Peritubular Myoid Cells of the Testis Produce Monocyte Chemotactic Protein 1 Upon Direct Exposure to Mono-(2-Ethylhexyl) Phthalate Through the IL-1 Signaling Pathway

Mono-(2-ethylhexyl) phthalate (MEHP) is a metabolite of the diester parent compound Di(2-ethylhexyl) phthalate (DEHP), a widespread environmental toxicant known for its harmful effects on Sertoli cells and the subsequent loss of germ cells through apoptosis in postnatal animals. Peritubular myoid cells (PTMCs) produce various signaling factors, including the chemokine monocyte chemotactic protein 1 (MCP-1); however, the MEHP exposure-induced BTB disruption followed by MCP-1 secretion by PTMCs, the recruitment, and activation of macrophages as well as molecular mechanisms that initiate the secretion in the testis has yet to be closely examined. In this study, we demonstrate for the first time that PTMCs generate MCP-1 via the interleukin-1 signaling pathway upon MEHP exposure. Primary PTMCs isolated from the testis of peripubertal rats were cultured and exposed to 100 μM and 200µM MEHP. Total RNA was used for bulk RNA sequencing, qRT-PCR, and protein lysates for proteomic analysis. Testis and their interstitial fluid (IF) were obtained from MEHP-exposed animals to evaluate the levels of pro-inflammatory cytokines and chemokines in IF through a multiplex assay and in tissue sections through immunofluorescence studies. The RNA sequencing data show significant enrichment of the interleukin-1 signaling pathway after MEHP (200µM) exposure for 48hours. This finding is further supported by the qRT-PCR results for select genes associated with the IL-1 signaling pathway, highlighting the crucial role of this pathway in the response of PTMCs to MEHP exposure. In summary, MEHP exposure stimulates MCP-1 production by PTMCs, and mechanistically, the IL-1 signal transduction pathway governs this response. Keywords: MCP-1, PTMCs, Rats, Testis, Chemokine, IL-1 signaling.