Regulation of wound healing pathways by NLRP10 in cutaneous Leishmaniasis

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PROJECT SUMMARY Cutaneous leishmaniasis results in skin ulcerations that can take months to years to resolve resulting in significant morbidity. Pharmacologic interventions to aid in healing of these lesions would lessen morbidity, but the mechanisms that regulate the repair of Leishmania lesions are not well understood. In addition, there has been little investigation into the role of innate immune Nucleotide-Binding Domain and Leucine Rich Repeat Receptor (NLR) family members in regulating wound healing. Using a mouse model of cutaneous leishmaniasis, we have found a novel role for the NLR family member NLRP10 in healing of infected wounds, as mice that lack NLRP10 develop larger lesions that fail to heal compared to wild-type mice. While most studies of the NLR family of pattern recognitions receptors have identified roles for these receptors in hematopoietic cells, in this model NLRP10 regulates wound healing from a non-hematopoietic cell population. Importantly, while the lesions in NLPRP10-deficient mice were larger than those of wild-type mice, this was not due to a failure to control the parasite, as there was no difference in parasite burden between the groups. In contrast, healing of sterile wounds was intact in NLRP10-deficient mice, suggesting the requirement for NLRP10 is specific to the presence of pathogenic microorganisms in the wound. In this proposal, we aim to identify the mechanism by which NLRP10 regulates wound repair in cutaneous leishmaniasis. We have found that NLRP10-deficient fibroblasts have blunted proliferation. While evaluating the reason for this failure, we identified that these fibroblasts arrested their proliferation at the G0/G1 phase of the cell cycle. We also found NLRP10-deficient fibroblasts displayed increased markers of senescence, with elevated β-galactosidase staining and increased p16 and p21 expression. NLRP10-deficient fibroblasts also showed morphologic features of senescence and had increased secretion of pro-inflammatory cytokines and chemokines, consistent with these cells having a senescence- associated secretory phenotype (SASP). We propose that NLRP10 acts within fibroblasts in cutaneous leishmaniasis lesions to mitigate senescence and in doing so aids in the wound repair response. Utilizing the p16-3MR mouse model, which will allow us to both identify and selectively kill senescent cells, we will be able to define the contribution of senescence to wound repair in cutaneous leishmaniasis and determine how NLRP10 regulates this process. We will determine the factors in L. major lesions that drive fibroblast senescence in the absence of NLRP10. We will further define the influence of NLRP10 on the SASP and determine the factor required for repair of cutaneous leishmaniasis wounds. Our studies will define the role of NLRP10 in regulating senescence pathways and identify novel therapeutic targets to accelerate cutaneous wound healing in a variety of pathologies.