Cytokine and Protein Markers of Leprosy Reactions in Skin and Nerves: Baseline Results for the North Indian INFIR Cohort

Abstract

BackgroundPrevious studies investigating the role of cytokines in the pathogenesis of leprosy have either been on only small numbers of patients or have not combined clinical and histological data. The INFIR Cohort study is a prospective study of 303 new multibacillary leprosy patients to identify risk factors for reaction and nerve damage. This study characterised the cellular infiltrate in skin and nerve biopsies using light microscopic and immunohistochemical techniques to identify any association of cytokine markers, nerve and cell markers with leprosy reactions.Methodology/Principal FindingsTNF-α, TGF-β and iNOS protein in skin and nerve biopsies were detected using monoclonal antibody detection immunohistochemistry techniques in 299 skin biopsies and 68 nerve biopsies taken from patients at recruitment. The tissues were stained with hematoxylin and eosin, modified Fite Faraco, CD68 macrophage cell marker and S100.Conclusions/SignificanceHistological analysis of the biopsies showed that 43% had borderline tuberculoid (BT) leprosy, 27% borderline lepromatous leprosy, 9% lepromatous leprosy, 13% indeterminate leprosy types and 7% had no inflammation. Forty-six percent had histological evidence of a Type 1 Reaction (T1R) and 10% of Erythema Nodosum Leprosum. TNF-α was detected in 78% of skin biopsies (181/232), iNOS in 78% and TGF-β in 94%. All three molecules were detected at higher levels in patients with BT leprosy. TNF-α was localised within macrophages and epithelioid cells in the granuloma, in the epidermis and in dermal nerves in a few cases. TNF-α, iNOS and TGF-β were all significantly associated with T1R (p<0.001). Sixty-eight nerve biopsies were analysed. CD68, TNF-α and iNOS staining were detectable in 88%, 38% and 28% of the biopsies respectively. The three cytokines TNF-α, iNOS and TGF-β detected by immunohistochemistry showed a significant association with the presence of skin reaction. This study is the first to demonstrate an association of iNOS and TGF-β with T1R.

Analysis of clinical data and T helper 1/T helper 2 responses in patients with different clinical forms of leprosy

“…The dermato-histopathological characteristics of skin lesions found in our study are consistent with findings in the literature 45,46,47,48 . Assessment of the patients by dermatologic and histopathological data are fundamental to arrive at a more accurate diagnosis 49,50 .…”

“…The involvement of the peripheral nerves is present in all clinical forms of leprosy, and in tuberculoid forms, the nerve damage is usually earlier, while in lepromatous leprosy it appears later 48,51 . This variable is an important epidemiological indicator responsible for causing irreversible consequences, resulting in deformities and disabilities 52,53 .…”

Development of Type 2, But Not Type 1, Leprosy Reactions is Associated with a Severe Reduction of Circulating and In situ Regulatory T-Cells

“…Recently, a large IHC study of leprosy biopsies reported that in situ TGF-β expression was associated with T1R, although this association showed low specificity as high TGF-β expression was also found in 50% of the LL biopsies and 54% of the T2R biopsies. 42 We verified high and comparable expression of TGF-β in MB and T1R biopsies, while its expression was at least 50% lower in T2R. We also assessed the in situ expression of IL-17 and IL-6 and noted high IL-17 expression in T2R but low expression in T1R and MB lesions while IL-6 expression was uniformly low in the three groups.…”

Lsr2 of Mycobacterium leprae and Its Synthetic Peptides Elicit Restitution of T Cell Responses in Erythema Nodosum Leprosum and Reversal Reactions in Patients with Lepromatous Leprosy

“…These reactions are also of interest because immunological reconstitution has been shown to occur in anergic lepromatous leprosy during these episodes (25,26). ENL, earlier thought to be predominantly due to immune complexes (27,28), was shown in the 1980s (25,26,29,30) to be associated with the transient emergence of T cell functions. RR has also been associated with increases in delayed-type hypersensitivity (31).…”