Reactive oxygen species (ROS) production triggered by prostaglandin D2 (PGD2) regulates lactate dehydrogenase (LDH) expression/activity in TM4 Sertoli cells

Impact of COVID-19 on sperm quality and the prostaglandin and polyamine systems in the seminal fluid

BACKGROUND

The implications of SARS-CoV-2 infection on male fertility remain largely unknown. Besides their well-known pro- and anti-inflammatory actions, prostaglandins and polyamines are present in semen, where they play key roles in sperm quality.

OBJECTIVES

To analyze semen parameters, oxidative profile and the seminal fluid prostaglandin and polyamine systems in samples collected from individuals without coronavirus disease 2019 diagnosis and men who recovered from coronavirus disease 2019.

MATERIALS AND METHODS

This study compared semen collected from men without positive coronavirus disease 2019 diagnosis with samples obtained from individuals 1-6 months and 7-30 months post SARS-CoV-2 infection. Semen parameters, thiobarbituric acid reactive substances, cyclooxygenase 2 expression by fluorescence immunocytochemistry and immunoblotting, prostaglandin levels by enzyme immunoassay, ornithine decarboxylase activity by a radioactive assay, and polyamine and acetylated polyamine levels by thin-layer chromatography were assessed.

RESULTS

In both groups of semen samples from coronavirus disease 2019 recovered men, sperm vitality, total and progressive sperm motility, and putrescine levels were significantly decreased when compared with samples from the uninfected group. In contrast, lipid peroxidation, leukocyte-associated cyclooxygenase 2 expression, and prostaglandin D2 levels were higher in semen from coronavirus disease 2019 recovered men than in samples from uninfected individuals. While sperm concentration and morphology, ornithine decarboxylase activity, and N-acetylputrescine levels were statistically diminished in semen obtained up to 6 months after coronavirus disease 2019 recovery, these parameters remained unchanged when samples were collected 7-30 months after coronavirus disease 2019 recovery. Coronavirus disease 2019 vaccination did not show negative effects on any of the parameters evaluated.

DISCUSSION AND CONCLUSION

Our work provides insights into the detrimental impact of coronavirus disease 2019 on several sperm parameters, in some cases, even more than a year after SARS-CoV-2 infection, which would be accompanied by alterations in the seminal fluid prostaglandin and polyamine profiles. Therefore, future treatments targeting the prostaglandin and polyamine pathways in coronavirus disease 2019 recovered men could lead to a successful reinstatement of semen parameters.

Effects of Reactive Oxygen and Nitrogen Species on Male Fertility

Significance: In recent decades, male fertility has been severely reduced worldwide. The causes underlying this decline are multifactorial, and include, among others, genetic alterations, changes in the microbiome, and the impact of environmental pollutants. Such factors can dysregulate the physiological levels of reactive species of oxygen (ROS) and nitrogen (RNS) in the patient, generating oxidative and nitrosative stress that impairs fertility. Recent Advances: Recent studies have delved into other factors involved in the dysregulation of ROS and RNS levels, such as diet, obesity, persistent infections, environmental pollutants, and gut microbiota, thus leading to new strategies to solve male fertility problems, such as consuming prebiotics to regulate gut flora or treating psychological conditions. Critical Issues: The pathways where ROS or RNS may be involved as modulators are still under investigation. Moreover, the extent to which treatments can rescue male infertility as well as whether they may have side effects remains, in most cases, to be elucidated. For example, it is known that prescription of antioxidants to treat nitrosative stress can alter sperm chromatin condensation, which makes DNA more exposed to ROS and RNS, and may thus affect fertilization and early embryo development. Future Directions: The involvement of extracellular vesicles, which might play a crucial role in cell communication during spermatogenesis and epididymal maturation, and the relevance of other factors such as sperm epigenetic signatures should be envisaged in the future.

Melatonin improves oxidative state and lactate metabolism in rodent Sertoli cells

Antioxidant actions of melatonin and its impact on testicular function and fertility have already been described. Considering that Sertoli cells contribute to provide structural support and nutrition to germ cells, we evaluated the effect of melatonin on oxidative state and lactate metabolism in the immature murine TM4 cell line and in immature hamster Sertoli cells. A prooxidant stimulus applied to rodent Sertoli cells expressing MT1/MT2 receptors, increased lipid peroxidation whereas decreased antioxidant enzymes (superoxide dismutase 1, catalase, peroxiredoxin 1) expression and catalase activity. These changes were prevented by melatonin. Furthermore, melatonin stimulated lactate dehydrogenase (LDH) expression/activity via melatonin receptors, and increased intracellular lactate production in rodent Sertoli cells. Interestingly, oral melatonin supplementation in infertile men positively regulated LDHA testicular mRNA expression. Overall, our work provides insights into the potential benefits of melatonin on Sertoli cells contributing to testicular development and the future establishment of a sustainable spermatogenesis.

Computer-Aided Designing Peptide Inhibitors of Human Hematopoietic Prostaglandin D2 Synthase Combined Molecular Docking and Molecular Dynamics Simulation

Human hematopoietic prostaglandin D2 synthase (HPGDS) is involved in the production of prostaglandin D2, which participates in various physiological processes, including inflammation, allergic reactions, and sleep regulation. Inhibitors of HPGDS have been investigated as potential anti-inflammatory agents. For the investigation of potent HPGDS inhibitors, we carried out a computational modeling study combining molecular docking and molecular dynamics simulation for selecting and virtual confirming the designed binders. We selected the structure of HPGDS (PDB ID: 2CVD) carrying its native inhibitor compound HQL as our research target. The random 5-mer peptide library was created by building the 3-D structure of random peptides using Rosetta Buildpeptide and performing conformational optimization. Molecular docking was carried out by accommodating the peptides into the location of their native binder and then conducting docking using FlexPepDock. The two peptides RMYYY and VMYMI, which display the lowest binding energy against HPGDS, were selected to perform a comparative study. The interaction of RMYYY and VMYMI against HPGDS was further confirmed using molecular dynamics simulation and aligned with its native binder, HQL. We show the selected binders to have stronger binding energy and more frequent interactions against HPGDS than HQL. In addition, we analyzed the solubility, hydrophobicity, charge, and bioactivity of the generated peptides, and we show that the selected strong binder may be further used as therapeutic drugs.

Dysregulation of Immature Sertoli Cell Functions by Exposure to Acetaminophen and Genistein in Rodent Cell Models

Sertoli cells are essential for germ cell development and function. Their disruption by endocrine disrupting chemicals (EDCs) or drugs could jeopardize spermatogenesis, contributing to male infertility. Perinatal exposure to EDCs and acetaminophen (APAP) disrupts male reproductive functions in animals and humans. Infants can be exposed simultaneously to the dietary soy phytoestrogen genistein (GEN) and APAP used for fever or pain relief. Our goal was to determine the effects of 10-100 µM APAP and GEN, alone or mixed, on immature Sertoli cells using mouse TM4 Sertoli cell line and postnatal-day 8 rat Sertoli cells, by measuring cell viability, proliferation, prostaglandins, genes and protein expression, and functional pathways. A value of 50 µM APAP decreased the viability, while 100 µM APAP and GEN decreased the proliferation. Sertoli cell and eicosanoid pathway genes were affected by GEN and mixtures, with downregulation of Sox9, Cox1, Cox2, and genes relevant for Sertoli cell function, while genes involved in inflammation were increased. RNA-seq analysis identified p53 and TNF signaling pathways as common targets of GEN and GEN mixture in both cell types. These results suggest that APAP and GEN dysregulate immature Sertoli cell function and may aid in elucidating novel EDC and drug targets contributing to the etiology of male infertility.

Pleiotropic actions of melatonin in testicular peritubular myoid cells of immature Syrian hamsters

BACKGROUND

Peritubular myoid cells are emerging as key regulators of testicular function in adulthood. However, little is known about the role of testicular peritubular myoid cells (TPMCs) in the development of the male gonad. We found that, compared to testes of young adult hamsters, gonads of 21 day-old animals show increased melatonin concentration, seminiferous tubular wall thickening and a heterogeneous packaging of its collagen fibers thus raising the question whether melatonin may be involved in the regulation of TPMCs.

METHODS

We established primary cultures of TPMCs from immature hamsters (ihaTPMCs), which we found express melatonergic receptors.

RESULTS

Exogeneous melatonin decreased the levels of inflammatory markers (NLRP3 inflammasome, IL1β) but increased the expression of cyclooxygenase 2 (COX2, key enzyme mediating prostaglandin synthesis) and of the glial cell line-derived neurotrophic factor (GDNF) in ihaTPMCs. Melatonin also stimulated ihaTPMCs proliferation and the expression of extracellular matrix proteins such as collagen type I and IV. Furthermore, collagen gel contraction assays revealed an enhanced ability of ihaTPMCs to contract in the presence of melatonin.

CONCLUSION

Melatonin regulates immune and inflammatory functions as well as contractile phenotype of the peritubular wall in the hamster testis.

GENERAL SIGNIFICANCE

If transferable to the in vivo situation, melatonin-dependent induction of ihaTPMCs to produce factors known to exert paracrine effects in other somatic cell populations of the gonad suggests that the influence of melatonin may go beyond the peritubular wall and indicates its contribution to testicular development and the establishment of a normal and sustainable spermatogenesis.

The innate immune system and fever under redox control: A Narrative Review

ABSTRACT:

In living cells, redox potential is vitally important for normal physiological processes that are closely regulated by antioxidants, free amino acids and proteins that either have reactive oxygen and nitrogen species capture capability or can be compartmentalized. Although hundreds of experiments support the regulatory role of free radicals and their derivatives, several authors continue to claim that these perform only harmful and non-regulatory functions. In this paper we show that countless intracellular and extracellular signal pathways are directly or indirectly linked to regulated redox processes. We also briefly discuss how artificial oxidative stress can have important therapeutic potential and the possible negative effects of popular antioxidant supplements.

A peripheral lipid sensor GPR120 remotely contributes to suppression of PGD2-microglia-provoked neuroinflammation and neurodegeneration in the mouse hippocampus

BACKGROUND

Neuroinflammation is a key pathological component of neurodegenerative disease and is characterized by microglial activation and the secretion of proinflammatory mediators. We previously reported that a surge in prostaglandin D₂ (PGD₂) production and PGD₂-induced microglial activation could provoke neuroinflammation. We also reported that a lipid sensor GPR120 (free fatty acid receptor 4), which is expressed in intestine, could be activated by polyunsaturated fatty acids (PUFA), thereby mediating secretion of glucagon-like peptide-1 (GLP-1). Dysfunction of GPR120 results in obesity in both mice and humans.

METHODS

To reveal the relationship between PGD₂-microglia-provoked neuroinflammation and intestinal PUFA/GPR120 signaling, we investigated neuroinflammation and neuronal function with gene and protein expression, histological, and behavioral analysis in GPR120 knockout (KO) mice.

RESULTS

In the current study, we discovered notable neuroinflammation (increased PGD₂ production and microglial activation) and neurodegeneration (declines in neurogenesis, hippocampal volume, and cognitive function) in GPR120 KO mice. We also found that Hematopoietic-prostaglandin D synthase (H-PGDS) was expressed in microglia, microglia were activated by PGD₂, H-PGDS expression was upregulated in GPR120 KO hippocampus, and inhibition of PGD₂ production attenuated this neuroinflammation. GPR120 KO mice exhibited reduced intestinal, plasma, and intracerebral GLP-1 contents. Peripheral administration of a GLP-1 analogue, liraglutide, reduced PGD₂-microglia-provoked neuroinflammation and further neurodegeneration in GPR120 KO mice.

CONCLUSIONS

Our results suggest that neurological phenotypes in GPR120 KO mice are probably caused by dysfunction of intestinal GPR120. These observations raise the possibility that intestinal GLP-1 secretion, stimulated by intestinal GPR120, may remotely contributed to suppress PGD₂-microglia-provoked neuroinflammation in the hippocampus.

Murburn precepts for lactic-acidosis, Cori cycle, and Warburg effect: Interactive dynamics of dehydrogenases, protons, and oxygen

It is unresolved why lactate is transported to the liver for further utilization within the physiological purview of Cori cycle, when muscles have more lactate dehydrogenase (LDH) than liver. We point out that the answer lies in thermodynamics/equilibriums. While the utilization of NADH for the reduction of pyruvate to lactate can be mediated via the classical mechanism, the oxidation of lactate (with/without the uphill reduction of NAD⁺ ) necessitates alternative physiological approaches. The latter pathway occurs via interactive equilibriums involving the enzyme, protons and oxygen or diffusible reactive oxygen species (DROS). Since liver has high DROS, the murburn activity at LDH would enable the cellular system to tide over the unfavorable energy barriers of the forward reaction (~476 kJ/mol; earlier miscalculated as ~26 kJ/mole). Further, the new mechanism does not necessitate any "smart decision-making" or sophisticated control by/of proteins. The DROS-based murburn theory explains the invariant active-site structure of LDH isozymes and their multimeric nature. The theoretical insights, in silico evidence and analyses of literature herein also enrich our understanding of the underpinnings of "lactic acidosis" (lowering of physiological pH accompanied by lactate production), Warburg effect (increased lactate production at high pO₂ by cancer cells) and approach for cancer therapy.

Antioxidant Capacity of Proteins and Hydrolysates from the Liver of Newborn Piglets, and Their Inhibitory Effects on Steatosis in vitro

Research background

Non-alcoholic steatohepatitis is a potentially progressive hepatic disorder that can lead to end-stage liver disease and hepatocellular carcinoma. The inhibitory effects of proteins and hydrolysates from the liver of newborn piglets on hepatic steatosis in oleic acid-induced hepatocellular carcinoma (HepG2) cells were investigated in vitro.

Experimental approach

The extracted proteins from the liver of newborn piglets were hydrolysed with papain, pepsin, trypsin and Alcalase. Based on the comparison of different enzyme digestion conditions, a protein hydrolysis protocol was established to obtain hydrolysates with lipid-lowering effect.

Results and conclusions

Trypsin-digested liver protein hydrolysate from newborn piglets exhibited strong antioxidant activity and good inhibitory effects against lipogenesis and cholesterol accumulation in HepG2 cells at the concentration of 150 μg/mL, with a triglyceride decrease of (43±3) % and cholesterol decrease of (31±5) %, compared with model group induced with 0.75 mM oleic acid. The addition of trypsin-digested liver protein hydrolysate from newborn piglets (300 μg/mL) decreased alanine aminotransferase and aspartate aminotransferase activities and increased superoxide dismutase activity.

Novelty and scientific contribution

This study demonstrated that the trypsin-digested liver protein hydrolysate from newborn piglets has a potential preventive effect against non-alcoholic fatty liver disease in its early stage, and a potential use as the modulator of lipid overaccumulation in form of food supplements.

Multi-omics study of silicosis reveals the potential therapeutic targets PGD2 and TXA2

Rationale: Silicosis is a severe occupational lung disease. Current treatments for silicosis have highly limited availability (i.e., lung transplantation) or, do not effectively prolong patient survival time (i.e., lung lavage). There is thus an urgent clinical need for effective drugs to retard the progression of silicosis.

Methods: To systematically characterize the molecular changes associated with silicosis and to discover potential therapeutic targets, we conducted a transcriptomics analysis of human lung tissues acquired during transplantation, which was integrated with transcriptomics and metabolomics analyses of silicosis mouse lungs. The results from the multi-omics analyses were then verified by qPCR, western blot, and immunohistochemistry. The effect of Ramatroban on the progression of silicosis was evaluated in a silica-induced mouse model.

Results: Wide metabolic alterations were found in lungs from both human patients and mice with silicosis. Targeted metabolite quantification and validation of expression of their synthases revealed that arachidonic acid (AA) pathway metabolites, prostaglandin D₂ (PGD₂) and thromboxane A₂ (TXA₂), were significantly up-regulated in silicosis lungs. We further examined the effect of Ramatroban, a clinical antagonist of both PGD₂ and TXA₂ receptors, on treating silicosis using a mouse model. The results showed that Ramatroban significantly alleviated silica-induced pulmonary inflammation, fibrosis, and cardiopulmonary dysfunction compared with the control group.

Conclusion: Our results revealed the importance of AA metabolic reprogramming, especially PGD₂ and TXA₂ in the progression of silicosis. By blocking the receptors of these two prostanoids, Ramatroban may be a novel potential therapeutic drug to inhibit the progression of silicosis.

Melatonin daily oral supplementation attenuates inflammation and oxidative stress in testes of men with altered spermatogenesis of unknown aetiology

We have previously shown an inverse correlation between testicular melatonin concentration and inflammation/oxidative stress-related markers levels in infertile men showing unexplained azoospermia. Here, we evaluated the impact of melatonin oral supplementation (daily 3 mg dose used to treat sleep disorders) in the incidence of local inflammation, oxidative stress, and tubular wall fibrosis development in young and middle-aged infertile adult men. Compared with testes without histological alterations, gonads with morphological abnormalities showed lower melatonin concentration along with increased macrophage numbers, TBARS generation, and expression levels of inflammation-related markers and antioxidant enzymes, as well as tubular wall collagen fibers disorganization and thickening. Melatonin oral supplementation not only increased its own testicular levels but also decreased inflammation- and oxidative stress-related markers levels, and improved the tubular wall aspect. Overall, our work provides insights into the potential benefits of melatonin on the inflammatory and oxidative status in testes of patients suffering from unexplained infertility.

Generation of Cellular Reactive Oxygen Species by Activation of the EP2 Receptor Contributes to Prostaglandin E2-Induced Cytotoxicity in Motor Neuron-Like NSC-34 Cells

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease characterized by progressive degeneration of motor neurons in the central nervous system. Prostaglandin E2 (PGE2) plays a pivotal role in the degeneration of motor neurons in human and transgenic models of ALS. We have shown previously that PGE2 directly induces neuronal death through activation of the E-prostanoid (EP) 2 receptor in differentiated NSC-34 cells, a motor neuron-like cell line. In the present study, to clarify the mechanisms underlying PGE2-induced neurotoxicity, we focused on generation of intracellular reactive oxygen species (ROS) and examined the effects of N-acetylcysteine (NAC), a cell-permeable antioxidant, on PGE2-induced cell death in differentiated NSC-34 cells. Dichlorofluorescein (DCF) fluorescence analysis of PGE2-treated cells showed that intracellular ROS levels increased markedly with time, and that this effect was antagonized by a selective EP2 antagonist (PF-04418948) but not a selective EP3 antagonist (L-798,106). Although an EP2-selective agonist, butaprost, mimicked the effect of PGE2, an EP1/EP3 agonist, sulprostone, transiently but significantly decreased the level of intracellular ROS in these cells. MTT reduction assay and lactate dehydrogenase release assay revealed that PGE2- and butaprost-induced cell death were each suppressed by pretreatment with NAC in a concentration-dependent manner. Western blot analysis revealed that the active form of caspase-3 was markedly increased in the PGE2- and butaprost-treated cells. These increases in caspase-3 protein expression were suppressed by pretreatment with NAC. Moreover, dibutyryl-cAMP treatment of differentiated NSC-34 cells caused intracellular ROS generation and cell death. Our data reveal the existence of a PGE2-EP2 signaling-dependent intracellular ROS generation pathway, with subsequent activation of the caspase-3 cascade, in differentiated NSC-34 cells, suggesting that PGE2 is likely a key molecule linking inflammation to oxidative stress in motor neuron-like NSC-34 cells.

Protective Role of Peroxiredoxins against Reactive Oxygen Species in Neonatal Rat Testicular Gonocytes

Peroxiredoxins (PRDXs) are antioxidant enzymes that protect cells from oxidative stress and play a role in reactive oxygen species (ROS)-mediated signaling. We reported that PRDXs are critical for human fertility by maintaining sperm viability and regulating ROS levels during capacitation. Moreover, studies on Prdx6^−/− mice revealed the essential role of PRDX6 in the viability, motility, and fertility competence of spermatozoa. Although PRDXs are abundant in the testis and spermatozoa, their potential role at different phases of spermatogenesis and in perinatal germ cells is unknown. Here, we examined the expression and role of PRDXs in isolated rat neonatal gonocytes, the precursors of spermatogonia, including spermatogonial stem cells. Gene array, qPCR analyses showed that PRDX1, 2, 3, 5, and 6 transcripts are among the most abundant antioxidant genes in postnatal day (PND) 3 gonocytes, while immunofluorescence confirmed the expression of PRDX1, 2, and 6 proteins. The role of PRDXs in gonocyte viability was examined using PRDX inhibitors, revealing that the 2-Cys PRDXs and PRDX6 peroxidases activities are critical for gonocytes viability in basal condition, likely preventing an excessive accumulation of endogenous ROS in the cells. In contrast to its crucial role in spermatozoa, PRDX6 independent phospholipase A₂ (iPLA₂) activity was not critical in gonocytes in basal conditions. However, under conditions of H₂O₂-induced oxidative stress, all these enzymatic activities were critical to maintain gonocyte viability. The inhibition of PRDXs promoted a two-fold increase in lipid peroxidation and prevented gonocyte differentiation. These results suggest that ROS are produced in neonatal gonocytes, where they are maintained by PRDXs at levels that are non-toxic and permissive for cell differentiation. These findings show that PRDXs play a major role in the antioxidant machinery of gonocytes, to maintain cell viability and allow for differentiation.

Pre-treatment with Beta Carotene Gives Protection Against Nephrotoxicity Induced by Bromobenzene via Modulation of Antioxidant System, Pro-inflammatory Cytokines and Pro-apoptotic Factors

Bromobenzene is an environmental toxin which causes hepatotoxicity, and the secondary metabolites on biotransformation cause nephrotoxicity. The objective of this study was to assess the alleviation of the nephrotoxic effect of bromobenzene by beta carotene in female Wistar albino rats. Beta carotene (10 mg/kg b.w.p.o.) was delivered orally to the rats for 9 days before bromobenzene (10 mM/kg b.w.p.o.) was intragastrically intubated. Kidney markers, antioxidant status and lipid peroxidation were evaluated. In addition, the levels of TNF-α, IL-6 and IL-1β were measured in serum and in kidney tissue homogenate using ELISA. Caspase, COX-2 and NF-κB were measured with the help of Western blotting. Histopathological analysis of the kidney was done for the control and experimental rats. Bromobenzene induction caused elevation in levels of creatinine, urea, uric acid, cytokines and lipid per oxidation along with deterioration in histological observations and antioxidant status. Pre-treatment with beta carotene significantly (*p < 0.05) normalised the levels of kidney markers and pro-inflammatory cytokines. It also reduced oxidative stress and lipid peroxidation, as shown by improved antioxidant status. The anti-apoptotic activity was evidenced by inhibition of protein expression of caspase, COX-2 and NF-κB. This significant reversal (*p < 0.05) of the above variations in comparison with the control group as noticed in the bromobenzene-administered rats demonstrates that beta carotene possesses promising nephroprotective effect through its antioxidant, anti-inflammatory and anti-apoptotic activity and therefore suggests its use as a potential therapeutic agent for protection from bromobenzene and hence environmental pollutant toxicity.

Peritubular cells of the human testis: prostaglandin E2 and more

BACKGROUND

Several layers of slender, smooth muscle-like, peritubular cells and extracellular matrix (ECM) form the peritubular compartment of the human testis. Peritubular cells are the least explored testicular cells.

MATERIALS AND METHODS

Human testicular peritubular cells (HTPCs) can be isolated from small testicular fragments of patients and studied in vitro. We have used this cellular model, in combination with human testicular samples, to examine how peritubular cells may contribute to male (in)fertility.

RESULTS

Human testicular peritubular cells (HTPCs) retain contractile abilities in vitro and secrete many proteins. Among them are factors, which serve intra-testicular roles, for example, glial cell line-derived neurotrophic factor (GDNF), thought to be important for the renewal of spermatogonial stem cells (SSCs). Studies in mutant mice indicated that peritubular cell-derived GDNF is crucial for lifelong spermatogenesis. Thus, peritubular cells are a functional part of the SSC niche. Peritubular cells of mice and men express androgen receptors (AR). In mouse peritubular cells, androgens enhanced GDNF production, but not in HTPCs. Rather, AR activation increased the levels of AR and smooth muscle proteins and thereby enhanced the smooth muscle-like phenotype. Following the lead of a proteomic analysis, which identified the key prostaglandin (PG)-synthesizing enzyme (PTGS1 = COX1), we found that HTPCs secrete PGE₂ . COX1, and PGE₂ receptors (EP1, 2, and 4) were identified in peritubular cells in situ, supporting in vivo relevance. In HTPCs, activation of EP1/4 increased GDNF and a smooth muscle protein. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID), which blocks PG synthesis. Added to HTPCs it reduced PGE₂ and GDNF production and lowered smooth muscle protein levels. If applicable to the in vivo situation, the results suggest that ibuprofen and possibly other NSAIDs may impair important peritubular cell functions and consequently testicular functions.

CONCLUSION

The few examples highlighted, together with others not mentioned here, indicate that HTPCs provide an experimental window into the human testis.

Exposure to Pb and Cd alters MCT4/CD147 expression and MCT4/CD147-dependent lactate transport in mice Sertoli cells cultured in vitro

Sertoli cells (SCs) provide lactate as an energy substrate to develop germ cells during spermatogenesis. Lead (Pb) and cadmium (Cd) can induce SC toxicity. However, the mechanisms remain unclear. This study aimed to investigate the molecular mechanisms by which Pb and Cd alter lactate transport and production by SCs. Mouse SC line (15P-1 cells) were cultured in the absence and presence of lead acetate (PbAc, 1, 10, 20 and 30 μM) or cadmium chloride (CdCl₂, 0.5, 5, 10 and 15 μM) for 24 h. The results showed that PbAc exposure significantly decreased lactate dehydrogenase (LDH) activity and mRNA level, intracellular and extracellular lactate, and MCT4 and CD147 protein levels but increased MCT4 and CD147 mRNA levels. However, PbAc did not alter the glucose uptake, glucose transporters 1 (GLUT1) and 3 (GLUT3) mRNA expression of SCs. Thus, PbAc mainly decreased lactate production by inhibiting LDH activity. In CdCl₂-treated SCs, intracellular lactate content increased but extracellular lactate content decreased significantly, P < .05. The glucose uptake, LDH activity, and mRNA expression of GLUT1, GLUT3 and LDH, all significantly increased. But the mRNA and protein levels of MCT4 and CD147 significantly decreased. Moreover, the fluorescence intensity of co-localizations of the MCT4-CD147 complex dose-dependently decreased in the cell membrane. Thus, CdCl₂ may reduce lactate export by suppressing MCT4 and CD147 expression. These results suggest that PbAc and CdCl₂ disrupt lactate production and transport in mouse SCs by disturbing glycolysis or inhibiting MCT4-CD147 transporter expression and co-localizations.

Active compounds present inRosmarinus officinalis leaves andScutellaria baicalensis root evaluated as new therapeutic agents for endometriosis

RESEARCH QUESTION

Can carnosic acid, (CA) rosmarinic acid (RA) and wogonin (WG) inhibit the growth of cultured human endometrial stromal cells and endometriotic-like lesions induced in a BALB/c model of endometriosis?

DESIGN

Primary stromal cell cultures were established from endometrial biopsies from women with endometriosis and controls. The human endometrial stromal cell line T-HESC was also used for in-vitro experiments. Endometriosis was surgically induced in BALB/c mice, which were randomly assigned to CA 2 mg/kg/day (n = 11); CA 20 mg/kg/day (n = 10); RA 1 mg/kg/day (n = 11); RA 3 mg/kg/day (n = 10); WG 20 mg/kg/day (n = 12); intraperitoneal vehicle control (n = 8) or oral vehicle control (n = 11). After surgery, CA and RA were administered intraperitoneally on days 14-28. WG was administered orally by intragastric gavage on days 14-26.

RESULTS

CA, RA and WG significantly inhibited in-vitro cell proliferation in primary and T-HESC cell cultures (P < 0.05). CA and WG induced cell cycle arrest of T-HESC at the G2/M phase (P < 0.01). RA reduced intracellular ROS accumulation (P < 0.001), whereas WG increased it (P < 0.05). WG significantly inhibited oestrogen receptor alpha expression in T-HESC (P < 0.01). In-vivo, CA, RA and WG significantly reduced lesions size (P < 0.05). All compounds significantly decreased the percentage of cells in proliferation (P < 0.05) whereas RA and WG further increased the percentage of apoptotic cells (P < 0.05) in endometriotic-like lesions.

CONCLUSIONS

The results are promising; further investigation of these compounds as new therapeutics is needed.

Alpha 1 adrenergic receptor-mediated inflammatory responses in human testicular peritubular cells

Stress activates the sympathetic nervous system and is linked to impaired fertility in man. We hypothesized that catecholamines by acting on testicular cells have a role in these events, possibly by fostering an inflammatory environment. The cells of the wall of seminiferous tubules, human testicular peritubular cells (HTPCs), express adrenergic receptors (ADRs) α1B, α1D, β1 and β2. A selective α1-ADR agonist, phenylephrine, increased intracellular Ca²⁺-levels in cultured HTPCs and induced COX-2, IL-6 and MCP-1 mRNA expression without affecting IL-1β mRNA. These changes were paralleled by a significant increase in the secretion of IL-6 and MCP-1. Epinephrine was also effective, but salbutamol, a selective β2-ADR agonist was not. Our results suggest that stress-associated elevation of catecholamines may be able to promote inflammatory events by targeting peritubular cells in the human testis. Blockage of α1-ADRs may therefore be a novel way to interfere with stress-related impairment of male reproductive functions.

Ca2+ Signaling and IL-8 Secretion in Human Testicular Peritubular Cells Involve the Cation Channel TRPV2

Peritubular cells are part of the wall of seminiferous tubules in the human testis and their contractile abilities are important for sperm transport. In addition, they have immunological roles. A proteomic analysis of isolated human testicular peritubular cells (HTPCs) revealed expression of the transient receptor potential channel subfamily V member 2 (TRPV2). This cation channel is linked to mechano-sensation and to immunological processes and inflammation in other organs. We verified expression of TRPV2 in peritubular cells in human sections by immunohistochemistry. It was also found in other testicular cells, including Sertoli cells and interstitial cells. In cultured HTPCs, application of cannabidiol (CBD), a known TRPV2 agonist, acutely induced a transient increase in intracellular Ca²⁺ levels. These Ca²⁺ transients could be blocked both by ruthenium red, an unspecific Ca²⁺ channel blocker, and tranilast (TRA), an antagonist of TRPV2, and were also abolished when extracellular Ca²⁺ was removed. Taken together this indicates functional TRPV2 channels in peritubular cells. When applied for 24 to 48 h, CBD induced expression of proinflammatory factors. In particular, mRNA and secreted protein levels of the proinflammatory chemokine interleukin-8 (IL-8/CXCL8) were elevated. Via its known roles as a major mediator of the inflammatory response and as an angiogenic factor, this chemokine may play a role in testicular physiology and pathology.

Prostaglandin E2 (PGE2) is a testicular peritubular cell-derived factor involved in human testicular homeostasis

In man, blockage of prostaglandin (PG)-production e.g. by non-steroidal anti-inflammatory drug (NSAIDs) may have negative testicular side effects, implying beneficial actions of PGs in the testis. We examined human testicular samples and isolated human testicular peritubular cells (HTPCs) to explore sites of PG-synthesis and targets. HTPCs express cyclooxygenase 1 (COX1) and secrete PGE2. Receptors (EP1, 2, 4) were specifically identified in peritubular cells. In HTPCs PGE2 significantly increased mRNA levels of the contractility protein calponin, but did not induce contractions. PGE2, as well as EP1 and EP4 receptor agonists, significantly increased glia cell line derived neurotrophic factor (GDNF) mRNA and/or protein levels. Importantly, the NSAID ibuprofen reduced PGE2 and this action also lowered SMA and calponin mRNA levels and levels of secreted GDNF protein. The results reveal an unknown PGE2 system in the human testis, in involving peritubular cells, which may be prone to interference by NSAIDs.

NLRP3 in somatic non-immune cells of rodent and primate testes

NLRP3 is part of the NLRP3 inflammasome and a global sensor of cellular damage. It was recently discovered in rodent Sertoli cells. We investigated NLRP3 in mouse, human and non-human primate (marmoset and rhesus macaque) testes, employing immunohistochemistry. Sertoli cells of all species expressed NLRP3, and the expression preceded puberty. In addition, peritubular cells of the adult human testes expressed NLRP3. NLRP3 and associated genes (PYCARD, CASP1, IL1B) were also found in isolated human testicular peritubular cells and the mouse Sertoli cell line TM4. Male infertility due to impairments of spermatogenesis may be related to sterile inflammatory events. We observed that the expression of NLRP3 was altered in the testes of patients suffering from mixed atrophy syndrome, in which tubules with impairments of spermatogenesis showed prominent NLRP3 staining. In order to explore a possible role of NLRP3 in male infertility, associated with sterile testicular inflammation, we studied a mouse model of male infertility. These human aromatase-expressing transgenic mice (AROM+) develop testicular inflammation and impaired spermatogenesis during aging, and the present data show that this is associated with strikingly elevated Nlrp3 expression in the testes compared to WT controls. Interference by aromatase inhibitor treatment significantly reduced increased Nlrp3 levels. Thus, throughout species NLRP3 is expressed by somatic cells of the testis, which are involved in testicular immune surveillance. We conclude that NLRP3 may be a novel player in testicular immune regulation.

Exogenous leptin affects sperm parameters and impairs blood testis barrier integrity in adult male mice

BACKGROUND

Serum leptin levels are augmented in obese infertile men and in men with azoospermia. They also correlate inversely with sperm concentration, motility and normal forms. The mechanisms underlying the adverse effects of excess leptin on male reproductive function remain unclear. The present study aimed to evaluate the effects of exogenous leptin on sperm parameters in mice and to explore the underlying mechanisms.

METHODS

We treated normal adult male mice with saline, 0.1, 0.5 or 3 mg/kg leptin daily for 2 weeks. After treatment, serum leptin levels, serum testosterone levels, sperm parameters and testicular cell apoptosis were evaluated. Blood testis barrier integrity and the expression of tight junction-associated proteins in testes were also assessed. We further verified the direct effects of leptin on tight junction-associated proteins in Sertoli cells and the possible leptin signaling pathways involved in this process.

RESULTS

After treatment, there were no significant differences in body weights, reproductive organ weights, serum leptin levels and serum testosterone levels between leptin-treated mice and control mice. Administration of 3 mg/kg leptin reduced sperm concentration, motility and progressive motility while increasing the percentage of abnormal sperm and testicular cell apoptosis. Mice treated with 3 mg/kg leptin also had impaired blood testis barrier integrity, which was related to decreased tight junction-associated proteins in testes. Leptin directly reduced tight junction-associated proteins in Sertoli cells, JAK2/STAT, PI3K and ERK pathways were suggested to be involved in this process.

CONCLUSIONS

Exogenous leptin negatively affects sperm parameters and impairs blood testis barrier integrity in mice. Leptin reduced tight junction-associated proteins in Sertoli cells, indicating that leptin has a direct role in impairing blood testis barrier integrity. Given the function of blood testis barrier in maintaining normal spermatogenesis, leptin-induced blood testis barrier impairment may be one of the mechanisms contributing to male subfertility and infertility.

Exposure to a Brazilian pulp mill effluent impacts the testis and liver in the zebrafish

While many studies have shown that pulp mill effluents can affect ovarian physiology in fish, far fewer studies have considered the effects in males. We conducted a lab study to examine the effects of effluent from a Brazilian pulp and paper mill on hepatic and testicular morphology and various aspects of testicular physiology in the zebrafish Danio rerio. Males were exposed to lab water (control) or 4% effluent for 14 days. Effluent exposure did not affect testis size as measured by the gonadosomatic index, but contributed to morphological changes in the seminiferous tubules. The number of cysts with histopathological changes was elevated in effluent-exposed fish and the number of cysts containing spermatids was significantly reduced. The testis of effluent exposed fish had reduced levels of lactate, elevated lactate dehydrogenase activity, increased levels of reactive oxygen species and reduced levels of phosphorylated P38 mitogen-activated protein kinase (pP38 MAPK). Separate studies showed that the addition of lactate to testicular tissue incubated in vitro increased the activation of P38 MAPK. Effluent exposure also increased vacuolization, necrosis, apoptosis, hyperemia, and fat infiltration of the hepatocytes. Collectively, we provide evidence of short term effects of pulp mill effluent on testicular and hepatic physiology and biochemistry in the zebrafish.

Polysaccharide from Ostrea rivularis attenuates reproductive oxidative stress damage via activating Keap1-Nrf2/ARE pathway

The purpose of this study was to investigate the effects of Ostrea rivularis polysaccharide (ORP) against testicular oxidative stress injury via kelch-like ECH-associated protein 1-nuclear erythroid 2-related factor 2/antioxidant response element (Keap1-Nrf2/ARE) pathway. In pharmacological experiments in vivo, ORP administration could dose-dependently inhibit body and testicular weight loss, ameliorate epididymal sperm quality and protect reproductive impairment in cyclophosphamide-induced male Balb/c mice. Moreover, the mechanism in vivo might be elucidated that ORP could increase expression level of Nrf2 and its downstream ARE gene battery in the testis, promote production of corresponding antioxidative enzymes and protein, and enhance Keap1-Nrf2/ARE signaling pathway to avoid male reproductive dysfunction. In addition, ORP treatment could improve survival capacity of H₂O₂-induced TM4 cells and its antioxidant mechanism in vitro also had been verified to activate Keap1-Nrf2/ARE signaling pathway. Overall, these results showed that ORP as a potent antioxidant could reduce reproductive oxidative stress damage related to Keap1-Nrf2/ARE pathway.

Essential roles of Akt/Snail pathway in microcystin-LR-induced tight junction toxicity in Sertoli cell

Microcystin (MC)-LR is a cyclic heptapeptide that acts as a potent reproductive system toxin. However, the underlying pathways of MCLR-induced reproductive system toxicity have not been well elucidated. The blood-testis barrier is mainly constituted by tight junctions (TJs) between adjacent Sertoli cells in the seminiferous epithelium near the basement membrane. The present study was designed to investigate changes in TJs and the underlying pathway in MC-LR-induced TJs toxicity in Sertoli cell. In our study, the transepithelial electrical resistance (TER) value was decreased in a dose dependent manner due to the markers of TJs occludin, claudin and zonula occludens-1 (ZO-1) expression decline. MC-LR is shown to induce cytotoxicity by inhibiting protein phosphatase 2A (PP2A) activity. Our results also showed that the PP2A activity presented a dose-dependent decline. Moreover, MC-LR stimulated protein expression of snail by Akt/GSK-3β activation. The activated Akt/GSK-3β and snail signaling pathway largely accounted for MC-LRinduced TJs toxicity, which could be partially reversed by snail siRNA interference or AKT chemical inhibitor in TM4 cells. These findings indicated that MC-LR inhibit the protein expression of TJs, and the activation of Akt/Snail signaling pathways due to PP2A inhibition is proposed to participate in this process.

Diclofenac-induced renal toxicity in female Wistar albino rats is protected by the pre-treatment of aqueous leaves extract of Madhuca longifolia through suppression of inflammation, oxidative stress and cytokine formation

CONTEXT

Kidney has a vital role in renal clearance, maintenance of blood pressure, elimination of toxic products and formation of prostaglandins. Certain medications are known to cause renal injury on its frequent usage and high dosage. Diclofenac is a non-steroidal anti-inflammatory drug which is used in the treatment of pain and arthritis. Madhuca longifolia is a deciduous tree which is known to the have anti-microbial, anti-ulcer, hepatoprotective, anti-diabetic, anti-inflammatory and analgesic activity. The aim of the present study is to evaluate the beneficial effect of aqueous leaf extract of Madhuca longifolia against DFC-induced renal toxicity in female Wistar albino rats.

METHODS

Thirty female Wistar albino rats were divided into five groups and the drugs were administrated specifically on each group. After the treatment period, the rats were sacrificed to evaluate the significant changes in renal enzyme markers, antioxidant activities in kidney tissue homogenate and plasma, renal histopathology and protein expression levels. The cytokines like TNF-α, IL-6 and IL-1β were measured through ELISA techniques and the levels of Caspase-3, COX-2 and NF-κB were measured through western blotting techniques. DiscussionMadhuca longifolia was observed to show a better result in normalizing the toxicity caused by diclofenac.

CONCLUSION

The significant result of the aqueous leaf extract ofMadhuca longifolia was due to its ability in restoring renal function by restoring antioxidants and preventing cellular damages.

Local Actions of Melatonin in Somatic Cells of the Testis

The pineal hormone melatonin regulates testicular function through the hypothalamic-adenohypophyseal axis. In addition, direct actions of melatonin in somatic cells of the testis have been described. Melatonin acts as a local modulator of the endocrine activity in Leydig cells. In Sertoli cells, melatonin influences cellular growth, proliferation, energy metabolism and the oxidation state, and consequently may regulate spermatogenesis. These data pinpoint melatonin as a key player in the regulation of testicular physiology (i.e., steroidogenesis, spermatogenesis) mostly in seasonal breeders. In patients with idiopathic infertility, melatonin exerts anti-proliferative and anti-inflammatory effects on testicular macrophages, and provides protective effects against oxidative stress in testicular mast cells. Consequently, melatonin is also involved in the modulation of inflammatory and oxidant/anti-oxidant states in testicular pathology. Overall, the literature data indicate that melatonin has important effects on testicular function and male reproduction.

Neonatal hypothyroidism affects testicular glucose homeostasis through increased oxidative stress in prepubertal mice: effects on GLUT3, GLUT8 and Cx43

Thyroid hormones (THs) play an important role in maintaining the link between metabolism and reproduction and the altered THs status is associated with induction of oxidative stress in various organs like brain, heart, liver and testis. Further, reactive oxygen species play a pivotal role in regulation of glucose homeostasis in several organs, and glucose utilization by Leydig cells is essential for testosterone biosynthesis and thus is largely dependent on glucose transporter 8 (GLUT8). Glucose uptake by Sertoli cells is mediated through glucose transporter 3 (GLUT3) under the influence of THs to meet energy requirement of developing germ cells. THs also modulate level of gap junctional protein such as connexin 43 (Cx43), a potential regulator of cell proliferation and apoptosis in the seminiferous epithelium. Although the role of transient neonatal hypothyroidism in adult testis in terms of testosterone production is well documented, the effect of THs deficiency in early developmental period and its role in testicular glucose homeostasis and oxidative stress with reference to Cx43 in immature mice remain unknown. Therefore, the present study was conducted to evaluate the effect of neonatal hypothyroidism on testicular glucose homeostasis and oxidative stress at postnatal days (PND) 21 and 28 in relation to GLUT3, GLUT8 and Cx43. Hypothyroidism induced by 6-propyl-2-thiouracil (PTU) markedly decreased testicular glucose level with considerable reduction in expression level of GLUT3 and GLUT8. Likewise, lactate dehydrogenase (LDH) activity and intratesticular concentration of lactate were also decreased in hypothyroid mice. There was also a rise in germ cell apoptosis with increased expression of caspase-3 in PTU-treated mice. Further, neonatal hypothyroidism affected germ cell proliferation with decreased expression of proliferating cell nuclear antigen (PCNA) and Cx43. In conclusion, our results suggest that neonatal hypothyroidism alters testicular glucose homeostasis via increased oxidative stress in prepubertal mice, thereby affecting germ cell survival and proliferation.

Nonsteroidal anti-inflammatory is more effective than anti-oxidant therapy in counteracting oxidative/nitrosative stress and heart disease in T. cruzi-infected mice

We compared the relevance of ibuprofen, vitamins C and E to control oxidative/nitrosative stress and heart disease in mice infected by Trypanosoma cruzi. Swiss mice were randomized into five groups: control, uninfected; infected without treatment; and infected treated with vitamins C, E or ibuprofen. Animals were inoculated with 2000 trypomastigote forms of T. cruzi. After 20 days, infected mice presented reduced vitamin C and E tissue levels, high cytokines (interferon gamma, tumour necrosis factor-α, interleukin 10 and chemokine ligand 2), prostaglandin F2α (PGF2α ) and nitric oxide (NO) cardiac production, intense myocarditis and reactive tissue damage, which was directly correlated with the intensity of the inflammatory infiltrate and the degree of pathological cardiac remodelling. Vitamins C and E supplementation were irrelevant to counteract reactive tissue damage and myocarditis in infected animals. Conversely, ibuprofen reduced tissue levels of cytokines, PGF2α and NO, as well as lipid and protein oxidation, antioxidant enzyme activity and the cardiac damage, without interfering with heart parasitism. Our results do not support the applicability of vitamin C and E supplementation in the management of acute Chagas cardiomyopathy. By controlling the inflammatory infiltrate, anti-inflammatory-based therapy proved to be a more rational strategy than a direct antioxidant therapy in attenuating oxidative/nitrosative stress and cardiac damage.