Bacterial lipopolysaccharide differently modulates steroidogenic enzymes gene expressions in the brain and testis in rats

How Does Maternal Lipopolysaccharide Exposure Impact Prenatal Testicular Development in Rats, and Could α-Tocopherol Provide a Protective Effect? A Histological, Immunohistochemical and Biochemical Study

BACKGROUND

Lipopolysaccharides or endotoxins trigger proinflammatory cytokines and nitric oxide release, whereas α-tocopherol protects cells from oxidative damage. This study investigated the effects of maternal lipopolysaccharide exposure on prenatal testicular development in male rat offspring and assessed α-tocopherol's protective role.

METHODS

Forty pregnant female rats were divided into four groups. Group I (control) included a negative control receiving normal saline and a positive control receiving 30 mg/kg of α-tocopherol intraperitoneally from the 3rd to 18th gestational day. Group II received 50 mg/kg of lipopolysaccharides intraperitoneally from the 13th to 17th gestational day, whereas Group III received both α-tocopherol and lipopolysaccharides at the same dosages. On the seventh day postpartum, fetuses were weighed, sexed, and dissected; sera from male fetuses were collected for biochemical analysis, and fetal testes were used for histology, immunohistochemistry, and morphometry.

RESULTS

Rats treated with lipopolysaccharide showed reduced body weight, testosterone, and luteinizing hormone levels, with histopathological changes, including thickened testicular capsules and abnormalities in the number, size, shape, and cellular components of seminiferous tubules. These adverse effects were improved by α-tocopherol supplementation.

CONCLUSION

We concluded that lipopolysaccharide exposure during pregnancy impairs testicular development and steroidogenesis, which are ameliorated by α-tocopherol coadministration.

The effects of olibanum on male reproductive system damage in a lipopolysaccharide induced systemic inflammation model in rat

BACKGROUND

Lipopolysaccharide (LPS) as a particle of Gram-negative bacteria is a main contributer in the pathogenesis of the male reproductive system infectious. Male infertility due to LPS is reported to be related to overproduction reactive oxygen species. This study aimed to investigate the effects of olibanum on oxidative stress and apoptosis in testes and sperm dysfunction induced by LPS.

METHODS

The male (n = 28) rats were allocated in four groups: control, LPS (1 mg/kg, i.p., 14 days), LPS + Olibanum 100 (100 mg/kg, i.p., 14 days), and LPS + Olibanum 200 (200 mg/kg, i.p., 14 days). Germ cell apoptosis was determined by TUNEL assays and computed using the stereological method. Additionally, semen samples of the animals were analyzed for sperm count and morphology. Oxidative stress indicators were also determined.

RESULTS

The count of TUNEL-positive germ cells in LPS-treated rats was more than that in the controls. Treatment of the animals with olibanum significantly attenuated the number of apoptotic cells compared to the LPS group. The sperm count and those with a normal morphology in LPS-treated rats was lower than that in the controls. Administration of olibanum significantly improved the sperms with normal morphology and sperm count. Olibanum treatment also improved superoxide dismutase, catalase, and total thiol in testicular tissue and decreased malondialdehyde.

CONCLUSION

Administering both doses of olibanum in LPS-treated rats had potentially a therapeutic value in reducing germ cell apoptosis, as well as improving sperm parameters.

Combined effects of polystyrene nanoplastics and lipopolysaccharide on testosterone biosynthesis and inflammation in mouse testis

Microplastics (MPs)/nanoplastics (NPs), as a source and vector of pathogenic bacteria, are widely distributed in the natural environments. Here, we investigated the combined effects of polystyrene NPs (PS-NPs) and lipopolysaccharides (LPS) on testicular function in mice for the first time. 24 male mice were randomly assigned into 4 groups, control, PS-NPs, LPS, and PS-NPs + LPS, respectively. Histological alterations of the testes were observed in mice exposed to PS-NPs, LPS or PS-NPs + LPS. Total sperm count, the levels of testosterone in plasma and testes, the expression levels of steroidogenic acute regulatory (StAR) decreased more remarkable in testes of mice treated with PS-NPs and LPS than the treatment with LPS or PS-NPs alone. Compared with PS-NPs treatment, LPS treatment induced more sever inflammatory response in testes of mice. Moreover, PS-NPs combined with LPS treatment increased the expression of these inflammatory factors more significantly than LPS treatment alone. In addition, PS-NPs or LPS treatment induced oxidative stress in testes of mice, but their combined effect is not significantly different from LPS treatment alone. These results suggest that PS-NPs exacerbate LPS-induced testicular dysfunction. Our results provide new evidence for the threats to male reproductive function induced by both NPs and bacterial infection in human health.

Protective role of Cytoglobin and Neuroglobin against the Lipopolysaccharide (LPS)-induced inflammation in Leydig cells ex vivo

Leydig cells are responsible for testosterone production in male testis upon stimulation by luteinizing hormone. Inflammation and oxidative stress related Leydig cell dysfunction is one of the major causes of male infertility. Cytoglobin (CYGB) and Neuroglobin (NGB) are two globin family member proteins which protect cells against oxidative stress. In the current study, we established a Lipopolysaccharide (LPS)-induced inflammation model in TM3 Leydig cell culture to study the function of CYGB and NGB proteins under inflammatory conditions. CYGB and NGB were downregulated using siRNA and shRNA based experimental strategies. Overexpression was conducted using lentiviral pLenti-III-CYGB-2A-GFP, and pLenti-III-NGB-2A-GFP vector systems. As testicular macrophages regulate immune function upon inflammation and steroidogenesis of Leydig cells, we generated direct/indirect co-culture systems of TM3 and mouse macrophage (RAW264.7) cells ex vivo. Downregulation of CYGB and NGB induced nitride oxide (NO) release, blocked cell cycle progression, reduced testosterone production and increased inflammatory and apoptotic pathway gene expression in the presence and absence of LPS. On the other hand, CYGB and NGB overexpression reduced TNFα and COX-2 protein expressions and increased the expression of testosterone biogenesis pathway genes upon LPS stimulation. In addition, CYGB and NGB overexpression upregulated testosterone production. The present study successfully established an inflammatory interaction model of TM3 and RAW264.7 cells. Suppression of CYGB and NGB in TM3 cells changed macrophage morphology, enhanced macrophage cell number and NO release in co-culture experiments upon LPS exposure. In summary, these results demonstrate that globin family members might control LPS induced inflammation by regulating apoptotic mechanisms and macrophage response.

The possible role of sirtuins in male reproduction

Global influence of male infertility is increasing in recent decades. Proper understanding of genetics, anatomy, physiology and the intricate interrelation of male reproductive system are much needed for explaining the etiology of male infertility; and a detailed study on the epigenetics, indeed, will reveal the molecular mechanism behind its etiology. Sirtuins, the molecular sensors, are NAD⁺ dependent histone deacetylases and ADP- ribosyl transferases, participate in the chief events of epigenetics. In mammals, sirtuin family comprises seven members (SIRT1-SIRT7), and they all possess a conserved NAD⁺ binding catalytic domain, termed the sirtuin core domain which is imperative for their activity. Sirtuins exert a pivotal role in cellular homeostasis, energy metabolism, apoptosis, age-related disorders and male reproductive system. However, their exact role in male reproduction is still obscure. This article specifically reviews the role of mammalian sirtuins in male reproductive function, thereby, prompting further research to discover the restorative methods and its implementation in reproductive medicine.

Effect of bacterial endotoxin lipopolysaccharide treatment on duck Leydig cells

This study aimed to investigate the effects of bacterial endotoxin lipopolysaccharide (LPS) on hormone production and gene expression in duck Leydig cells and its underlying mechanisms. Leydig cells were collected from 200-day-old mallard ducks and divided into five treatment groups (0, 50, 100, 200, and 400 ng/mL LPS). After treatment with LPS for 6, 12, 24, and 48 h, testosterone, activin, and inhibin levels in the cell supernatants were determined using enzyme-linked immunosorbent assay (ELISA) kits. The expression levels of testosterone synthesis-related genes, including steroidogenic acute regulatory protein (StAR), 3-beta-hydroxysteroid dehydrogenase (3β-HSD), and cytochrome P450 aromatase (P450arom), and reproductive-related genes, including gonadotropin-inhibitory hormone receptor (GnIHR), follicle stimulating hormone receptor (FSHR), and luteinizing hormone receptor (LHR) were detected using quantitative real-time polymerase chain reaction (qRT-PCR). We successfully isolated and cultured duck Leydig cells with cell purity above 90%. Compared with the control group, the levels of testosterone, activin, and inhibin secreted in Leydig cells decreased gradually with increasing LPS concentration. After treatment with LPS, the expression of StAR and 3β-HSD genes in Leydig cells was upregulated at 12 h, and that of GnIHR was upregulated at 24 h; whereas the expression of FSHR and LHR was reduced at 24 h. This study indicates that LPS can inhibit the secretion of hormones and regulate the expression of related genes in duck Leydig cells.

Histomorphometric evaluation of mice testicular tissue following short- and long-term effects of lipopolysaccharide-induced endotoxemia

Objective(s)::

Lipopolysaccharide (LPS)-induced endotoxemia is known to cause male infertility. This study was designed to explore the effects of bacterial LPS on histomorphometric changes of mice testicular tissues.

Materials and Methods:

In experiment 1, a pilot dose responsive study was performed with mice that were divided into five groups, receiving 36000, 18000, 9000, and 6750 µg/kg body weight (B.W) of LPS or only saline (control). White blood cells (WBC) were observed for 3 days after LPS inoculation. In experiment 2, two groups of mice were treated with 6750 µg/kg B.W of LPS or only saline (control). Five cases from each experimental group were sacrificed at 3, 30, and 60 days after LPS inoculation. Left testes were fixed in Bouin’s solution, and stained for morphometrical assays.

Results:

Time-course changes of WBC obtained from different doses of LPS-treated mice showed that inoculation of 6750 µg/kg B.W produced a reversible endotoxemia that lasts for 72 hr and so it was used in the second experiment. In experiment 2, during the first 3 days, no significant changes were observed in the evaluated parameters instead of seminiferous tubules diameter. Spermatogenesis, Johnsen’s score, meiotic index, and epithelial height were significantly affected at 30^th day. However, complete recovery was only observed for the spermatogenesis at day 60. Interestingly, deleterious effects of LPS on spermatogonia were only seen at 60^th day (P<0.05).

Conclusion:

Endotoxemia induced by LPS has long-term detrimental effects on spermatogonia and later stage germ cells, which are reversible at the next spermatogenic cycle.

Adrenomedullin protects Leydig cells against lipopolysaccharide-induced oxidative stress and inflammatory reaction via MAPK/NF-κB signalling pathways

This study aimed to explore the possible benefits of adrenomedullin (ADM) in preventing oxidative stress and inflammation by using an in vitro primary culture model of rat Leydig cells exposed to lipopolysaccharide (LPS). Cell proliferation was detected through CCK-8 and BrdU incorporation assays. ROS were determined with a DCFDA kit, and cytokine concentrations were measured with ELISA assay kits. Protein production was examined by immunohistochemical staining and Western blot, and gene expression was observed through RT-qPCR. Results revealed that ADM significantly reduced LPS-induced cytotoxicity, and pretreatment with ADM significantly suppressed ROS overproduction and decreased 4-HNE and 8-OHdG expression levels and concentrations. ADM pretreatment also significantly attenuated the overactivation of enzymatic antioxidants, namely, superoxide dismutase, catalase, thioredoxin reductase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase. ADM supplementation reversed the significantly increased gene expression levels and concentrations of TNF-α, IL-1β, TGF-β1, MCP-1 and MIF. ADM pretreatment significantly inhibited the gene expression and protein production of TLR-2 and 4. Furthermore, ADM pretreatment markedly reduced the phosphorylation of JNK, ERK 1/2 and p38, phosphorylation and degradation of IκBα and nuclear translocation of p65. Our findings demonstrated that ADM protects Leydig cells from LPS-induced oxidative stress and inflammation, which might be associated with MAPK/NF-κB signalling pathways.

Effect of Lipopolysaccharide (LPS) Exposure on the Reproductive Organs of Immature Female Rats

Lipopolysaccharide (LPS), an endotoxin, elicits strong immune responses in mammals. Several lines of evidence demonstrate that LPS challenge profoundly affects female reproductive function. For example, LPS exposure affects steroidogenesis and folliculogenesis, resulting in delayed puberty onset. The present study was conducted to clarify the mechanism underlying the adverse effect of LPS on the delayed puberty in female rats. LPS was daily injected for 5 days (50 μg/kg, PND 25-29) to treated animals and the date at VO was evaluated through daily visual examination. At PND 39, animals were sacrificed, and the tissues were immediately removed and weighed. Among the reproductive organs, the weights of the ovaries and oviduct from LPS-treated animals were significantly lower than those of control animals. There were no changes in the weights of uterus and vagina between the LPS-treated and their control animals. Immunological challenge by LPS delayed VO. Multiple corpora lutea were found in the control ovaries, indicating ovulations were occurred. However, none of corpus luteum was present in the LPS-treated ovary. The transcription level of steroidogenic acute regulatory protein (StAR), CYP11A1, CYP17A1 and CYP19 were significantly increased by LPS treatment. On the other hand, the levels of 3β- HSD, 17β-HSD and LH receptor were not changed by LPS challenge. In conclusion, the present study demonstrated that the repeated LPS exposure during the prepubertal period could induce multiple alterations in the steroidogenic machinery in ovary, and in turn, delayed puberty onset. The prepubertal LPS challenge model used in our study is useful to understand the reciprocal regulation of immune (stress) - reproductive function in early life.

Expression of 3β-hydroxysteroid dehydrogenase in ovarian and uterine tissue during diestrus and open cervix cystic endometrial hyperplasia-pyometra in the bitch

The purpose of this study was to compare the expression of 3β-hydroxystreroid dehydrogenase (3β-HSD) in the uterus and ovary of healthy dogs and those with cystic endometrial hyperplasia and/or pyometra complex (CEH-pyometra). Eighteen female dogs were included in the study. Eleven bitches with open cervix CEH-pyometra were included in the CEH-pyometra group and seven diestrus bitches in the control group. For immunostaining a rabbit polyclonal, one raised against recombinant human type 2 (adrenal/gonadal) 3β-HSD was used. Progesterone (P4) concentrations were not statistically different between the groups. Strongly stained large interstitial cell groups in the ovarian medulla were observed particularly in CEH-pyometra group although these cells in the control group were weakly or moderately stained and existed singly or paired. The expressions of 3β-HSD in luminal epithelium (42.40 ± 22.40% vs. 18.42 ± 13.15%, P < 0.05) and glandular epithelium (32.80 ± 27.05% vs. 2.94 ± 7.79%, P < 0.01) of endometrium were significantly higher in CEH-pyometra group than those in the control group. The expression of 3β-HSD in CL was higher (29.38 ± 9.58% vs. 22.94 ± 4.97%) in CEH-pyometra group than that of control group although the differences were not significant (P > 0.05). Similarly, the significant increase in the expression of 3β-HSD in ovarian interstitial cells (33.86 ± 29.44 vs. 1.13 ± 2.97, P < 0.05) was found in CEH-pyometra group compared to the control group. The study revealed that 3β-HSD expression in the endometrium of canine CEH-pyometra was significantly high.

Sirtuin 4 Regulates Lipopolysaccharide Mediated Leydig Cell Dysfunction

Bacterial lipopolysaccharide (LPS) is the most important contributing factor in pathogenesis of bacterial infection in male accessory glands; and it has shown to inhibit testicular steroidogenesis and induce apoptosis. The present study demonstrates that LPS causes mitochondrial dysfunction via suppression of sirtuin 4 (SIRT4); which in turn affects Leydig cell function by modulating steroidogenesis and apoptosis. LC-540 Leydig cells treated with LPS (10 µg/ml) showed impaired steroidogenesis and increased cellular apoptosis. The mRNA and protein expression of SIRT4 were decreased in LPS treated cells when compared to controls. The obtained data suggest that the c-Jun N-terminal kinase (JNK) activation suppresses SIRT4 expression in LPS treated Leydig cells. Furthermore, the overexpression of SIRT4 prevented LPS induced impaired steroidogenesis and cellular apoptosis by improving mitochondrial function. These findings provide valuable information that SIRT4 regulates LPS mediated Leydig cell dysfunction.

LPS Induces Occludin Dysregulation in Cerebral Microvascular Endothelial Cells via MAPK Signaling and Augmenting MMP-2 Levels

Disrupted blood-brain barrier (BBB) integrity contributes to cerebral edema during central nervous system infection. The current study explored the mechanism of lipopolysaccharide- (LPS-) induced dysregulation of tight junction (TJ) proteins. Human cerebral microvascular endothelial cells (hCMEC/D3) were exposed to LPS, SB203580 (p38MAPK inhibitor), or SP600125 (JNK inhibitor), and cell vitality was determined by MTT assay. The proteins expressions of p38MAPK, JNK, and TJs (occludin and zonula occludens- (ZO-) 1) were determined by western blot. The mRNA levels of TJ components and MMP-2 were measured with quantitative real-time polymerase chain reaction (qRT-PCR), and MMP-2 protein levels were determined by enzyme-linked immunosorbent assay (ELISA). LPS, SB203580, and SP600125 under respective concentrations of 10, 7.69, or 0.22 µg/mL had no effects on cell vitality. Treatment with LPS decreased mRNA and protein levels of occludin and ZO-1 and enhanced p38MAPK and JNK phosphorylation and MMP-2 expression. These effects were attenuated by pretreatment with SB203580 or SP600125, but not in ZO-1 expression. Both doxycycline hyclate (a total MMP inhibitor) and SB-3CT (a specific MMP-2 inhibitor) partially attenuated the LPS-induced downregulation of occludin. These data suggest that MMP-2 overexpression and p38MAPK/JNK pathways are involved in the LPS-mediated alterations of occludin in hCMEC/D3; however, ZO-1 levels are not influenced by p38MAPK/JNK.