Short- and long-term effects of lipopolysaccharide-induced inflammation on rabbit sperm quality

The potential influence and intervention measures of gut microbiota on sperm: it is time to focus on testis-gut microbiota axis

As the global male infertility rate continues to rise, there is an urgent imperative to investigate the underlying causes of sustained deterioration in sperm quality. The gut microbiota emerges as a pivotal factor in host health regulation, with mounting evidence highlighting its dual influence on semen. This review underscores the interplay between the Testis-Gut microbiota axis and its consequential effects on sperm. Potential mechanisms driving the dual impact of gut microbiota on sperm encompass immune modulation, inflammatory responses mediated by endotoxins, oxidative stress, antioxidant defenses, gut microbiota-derived metabolites, epigenetic modifications, regulatory sex hormone signaling. Interventions such as probiotics, prebiotics, synbiotics, fecal microbiota transplantation, and Traditional natural herbal extracts are hypothesized to rectify dysbiosis, offering avenues to modulate gut microbiota and enhance Spermatogenesis and motility. Future investigations should delve into elucidating the mechanisms and foundational principles governing the interaction between gut microbiota and sperm within the Testis-Gut microbiota Axis. Understanding and modulating the Testis-Gut microbiota Axis may yield novel therapeutic strategies to enhance male fertility and combat the global decline in sperm quality.

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.

Dietary supplementation with n-3 polyunsaturated fatty acids: Effects on reproductive and productive performance and meat quality in rabbit breeding

Rabbit breeding has many critical aspects related to reproduction, production, and animal welfare, which reduce its profitability as well as consumer attractiveness. Dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) seems to be a good nutritional strategy to improve several aspects of rabbit breeding, enhance animal welfare and produce a new functional food considered healthy for human consumption. For this reason, the main available scientific research regarding the physiological effects of n-3 PUFA rich products supplemented to the rabbit diet will be reviewed. In particular, consequences on the reproductive performances of both doe and buck, the productive parameters, and the meat quality will be analysed.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

Seminal and histopathological alterations in bucks challenged with Mannheimia haemolytica serotype a2 and its LPS endotoxin

Pneumonic mannheimiosis is a widespread respiratory bacterial disease of small ruminants caused by Mannheimia haemolytica serotype A2. The disease is known to affect the respiratory organs of infected animals, but its effect on other vital and reproductive organs has not been fully explored. Previous studies have demonstrated increased serum pro-inflammatory cytokine concentration post-challenge with M. haemolytica A2 and its LPS, indicating systemic inflammation in the host. This study determined the potential tissue changes and alterations of sperm parameters due to infection of M. haemolytica A2 and its LPS endotoxin. In this study, twelve experimental bucks were randomly assigned to three groups of four bucks each: group 1 (control group) were intranasally inoculated with 2 mL of PBS pH 7.0, group 2 received 2 mL of 1.2 × 10⁹ CFU/mL M. haemolytica A2 intranasally, and group 3 received 2 mL of LPS extracted from 1.2 × 10⁹ CFU/mL of M. haemolytica A2 intravenously. Semen samples were collected at pre-determined intervals using an electro-ejaculator and analysed immediately after collection. All experimental bucks were slaughtered via exsanguination on day 60 to collect their vital and reproductive organs at necropsy, and the samples were processed and analysed for histopathological changes. The current study has revealed that bucks challenged with M. haemolytica A2 and its LPS exhibited alterations in semen parameters such as motility, wave pattern, viability, and morphological abnormalities. Mild to moderate histopathological changes of the lung, liver, testis, epididymis, vas deferens, prostate, and lymph nodes were also observed in both challenged groups. Therefore, this study revealed the potential harmful effects of respiratory mannheimiosis on the reproductive organs of the infected bucks and sheds light on the expanse of systemic effects of this disease.

Female presence does not increase testosterone but still ameliorates sickness behaviours in male Japanese quail

Infections can dramatically modify animal behaviour. The extent of these changes depends on an animal's environment. It has been proposed that testosterone modulates the suppression of behavioural symptoms of sickness under certain reproductive contexts. To further understand the role played by testosterone in modulating sickness behaviours under reproductive contexts, we studied a species, the Japanese quail, in which female exposure rapidly decreases circulating testosterone in males. Males received either an immune challenge (lipopolysaccharide - LPS) or a control injection and their behaviours, mass change and testosterone levels were quantified in the presence or absence of a female. Both the presence of a female and LPS treatment reduced testosterone levels. LPS-treated males maintained in isolation expressed expected sickness behaviours, including increased resting (quantified as crouching) and decreased food and water intake. Despite the reduction in testosterone, when paired with females LPS-treated males showed similar amounts of mating behaviours to controls and reduced crouching. In sum, even under very low levels of testosterone, male quail had reduced sickness behaviours when exposed to females, indicating that testosterone may not be key in modulating sickness behaviours, at least in this species.

Goji Berries Supplementation in the Diet of Rabbits and Other Livestock Animals: A Mini-Review of the Current Knowledge

In the last decades, several nutraceutical substances have received great attention for their potential role in the prevention and treatment of different diseases as well as for their beneficial effects in promoting the health of humans and animals. Goji berries (GBs) are the fruit of Lycium barbarum and other species of Lycium, used in traditional Chinese medicine, and they have recently become very popular in the Occidental world because of their properties, such as anti-aging, antioxidant, anticancer, neuroprotective, cytoprotective, antidiabetic, and anti-inflammatory activities. These effects are essentially evaluated in clinical trials in humans; in experimental animal models, such as mice and rats; and in cell lines in in vitro studies. Only recently has scientific research evaluated the effects of GBs diet supplementation in livestock animals, including rabbits. Although studies in the zootechnical field are still limited and the investigation of the GB mechanisms of action is in an early stage, the results are encouraging. This review includes a survey of the experimental trials that evaluated the effects of the GBs supplementation on reproductive and productive performances, immune system, metabolic homeostasis, and meat quality principally in the rabbit with also some references to other livestock animal species. Evidence supports the idea that GB supplementation could be used in rabbit breeding, although future studies should be conducted to establish the optimal dose to be administered and to assess the sustainability of the use of GBs in the diet of the rabbit.

The double-edged sword role of TGF-β signaling pathway between intrauterine inflammation and cranial neural crest development

Intrauterine infection would harm a developing embryo/fetus, thereby increasing the risk of developmental malformation. But, whether or not the infection-induced inflammation affects neural crest development still remains obscure. In this study, we employed meta-analysis to demonstrate the potential correlation between infection-induced inflammation and craniofacial anomalies, which was usually derived from the problems in neural crest cell development. The correlation was further verified by inflammatory cytokine release and the activation of nuclear factor kappa-light-chain enhancer of activated B cells signaling in lipopolysaccharide-treated HH10 chicken embryos. In such an inflammatory condition, AP-2α- and Pax7-labeled pre-migratory and migratory neural crest cells in HH10 chicken embryos were significantly less than the ones in control. The bioinformatics analysis of RNA-seq data demonstrated that the principal differential gene expression occurred in transforming growth factor-beta (TGF-β) signaling pathway, which was confirmed by the subsequent experimental results of quantitative PCR and immunofluorescent staining. Under this inflammatory circumstance, whole-mount in situ hybridization, immunofluorescence, and quantitative PCR showed the gene expression changes of key EMT-related transcription factors including upregulated Msx1, downregulated Slug, and FoxD3, as well as adhesion molecules and extracellular matrix protein including upregulated Cadherrin6B, E-cadherin, N-cadherin, and Laminin at the dorsal portion of neural tube of HH10 chicken embryos. Meanwhile, the bioinformatics analysis of RNA-seq data also manifested the differential gene expressions relevant to cell proliferation, which was confirmed by proliferating cell nuclear antigen Western blot data and co-immunofluorescence staining of human natural killer-1 and phosphorylated histone H3. In brief, this study revealed for the first time that the double-edged sword role of TGF-β signaling pathway between intrauterine inflammation (protective role) and cranial neural crest development (harmful role).

Effect of Goji Berry (Lycium barbarum) Supplementation on Reproductive Performance of Rabbit Does

Simple Summary

Infectious diseases represent serious problems for the reproductive performance of livestock animals because they negatively affect not only the welfare of the animals, but also the profitability of the farm. Moreover, the European Community continues to promote the reduction of the use of antibiotics and hormones in animal breeding. In this context, it is necessary to find new nutritional approaches to reduce the negative energy balance, and at the same time, to reinforce the immune system of the animals. In this research, the effect of goji berry supplementation on the reproductive activity and productive performance of rabbits is evaluated. Lycium barbarum fruit is considered a nutraceutical natural product containing various biologically active substances that show health benefits for both humans and animals. In particular, the berry can modulate hormones and metabolites involved in energy balance and reproduction, stimulate and balance the immune system activity, contributing to the defense of the organism against pathogens. Our results suggest that the integration with goji berry in the rabbit diet at 1% affects the reproductive activity, influencing the pattern secretion of luteinizing hormone (LH) and estrogens, as well as the sexual receptivity. Moreover, the fruit induced a higher milk production, improving the productive performance of young rabbits.

Abstract

Goji berry shows a wide range of beneficial properties in human health, but only a few studies evaluated its effects in livestock animals. The objective of this research was to assess the effects of goji berry supplementation on the hormonal profile, productive, and reproductive performance of does. Two months before artificial insemination, 105 nulliparous does were randomly divided into three groups (n = 35) based on the dietary treatment: commercial diet (C), or a diet supplemented with either 1% (G1), or 3% (G3) of goji berry, respectively. The results showed that receptivity was higher in G1 than in the C group (p < 0.05). Trends toward significance for differences between the G1 and G3 groups in marginal means of LH concentrations (p = 0.059), and between G1 and C in LH AUC values (p = 0.078), were evidenced. Estrogen concentrations showed a more fluctuating trend but a significant interaction effect (p < 0.001). The G1 group showed higher litter weight than C at birth (p = 0.008) and weaning (p < 0.001), as well as higher litter size at weaning (p = 0.020). The G1 group also exhibited the highest mean milk production (p < 0.01). In conclusion, goji berry influenced reproductive and productive performance, probably via modulating hormonal patterns and milk production in rabbits. However, further studies are needed to validate these preliminary results.

Oxidative and/or Inflammatory Thrust Induced by Silver Nanoparticles in Rabbits: Effect of Vitamin E or NSAID Administration on Semen Parameters

The aim of this research was to evaluate the inflammatory and/or oxidative damage related to silver nanoparticles (AgNPs), which are responsible for negative effects on sperm physiology and metabolism. Thirty New Zealand White rabbit bucks were divided into 5 experimental groups (6 animals/group): Control, treated with 0.9% NaCl; AgNP, treated with a 5 mM AgNP solution; LPS, treated with 50 g/kg b.w. E. coli LPS; AgNPs + NSAID, treated with an anti-inflammatory drug at 0.2 mg/kg b.w. and 5 mM AgNPs; and AgNPs + Vit E, treated with 0.18 mg/kg b.w. vitamin E and 5 mM AgNPs. Sperm quality and oxidative and inflammatory status were assessed at different times (0-60 days). Two statistical models were built: the first evaluated the effects of AgNPs and LPS (vs. Control), whereas the second evaluated the protective effect of an NSAID and vitamin E against AgNP-induced damage. Three principal component analyses were performed: sperm traits (motility, volume), oxidative status (antioxidants, oxidative metabolites, and redox reactions), and cytokines (TNF-α, IL-8, and IL-6). A negative effect on reproductive traits resulted after NP administration. In particular, an inflammatory/oxidative response took place in the reproductive tract during the first 2-3 wks of AgNP administration (cytokine and oxidative metabolite generation); the inflammatory/oxidative thrust impaired the status of rabbit tissues (seminal plasma, sperm, and blood), inducing a response (increased antioxidant enzymes and redox reactions) at 4-7 wks; oxidative stress, if not totally counteracted, likely induced toxicity in the late phases of AgNP administration (8-9 wks). In conclusion, exposure to silver nanoparticles produced a similar but more persistent effect than that of LPS on rabbit reproductive tissues: AgNP administration triggered a proinflammatory response linked to oxidative thrust, worsening many sperm parameters. However, only anti-inflammatory treatment counteracted the negative effects of AgNPs, whereas vitamin E seemed to act as an adjuvant, attenuating the oxidative cascade.

Effects of Diets Enriched in Linseed and Fish Oil on the Expression Pattern of Toll-Like Receptors 4 and Proinflammatory Cytokines on Gonadal Axis and Reproductive Organs in Rabbit Buck

Infections of the genital tract can perturb the fertility in humans and animals. Pathogen recognition and activation of innate immunity onset through the pattern recognition receptor activation, such as Toll-like receptor 4 (TLR4), leading to the production of proinflammatory cytokines and mediators. TLR4 is expressed both on leukocytes and nonimmune cells. Rabbit TLR4 shows great similarity to its human counterpart. Moreover, the TLR4 signalling pathway could be modulated by long-chain polyunsaturated fatty acids (LC-PUFA). The objectives of this study were (i) to determine the expression levels of TLR4 and proinflammatory cytokines in the reproductive hypothalamic-gonadal axis of the male rabbit and (ii) to evaluate if the n-3 PUFA-enriched diets can modify their expression levels in the tissues and LC-PUFA profiles in seminal plasma. Fifteen rabbit bucks (n = 5/experimental group) were fed with different diets: commercial standard (group C), rich in extruded linseed (10%, group L), and in fish oil (3%, group FO) for 110 days. TLR4, TNF-α, and IL-1β mRNA were ubiquitously expressed throughout the hypothalamic-gonadal axis. However, TLR4 mRNA expression was lower in the hypothalamus than the epididymis (P < 0.01), seminal vesicles (P < 0.01), and pituitary gland (P < 0.05). Dietary enrichment in PUFA did not modify the gene expression profile nor the histological characteristics of the tissues. Conversely in seminal plasma, rabbits fed with L and FO had lower n-6 (P < 0.05), LC-PUFA n-6 (P < 0.05), and n-6/n-3 ratio (P < 0.05) but higher n-3 (P < 0.001) and LC-PUFA n-3 (P < 0.01) compared to the control group. Our study builds a map of the gene expression of TRL4 and proinflammatory cytokines in the reproductive hypothalamic-gonadal axis of the male rabbit, fundamental step for understanding the immune defence mechanisms. Diets enriched in LC-PUFA did not affect basal gene expression but modulated sperm fatty acid composition. Finally, rabbit may be an excellent animal model to study the relationship between inflammation and infertility, and the nutritional modulation of immune functions.

Effect of Dietary n-3 Source on Rabbit Male Reproduction

In the last two decades, the human sperm count linearly decreased in Western countries. Health problems, lifestyle, pollutants, and dietary behaviours are considered as the main risk factors, and the unbalance of dietary n‐6/n‐3 fatty acids is one of the most relevant. The aim of the present research is to study the effect of different dietary sources of n‐3 polyunsaturated fatty acids (PUFA) on reproductive traits using rabbit buck as the animal model. Fifteen rabbit bucks were assigned to three experimental groups: the control group, the FLAX group fed 10% extruded flaxseed, and the FISH group fed 3.5% fish oil for 110 days (50-day adaptation and 60-day experimental periods). Semen samples were collected weekly, whereas blood was collected every two weeks for the analytical determination of semen traits, oxidative status, fatty acid profiles, isoprostanes, neuroprostanes, and the immunocytochemistry of docosahexaenoic acid (DHA) and eicosapentaenoic (EPA) acid. At the end of the trial, the rabbits were killed and the testes were removed and stored for the analysis of fatty acid profile and immunocytochemistry. Results showed that dietary administration of n‐3 PUFA improved the track speed of the sperm and increased the n‐3 long-chain PUFA mainly confined in the sperm tail. Seminal plasma increased the thiobarbituric reactive substances (TBARs) by three times in the groups fed supplemental n‐3, whereas the F₂-isoprotanes (F₂-IsoPs) and F₄-neuroprostanes (F₄-NeuroPs) were lower and higher, respectively, in both supplemented groups than in the control. The testes and sperm showed a higher DHA and EPA distribution in rabbits from the n‐3 supplemented groups compared with the control. In conclusion, supplemental dietary n‐3 PUFA improved sperm motion traits and resulted in an enrichment of membrane fatty acid in the sperm and testes of the rabbits. However, such an increased amount of PUFA negatively affected the sperm oxidative status, which was mainly correlated with the generation of F₄-NeuroPs with respect to F₂-IsoPs. Accordingly, the latter cannot be considered a good marker of oxidation when diets rich in n‐3 PUFA are provided.

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.

n-3 PUFA Sources (Precursor/Products): A Review of Current Knowledge on Rabbit

This review compares the effects of different n-3 polyunsaturated fatty acid (PUFA) sources on biological activity, physiological/reproductive endpoints, and health implications with a special emphasis on a rabbit case study. Linoleic acid (LA) and α-linolenic acid (ALA) are members of two classes of PUFAs, namely the n-6 and n-3 series, which are required for normal human health. Both are considered precursors of a cascade of molecules (eicosanoids), which take part in many biological processes (inflammation, vasoconstriction/vasodilation, thromboregulation, etc.). However, their biological functions are opposite and are mainly related to the form (precursor or long-chain products) in which they were administered and to the enzyme-substrate preference. ALA is widely present in common vegetable oils and foods, marine algae, and natural herbs, whereas its long-chain PUFA derivatives are available mainly in fish and animal product origins. Recent studies have shown that the accumulation of n-3 PUFAs seems mostly to be tissue-dependent and acts in a tissue-selective manner. Furthermore, dietary n-3 PUFAs widely affect the lipid oxidation susceptibility of all tissues. In conclusion, sustainable sources of n-3 PUFAs are limited and exert a different effect about (1) the form in which they are administered, precursor or derivatives; (2) their antioxidant protections; and (3) the purpose to be achieved (health improvement, physiological and reproductive traits, metabolic pathways, etc.).

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.

Efficacy of Phage Therapy in Controlling Rabbit Colibacillosis and Changes in Cecal Microbiota

Phage therapy is a valid weapon that we could use to fight against pathogens. Bacteriophages kill bacteria and self-proliferate in the digestive tract. Furthermore, it was assumed that phage therapy could preserve the existing gut microbiota. In this study, 45 rabbits were equally divided into three groups after they were orally inoculated with pathogenic Escherichia coli to induce gut infection. Each group was treated with bacteriophage ZRP1 (Group P), ciprofloxacin lactate (Group A), or phosphate-buffered solution (PBS) (Group N). Another 15 healthy rabbits composed the control group (Group C). The body weight gain decreased significantly, but the white blood cell (WBC) count, especially the percentage of large WBCs, and the serum endotoxin levels increased significantly after infection. The result of microscopic examination of the ileum showed that E. coli ZR1 adhered to villi and caused hemorrhage inside the villi. Groups P and A rabbits recovered after treatments, and both bacteriophage and antibiotic treatment significantly decreased the eaeA gene concentration in cecal contents. The microbiota in cecal contents changed in infected rabbits that were treated with PBS. The relative abundance of Clostridiales and YS2 decreased but the relative abundance of Enterobacteriales increased significantly. According to the principal components analysis, the microbiota of Groups P and C rabbits were similar to one another in type and relative abundance but different from those of Groups N and A rabbits. The results demonstrated that oral administration of bacteriophage can cure gut infection with minimal impact on the cecal microbiota.

Human sperm Toll-like receptor 4 (TLR4) mediates acrosome reaction, oxidative stress markers, and sperm parameters in response to bacterial lipopolysaccharide in infertile men

PURPOSE

To study the role of Toll-like receptor 4 (TLR4) in human spermatozoa and to assess sperm parameters, oxidative stress markers, and acrosome reaction in response to the stimulation of TLR4 by its ligand, the lipopolysaccharide (LPS), as a major endotoxin of Gram-negative bacteria.

METHODS

Our study was carried out in 73 sperm samples from patients undergoing semen analysis for couple infertility investigations. The studied patients were divided into three groups: normozoospermic fertile patients (n = 13), patients with abnormal and leukospermic semen (n = 13), and patients with abnormal and non-leukospermic semen (n = 47). TLR4 expression in human spermatozoa was initially analyzed by western blot. Sperm samples were incubated in the presence of LPS (200 ng/ml) for 18 h. Then, sperm motility and vitality were evaluated by microscopic observation and oxidative stress markers as malondialdehyde (MDA) and carbonyl groups (CG) were spectrophotometrically assessed in neat and selected sperm. A triple-stain technique was also performed to evaluate acrosome reaction in 15 sperm samples from infertile patients.

RESULTS

TLR4 expression was confirmed in human spermatozoa with a molecular weight of 69 kDa. In the normozoospermic group, no significant differences in sperm parameters and oxidative stress markers were shown after incubation with LPS in neat and selected sperms. Regarding samples from the non-leukospermic group, LPS reduced spermatozoa motility and vitality rates in selected sperm (P = 0.003; P = 0.004, respectively). A significant increase of MDA and CG levels was also detected (P = 0.01; P = 0.02, respectively). However, only the MDA levels were significantly increased (P = 0.01) in neat LPS-stimulated sperm. The same results were shown within the leukospermic group. The comparison between the two groups, leukospermic and non-leukospermic, in selected sperms showed a more important LPS effect in the leukospermic group significantly on motility and MDA rates (P = 0.006; P = 0.009, respectively). Furthermore, a significant decrease in reacted spermatozoa rate was detected in response to LPS in selected sperm samples from infertile men (P = 0.03).

CONCLUSIONS

These findings indicate that human spermatozoa express TLR4 and respond to LPS stimulation with alterations in viability, motility, and the acrosome reaction implicating reactive oxygen species (ROS) production in sperm samples from infertile patients.

The upregulation of pro-inflammatory cytokines in the rabbit uterus under the lipopolysaccaride-induced reversible immunoresponse state

The reproductive organs are more likely to develop gram-negative bacterial infection than other internal organs because of direct access to the body surface. The objective of this study was (1) to provide a suitable intravenous injection dose of lipopolysaccharides (LPS) instead of gram-negative bacterial infection in order to induce a reversible immunoresponse state and (2) to examine the expression levels of pro-inflammatory cytokines in the uterus of rabbits while in an immunoresponse state. Two series of experiments were performed to accomplish these objectives. In the first series, 20 healthy New Zealand White female rabbits were divided into 5 homogeneous groups (n=4), and intravenously injected with 0, 0.5, 1, 2, or 4mg/kg body weight (BW) of LPS derived from Escherichia coli dissolved in 2ml of sterile saline (LPS carrier). The control group received only saline. The concentrations of IL-1β, IL-6, and TNF-α in serum and the white blood cell count changed with time after LPS stimulation, and certain doses of LPS led to the death of some rabbits. The results suggested that a dose of 0.5mg/kg of LPS induced a reversible immunoresponse state. In the second series, 4 rabbits were not injected (0h), 16 rabbits were injected with 0.5mg/kg LPS, and 16 rabbits in the control group were injected with 2ml of sterile saline. Tissues of the uterine horn, uterine body, and cervix from the 36 rabbits were collected at 0, 1.5, 3, 6, and 12h (n=4) postinjection for examination of the expression levels of IL-1β, IL-6, and TNF-α by quantitative real-time PCR (qRT-PCR). The results suggested that 0.5mg/kg of LPS upregulated the expression levels of IL-1β, IL-6 and TNF-α in the uterine body and uterine horn, and IL-6 in the cervix. In conclusion, the expression levels of IL-1β, IL-6 and TNF-α were upregulated in the uterus of rabbits under the reversible immunoresponse state induced by 0.5mg/kg of LPS-injection.

Lipopolysaccharide Compromises Human Sperm Function by Reducing Intracellular cAMP

A worldwide decline in the quality of human semen is currently occurring. In mammals, sperm are produced from diploid stem-cell spermatogonia by spermatogenesis in testes and become mature in epididymis. Nevertheless, these biological processes can be affected by Gram-negative bacterial infection mediated by lipopolysaccharide (LPS), the major endotoxin of Gram-negative bacteria. It is well known that LPS can disturb spermatogenesis and affect sperm maturation and quality in vivo. However, the effect of LPS on the ejaculated mature sperm in vitro remains unclear. Thus, this study aimed to assess the in vitro toxicity of LPS on human sperm function and to elucidate the underlying mechanism. Human sperm were incubated with LPS (0.1-100 μg/ml) for 1-12 h in vitro and, subsequently, sperm viability, motility and capacitation, and the acrosome reaction were examined. LPS dose-dependently inhibited total and progressive motility and the ability to move through a viscous medium of the sperm but did not affect sperm viability, capacitation, and the acrosome reaction. To explore the underlying mechanism of LPS's actions, we examined the effects of LPS on the intracellular concentrations of cyclic adenosine monophosphate (cAMP) and calcium ([Ca(2+)]i) and protein-tyrosine phosphorylation of human sperm, which are key regulators of human sperm function. LPS decreased intracellular cAMP dose-dependently but had no effect on [Ca(2+)]i and protein-tyrosine phosphorylation of human sperm. These findings suggest that LPS inhibits human sperm motility by decreasing intracellular cAMP.

The Protective Effects of Melatonin Against Oxidative Stress and Inflammation Induced by Acute Cadmium Exposure in Mice Testis

Cadmium (Cd) is widely used in daily life and was recently recognized as a possible source of human toxicity due to its ability to accumulate in organs. Previous studies have shown that Cd exposure may cause testicular toxicity through oxidative stress and an inflammatory effect. Melatonin has been demonstrated to be an effective anti-oxidant and has an anti-inflammatory effect. The aim of the present study was to investigate the toxicological effects of Cd on reproduction in male mice and the potential protective action of melatonin against these adverse effects. Adult male mice were injected intraperitoneally with Cd at a dose of 2 mg/kg body weight per day for seven consecutive days with or without melatonin pretreatment. Sex organ weight, sperm parameters including sperm quality, apoptosis, acrosome integrity, mitochondrial membrane potential, testicular morphology, serum sex hormone, inflammatory status, and oxidative stress were evaluated. The results showed that significant adverse effects were observed in the male reproductive system after Cd exposure, including alterations in sperm parameters, increased DNA damage, and sex hormone disturbance. Acute Cd exposure also significantly increased malondialdehyde (MDA) contents, decreased glutathione (GSH) and superoxide dismutase (SOD) activities, and upregulated levels of the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), and interleukin-1beta (IL-1β), in the testis. In contrast, melatonin pretreatment significantly alleviated these toxic effects, and its mechanism may involve inhibiting MDA level, restoring GSH and SOD activities, and reducing the upregulation of TNF-α and IL-1β. Our data suggest that oxidative stress and inflammation are involved in Cd-induced toxicity in the male reproductive system and that co-administration of melatonin exerts a protective effect against Cd-induced male reproductive toxicity.

Cytokines release and oxidative status in semen samples from rabbits treated with bacterial lipopolysaccharide

This study was aimed to evaluate the effects of a lipopolysaccharide- (LPS) induced inflammation on cytokines release and oxidative status of semen samples from buck rabbits at different times after treatment. Semen analysis was performed by optical microscopy and sperm motility evaluation by the computer-assisted sperm analyzer. The presence of activated macrophages and apoptotic/necrotic sperm was evaluated by fluorescent microscopy. A panel of cytokines, interleukin (IL)-6, IL-8, IL-1β, and tumor necrosis factor-α, were detected and quantified in seminal plasma using the Bio-Plex Cytokine assay. Reactive oxygen metabolite and thiobarbituric acid-reactive substance determinations were carried out by spectrophotometry and tocopherol analysis by high performance liquid chromatography. The sperm motility and track speed were reduced in LPS-treated rabbits. The activated macrophages in LPS-treated buck rabbits significantly increased from 0.50 × 10(6)/mL (baseline) to 27 × 10(6)/mL on Day 21; successively, there was a progressive reduction. Apoptotic and necrotic sperm in LPS rabbits followed more or less the same trend. The reactive oxygen metabolite levels in semen from LPS-treated rabbits showed higher values compared with those evaluated in controls, particularly during the lag time, Days 1 to 3. The sperm thiobarbituric acid-reactive substances highlighted a peak in LPS-treated rabbits compared with those of controls on Day 1 after LPS treatment, and the different T isoforms (α, δ, and γ+β) showed a similar trend with a significant decrease on Day 1 after injection and a recovery on Days 30 to 56. Until Days 3 to 21 from the treatment, higher levels of IL-1β and tumor necrosis factor-α were detected in seminal plasma of LPS-treated rabbits. Interleukin-6 showed a peak on Day 3 after LPS treatment, and on Day 7, the value was similar to the control group. In conclusion, this study confirms that the buck rabbit is a good model for mimicking and understanding the inflammation mechanisms, which may induce male infertility, in particular that a systemic inflammatory status causes alterations to the sperm cells through a shift in the balance between the oxidant and antioxidant systems.

Effects of red palm oil and rooibos on sperm motility parameters in streptozotocin-induced diabetic rats

BACKGROUND

Diabetes mellitus characterized by hyperglycaemia could affect sperm quality as a result of increased oxidative stress. This study was performed to investigate the effects of red palm oil (RPO), aqueous rooibos tea extracts (RTE) as well as their combination (RPO + RTE) on sperm motility parameters in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced by a single administration of streptozotocin (50 mg/kg) and the rats were treated with red palm oil (2 ml/day) and / or aqueous rooibos tea extract (2%) for 7 weeks. Sperm motility parameters were measured using Computer Assisted Sperm Analyzer (CASA).

RESULTS

Hyperglycaemia negatively affected the sperm progressive motility significantly at p<0.05. There was a significant decrease (p<0.05) in sperm linearity (LIN) in the diabetic group when compared with the normal control group. RPO supplemented diabetic rats exhibited increased progressive sperm motility, sperm linearity (LIN) and wobble (WOB). Significant decreases (p<0.05) in straight line velocity (VSL) and average path velocity (VAP) of the sperms were observed in all the diabetic groups when compared to the control group. Significant (p<0.05) elevated levels of WOB and LIN were observed following RTE treatment and co-administration with RPO respectively.

CONCLUSION

The present study suggests that red palm oil and / or rooibos administration exhibited no adverse effects on sperm motility parameters but rather showed some beneficial effects.

Effects of a bacterial lipopolysaccharide on the reproductive functions of rabbit does

Systemic and local infections and inflammations are known to cause infertility in humans and animals. However, the mechanisms by which infection/inflammation induces infertility are only partially known. The objectives of this study were: (i) to provide models of systemic (acute) and local (sub-acute) inflammation by intra-peritoneal injection or intra-cervical deposition of lipopolysaccharide (LPS) in the rabbit and (ii) to assess their effects on uterine tissues and sperm transport in the genital tract of rabbit does. Intra-peritoneal administration of different doses of LPS induced systemic effects such as fever, anorexia and changes in white blood cells (WBC) count. In our study, LPS inoculation (100μg/kg) produced an inflammation-like status that lasted for about 3 days, with minimal distress for the animals. Intra-peritoneal administration of LPS 60h before artificial insemination induced a rapid increase of IL-1β concentrations. The intra-cervical inoculation of LPS did not show any systemic effects, as confirmed by the lack of changes in body temperature, feed intake and WBC count. Histological examination of uterine tissues showed an endometritis-like inflammation status in LPS-treated does, more severe in those inoculated intra-cervically. The number of spermatozoa recovered from uterine horns and oviducts of intra-cervically treated does was less than that retrieved from intra-peritoneally treated animals and controls. These results suggest (i) that sub-acute or acute inflammation may cause infertility by compromising the uterine environment and/or impairing sperm transport and (ii) that the LPS-induced -infection/inflammation experimental model is useful for studying the mechanisms involved in reproductive dysfunctions in the rabbit.

Effect of chocolate and Propolfenol on rabbit spermatogenesis and sperm quality following bacterial lipopolysaccharide treatment

The aims of the study were to evaluate the effects of chocolate and propolis-enriched diets on rabbit spermatogenesis, sperm motility, and ultrastructure following bacterial lipopolysaccharide (LPS) treatment. Thirty-two New Zealand White rabbits were divided into four groups. The LPS-Propolfenol(®) group received propolis (500 mg/kg/day) in their diet for 15 days, while the LPS-chocolate group was fed 70% cacao chocolate (1 g/1 kg/day) for the same period. Following the diet treatments, rabbits in the LPS-Propolfenol(®) and LPS-chocolate groups, and an LPS group received a single intraperitoneal dose of 50 μg/kg LPS, and the control group received only saline. Kinematic sperm traits were evaluated with a computer assisted sperm analyzer (CASA) system, and ultrastructural characteristics were examined by transmission electron microscopy (TEM). Testicular and epididymal tissues were observed by light microscopy and TEM and multiplex real time reverse transcriptase-polymerase chain reaction (RT-PCR) assay was used to detect and quantify toll-like receptor-4 (TLR-4) gene expression. The values of the analyzed semen parameters of rabbits treated with LPS-Propolfenol(®) and LPS-chocolate did not show any variations compared with the control group, but they were lower in rabbits treated only with LPS. Alterations observed in the testicular tissue of LPS treated-rabbits were not detected in specimens from the LPS-chocolate and LPS-Propolfenol(®) groups, which showed normal spermatogenesis. The TLR-4 mRNA expression was similar in controls, in LPS treated, and in LPS-chocolate groups, but it was significantly (p < 0.01) decreased in LPS-Propolfenol(®) rabbits. In conclusion, a chocolate and propolis-enriched diet showed a protective effect on the spermatogenetic process of buck rabbits following LPS treatment.

Lipopolysaccharide inhibits the self-renewal of spermatogonial stem cells in vitro via downregulation of GDNF expression in Sertoli cells

Lipopolysaccharide (LPS) can reduce sperm count and sperm quality. The molecular mechanisms underlying this process are not fully understood. In this report, we investigated the effects of LPS-treated Sertoli cells on self-renewal and differentiation of spermatogoinial stem cells (SSCs). Sertoli cell cultures were established and incubated with LPS (10μg/ml) for 1, 2 or 3 days, respectively. The culture media were collected and used as conditioned media (CM) to culture SSCs. The expression of glial cell-derived neurotrophic factor (GDNF), stem cell factor (SCF) and bone morphogenetic protein 4 (BMP4) in Sertoli cells treated with LPS was analyzed by RT-PCR and Western blotting. The results showed that the expression of SSC differentiation markers, c-kit and Sohlh2, was increased, while the expression of SSC self-renewal markers, plzf, oct4, and PCNA, was repressed when cultured in CM from LPS-treated Sertoli cells. GDNF levels in Sertoli cells and CM reduced dramatically after LPS treatments, while SCF and BMP4 levels did not show any significant changes. Moreover, correlated with the GDNF levels in CM, GDNF target genes, Bcl6b and Etv5, were reduced markedly in SSCs. Our results suggest that LPS inhibits the expression of GDNF in Sertoli cells, and might prevent the SSC self-renewal via down-regulation of GDNF target genes.

Immune activation reduces sperm quality in the great tit

Mounting an immune response against pathogens incurs costs to organisms by its effects on important life-history traits, such as reproductive investment and survival. As shown recently, immune activation produces large amounts of reactive species and is suggested to induce oxidative stress. Sperm are highly susceptible to oxidative stress, which can negatively impact sperm function and ultimately male fertilizing efficiency. Here we address the question as to whether mounting an immune response affects sperm quality through the damaging effects of oxidative stress. It has been demonstrated recently in birds that carotenoid-based ornaments can be reliable signals of a male's ability to protect sperm from oxidative damage. In a full-factorial design, we immune-challenged great tit males while simultaneously increasing their vitamin E availability, and assessed the effect on sperm quality and oxidative damage. We conducted this experiment in a natural population and tested the males' response to the experimental treatment in relation to their carotenoid-based breast coloration, a condition-dependent trait. Immune activation induced a steeper decline in sperm swimming velocity, thus highlighting the potential costs of an induced immune response on sperm competitive ability and fertilizing efficiency. We found sperm oxidative damage to be negatively correlated with sperm swimming velocity. However, blood resistance to a free-radical attack (a measure of somatic antioxidant capacity) as well as plasma and sperm levels of oxidative damage (lipid peroxidation) remained unaffected, thus suggesting that the observed effect did not arise through oxidative stress. Towards the end of their breeding cycle, swimming velocity of sperm of more intensely colored males was higher, which has important implications for the evolution of mate choice and multiple mating in females because females may accrue both direct and indirect benefits by mating with males having better quality sperm.