Mice lacking the IFN-gamma receptor or fyn develop severe experimental autoimmune uveoretinitis characterized by different immune responses

Endogenous interferon (IFN)-gamma negatively regulates experimental autoimmune uveoretinitis (EAU), a Th1-mediated disease. Although it is well known that IFN-gamma exerts its effects by binding to the IFN-gamma receptor (IFN-gammaR), the role that IFN-gammaR plays in the development of EAU has not been investigated. Fyn has been reported to inhibit Th2 differentiation. We aimed to investigate how endogenous IFN-gammaR and fyn, which influence Th1/Th2 differentiation, participate in the development of EAU. Sex-matched 6- to 10-week-old C57BL/6 wild-type (WT), IFN-gammaR knockout (GRKO) and fyn knockout (fyn KO) mice were compared. Mice were immunized subcutaneously with human interphotoreceptor retinoid-binding protein peptide 1-20 emulsified in Freund's complete adjuvant together with an intraperitoneal injection of Bordetella pertussis toxin. Three weeks later, mice were sacrificed, and their eyes and spleens were harvested for histopathologic analyses and examination of cellular immune responses, respectively. Cellular immune responses were evaluated by measuring the proliferative responses and cytokine production [interleukin (IL)-4, IL-5, IL-6, IL-13, IFN-gamma and tumor necrosis factor (TNF)-alpha] of splenocytes. The incidence of EAU was 40.0% in WT mice, 59.3% in GRKO mice and 78.6% in fyn KO mice. The average EAU score was 0.294 in WT mice, 0.917 in GRKO mice and 1.063 in fyn KO mice. Upon EAU induction, significant infiltration of eosinophils into the eyes was observed in GRKO and fyn KO mice compared to WT mice. Splenocytes from GRKO mice proliferated against the antigen and a mitogen more vigorously than those from WT and fyn KO mice. Stimulation of splenocytes with the antigen induced a higher production of IL-4, IL-6, IL-13 and IFN-gamma in GRKO mice compared to WT and fyn KO mice. In contrast, IL-5 and TNF-alpha were most abundantly produced by splenocytes from fyn KO mice compared to WT and GRKO mice. The incidence and mean severity of EAU were significantly higher in GRKO and fyn KO mice than in WT mice, suggesting that endogenous IFN-gammaR and fyn negatively regulate the development of EAU. The different cytokine production patterns by the GRKO and fyn KO mice indicate that the negative regulatory mechanism mediated by IFN-gammaR and fyn may differ.

Elastin-derived peptides induce a T-helper type 1 polarization of human blood lymphocytes

OBJECTIVE

Increased level of elastin-derived peptides (EDPs) is observed in the serum of patients with manifestations of arterial diseases. We here investigated whether EDPs might exert, at systemic level, a regulatory role for the T-helper type 1 (Th-1)/Th-2 cellular immune response by human peripheral blood lymphocytes (PBLs) expressing the spliced-galactosidase (S-gal)-elastin receptor.

METHODS AND RESULTS

Using flow cytometry and Western blot analysis, we demonstrated that EDPs led to an activation of the S-gal-elastin receptor associated with cytokine production on PBLs and CD4+ T cell subpopulations. The constitutive expression of the S-gal-elastin receptor at the surface of human PBLs was upregulated at the mRNA (RT-PCR) and protein (ELISA) levels on cell activation. In nonactivated and phytohemagglutinin-activated conditions, expressions of the predominant Th-2 cytokine interleukin-5 (IL-5) and IL-10 were reduced, whereas those of the major Th-1 cytokines interferon-gamma and IL-2 were enhanced by EDPs. Furthermore, we evidenced that EDPs could not only potentiate the IL-12-induced Th-1 profile but also could reverse the Th-2 (over Th-1) profile induced by IL-4. Finally, Th-1 cytokine upregulation was associated to an increased activator protein-1 DNA binding and enhanced pro-matrix metalloproteinase-9 secretion.

CONCLUSIONS

This study highlights the importance of EDPs as stimuli for Th-1 differentiation, whether T cells are in an inactivated state or already orientated toward a Th-1 (IL-12) or Th-2 (IL-4) response.

High prevalence of circulating CD4+CD28- T-cells in patients with small abdominal aortic aneurysms

OBJECTIVE

To assess the possible role of proinflammatory CD28- T cells in abdominal aortic aneurysms (AAAs). Animal studies and human tissue studies suggest a role for interferon (IFN)-gamma-producing T cells in the development and progression of AAAs.

METHODS AND RESULTS

Fluorescence-activated cells sorter analysis of peripheral blood samples and measurement of AAA size using sonography were performed in 101 AAA patients and 38 healthy controls. Peripheral percentages of CD28- T cells of the CD3+CD4+ and the CD3+CD8+ were enriched in AAA patients with 7.8+/-8.8% and 41.9+/-15.7% compared with healthy controls with 2.2+/-6.1% and 24.9+/-15.5%, respectively (P=0.002 and P<0.001, respectively). Both CD4+CD28- and CD8+CD28- T cells produced large amounts of IFN-[gamma] and perforin. Patients with small AAAs (<4 cm) showed higher peripheral levels of CD4+CD28- T cells than those with larger AAAs (P=0.025). Immunohistological examinations revealed 39.1+/-17.2% CD4+CD28- and 44.0+/-13.8% CD8+CD28- in AAA tissue specimens with inflammatory infiltratestes.

CONCLUSIONS

IFN-gamma- and perforin-producing CD28- T cells are present in the periphery and the vessel wall of a majority of AAAs. This observation in humans favors the concept of a T cell-mediated pathophysiology of AAAs, especially during the early development of AAAs.

Adaptive cellular immunity in aortic aneurysms: cause, consequence, or context?

Abdominal aortic aneurysms are common and life threatening. Although CD4(+) T cells are abundant in aneurysm tissue, their role in disease progression remains unclear. A new study shows that mouse aortic allografts placed in animals lacking IFN-gamma receptors develop a Th2 inflammatory response with aortic aneurysms, whereas Th1 responses promote intimal hyperplasia. It is expected that these surprising findings will stimulate further efforts to clarify whether adaptive cellular immunity in aneurysm disease is detrimental or potentially beneficial.