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

Leprosy affects skin and peripheral nerves. Although we have effective antibiotics to treat the mycobacterial infection, a key part of the disease process is the accompanying inflammation. This can worsen after starting antibacterial treatment with episodes of immune mediated inflammation, so called ‘reactions’. These reactions are associated with worsening of the nerve damage. We recruited a cohort of 303 newly diagnosed leprosy patients in North India with the aim of understanding and defining the pathological processes better. We took skin and nerve biopsies from patients and examined them to define which molecules and mediators of inflammation were present. We found high levels of the cytokines Tumour Necrosis Factor alpha, Transforming Growth Factor beta and inducible Nitric Oxide Synthase in biopsies from patients with reactions. We also found high levels of bacteria and inflammation in the nerves. These experiments tell us that we need to determine which other molecules are present and to explore ways of switching off the production of these pro-inflammatory molecules

Analysis of Antibody and Cytokine Markers for Leprosy Nerve Damage and Reactions in the INFIR Cohort in India

Leprosy is one of the oldest known diseases. In spite of the established fact that it is least infectious and a completely curable disease, the social stigma associated with it still lingers in many countries and remains a major obstacle to self reporting and early treatment. The nerve damage that occurs in leprosy is the most serious aspect of this disease as nerve damage leads to progressive impairment and disability. It is important to identify markers of nerve damage so that preventive measures can be taken. This prospective cohort study was designed to look at the potential association of some serological markers with reactions and nerve function impairment. Three hundred and three newly diagnosed patients from north India were recruited for this study. The study attempts to reflect a model of nerve damage initiated by mycobacterial antigens and maintained by ongoing inflammation through cytokines such as Tumour Necrosis Factor alpha and perhaps extended by antibodies against nerve components

Skin stained for TGF-β.

<p>Skin showing TGF-β positive macrophages. IHC staining ×100.</p

Nerve stained for CD68 cells.

<p>Nerve showing CD68 positive macrophages. IHC staining ×40.</p

Delayed-type hypersensitivity in dermal nerve.

<p>Skin - BT in Type 1 Reaction showing aggressive DTH with epithelioid granuloma destroying a deep dermal nerve, areas of necrosis and focal lymphocytic response. H&E staining ×20.</p

Immuno-staining in nerve biopsies for CD68, TNF-α, TGF-β and iNOS.^*

<p>*Percentages rounded to nearest integer because of small numbers.</p><p>**Borderline tuberculoid leprosy;</p><p>***Borderline lepromatous leprosy;</p>†<p>Lepromatous leprosy;</p>‡<p>Reversal reaction.</p

Ridley-Jopling classification, Bacterial Index and Granuloma Fraction for skin biopsies.

<p>Ridley-Jopling classification, Bacterial Index and Granuloma Fraction for skin biopsies.</p

Nerve stained for TGF-β.

<p>Nerve showing TGF-β positive macrophages. IHC staining ×100.</p

Comparison of Bacterial Index in skin and nerve biopsies.

<p>Comparison of Bacterial Index in skin and nerve biopsies.</p

Skin borderline tuberculoid leprosy in Type 1 Reaction.

<p>Skin - BT in Type 1 Reaction showing aggressive epithelioid granuloma, epidermal erosion, extracellular oedema and lymphocytic influx. H&E staining ×20.</p