure 6A–C). Concomitant inhibition of TNF and NKCC2A reversed the inhibitory effects of TNF silencing on urine volume, sodium, and chloride excretion. Taken together, these data suggest that renal TNF silencing sets in motion changes in NKCC2A expression and NKCC2 activity that attenuate the diuretic and natriuretic response to NaCl.

Figure 6. Effects of silencing TNF and NKCC2A on renal excretory function.

Figure 6

Open in a new tab

Mice were injected with U6, U6-TNF-ex4, or a combination of U6-TNF-ex4 and U6-N2A-ex4 and were acclimatized for 3 days in metabolic cages and given tap water ad libitum. Urine was collected for determinations of (A) volume, (B) sodium, and (C) chloride 24 hr after ingestion of 1% NaCl (n=6).

DISCUSSION

This study provides evidence of a paradigm shift regarding the role of TNF in hypertension and shows that TNF, produced within the kidney and acting within the tubular compartment in normotensive mice, is part of an adaptive mechanism that regulates blood pressure in response to increases in sodium intake via a mechanism involving regulation of the NKCC2A isoform along the cortical and medullary TAL. We demonstrated that 1% NaCl in the drinking water, which increases urinary but not plasma levels of TNF, increased blood pressure in mice in which renal TNF expression was silenced, but had no effect when ingested by mice injected with control lentivirus. The increase in blood pressure was observed 1 day after 1% NaCl was provided, remained elevated until mice were subsequently given tap water, and was accompanied by a selective increase in NKCC2A isoform and pNKCC2 expression. Concomitant silencing of NKCC2A and TNF in the kidney not only prevented the increase in blood pressure, but also reversed the decrease in urine volume as well as the urinary excretion of Na+ and Cl− induced by renal silencing of TNF.

Previously we showed that global genetic deletion of TNF in mice on a normal salt diet selectively increases NKCC2A isoform expression, NKCC2 activity, and ambient urine osmolality20. While those findings suggested that TNF was an endogenous regulator of NKCC2, consistent with previous work in rats41, expression of TNF by many cell types throughout the body prevented exclusion of non-renal and/or developmental effects of this cytokine on the kidney. For the present study, we designed lentivirus constructs suitable for intrarenal administration in adult mice that silence key components hypothesized to regulate a TNF-dependent regulatory axis important for the adaptive response to increases in NaCl intake. We demonstrated that renal silencing of TNF did not change baseline blood pressure in mice ingesting a normal salt diet. However, rapid, sustained, and reversible increases in blood pressure were observed when mice that received intrarenal injections of TNF silencing lentivirus ingested 1% NaCl in the drinking water. Moreover, concurrent decreases in sodium excretion were observed as NKCC2A and pNKCC2 expression increased in the context of TNF silencing and an increase in NaCl intake. Importantly, both the increase in blood pressure and decrease in sodium excretion were prevented by concomitant silencing of TNF and NKCC2A in the kidney. Pressure natriuresis involves inhibition of sodium transporters in several nephron segments including the TAL, which reabsorbs approximately 25% of filtered NaCl. Our earlier studies using primary cultures of mTAL cells showed that TNF inhibited in vitro correlates of natriuresis in a COX-2-dependent manner2, 21, 42. Importantly, these findings were supported and extended by the first in vivo demonstration that TNF affects renal hemodynamics and excretory function in mice22. In those studies, acute administration of TNF to anesthetized mice increased urine flow, sodium excretion, and fractional sodium excretion while decreasing renal blood flow and GFR. The present study in conscious mice is the first fully integrated analysis linking endogenous TNF produced within the kidney to the attenuation of salt-induced increases in blood pressure by a mechanism involving NKCC2A.

The reabsorption of NaCl along the TAL occurs mainly via NKCC2 expressed exclusively in the apical membrane of the TAL and macula densa43, 44. Mutations of the NKCC2 gene (SLC12A1) demonstrated to cause reduced NKCC2 activity, and detected by screening more than 3000 members of the Framingham Heart Study, were associated with a significant reduction in blood pressure and risk of death due to cardiovascular disease45, 46. Although a single gene encodes for NKCC2, differential splicing of NKCC2 pre-mRNA results in formation of three major isoforms, NKCC2A, NKCC2B, and NKCC2F arising from variable exon 447, 48. Prominent differences between the isoforms include their relative affinities for chloride; namely, high affinity NKCC2B and NKCC2A versus low affinity NKCC2F, and the designation of NKCC2A as a high capacity transporter whose expression is induced by high NaCl concentration in mTAL cells38, 49. As renal-derived TNF is an inhibitor of NKCC2A mRNA accumulation it is important to note that the functional changes we observed in this, and a previous20, study could have been foretold by the elegant studies performed using NKCC2A knockout mice50. Particularly, relevant are the findings that NKCC2A may be important for preventing salt loss under conditions of elevated rates of NaCl delivery to the TAL as they are consistent with the relatively high transport capacity of NKCC2A and the observation that the regulatory effects of this isoform were seen only after intraluminal flow was increased in the context of saline loading50. It is interesting to note that while genetic deletion of TNF was associated with an increase in NKCC2A and ambient urine osmolality, NKCC2A knockout mice exhibited a decrease in osmolality20, 50. It also is intriguing to speculate how the contribution of NKCC2A to TGF responses when tubular NaCl concentration is high may relate to the decreasing renal blood flow and GFR in response to TNF22, 50. While the mechanism by which TNF selectively influences NKCC2A remains to be determined, changes in salt intake can influence the expression of NKCC2 isoforms51, and differential splicing of NKCC2 pre-mRNA and NKCC2 protein phosphorylation are important pathways for the regulation of NKCC2 that may be under tonic suppression by TNF.

Hypertension is a major independent risk factor for heart attack, stroke, and end-stage renal disease52 and increased NaCl reabsorption by the TAL contributes to salt-sensitive hypertension18, 19, 53. Although a link between dietary salt intake and hypertension is well established, elevations in blood pressure subsequent to an increase in salt intake occur in some individuals but not others54. Mechanisms that underlie the development of salt-dependent hypertension are not completely understood. Indeed, multiple reasons likely account for alterations of renal salt and water handling that may predispose individuals to changes in blood pressure in response to salt intake. The TAL has been implicated in genetic and race factors that increase sodium reabsorption, and variations in Na+ reabsorption in this segment have been linked to hypertension in both animal models and humans55–57. Collectively, these studies are consistent with the concept that elevated NKCC2 activity along the TAL may contribute to increases in blood pressure related to dietary NaCl intake58, 59. A variety of molecules acting via autocrine and/or paracrine mechanisms regulate transport function in the TAL, and additional regulatory pathways remain to be discovered60. Thus, it is critically important to understand the local endogenous actions of cytokines such as TNF along the nephron.

In several experimental models of hypertension associated with renal injury, inflammation and immune system activation, genetic deletion of TNF or administration of etanercept decreases blood pressure. Baseline blood pressure was not altered by either genetic deletion or pharmacologic inhibition of TNF, similar to our studies, however, the hypertensive effects of salt intake were observed in the context of Ang II infusion30, 31, 33. Accordingly, the increase in blood pressure after intrarenal silencing of TNF in the present study are not in conflict with these previous findings but rather illustrate an intrinsic effect of this cytokine in the context of a normotensive and non-inflammatory setting in which the renin angiotensin system was not activated. This paradigm shift regarding a renal regulatory function of TNF via a selective inhibitory effect on NKCC2A indicates that this cytokine functions as part of an axis that attenuates increases in blood pressure in response to increases in salt intake. Interestingly, hypertension has consistently been observed as a side effect in randomized clinical trials of anti-TNF therapy being administered for rheumatoid arthritis35. However, as the present study is the first to determine the mechanistic relationship between TNF production in the kidney, NKCC2 activity, and blood pressure regulation in response to increases in sodium intake, and the previous clinical trials could not have been designed to address this relationship, further studies will be needed to extrapolate the current findings in mice to salt-dependent increases in blood pressure in humans.

Perspectives

This study is the first to demonstrate that endogenous TNF produced within the kidney is part of a heretofore unrecognized intratubular cytokine-based mechanism that regulates blood pressure responses to salt intake via specific inhibition of NKCC2A, the NKCC2 isoform with transport and binding characteristics best suited to respond to increases in tubular fluid salt concentration and flow. The data support a paradigm shift from the concept that TNF only exerts detrimental effects in the kidney, and are relevant not only to novel mechanisms that regulate blood pressure and electrolyte excretion, but also towards an appreciation of the elevated blood pressure reported in randomized clinical trials designed to test the efficacy of anti-TNF reagents in patients with rheumatoid arthritis.

Supplementary Material

Legacy Supplemental File

Novelty and Significance.

1) What is New?

  • -

    This study identifies the intrinsic effects of TNF generated endogenously within the kidney on renal function and blood pressure.

  • -

    TNF produced by the kidney in the absence of ongoing inflammation or damage is part of an adaptive mechanism that regulates blood pressure and electrolyte excretion in response to increased salt intake.

2) What is Relevant?

  • -

    Upregulation of the NKCC2A isoform is sufficient to set in motion rapid changes in electrolyte handling that contributes to an increase in blood pressure in the context of high salt intake.

  • -

    The NKCC2A isoform is constitutively suppressed by TNF produced locally within the kidney.

3) Summary of conclusions of the study

  • -

    Silencing of renal TNF did not affect baseline blood pressure but revealed a mechanism involving NKCC2A that increases blood pressure in response to high salt intake.

Acknowledgments

Sources of funding:

This work was supported by grants from NIH R01 HL133077, NYMC/Touro Bridge grant, and the George M. O'Brien Kidney Center at Yale, NIH P30 DK079310.

Footnotes

Conflicts of interest:

None

References

  • 1.Ernandez T, Mayadas TN. Immunoregulatory role of tnfalpha in inflammatory kidney diseases. Kidney Int. 2009;76:262–276. doi: 10.1038/ki.2009.142. [DOI] [PubMed] [Google Scholar]
  • 2.Escalante BA, Ferreri NR, Dunn CE, McGiff JC. Cytokines affect ion transport in primary cultured thick ascending limb of henle's loop cells. Am. J. Physiol. 1994;266:C1568–C1576. doi: 10.1152/ajpcell.1994.266.6.C1568. [DOI] [PubMed] [Google Scholar]
  • 3.Rezaiguia S, Garat C, Delclaux C, Meignan M, Fleury J, Legrand P, Matthay MA, Jayr C. Acute bacterial pneumonia in rats increases alveolar epithelial fluid clearance by a tumor necrosis factor-alpha-dependent mechanism. J Clin Invest. 1997;99:325–335. doi: 10.1172/JCI119161. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Amasheh S, Barmeyer C, Koch CS, Tavalali S, Mankertz J, Epple H-J, Gehring MM, Florian P, Kroesen A-J, Zeitz M. Cytokine-dependent transcriptional down-regulation of epithelial sodium channel in ulcerative colitis. Gastroenterology. 2004;126:1711–1720. doi: 10.1053/j.gastro.2004.03.010. [DOI] [PubMed] [Google Scholar]
  • 5.Papathanasiou S, Rickelt S, Soriano ME, Schips TG, Maier HJ, Davos CH, Varela A, Kaklamanis L, Mann DL, Capetanaki Y. Tumor necrosis factor-alpha confers cardioprotection through ectopic expression of keratins k8 and k18. Nat Med. 2015;21:1076–1084. doi: 10.1038/nm.3925. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Khanna D, McMahon M, Furst DE. Anti-tumor necrosis factor alpha therapy and heart failure: What have we learned and where do we go from here? Arthritis Rheum. 2004;50:1040–1050. doi: 10.1002/art.20164. [DOI] [PubMed] [Google Scholar]
  • 7.Jacob N, Stohl W. Cytokine disturbances in systemic lupus erythematosus. Arthritis research & therapy. 2011;13:228. doi: 10.1186/ar3349. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Caverzasio J, Rizzoli R, Dayer J-M, Bonjour J-P. Interleukin-1 decreases renal sodium reabsorption: Possible mechanism of endotoxin-induced natriuresis. Am. J. Physiol. 1987;252:F943–F946. doi: 10.1152/ajprenal.1987.252.5.F943. [DOI] [PubMed] [Google Scholar]
  • 9.Kohan DE, Schreiner GF. Interleukin 1 modulation of renal epithelial glucose and amino acid transport. Am. J. Physiol. 1988;254:F879–F886. doi: 10.1152/ajprenal.1988.254.6.F879. [DOI] [PubMed] [Google Scholar]
  • 10.Kohan DE, Merli CA, Simon EE. Micropuncture localization of the natriuretic effect of interleukin-1. Am. J. Physiol. 1989;256:F810–F813. doi: 10.1152/ajprenal.1989.256.5.F810. [DOI] [PubMed] [Google Scholar]
  • 11.Kohan DE. Interleukin-1 regulation of prostaglandin e2 synthesis by the papillary collecting duct. J. Lab. Clin. Med. 1989;114:717–723. [PubMed] [Google Scholar]
  • 12.Beasley D, Dinnarello CA, Cannon JG. Interleukin-1 induces natriuresis in conscious rats: Role of renal prostaglandins. Kidney Inter. 1988;33:1059–1065. doi: 10.1038/ki.1988.111. [DOI] [PubMed] [Google Scholar]
  • 13.Jevnikar AM, Brennan DC, Singer GG, Heng JE, Malinski W, Wuthrich RP, Glimcher LH, Kelley VER. Stimulated kidney tubular epithelial cells express membrane associated and secreted tnfa. Kidney Inter. 1991;40:203–211. doi: 10.1038/ki.1991.201. [DOI] [PubMed] [Google Scholar]
  • 14.Macica C, Escalante BA, Conners MS, Ferreri NR. Tnf production by the medullary thick ascending limb of henle's loop. Kidney Inter. 1994;46:113–121. doi: 10.1038/ki.1994.250. [DOI] [PubMed] [Google Scholar]
  • 15.Markewitz BA, Michael JR, Kohan DE. Cytokine-induced expression of a nitric oxide synthase in rat renal tubule cells. J. Clin. Invest. 1993;91:2138–2143. doi: 10.1172/JCI116439. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Lai KN, Leung JC, Chan LY, Saleem MA, Mathieson PW, Lai FM, Tang SC. Activation of podocytes by mesangial-derived tnf-alpha: Glomerulo-podocytic communication in iga nephropathy. Am J Physiol Renal Physiol. 2008;294:F945–955. doi: 10.1152/ajprenal.00423.2007. [DOI] [PubMed] [Google Scholar]
  • 17.Rosa AC, Rattazzi L, Miglio G, Collino M, Fantozzi R. Angiotensin ii induces tumor necrosis factor-alpha expression and release from cultured human podocytes. Inflammation research : official journal of the European Histamine Research Society … [et al.] 2012;61:311–317. doi: 10.1007/s00011-011-0412-8. [DOI] [PubMed] [Google Scholar]
  • 18.Garcia NH, Plato CF, Stoos BA, Garvin JL. Nitric oxide-induced inhibition of transport by thick ascending limbs from dahl salt-sensitive rats. Hypertension. 1999;34:508–513. doi: 10.1161/01.hyp.34.3.508. [DOI] [PubMed] [Google Scholar]
  • 19.Hoagland KM, Flasch AK, Dahly-Vernon AJ, dos Santos EA, Knepper MA, Roman RJ. Elevated bsc-1 and romk expression in dahl salt-sensitive rat kidneys. Hypertension. 2004;43:860–865. doi: 10.1161/01.HYP.0000120123.44945.47. [DOI] [PubMed] [Google Scholar]
  • 20.Battula S, Hao S, Pedraza PL, Stier CT, Ferreri NR. Tumor necrosis factor-alpha is an endogenous inhibitor of the na+-k+-2cl− cotransporter (nkcc2) isoform a in the thick ascending limb. Am J Physiol Renal Physiol. 2011;301:F94–F100. doi: 10.1152/ajprenal.00650.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Ferreri NR, Escalante BA, Zhao Y, An S, McGiff JC. Angiotensin ii induces tnf production by the thick ascending limb: Functional implications. Am. J. Physiol. 1998;274:F148–F155. doi: 10.1152/ajprenal.1998.274.1.F148. [DOI] [PubMed] [Google Scholar]
  • 22.Shahid M, Francis J, Majid DS. Tumor necrosis factor-alpha induces renal vasoconstriction as well as natriuresis in mice. Am J Physiol Renal Physiol. 2008;295:F1836–1844. doi: 10.1152/ajprenal.90297.2008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Hao S, Zhao H, Darzynkiewicz Z, Battula S, Ferreri NR. Expression and function of nfat5 in medullary thick ascending limb (mtal) cells. Am J Physiol Renal Physiol. 2009;296:F1494–1503. doi: 10.1152/ajprenal.90436.2008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 24.Hao S, Bellner L, Ferreri NR. Nkcc2a and nfat5 regulate renal tnf production induced by hypertonic nacl intake. AJP: Renal Physiology. 2013;304:F533–F542. doi: 10.1152/ajprenal.00243.2012. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 25.Crowley SD, Song YS, Lin EE, Griffiths R, Kim HS, Ruiz P. Lymphocyte responses exacerbate angiotensin ii-dependent hypertension. Am J Physiol Regul Integr Comp Physiol. 2010;298:R1089–1097. doi: 10.1152/ajpregu.00373.2009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Alexander BT, Cockrell KL, Massey MB, Bennett WA, Granger JP. Tumor necrosis factor-alpha-induced hypertension in pregnant rats results in decreased renal neuronal nitric oxide synthase expression. Am J Hypertens. 2002;15:170–175. doi: 10.1016/s0895-7061(01)02255-5. [DOI] [PubMed] [Google Scholar]
  • 27.LaMarca BB, Cockrell K, Sullivan E, Bennett W, Granger JP. Role of endothelin in mediating tumor necrosis factor-induced hypertension in pregnant rats. Hypertension. 2005;46:82–86. doi: 10.1161/01.HYP.0000169152.59854.36. [DOI] [PubMed] [Google Scholar]
  • 28.Evans DA, Jacobs DO, Revhaug A, Wilmore DW. The effects of tumor necrosis factor and their selective inhibition by ibuprofen. Ann Surg. 1989;209:312–321. doi: 10.1097/00000658-198903000-00011. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Van Zee KJ, Stackpole SA, Montegut WJ, Rogy MA, Calvano SE, Hsu KC, Chao M, Meschter CL, Loetscher H, Stuber D, et al. A human tumor necrosis factor (tnf) alpha mutant that binds exclusively to the p55 tnf receptor produces toxicity in the baboon. J Exp Med. 1994;179:1185–1191. doi: 10.1084/jem.179.4.1185. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Guzik TJ, Hoch NE, Brown KA, McCann LA, Rahman A, Dikalov S, Goronzy J, Weyand C, Harrison DG. Role of the t cell in the genesis of angiotensin ii induced hypertension and vascular dysfunction. J Exp Med. 2007;204:2449–2460. doi: 10.1084/jem.20070657. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Sriramula S, Haque M, Majid DS, Francis J. Involvement of tumor necrosis factor-alpha in angiotensin ii-mediated effects on salt appetite, hypertension, and cardiac hypertrophy. Hypertension. 2008;51:1345–1351. doi: 10.1161/HYPERTENSIONAHA.107.102152. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Muller DN, Shagdarsuren E, Park JK, Dechend R, Mervaala E, Hampich F, Fiebeler A, Ju X, Finckenberg P, Theuer J, Viedt C, Kreuzer J, Heidecke H, Haller H, Zenke M, Luft FC. Immunosuppressive treatment protects against angiotensin ii-induced renal damage. Am J Pathol. 2002;161:1679–1693. doi: 10.1016/S0002-9440(10)64445-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Elmarakby AA, Quigley JE, Pollock DM, Imig JD. Tumor necrosis factor alpha blockade increases renal cyp2c23 expression and slows the progression of renal damage in salt-sensitive hypertension. Hypertension. 2006;47:557–562. doi: 10.1161/01.HYP.0000198545.01860.90. [DOI] [PubMed] [Google Scholar]
  • 34.Mehaffey E, Majid DSA. Tumor necrosis factor-alpha, kidney function, and hypertension. Am J Physiol Renal Physiol. 2017;313:F1005–F1008. doi: 10.1152/ajprenal.00535.2016. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 35.Zhao Q, Hong D, Zhang Y, Sang Y, Yang Z, Zhang X. Association between anti-tnf therapy for rheumatoid arthritis and hypertension: A meta-analysis of randomized controlled trials. Medicine (Baltimore) 2015;94:e731. doi: 10.1097/MD.0000000000000731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.Grivennikov SI, Tumanov AV, Liepinsh DJ, Kruglov AA, Marakusha BI, Shakhov AN, Murakami T, Drutskaya LN, Forster I, Clausen BE, Tessarollo L, Ryffel B, Kuprash DV, Nedospasov SA. Distinct and nonredundant in vivo functions of tnf produced by t cells and macrophages/neutrophils: Protective and deleterious effects. Immunity. 2005;22:93–104. doi: 10.1016/j.immuni.2004.11.016. [DOI] [PubMed] [Google Scholar]
  • 37.Awad AS, You H, Gao T, Cooper TK, Nedospasov SA, Vacher J, Wilkinson PF, Farrell FX, Brian Reeves W. Macrophage-derived tumor necrosis factor-alpha mediates diabetic renal injury. Kidney Int. 2015;88:722–733. doi: 10.1038/ki.2015.162. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Hao S, Zhao H, Darzynkiewicz Z, Battula S, Ferreri NR. Differential regulation of nfat5 by nkcc2 isoforms in medullary thick ascending limb (mtal) cells. Am J Physiol Renal Physiol. 2011;300:F966–F975. doi: 10.1152/ajprenal.00408.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Hao S, Bellner L, Zhao H, Ratliff B, Darzynkiewicz Z, Vio CP, Ferreri NR. Nfat5 is protective against ischemic acute kidney injury. Hypertension. 2014;63:e46–e52. doi: 10.1161/HYPERTENSIONAHA.113.02476. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Wang D, Pedraza PL, Abdullah HI, McGiff JC, Ferreri NR. Calcium-sensing receptor-mediated tnf production in medullary thick ascending limb cells. Am. J. Physiol. 2002;283:F963–F970. doi: 10.1152/ajprenal.00108.2002. [DOI] [PubMed] [Google Scholar]
  • 41.Kreydiyyeh SI, Markossian S. Tumor necrosis factor alpha down-regulates the na+-k+ atpase and the na+-k+2cl− cotransporter in the kidney cortex and medulla. Cytokine. 2006;33:138–144. doi: 10.1016/j.cyto.2005.12.007. [DOI] [PubMed] [Google Scholar]
  • 42.Abdullah HI, Pedraza PL, McGiff JC, Ferreri NR. Calcium-sensing receptor signaling pathways in medullary thick ascending limb cells mediate cox-2-derived pge2 production: Functional significance. Am J Physiol Renal Physiol. 2008;295:F1082–1089. doi: 10.1152/ajprenal.90316.2008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Igarashi P, Vanden Heuvel GB, Payne JA, Forbush B., 3rd Cloning, embryonic expression, and alternative splicing of a murine kidney-specific na-k-cl cotransporter. Am J Physiol. 1995;269:F405–418. doi: 10.1152/ajprenal.1995.269.3.F405. [DOI] [PubMed] [Google Scholar]
  • 44.Gamba G, Miyanoshita A, Lombardi M, Lytton J, Lee WS, Hediger MA, Hebert SC. Molecular cloning, primary structure, and characterization of two members of the mammalian electroneutral sodium-(potassium)-chloride cotransporter family expressed in kidney. J Biol Chem. 1994;269:17713–17722. [PubMed] [Google Scholar]
  • 45.Acuna R, Martinez-de-la-Maza L, Ponce-Coria J, Vazquez N, Ortal-Vite P, Pacheco-Alvarez D, Bobadilla NA, Gamba G. Rare mutations in slc12a1 and slc12a3 protect against hypertension by reducing the activity of renal salt cotransporters. J Hypertens. 2010;29:475–483. doi: 10.1097/HJH.0b013e328341d0fd. [DOI] [PubMed] [Google Scholar]
  • 46.Monette MY, Rinehart J, Lifton RP, Forbush B. Rare mutations in the human na-k-cl cotransporter (nkcc2) associated with lower blood pressure exhibit impaired processing and transport function. Am J Physiol Renal Physiol. 2011;300:F840–847. doi: 10.1152/ajprenal.00552.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47.Gimenez I, Forbush B. The residues determining differences in ion affinities among the alternative splice variants f, a, and b of the mammalian renal na-k-cl cotransporter (nkcc2) J Biol Chem. 2007;282:6540–6547. doi: 10.1074/jbc.M610780200. [DOI] [PubMed] [Google Scholar]
  • 48.Mount DB, Baekgaard A, Hall AE, Plata C, Xu J, Beier DR, Gamba G, Hebert SC. Isoforms of the na-k-2cl cotransporter in murine tal i. Molecular characterization and intrarenal localization. Am J Physiol. 1999;276:F347–358. doi: 10.1152/ajprenal.1999.276.3.F347. [DOI] [PubMed] [Google Scholar]
  • 49.Gamba G. Molecular physiology and pathophysiology of electroneutral cation-chloride cotransporters. Physiol Rev. 2005;85:423–493. doi: 10.1152/physrev.00011.2004. [DOI] [PubMed] [Google Scholar]
  • 50.Oppermann M, Mizel D, Kim SM, Chen L, Faulhaber-Walter R, Huang Y, Li C, Deng C, Briggs J, Schnermann J, Castrop H. Renal function in mice with targeted disruption of the a isoform of the na-k-2cl co-transporter. J Am Soc Nephrol. 2007;18:440–448. doi: 10.1681/ASN.2006091070. [DOI] [PubMed] [Google Scholar]
  • 51.Schiessl IM, Rosenauer A, Kattler V, Minuth WW, Oppermann M, Castrop H. Dietary salt intake modulates differential splicing of the na/k/2cl cotransporter nkcc2. Am J Physiol Renal Physiol. 2013;305:F1139–F1148. doi: 10.1152/ajprenal.00259.2013. [DOI] [PubMed] [Google Scholar]
  • 52.Meneton P, Jeunemaitre X, de Wardener HE, MacGregor GA. Links between dietary salt intake, renal salt handling, blood pressure, and cardiovascular diseases. Physiol Rev. 2005;85:679–715. doi: 10.1152/physrev.00056.2003. [DOI] [PubMed] [Google Scholar]
  • 53.Roman RJ, Kaldunski ML. Enhanced chloride reabsorption in the loop of henle in dahl salt-sensitive rats. Hypertension. 1991;17:1018–1024. doi: 10.1161/01.hyp.17.6.1018. [DOI] [PubMed] [Google Scholar]
  • 54.Weinberger MH, Fineberg NS, Fineberg SE, Weinberger M. Salt sensitivity, pulse pressure, and death in normal and hypertensive humans. Hypertension. 2001;37:429–432. doi: 10.1161/01.hyp.37.2.429. [DOI] [PubMed] [Google Scholar]
  • 55.Jung J, Basile DP, Pratt JH. Sodium reabsorption in the thick ascending limb in relation to blood pressure: A clinical perspective. Hypertension. 2011;57:873–879. doi: 10.1161/HYPERTENSIONAHA.108.120246. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 56.Felder RA, Jose PA. Mechanisms of disease: The role of grk4 in the etiology of essential hypertension and salt sensitivity. Nature clinical practice. Nephrology. 2006;2:637–650. doi: 10.1038/ncpneph0301. [DOI] [PubMed] [Google Scholar]
  • 57.Chun TY, Bankir L, Eckert GJ, Bichet DG, Saha C, Zaidi SA, Wagner MA, Pratt JH. Ethnic differences in renal responses to furosemide. Hypertension. 2008;52:241–248. doi: 10.1161/HYPERTENSIONAHA.108.109801. [DOI] [PubMed] [Google Scholar]
  • 58.Sonalker PA, Tofovic SP, Jackson EK. Increased expression of the sodium transporter bsc-1 in spontaneously hypertensive rats. J Pharmacol Exp Ther. 2004;311:1052–1061. doi: 10.1124/jpet.104.071209. [DOI] [PubMed] [Google Scholar]
  • 59.Haque MZ, Ares GR, Caceres PS, Ortiz PA. High salt differentially regulates surface nkcc2 expression in thick ascending limbs of dahl salt-sensitive and salt-resistant rats. Am J Physiol Renal Physiol. 2011;300:F1096–1104. doi: 10.1152/ajprenal.00600.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 60.Garvin JL, Herrera M, Ortiz PA. Regulation of renal nacl transport by nitric oxide, endothelin, and atp: Clinical implications. Annu Rev Physiol. 2011;73:359–376. doi: 10.1146/annurev-physiol-012110-142247. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Legacy Supplemental File
NIHMS954434-supplement-Legacy_Supplemental_File.pdf (182KB, pdf)

RESOURCES