Investigating the Macrophage Polarization in Cutaneous Leishmaniasis

Cutaneous Leishmaniasis (CL) is reported as the most neglected tropical disease. The polarization of macrophages such as M1 or M2 phenotypes significantly affects the development of leishmaniasis disease. However, the accurate immune responses behind the macrophage polarization process in cutaneous Leishmaniasis are poorly understood. This study was designed to determine the status of macrophage polarization in cutaneous Leishmaniasis.

This case-control study was conducted at Princess Nourah bint Abdulrahman University, Saudi Arabia, from January to December 2023. Patients aged 18 to 65 yrs diagnosed with cutaneous Leishmaniasis were included. Patients with other immunocompromising conditions (e.g., HIV infection), those receiving immunosuppressive therapy, or those with systemic Leishmaniasis were excluded.

In a sample of 70 cutaneous leishmaniasis patients, macrophage polarization profiles were assessed in 43 (61.42%) patients in the case group and 27 (38.57%) in the control group. The experimental group had a higher prevalence of mild iNOS expression (24/43), while the control group had more iNOS-negative subjects (11/27). Arg-1 expression analysis showed a higher adverse and mild expression incidence in both groups, with 26/43 and 16/43 cases, respectively. Ml macrophage polarization was significantly higher in patients with lesions <4 (65.11%) compared to M2 polarization (11.62%). Lesions lasting <12 months also showed greater M1 polarization (51.61%) compared to M2 (30.23%), with statistical significance (p < 0.001). Additionally, ulcerated lesions were more common in the M1 group (37.20%) than in the M2 group (16.27%) (p < 0.001).

The findings reported that M1 macrophages are more prevalent in CL's early and acute stages, while M2 macrophages may be more active in the long-term or healing phases. There were also notable changes in macrophage polarization among the experimental and control groups.