Abstract
Purpose :
Tuberculosis-associated uveitis (TBU) has widespread intraocular inflammation and parallel changes in peripheral immune cells. Here we study T cells and their immune-regulatory and inflammatory phenotypes in TB Uveitis patients and the possible association of CD45 T cells.
Methods :
A prospective study was done recruiting patients visiting uvea clinic with the diagnosis of TBU with age-matched control. Patients were chosen based on anatomical site of involvement of uveitis (Anterior, Intermediate, Posterior and Panuveitis), Positive Mantoux, Positive QuantiFERON TB Gold Test, abnormal findings in High Resolution Computed Tomography of chest. Freshly collected peripheral blood sample were used to isolate PBMCs by density gradient centrifugation. Results from manual gating were analysed with Incyte 3.0 software and relevant statistics.
Results :
67 patients were recruited from a largely South Indian population, with median age of patients as median 37 years. 33 age matched patients without any ocular complaints were designated as controls and used for comparison. IL17 T cells show marginal increase in expression of both TBU patients and those with non-infectious uveitis. TB uveitis patients IL17 T cells show marked increase in activation and expression of IL17 in their T cells (p less than 0.048). Immunophenotyping for IL17 after stimulation in culture, showed these cells produce copious IL17 a critical T cell cytokine associated with uveitis. T regulatory cells were identified as positive for CD4 CD25 FoxP3. In both ocular TB and NIU patients, T regs were marginally increased compared to healthy group without ocular complications. In TBU patients, increase in the mean value of CD45RO positive memory T reg expression was observed in cells gated for CD4, CD25, FoxP3, CD45RO. NIU patients showed increase in both memory CD45RO and naive marker CD45RA T cells (p less than 0.02).
Conclusions :
Increased proportions of IL17 positive T helper cells towards inflammatory activity is the defining phenotype and may be of greater importance compared to T regulatory cell percentage in the uveitis cohorts which show marginal increase in expression of these and T regs. The present study suggest that activated Th17 T cells and their inflammatory phenotype have potential in contributing to chronicity in inflammation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.