Elevated Pentraxin-3 concentrations in leprosy patients: potential biomarker of Erythema Nodosum Leprosum

Leprosy, the leading infectious cause of disability worldwide, remains a major public health challenge in the most severely affected countries despite the sharp decline in new cases in recent years. The search for biomarkers is essential to achieving a better understanding of the molecular and cellular mechanisms underlying the disease.

Pentraxin-3 (PTX3) analyses of sera from 87 leprosy patients with or without reactions were conducted via ELISA. In situ identification of PTX3 in skin lesion was confirmed by RT-qPCR, immunohistochemistry and immunofluorescence assays.

We found that PTX3serum levels were higher in multibacillary patients when evaluated before the onset of acute Erythema Nodosum Leprosum (ENL) and persistently elevated during reaction. Thalidomide treatment reduced PTX3 in the serum 7 days after starting treatment. In situ analysis have also demonstrated enhancement of PTX3 in ENL lesions and showed that treatment with thalidomide reduced its expression and the prominent neutrophilic infiltrate, a hallmark of the disease.

In summary, our study provides in vivo evidence that PTX3 is enhanced during ENL but not in RR and provides a new molecular target in ENL pathogenesis.