Roscovitine protects murine Leydig cells from lipopolysaccharide-induced inflammation

Cyclin-dependent kinase inhibitor roscovitine attenuates liver inflammation and fibrosis by influencing initiating steps of liver injury

Liver diseases present a significant public health burden worldwide. Although the mechanisms of liver diseases are complex, it is generally accepted that inflammation is commonly involved in the pathogenesis. Ongoing inflammatory responses exacerbate liver injury, or even result in fibrosis and cirrhosis. Here we report that roscovitine, a cyclin-dependent kinase (CDK) inhibitor, exerts beneficial effects on acute and chronic liver inflammation as well as fibrosis. Animal models of lipopolysaccharide (LPS)/d-galactosamine- and acute or chronic CCl4-induced liver injury showed that roscovitine administration markedly attenuated liver injury, inflammation and histological damage in LPS/d-galactosamine- and CCl4-induced acute liver injury models, which is consistent with the results in vitro. RNA sequencing (RNA-seq) analysis showed that roscovitine treatment repressed the transcription of a broad set of pro-inflammatory genes involved in many aspects of inflammation, including cytokine production and immune cell proliferation and migration, and inhibited the TGF-β signaling pathway and the biological process of tissue remodeling. For further validation, the beneficial effect of roscovitine against inflammation was evaluated in chronic CCl4-challenged mice. The anti-inflammation effect of roscovitine was observed in this model, accompanied with reduced liver fibrosis. The anti-fibrotic mechanism involved inhibition of profibrotic genes and blocking of hepatic stellate cell (HSC) activation. Our data show that roscovitine administration protects against liver diseases through inhibition of macrophage inflammatory actions and HSC activation at the onset of liver injury.

Dmrt1 regulates the immune response by repressing the TLR4 signaling pathway in goat male germline stem cells

Double sex and mab-3-related transcription factor 1 (Dmrt1), which is expressed in goat male germline stem cells (mGSCs) and Sertoli cells, is one of the most conserved transcription factors involved in sex determination. In this study, we highlighted the role of Dmrt1 in balancing the innate immune response in goat mGSCs. Dmrt1 recruited promyelocytic leukemia zinc finger (Plzf), also known as zinc finger and BTB domain-containing protein 16 (Zbtb16), to repress the Toll-like receptor 4 (TLR4)-dependent inflammatory signaling pathway and nuclear factor (NF)-κB. Knockdown of Dmrt1 in seminiferous tubules resulted in widespread degeneration of germ and somatic cells, while the expression of proinflammatory factors were significantly enhanced. We also demonstrated that Dmrt1 stimulated proliferation of mGSCs, but repressed apoptosis caused by the immune response. Thus, Dmrt1 is sufficient to reduce inflammation in the testes, thereby establishing the stability of spermatogenesis and the testicular microenvironment.

A High Phosphorus Diet Impairs Testicular Function and Spermatogenesis in Male Mice with Chronic Kidney Disease

Hyperphosphatemia is a serious complication in chronic kidney disease (CKD) that occurs due to insufficient excretion of phosphorus during failure of renal function. Both CKD and an excessive phosphorus intake have been reported to increase oxidative stress and result in poor male fertility, but little is known about the reproductive function of the CKD under a poorly controlled phosphate intake. Eight-week-old C57BL/6 mice (n = 66) were randomly divided into four groups: a sham operation group received a chow diet as control (SC group, n = 14), CKD-induced mice received a chow diet (CKDC group, n = 16), control mice received a high phosphorus (HP) diet (SP group, n = 16), and CKD-induced mice received a HP diet (CKDP group, n = 20). CKD was induced by performing a 5/6 nephrectomy. The chow diet contained 0.6% phosphorus, while the HP diet contained 2% phosphorus. Impaired testicular function and semen quality found in the CKD model may result from increased oxidative stress, causing apoptosis and inflammation. The HP diet aggravated the negative effects of testicular damage in the CKD-induced mice.

Proteasome activator REGγ promotes inflammation in Leydig cells via IkBε signaling

The development of testicular inflammation affects the normal male reproductive function. The proteasome activator complex subunit 3 (REGγ) has been suggested to regulate experimental colitis. However, to the best of our knowledge, a potential association between REGγ and testicular inflammation has not been demonstrated. The present study successfully established inflammatory models in C57 mice, primary Leydig cells and the TM3 cell line. It was observed that the absence of REGγ conveyed a significantly protective effect toward testosterone secretion in Leydig cells. REGγ deficiency significantly decreased the expression levels of phosphorylated transcription factor p65 and inflammatory factors in testis tissues, primary Leydig cells and the TM3 cell line. Inflammation also upregulated the expression levels of REGγ. Furthermore, the degradation of the nuclear factor light‑chain‑enhancer of activated B cells (NF‑κB) inhibitor ε (IkBε) signaling pathway regulated REGγ and NF‑κB expression. Double knockdown of REGγ and IkBε restored the response in wild‑type cells to LPS‑induced inflammation. In summary, these results demonstrated that REGγ regulates NF‑κB activity by specifically degrading IkBε to regulate inflammation in testicular Leydig cells.

Microcystin-leucine arginine mediates apoptosis and engulfment of Leydig cell by testicular macrophages resulting in reduced serum testosterone levels

Microcystin-leucine arginine (MC-LR) causes decline of serum testosterone levels resulting in impaired spermatogenesis; however, the underlying molecular mechanisms are not fully understood. In this study, we aimed to investigate the effects of MC-LR exposure on the number of Leydig cells (LCs) in testis. Following chronic low dose exposure to MC-LR, the number of LCs was markedly decreased while macrophages were significantly increased. Then, we established a co-culture system to study the interaction between macrophages and LCs in the presence of MC-LR. No significant apoptosis of LCs cultured alone was observed after MC-LR (< 5 000 nM) treatment; however, apoptosis was robustly increased when LCs were co-cultured with macrophages in the presence of MC-LR. Further studies identified that MC-LR could stimulate macrophage to produce TNF-α, and secreted TNF-α induced LC apoptosis by binding to the tumor necrosis factor receptor 1 (TNFR1) on the LCs and thus activating reactive oxygen species (ROS)-p38MAPK signaling pathway. Furthermore, we also examined increased expression of Axl receptor and growth arrest-specific 6 (Gas6) in macrophages after MC-LR treatment. GAS6 mediates phagocytosis of apoptotic LCs by binding to the Axl receptor on macrophages and phosphatidylserine (PtdSer) on apoptotic LCs. Together, these results suggested that reduced serum testosterone levels may be associated with decrease of LCs as a result of LC apoptosis and phagocytosis by immune cells in MC-LR-treated mice.