Phenotypic characterization of testicular immune cells expressing immune checkpoint molecules in wild‐type and pituitary adenylate cyclase‐activating polypeptide‐deficient mice

Abstract

Problem Pituitary adenylate cyclase‐activating polypeptide (PACAP) is a neuropeptide having several regulatory functions in the nervous system and in peripheral organs including those of the reproductive system. PACAP‐deficient male mice have several morphological, biochemical, behavioral defects and show disturbed signaling in spermatogenesis affecting fertility in PACAP KO mice. Reproductive functions such as fertility, mating, and maternal behaviors have been widely investigated, but no immune analyses are available regarding the testicular immune‐privileged environment in male PACAP‐deficient mice. Method of Study We performed detailed immunophenotyping of testicular immune cells and investigated the expression of TIM‐3 and PD‐1 Immune checkpoint molecules of immune cells together with the detection of galectin‐9 and perforin. We investigated the percentage of numerous immune cell populations in the testis of wild‐type and PACAP‐deficient mice. Results We demonstrated a significant increase in the frequency of testicular CD8+ T cells together with the decrease in Treg cell number obtained from PACAP KO mice compared with wild‐type mice. Investigating Immune checkpoint receptors, only PD‐1 showed a significantly decreased expression in CD8+ T cells in PACAP KO mice compared with wild‐type suggesting an impaired PD‐1/PD‐L1 pathway. Regarding TIM‐3 expression, we did not find any significant difference between the investigated groups. Conclusion We hypothesize that these local changes may result in an immune activation with disturbed testicular immunoregulation in PACAP KO mice; however, determining the exact function requires further investigations. Our data further support the view that besides a systemic immune tolerance, localized active immunosuppression is involved in the regulation of testicular immune privilege.

Single-cell RNA sequencing uncovers dynamic roadmap and cell-cell communication during buffalo spermatogenesis

“…Simultaneously, prepubertal testicular somatic cell communication was predominantly clustered in the IGF, MIF, MK, PTN, GALECTIN, RESISTIN, CALCR, and TNF pathways, whereas pubertal cells were concentrated in PARs, GALECTIN, PSAP, GAS, and PTN pathways. PTPRC ( CD45 ) was increased in abundance in M and NK cells of PERI, demonstrating that the GALECTIN pathway is involved in PTPRC + cell proliferation, differentiation, angiogenesis (formed by EC expressing ligand LGALS9 ), and immune response during buffalo testis development 94 , 95 ( Figures 7 E and S7 E). Briefly, our data showed similarities and dissimilarities of microenvironments in prepubertal and pubertal spermatogenic cells, provided evidence for understanding cellular interactions during spermatogenesis, and highlighted the mechanisms of stem cell maintenance.…”

“… 131 , 132 The GALECTIN pathway was found in buffalo EC and PTPRC + immune cells (M and NK), confirming a crucial role in angiogenesis and the maintenance of an immunologically privileged environment in the testis. 94 Importantly, TNF is a pro-inflammatory cytokine produced by SC and LC, which increases the secretion of transferrin in SC. 133 However, only TNF and its receptor TNFRSF1B were detected in buffalo M and NK cells, whereas TNFRSF1A was present mainly in PTM, LC, M, immature SC, and EC.…”

Alzheimer’s Disease Mouse as a Model of Testis Degeneration

“…There are many structural and functional similarities between the different cells of CNS and testis such as Sertoli-germ cell and neuron-glial cell relation is comparable and shows similar basic signaling activation mechanisms [78]. Furthermore, correct microcirculation and barrier formation show similar alterations both in testis and CNS [12,79,80]. Thus, it can be presumed that examination of signaling pathways in AD testis could be a plausible way for modeling pathologic degeneration conditions of testis where the effects of various interventions such as physical activity can be investigated.…”

“…PACAP has been shown to regulate proper testis formation and spermatogenesis [7], and it has a positive effect on sperm motility [10]. As suggested from the high testicular expression, it plays a role also in testicular hormone production [11] and in testicular immune cell regulation [12]. Based on these functions, it is not surprising that lack of PACAP leads to several morphological and functional changes in PACAP knockout (KO) mice [7].…”

Protective Effects of PACAP in Peripheral Organs

“…In the testis, PACAP plays a role in spermatogenesis and is supposed to be involved in tumor growth ( 100 , 208 , 209 ). Interestingly, in spite of PACAP deficient mice displaying disturbed spermatogenesis and altered testicular immunity ( 100 , 210 ), they also show delayed testicular aging supposedly due to the stimulatory effect of PACAP on testosterone production, which, in turn, accelerates aging due to increased oxidative stress ( 211 ). The involvement of PACAP has been described in numerous reproductive processes from fertilization to implantation ( 212 – 214 ).…”