TABLE 1.
Fructose exposures in cell line models
| Model-system | Dose | Exposure duration | Methods | Key findings | References |
|---|---|---|---|---|---|
| Reactive species formation | |||||
| Dendritic cells (human) | 15 mM fructose | 24–72 hr | ROS measured using flow cytometry to determine oxidation of dihydrorhodamine 123 to rhodamine 123; AGE formation measured using AGE ELISA kits | Reduced level of ROS production in high fructose treated groups compared to high glucose and control groups | Jaiswal et al., 2019 |
| HEK293 | 30 mM fructose | 4 hr | Total ROS production was quantified by DCFDA | ROS significantly increased in cells exposed to fructose and salt | Dornas et al., 2017 |
| HepG2 | 5 mM fructose | Incubation with 5 mM fructose for 48 hr and incubation with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | Total ROS production was quantified by DCFDA | Elevated ROS, iNOS, and hydrogen peroxide levels in HepG2 cells | Zhang et al., 2015 |
| HLO2 | 5 mM fructose | Incubation with 5 mM fructose for 48 hr and incubation with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | Total ROS production was quantified by DCFDA | Increases in ROS, iNOS, and hydrogen peroxide levels in HLO2 cells | Zhang et al., 2015 |
| Kupffer cells | 5 mM fructose | Incubation with 5 mM fructose for 48 hr and incubation with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | Total ROS production was quantified by DCFDA | No elevation in ROS, hydrogen peroxide, and MDA levels | Zhang et al., 2015 |
| L6 Myotubes | 15 mM fructose | mtROS-1, 3, 6, and 24 hr; superoxide and hydrogen peroxide- 1, 3, and 6 hr | mtROS measured through MitoSOX red fluorescence; superoxide and hydrogen peroxide determined by fluorimetric assay | Increased production of mtROS with 1 hr and NO within 6 hr exposure; NO level reached maximum at 48 hr; non-mitochondrial respiration presented no significant change; iNOS levels peaked at 6 hr of exposure | Jaiswal et al., 2015a |
| L6 Myotubes | 15 mM fructose | 1, 3, and 6 hr | Cytoplasmic ROS measured by DCFDA fluorescence | Time-dependent increase in ROS which peaked at 3 hr; oxidative stress results from increased content of ROS and/or RNS | Jaiswal et al., 2015b |
| Rat hepatic parenchymal cell (RHPC) | 5 mM fructose | Incubation with 5 mM fructose for 48 hr and incubation with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | Total ROS production was quantified by DCFDA | Increased ROS, iNOS, and hydrogen peroxide levels | Zhang et al., 2015 |
| Mitochondrial and metabolic dysfunction | |||||
| Dendritic cells (human) | 15 mM fructose | 24–72 hr | Energetic state measurement- seahorse analyzer | 72 hr exposure induced shift from oxidative phosphorylation toward glycolysis compared to high glucose exposures; decrease in ECAR and OCR at 24 hr; fructose-treated cells exhibited the least OCR compared to all treatment and control groups | Jaiswal et al., 2019 |
| Hepatocytes | 5.5 mM fructose | 72 hr | Apoptosis, lipid content, and lipid peroxidation measured through spectrometry; oxygen consumption monitored using seahorse analyzer; liver steatosis and dysfunction measured through RT-qPCR | Elevated steatosis and liver dysfunction, increased apoptosis, oxidative stress and mitochondrial respiration | Grasselli et al., 2019 |
| HepG2 | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | MMP detection | Altered mitochondrial membrane potential | Zhang et al., 2015 |
| HLO2 | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | MMP detection | Altered mitochondrial membrane potential | Zhang et al., 2015 |
| L6 Myotubes | 15 mM fructose | mtDNA content and mitochondrial membrane potential- 3, 6, 24h, 48, and 72 hr; mitochondrial respiratory function- 3, 6, 24, and 48 hr | mtDNA content- PCR through amplification of a mitochondrial encoded gene; mitochondrial membrane potential- change analyzed with JC-1 absorption; mitochondrial respiratory function- seahorse XF-e24 extracellular flux assay; ATP levels- stay Brite ATP assay; citrate synthase activity monitored by spectrophotometry | Reductions in mtDNA content; loss of mitochondrial membrane potential; impaired mitochondrial energy metabolism; decreased activities of citrate synthase, mitochondrial dehydrogenases, ATP-linked respiration, cellular ATP content, and mitochondrial respiratory complexes | Jaiswal et al., 2015a |
| L6 Myotubes | 15 mM fructose | 1, 3, and 6 hr | 2-DG uptake assay | Reduction in 2-deoxyglucose uptake and an impairment of glucose utilization and insulin signaling through ROS-mediated activation of JNK and ERK1/2 pathways | Jaiswal et al., 2015b |
| RHPC | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | MMP detection | Altered mitochondrial membrane potential | Zhang et al., 2015 |
| Transcriptional changes | |||||
| 3 T3-L1 Preadipocytes | 550 μm | 48 hr | Protein expression measured by immunoblotting | Increase in adipogenesis and overexpression of Pparγ, C/Ebpα and GluT4 | Du and Heaney, 2012 |
| 3 T3-L1 Preadipocytes | 30 mM fructose | Up to 8 days | mRNA expression measured using qPCR; protein expression measured by immunoblotting | FabP4, Pparγ, C/Ebpα and 11β-Hsd1 increased after 4, 6 and 8 days of exposure; C/Ebpβ decreased in same time period; GluT4 increased at days 4 through 6. | Legeza et al., 2014 |
| Dendritic cells (human) | 15 mM fructose | 24–72 hr | CD86 expression measured through mean fluorescence intensity; NF-κB activity determined through Alexa-594 antibody staining; IL-6 and IL-1β determined with corresponding antibody | Increased expression of IL-6, IL-1β, TNF-α, and CD86; exposure caused T-cells to increase secretion of IFN-y; increased production of AGEs led to activation of RAGE and expression of inflammatory cytokines; no significant difference in the expression of pAMPK-α, HIF-1α and p70S6 kinase; GLUT1 expression was 15% higher | Jaiswal et al., 2019 |
| HEK293 | 30 mM fructose | 4 hr | mRNA expression measured using qPCR; protein expression measured by immunoblotting | No significant change in SOD activity; NF-kB subunit p65 was increased when exposed to fructose and salt together | Dornas et al., 2017 |
| Hepatocytes (primary rat) | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | mRNA expression measured using qPCR; protein expression measured by immunoblotting | Increased protein expression levels of Txnip, Nlrp3, Asc, Caspase-1, Il-1β and Il-18; | Zhang et al., 2015 |
| HepG2 | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | mRNA expression measured using qPCR; protein expression measured by immunoblotting | Increased expression of TXNIP and NLRP3 levels; 72 hr exposure led to increased levels of ASC, Caspase-1, STAT3, SOCS3, IL-18, and IL-1β | Zhang et al., 2015 |
| HLO2 | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | mRNA expression measured using qPCR; protein expression measured by immunoblotting | Increased expression of TXNIP and NLRP3 levels; 72 hr exposure led to increased levels of ASC, Caspase-1, STAT3, SOCS3, IL-18, and IL-1β | Zhang et al., 2015 |
| L6 Myotubes | 15 mM fructose | iNOS expression- 3, 6, 24, 48, and 72 hr; Nrf-2 translocation- 24 and 48 hr | Nitrite values determined with differing concentrations of sodium nitrite as a standard; Nrf-2 expression monitored by immunofluorescence; cytochrome C levels determined by immunoblotting | Increased NO production and iNOS expression; iNOS expression highest at 6 hr; elevated localization of Nrf-2 to the nucleus at 24 and 48 hr; apoptosis evident by increased levels of cleaved caspase 3, 9 and 7; Bcl-2 protein expression was significantly reduced and there was an increase in Bax; 48 and 72 hr exposure elevated cytochrome C levels in the cytoplasm from the mitochondria | Jaiswal et al., 2015a |
| L6 Myotubes | 15 mM fructose | 1, 3, and 6 hr | GluT4 translocation measured by the cell surface level of GluT4myc through an antibody-based colorimetric assay; mRNA expression measured using qPCR; protein expression measured by immunoblotting | GluT1 and GluT4 protein and mRNA levels not altered at 3 and 6 hr; no significant change in GluT5 mRNA expression; impaired insulin-stimulated translocation of GluT4myc to the cell surface; lower insulin-stimulated tyrosine phosphorylation of Irs-1; no differences in Irs-1 protein expression; inhibition of insulin-stimulated phosphorylation of Akt without altered total amount of Akt; no altered mRNA expression of Irs-1, Pi3k, Akt, GluT4, and GluT1; elevated ROS activated Jnk, Erk, p38, MapK, and Nf-κb inflammation pathways; increased phosphorylation of Jnk and Erk1/2 without any significant change in the total content; increase in the activity of Nf-κb pathway | Jaiswal et al., 2015b |
| Rat hepatic parenchymal cell (RHPC) | 5 mM fructose | 5 mM fructose for 48 hr with 2 μM allopurinol or 20 μM quercetin for additional 24 hr | mRNA expression measured using qPCR; protein expression measured by immunoblotting | Increased expression of Txnip and Nlrp3 levels; 72 hr exposure led to increased levels of Asc, Caspase-1, Stat3, Socs3, Il-18, and Il-1β | Zhang et al., 2015 |