Skip to main content
PMC home page
Infection and Immunity logoLink to Infection and Immunity
. 1996 Oct;64(10):4188–4196. doi: 10.1128/iai.64.10.4188-4196.1996

Mechanisms of interferon-induced inhibition of Toxoplasma gondii replication in human retinal pigment epithelial cells.

C N Nagineni 1, K Pardhasaradhi 1, M C Martins 1, B Detrick 1, J J Hooks 1
PMCID: PMC174355  PMID: 8926087

Abstract

Inflammation associated with retinochoroiditis is a major complication of ocular toxoplasmosis in infants and immunocompetent individuals. Moreover, Toxoplasma gondii-induced retinal disease causes serious complications in patients with AIDS and transplant patients. The retinal pigment epithelial (RPE) cell is an important regulatory cell within the retina and is one of the cells infected with T. gondii in in vivo. We have developed a human RPE (HRPE) cell in vitro model system to evaluate T. gondii replication and the regulation of this replication by cytokines. T. gondii replication was quantitated by counting the foci of infection (plaque formation) and the numbers of tachyzoites released into the supernatant fluids. Pretreatment of cultures with recombinant human tumor necrosis factor alpha, alpha interferon (IFN-alpha), IFN-beta, or IFN-gamma for 24 h prior to inoculation inhibited T. gondii replication in a dose-dependent manner. Of these cytokines, IFN-gamma was the most potent, and T. gondii replication was completely inhibited at a concentration of 100 U/ml. The anti-toxoplasmotic activity of IFN-gamma was significantly blocked by monoclonal antibody to IFN-gamma. Treatment of the cultures with IFN-gamma from day 1 or 2 postinoculation with T. gondii also offered protection against the parasite. The anti-toxoplasmotic activity of tumor necrosis factor alpha or IFN-alpha, -beta, or -gamma in these cultures was found to be independent of the nitric oxide (NO) pathway, since NO production was not found in HRPE cells treated with these cytokines. However, addition of tryptophan to IFN-gamma-treated cells significantly reversed the inhibitory effects of IFN-gamma, suggesting that IFN-gamma acts by depleting cellular tryptophan. This effect was further confirmed by reverse transcription-PCR and Northern (RNA) blot analysis, which indicated induction of indoleamine 2,3-dioxygenase (IDO), an enzyme that converts tryptophan to kynurenine. These results indicated that interferons inhibited T. gondii replication in HRPE by NO-independent but IDO-dependent mechanisms. This in vitro model of T. gondii replication in HRPE may be useful in evaluating the effects of cytokines and drugs on T. gondii replication within the retina.

Full Text

The Full Text of this article is available as a PDF (966.3 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Adams L. B., Hibbs J. B., Jr, Taintor R. R., Krahenbuhl J. L. Microbiostatic effect of murine-activated macrophages for Toxoplasma gondii. Role for synthesis of inorganic nitrogen oxides from L-arginine. J Immunol. 1990 Apr 1;144(7):2725–2729. [PubMed] [Google Scholar]
  2. Arai K. I., Lee F., Miyajima A., Miyatake S., Arai N., Yokota T. Cytokines: coordinators of immune and inflammatory responses. Annu Rev Biochem. 1990;59:783–836. doi: 10.1146/annurev.bi.59.070190.004031. [DOI] [PubMed] [Google Scholar]
  3. Beaman M. H., Wong S. Y., Remington J. S. Cytokines, Toxoplasma and intracellular parasitism. Immunol Rev. 1992 Jun;127:97–117. doi: 10.1111/j.1600-065x.1992.tb01410.x. [DOI] [PubMed] [Google Scholar]
  4. Caplen H. S., Gupta S. L. Differential regulation of a cellular gene by human interferon-gamma and interferon-alpha. J Biol Chem. 1988 Jan 5;263(1):332–339. [PubMed] [Google Scholar]
  5. Chang H. R., Grau G. E., Pechère J. C. Role of TNF and IL-1 in infections with Toxoplasma gondii. Immunology. 1990 Jan;69(1):33–37. [PMC free article] [PubMed] [Google Scholar]
  6. Chao C. C., Anderson W. R., Hu S., Gekker G., Martella A., Peterson P. K. Activated microglia inhibit multiplication of Toxoplasma gondii via a nitric oxide mechanism. Clin Immunol Immunopathol. 1993 May;67(2):178–183. doi: 10.1006/clin.1993.1062. [DOI] [PubMed] [Google Scholar]
  7. Chao C. C., Gekker G., Hu S., Peterson P. K. Human microglial cell defense against Toxoplasma gondii. The role of cytokines. J Immunol. 1994 Feb 1;152(3):1246–1252. [PubMed] [Google Scholar]
  8. Dai W., Gupta S. L. Molecular cloning, sequencing and expression of human interferon-gamma-inducible indoleamine 2,3-dioxygenase cDNA. Biochem Biophys Res Commun. 1990 Apr 16;168(1):1–8. doi: 10.1016/0006-291x(90)91666-g. [DOI] [PubMed] [Google Scholar]
  9. Dai W., Pan H., Kwok O., Dubey J. P. Human indoleamine 2,3-dioxygenase inhibits Toxoplasma gondii growth in fibroblast cells. J Interferon Res. 1994 Dec;14(6):313–317. doi: 10.1089/jir.1994.14.313. [DOI] [PubMed] [Google Scholar]
  10. Detrick B., Newsome D. A., Percopo C. M., Hooks J. J. Class II antigen expression and gamma interferon modulation of monocytes and retinal pigment epithelial cells from patients with retinitis pigmentosa. Clin Immunol Immunopathol. 1985 Aug;36(2):201–211. doi: 10.1016/0090-1229(85)90121-7. [DOI] [PubMed] [Google Scholar]
  11. Elner V. M., Schaffner T., Taylor K., Glagov S. Immunophagocytic properties of retinal pigment epithelium cells. Science. 1981 Jan 2;211(4477):74–76. doi: 10.1126/science.7444450. [DOI] [PubMed] [Google Scholar]
  12. Elner V. M., Strieter R. M., Elner S. G., Baggiolini M., Lindley I., Kunkel S. L. Neutrophil chemotactic factor (IL-8) gene expression by cytokine-treated retinal pigment epithelial cells. Am J Pathol. 1990 Apr;136(4):745–750. [PMC free article] [PubMed] [Google Scholar]
  13. Farrar M. A., Schreiber R. D. The molecular cell biology of interferon-gamma and its receptor. Annu Rev Immunol. 1993;11:571–611. doi: 10.1146/annurev.iy.11.040193.003035. [DOI] [PubMed] [Google Scholar]
  14. Frenkel J. K. Pathophysiology of toxoplasmosis. Parasitol Today. 1988 Oct;4(10):273–278. doi: 10.1016/0169-4758(88)90018-x. [DOI] [PubMed] [Google Scholar]
  15. Gazzinelli R. T., Brézin A., Li Q., Nussenblatt R. B., Chan C. C. Toxoplasma gondii: acquired ocular toxoplasmosis in the murine model, protective role of TNF-alpha and IFN-gamma. Exp Parasitol. 1994 Mar;78(2):217–229. doi: 10.1006/expr.1994.1022. [DOI] [PubMed] [Google Scholar]
  16. Glasner P. D., Silveira C., Kruszon-Moran D., Martins M. C., Burnier Júnior M., Silveira S., Camargo M. E., Nussenblatt R. B., Kaslow R. A., Belfort Júnior R. An unusually high prevalence of ocular toxoplasmosis in southern Brazil. Am J Ophthalmol. 1992 Aug 15;114(2):136–144. doi: 10.1016/s0002-9394(14)73976-5. [DOI] [PubMed] [Google Scholar]
  17. Gupta S. L., Carlin J. M., Pyati P., Dai W., Pfefferkorn E. R., Murphy M. J., Jr Antiparasitic and antiproliferative effects of indoleamine 2,3-dioxygenase enzyme expression in human fibroblasts. Infect Immun. 1994 Jun;62(6):2277–2284. doi: 10.1128/iai.62.6.2277-2284.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Henderly D. E., Genstler A. J., Smith R. E., Rao N. A. Changing patterns of uveitis. Am J Ophthalmol. 1987 Feb 15;103(2):131–136. doi: 10.1016/s0002-9394(14)74217-5. [DOI] [PubMed] [Google Scholar]
  19. Holland G. N., Engstrom R. E., Jr, Glasgow B. J., Berger B. B., Daniels S. A., Sidikaro Y., Harmon J. A., Fischer D. H., Boyer D. S., Rao N. A. Ocular toxoplasmosis in patients with the acquired immunodeficiency syndrome. Am J Ophthalmol. 1988 Dec 15;106(6):653–667. doi: 10.1016/0002-9394(88)90697-6. [DOI] [PubMed] [Google Scholar]
  20. Hughes H. P., Hudson L., Fleck D. G. In vitro culture of Toxoplasma gondii in primary and established cell lines. Int J Parasitol. 1986 Aug;16(4):317–322. doi: 10.1016/0020-7519(86)90109-8. [DOI] [PubMed] [Google Scholar]
  21. Johnson L. L. A protective role for endogenous tumor necrosis factor in Toxoplasma gondii infection. Infect Immun. 1992 May;60(5):1979–1983. doi: 10.1128/iai.60.5.1979-1983.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Kutty R. K., Kutty G., Hooks J. J., Wiggert B., Nagineni C. N. Transforming growth factor-beta inhibits the cytokine-mediated expression of the inducible nitric oxide synthase mRNA in human retinal pigment epithelial cells. Biochem Biophys Res Commun. 1995 Oct 4;215(1):386–393. doi: 10.1006/bbrc.1995.2477. [DOI] [PubMed] [Google Scholar]
  23. Lindsay D. S., Dubey J. P., Blagburn B. L., Toivio-Kinnucan M. Examination of tissue cyst formation by Toxoplasma gondii in cell cultures using bradyzoites, tachyzoites, and sporozoites. J Parasitol. 1991 Feb;77(1):126–132. [PubMed] [Google Scholar]
  24. McCabe R. E., Luft B. J., Remington J. S. Effect of murine interferon gamma on murine toxoplasmosis. J Infect Dis. 1984 Dec;150(6):961–962. doi: 10.1093/infdis/150.6.961. [DOI] [PubMed] [Google Scholar]
  25. McNair A. N., Kerr I. M. Viral inhibition of the interferon system. Pharmacol Ther. 1992;56(1):79–95. doi: 10.1016/0163-7258(92)90038-2. [DOI] [PubMed] [Google Scholar]
  26. Murray H. W., Szuro-Sudol A., Wellner D., Oca M. J., Granger A. M., Libby D. M., Rothermel C. D., Rubin B. Y. Role of tryptophan degradation in respiratory burst-independent antimicrobial activity of gamma interferon-stimulated human macrophages. Infect Immun. 1989 Mar;57(3):845–849. doi: 10.1128/iai.57.3.845-849.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Nagineni C. N., Detrick B., Hooks J. J. Synergistic effects of gamma interferon on inflammatory mediators that induce interleukin-6 gene expression and secretion by human retinal pigment epithelial cells. Clin Diagn Lab Immunol. 1994 Sep;1(5):569–577. doi: 10.1128/cdli.1.5.569-577.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Nathan C. F., Murray H. W., Wiebe M. E., Rubin B. Y. Identification of interferon-gamma as the lymphokine that activates human macrophage oxidative metabolism and antimicrobial activity. J Exp Med. 1983 Sep 1;158(3):670–689. doi: 10.1084/jem.158.3.670. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Nathan C. F., Prendergast T. J., Wiebe M. E., Stanley E. R., Platzer E., Remold H. G., Welte K., Rubin B. Y., Murray H. W. Activation of human macrophages. Comparison of other cytokines with interferon-gamma. J Exp Med. 1984 Aug 1;160(2):600–605. doi: 10.1084/jem.160.2.600. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Nicholson D. H., Wolchok E. B. Ocular toxoplasmosis in an adult receiving long-term corticosteroid therapy. Arch Ophthalmol. 1976 Feb;94(2):248–254. doi: 10.1001/archopht.1976.03910030120009. [DOI] [PubMed] [Google Scholar]
  31. Orellana M. A., Suzuki Y., Araujo F., Remington J. S. Role of beta interferon in resistance to Toxoplasma gondii infection. Infect Immun. 1991 Sep;59(9):3287–3290. doi: 10.1128/iai.59.9.3287-3290.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Oura C. A., Innes E. A., Wastling J. M., Entrican G., Panton W. R. The inhibitory effect of ovine recombinant interferon-gamma on intracellular replication of Toxoplasma gondii. Parasite Immunol. 1993 Sep;15(9):535–538. doi: 10.1111/j.1365-3024.1993.tb00641.x. [DOI] [PubMed] [Google Scholar]
  33. Percopo C. M., Hooks J. J., Shinohara T., Caspi R., Detrick B. Cytokine-mediated activation of a neuronal retinal resident cell provokes antigen presentation. J Immunol. 1990 Dec 15;145(12):4101–4107. [PubMed] [Google Scholar]
  34. Perkins E. S. Ocular toxoplasmosis. Br J Ophthalmol. 1973 Jan;57(1):1–17. doi: 10.1136/bjo.57.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Peterson P. K., Gekker G., Hu S., Chao C. C. Human astrocytes inhibit intracellular multiplication of Toxoplasma gondii by a nitric oxide-mediated mechanism. J Infect Dis. 1995 Feb;171(2):516–518. doi: 10.1093/infdis/171.2.516. [DOI] [PubMed] [Google Scholar]
  36. Pfefferkorn E. R., Eckel M., Rebhun S. Interferon-gamma suppresses the growth of Toxoplasma gondii in human fibroblasts through starvation for tryptophan. Mol Biochem Parasitol. 1986 Sep;20(3):215–224. doi: 10.1016/0166-6851(86)90101-5. [DOI] [PubMed] [Google Scholar]
  37. Pfefferkorn E. R., Guyre P. M. Inhibition of growth of Toxoplasma gondii in cultured fibroblasts by human recombinant gamma interferon. Infect Immun. 1984 May;44(2):211–216. doi: 10.1128/iai.44.2.211-216.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Pfefferkorn E. R. Interferon gamma blocks the growth of Toxoplasma gondii in human fibroblasts by inducing the host cells to degrade tryptophan. Proc Natl Acad Sci U S A. 1984 Feb;81(3):908–912. doi: 10.1073/pnas.81.3.908. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Pfefferkorn E. R., Rebhun S., Eckel M. Characterization of an indoleamine 2,3-dioxygenase induced by gamma-interferon in cultured human fibroblasts. J Interferon Res. 1986 Jun;6(3):267–279. doi: 10.1089/jir.1986.6.267. [DOI] [PubMed] [Google Scholar]
  40. Schmitz J. L., Carlin J. M., Borden E. C., Byrne G. I. Beta interferon inhibits Toxoplasma gondii growth in human monocyte-derived macrophages. Infect Immun. 1989 Oct;57(10):3254–3256. doi: 10.1128/iai.57.10.3254-3256.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Shirahata T., Mori A., Ishikawa H., Goto H. Strain differences of interferon-generating capacity and resistance in toxoplasma-infected mice. Microbiol Immunol. 1986;30(12):1307–1316. doi: 10.1111/j.1348-0421.1986.tb03051.x. [DOI] [PubMed] [Google Scholar]
  42. Sibley L. D. Interactions between Toxoplasma gondii and its mammalian host cells. Semin Cell Biol. 1993 Oct;4(5):335–344. doi: 10.1006/scel.1993.1040. [DOI] [PubMed] [Google Scholar]
  43. Silveira C., Belfort R., Jr, Burnier M., Jr, Nussenblatt R. Acquired toxoplasmic infection as the cause of toxoplasmic retinochoroiditis in families. Am J Ophthalmol. 1988 Sep 15;106(3):362–364. doi: 10.1016/0002-9394(88)90382-0. [DOI] [PubMed] [Google Scholar]
  44. Slavin M. A., Meyers J. D., Remington J. S., Hackman R. C. Toxoplasma gondii infection in marrow transplant recipients: a 20 year experience. Bone Marrow Transplant. 1994 May;13(5):549–557. [PubMed] [Google Scholar]
  45. Suzuki Y., Conley F. K., Remington J. S. Importance of endogenous IFN-gamma for prevention of toxoplasmic encephalitis in mice. J Immunol. 1989 Sep 15;143(6):2045–2050. [PubMed] [Google Scholar]
  46. Suzuki Y., Orellana M. A., Schreiber R. D., Remington J. S. Interferon-gamma: the major mediator of resistance against Toxoplasma gondii. Science. 1988 Apr 22;240(4851):516–518. doi: 10.1126/science.3128869. [DOI] [PubMed] [Google Scholar]
  47. Tabbara K. F. Disruption of the choroidoretinal interface by toxoplasma. Eye (Lond) 1990;4(Pt 2):366–373. doi: 10.1038/eye.1990.49. [DOI] [PubMed] [Google Scholar]
  48. WILDER H. C. Toxoplasma chorioretinitis in adults. AMA Arch Ophthalmol. 1952 Aug;48(2):127–136. doi: 10.1001/archopht.1952.00920010132001. [DOI] [PubMed] [Google Scholar]
  49. Wilson C. B., Westall J. Activation of neonatal and adult human macrophages by alpha, beta, and gamma interferons. Infect Immun. 1985 Aug;49(2):351–356. doi: 10.1128/iai.49.2.351-356.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Infection and Immunity are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES