Regional modulation of toll-like receptor signaling pathway genes in acute epididymitis in mice.

BACKGROUND: Region-specific immune environments in the epididymis influence the immune responses to uropathogenic Escherichia coli (UPEC) infection, a relevant cause of epididymitis in men. Toll-like receptors (TLRs) are essential to orchestrate immune responses against bacterial infections. The epididymis displays region-specific inflammatory responses to bacterial-derived TLR agonists, such as lipopolysaccharide (LPS; TLR4 agonist) and lipoteichoic acid (LTA; TLR2/TLR6 agonist), suggesting that TLR-associated signaling pathways could influence the magnitude of inflammatory responses in epididymitis. OBJECTIVES: To investigate the expression and regulation of key genes associated with TLR4 and TLR2/TLR6 signaling pathways during epididymitis induced by UPEC, LPS, and LTA in mice. MATERIAL AND METHODS: Epididymitis was induced in mice using UPEC, ultrapure LPS, or LTA, injected into the interstitial space of the initial segment or the lumen of the vas deferens close to the cauda epididymidis. Samples were harvested after 1, 5, and 10 days for UPEC-treated animals and 6 and 24 h for LPS-/LTA-treated animals. Ex vivo epididymitis was induced by incubating epididymal regions from naive mice with LPS or LTA. RT-qPCR and Western blot assays were conducted. RESULTS: UPEC infection up-regulated Tlr2, Tlr4, and Tlr6 transcripts and their associated signaling molecules Cd14, Ticam1, and Traf6 in the cauda epididymidis but not in the initial segment. In these epididymal regions, LPS and LTA differentially modulated Tlr2, Tlr4, Tlr6, Cd14, Myd88, Ticam1, Traf3, and Traf6 expression levels. NFKB and AP1 activation was required for LPS- and LTA-induced up-regulation of TLR-associated signaling transcripts in the cauda epididymidis and initial segment, respectively. CONCLUSION: The dynamic modulation of TLR4 and TLR2/TLR6 signaling pathways gene expression during epididymitis indicates bacterial-derived antigens elicit an increased tissue sensitivity to combat microbial infection in a spatial manner in the epididymis. Differential activation of TLR-associated signaling pathways may contribute to fine-tuning inflammatory responses along the epididymis.

The regional distribution of resident immune cells shapes distinct immunological environments along the murine epididymis.

The epididymis functions as transition zone for post-testicular sperm maturation and storage and faces contrasting immunological challenges, i.e. tolerance towards spermatozoa vs. reactivity against pathogens. Thus, normal organ function and integrity relies heavily on a tightly controlled immune balance. Previous studies described inflammation-associated tissue damage solely in the distal regions (corpus, cauda), but not in the proximal regions (initial segment, caput). To understand the observed region-specific immunity along the epididymal duct, we have used an acute bacterial epididymitis mouse model and analyzed the disease progression. Whole transcriptome analysis using RNAseq 10 days post infection showed a pro-inflammatory environment within the cauda, while the caput exhibited only minor transcriptional changes. High-dimensional flow cytometry analyses revealed drastic changes in the immune cell composition upon infection with uropathogenic Escherichia coli. A massive influx of neutrophils and monocytes was observed exclusively in distal regions and was associated with bacterial appearance and tissue alterations. In order to clarify the reasons for the region-specific differences in the intensity of immune responses, we investigated the heterogeneity of resident immune cell populations under physiological conditions by scRNASeq analysis of extravascular CD45+ cells. Twelve distinct immune cell subsets were identified, displaying substantial differences in distribution along the epididymis as further assessed by flow cytometry and immunofluorescence staining. Macrophages constituted the majority of resident immune cells and were further separated in distinct subgroups based on their transcriptional profile, tissue location and monocyte-dependence. Crucially, the proximal and distal regions showed striking differences in their immunological landscapes. These findings indicate that resident immune cells are strategically positioned along the epididymal duct, potentially providing different immunological environments required for addressing the contrasting immunological challenges and thus, preserving tissue integrity and organ function.

The Relationship Between Phospho-p38, Matrix Metalloproteinase 9, and Major Histocompatibility Complex Class I Chain-Related Molecule A Expression in Pituitary Adenomas Demonstrates a New Mechanism of Pituitary Adenoma Immune Escape.

BACKGROUND: The major histocompatibility complex class I chain-related molecule A (MICA) is one of the natural killer group 2D ligands. Soluble major histocompatibility complex class I chain-related molecule A (sMICA) mediates tumor immune escape, but the mechanism is not fully understood. In this study, we examined the expression of phospho-p38, matrix metalloproteinase 9 (MMP-9), and MICA and their relationships among each other in pituitary adenoma tissues to provide a histologic basis for the mechanism of pituitary adenoma immune escape. METHODS: We applied immunohistochemistry, real-time quantitative reverse-transcriptase polymerase chain reaction, and Western blot to detect phospho-p38, MMP-9, and MICA expression at the mRNA and protein levels in pituitary adenoma tissues. Enzyme-linked immunosorbent assay was used to examine the expression levels of MMP-9 and sMICA in peripheral blood serum from patients with pituitary adenoma. RESULTS: We found that p38, MICA, and MMP-9 mRNA levels were greater in pituitary adenomas than in normal tissues. The phospho-p38, MMP-9, and MICA proteins were overexpressed in pituitary adenomas, and the expression of MMP-9 and MICA were positively correlated with the expression of phospho-p38. In addition, the serum levels of sMICA and MMP-9 proteins in pituitary adenoma patients were significantly greater than those in normal controls. CONCLUSIONS: These findings suggest that activation of the p38/mitogen-activated protein kinase pathway may increase MICA expression and induce MMP-9 expression. MMP-9 is involved in the shedding of sMICA from MICA to promote tumor immune escape. Furthermore, p38/mitogen-activated protein kinase could potentially represent a novel target for inhibiting pituitary adenoma immune escape.