Leprosy Reactions: Experience in the Puerto Rico Hansen's Disease Population

OBJECTIVE

Hansen's disease (HD) is a chronic granulomatous infection endemic in the tropics. Its main clinical manifestations involve the cutaneous, nervous, and musculoskeletal systems. Leprosy reactions (LR) are systemic inflammatory and immune-mediated complications of HD. These include reversal reactions (RR), erythema nodosum leprosum (ENL), and Lucio phenomenon. These reactions significantly increase disease-related morbidity and disability. We aimed to determine the number and type of LR, their association to hosts' immune responses (Ridley Jopling classification), timing of development, and treatment of HD patients in Puerto Rico.

METHODS

A retrospective medical record review was performed on 291 HD patients containing LR status data available from the Dermatology Service at the Hispanic Alliance for Clinical & Translational Research.

RESULTS

Our data revealed that 83 (29%) patients developed LR, of which 31% had RR and 69% had ENL. Most LR were observed in patients in the lepromatous border (97%): Borderline lepromatous leprosy (BL) and Lepromatous Leprosy (LL). Most patients with RR and ENL had a single episode (83% and 62%, respectively), and those that received multi-drug therapy (MDT) had a reaction onset occurring most frequently within the first year of MDT and after the first year of MDT, respectively. Prednisone was the first line treatment used to manage both types of LR.

CONCLUSION

Most lepromatous reactions occur within the lepromatous border. ENL was the most common LR. Prompt recognition and management of these immunologic reactions is essential to prevent long term nerve function impairment.

Mycobacterium leprae Induces Neutrophilic Degranulation and Low-Density Neutrophil Generation During Erythema Nodosum Leprosum

Erythema Nodosum Leprosum (ENL) is a recurrent acute inflammatory complication of leprosy affecting up to 50% of all Borderline Lepromatous and Lepromatous Leprosy (BL/LL) patients. Although ENL is described as an immune reaction mediated by neutrophils, studies demonstrating the direct role of neutrophils in ENL are still rare. One subpopulation of low-density neutrophils (LDNs), present within the fraction of peripheral blood mononuclear cells (PBMC), has been associated with the pathogenesis and severity of diseases like sepsis, lupus, and tuberculosis. We herein analyzed LDNs and high-density neutrophils (HDNs) in terms of frequency, phenotype, and morphology. Serum levels of MMP-9 (a neutrophilic degranulation marker) were evaluated by ELISA; and LDNs were generated in vitro by stimulating healthy-donor, whole-blood cultures. PBMC layers of ENL patients presented segmented/hypersegmented cells that were morphologically compatible with neutrophils. Immunofluorescence analyses identified LDNs in ENL. Flow cytometry confirmed the elevated frequency of circulating LDNs (CD14⁻CD15⁺) in ENL patients compared to healthy donors and nonreactional Borderline Tuberculoid (BT) patients. Moreover, flow cytometry analyses revealed that ENL LDNs had a neutrophilic-activated phenotype. ENL patients under thalidomide treatment presented similar frequency of LDNs as observed before treatment but its activation status was lower. In addition, Mycobacterium leprae induced in vitro generation of LDNs in whole blood in a dose-dependent fashion; and TGF-β, an inhibitor of neutrophilic degranulation, prevented LDNs generation. MMP-9 serum levels of BL/LL patients with or without ENL correlated with LDNs frequency at the same time that ultrastructural observations of ENL LDNs showed suggestive signs of degranulation. Together, our data provide new insights into the knowledge and understanding of the pathogenesis of ENL while enriching the role of neutrophils in leprosy.