Analysis of the myeloid-derived suppressor cells and annexin A1 in multibacillary leprosy and reactional episodes

Application of a physiotherapeutic protocol associated with photobiomodulation for the treatment of leprosy patients

Leprosy is a chronic infectious disease characterized by acute inflammatory episodes that affect the skin and peripheral nerves and can develop progressive and irreversible disabilities and deformities. In addition, drug therapy and physiotherapy offer resources and techniques capable of mitigating the consequences of neural lesions, but neural lesions can occur before, during, and even after drug treatment. Thus, new treatments are needed. Photobiomodulation (PBM) might be a promissor therapy since it aims to reduce the inflammatory process and restore motor and sensory functions in the affected area. This study aims to compare the evolution of neural status, pain, and functionality in patients with leprosy and neuritis after a physiotherapeutic protocol and PBM treatment. This was a randomized controlled clinical trial that analyzed a group of patients receiving a physiotherapeutic protocol (PPG) and another receiving physiotherapeutic protocol associated with PBM (PLG) (wavelength 904 nm, potency 70 mW, time per point 9 s). Our results showed when evaluating functional capacity limitations with the SALSA scale, the PLG patients improved from moderate to mild limitations. On the other hand, the PPG remained as moderate limitations. Also, the PLG showed a significant reduction in pain on the VAS scale. The neurological assessment showed that PLG improved palpation of the median, radial, and peroneal nerves. In the strength test, PLG patients improved in the 5th finger abduction and ankle dorsiflexion. Assessing sensitivity, it was identified an improvement in PLG for the ulnar nerve and tibial nerve. All those changes were statistically significant when compared to the PPG patients. Finally, the PLG patients improved disabilities, identified by the neurological assessment of the eyes, hands, and feet. In conclusion, this study demonstrated that combining a physiotherapeutic protocol with PBM treatment effectively improved functional status and reduced pain in leprosy patients.

Fibroblast-derived PI16 sustains inflammatory pain via regulation of CD206+ myeloid cells

Originally identified in fibroblasts, Protease Inhibitor (PI)16 was recently shown to be crucial for the development of neuropathic pain via effects on blood-nerve barrier permeability and leukocyte infiltration, though its impact on inflammatory pain has not been established. Using the complete Freund's Adjuvant inflammatory pain model, we show that Pi16-/- mice are protected against sustained inflammatory pain. Accordingly, intrathecal delivery of a PI16 neutralizing antibody in wild-type mice prevented sustained CFA pain. In contrast to neuropathic pain models, we did not observe any changes in blood-nerve barrier permeability due to PI16 deletion. Instead, Pi16-/- mice display reduced macrophage density in the CFA-injected hindpaw. Furthermore, there was a significant bias toward CD206hi (anti-inflammatory) macrophages in the hindpaw and associated dorsal root ganglia. Following CFA, intrathecal depletion of CD206+ macrophages using mannosylated clodronate liposomes promoted sustained pain in Pi16-/- mice. Similarly, an IL-10 neutralizing antibody also promoted sustained CFA pain in the Pi16-/ when administered intrathecally. Collectively, our results point to fibroblast-derived PI16 mediating substantial differences in macrophage phenotype in the pain neuroaxis under conditions of inflammation. The co-expression of PI16 alongside fibroblast markers in human DRG raise the likelihood that a similar mechanism operates in human inflammatory pain states. Collectively, our findings may have implications for targeting fibroblast-immune cell crosstalk for the treatment of chronic pain.

CD11b+Gr-1low cells that accumulate in M.leprae-induced granulomas of the footpad skin of nude mice have the characteristics of monocytic-myeloid-derived suppressor cells

CD11b⁺Gr-1^low cells that are increased in the lungs of a Mycobacterium (M) tuberculosis-infection mouse model have the characteristics of monocytic (M)-myeloid-derived suppressor cells (MDSCs) and harbor M.tuberculosis. Interestingly, a high number of M-MDSCs have also been observed in skin lesions of patients with lepromatous leprosy. We hypothesized that CD11b⁺Gr-1^low cells might be involved in the pathogenesis of leprosy, as they are in tuberculosis. In the current study, we investigated the issue of whether CD11b⁺Gr-1^low cells accumulate in Mycobacterium (M) leprae-induced granulomas of the footpad skin of nude mice. Our results show that CD11b⁺Gr-1^low cells began to accumulate in the 7-month-old M.leprae-induced granulomas and were replaced by other leukocytes, including CD11b⁺Gr-1^high over time during M.leprae infections. CD11b ⁺ Gr-1^low cells expressed the surface markers of M-MDSC, Ly6C^high and Ly6G^low. In addition, CD11b⁺Gr-1^low cells have the nuclei of a mononuclear cell type and expressed higher levels of arginase 1 (Arg1) and inducible NO synthetase (iNOS). Furthermore, they showed a higher infection rate by M.leprae. Taken together, our results indicate that the inoculation with M.leprae induced an accumulation of CD11b ⁺ Gr-1^low at a relatively early stage, 7-month-old M.leprae-induced granulomas, and that CD11b⁺Gr-1^low have the characteristics of M-MDSC and may act as a reservoir for M.leprae.