D. N. Rao

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. FoxP3 have been shown to have important implications in various diseases. The present study describes the mechanism of action of FoxP3 in CD4⁺CD25⁺ T cells derived from leprosy patients. Increased molecular interactions of FoxP3 with histone deacetylases 7/9 in the nucleus of CD4⁺CD25⁺ T cells derived from borderline lepromatous leprosy/lepromatous leprosy (BL/LL) patients were found to be responsible for FoxP3‐driven immune suppression activities during the progression of leprosy. Further, downregulation of CTLA‐4 and CD25 genes in siFoxP3‐treated PBMCs derived from BL/LL patients elucidated the transcription‐activating nature of FoxP3. This observation was supported by direct binding of FoxP3 to the promoter region of the CTLA‐4 and CD25 genes, and FoxP3's molecular interaction with histone acetyl transferases. The study also revealed that the increased expression of miR155 in CD4⁺CD25⁺ cells from BL/LL governs the competitive fitness of these cells. Again, reduced Annexin V & propidium iodide staining and Nur77 expression, and concomitantly increased Ki‐67 positivity suggested that CD4⁺CD25⁺ cells derived from BL/LL patients are more competitively fit than those from borderline tuberculoid leprosy/tuberculoid leprosy and healthy controls. Taken together, the study shows the orchestration of FoxP3 leading to competitive fitness of Treg cells in leprosy.

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