Lipopolysaccharide Stimulates the Growth of Bacteria That Contribute to Ruminal Acidosis

Effects of Embryonic Thermal Manipulation on Body Performance and Cecum Microbiome in Broiler Chickens Following a Post-Hatch Lipopolysaccharide Challenge

Thermal manipulation (TM) during embryogenesis has emerged as a promising strategy to enhance post-hatch performance and improve resilience to environmental and bacterial stress, which offers a potential alternative to reduce the reliance on antibiotic growth promoters (AGPs) in broiler production. This study investigated TM's ability to modulate broilers' cecal microbiota and enhance resilience to lipopolysaccharide (LPS)-induced stress. Eggs in the control group (CON) were incubated at 37.8 °C and 56% relative humidity (RH), while TM eggs were exposed to 39 °C and 65% RH for 18 h daily from embryonic days 10-18. Post-hatch, the LPS subgroups (LPS-CON, LPS-TM) received intraperitoneal LPS injections, and body weight (BW) and temperature (BT) were monitored. Cecal samples were collected for microbiome sequencing. Alpha diversity showed no differences (p > 0.05), but beta diversity revealed differences between groups (PERMANOVA, p < 0.05). Firmicutes and Bacteroidota dominated the microbiota at the phylum level. Oscillospirales were enriched in the TM groups (p < 0.001) and Lactobacillales were increased in the LPS-CON group (p < 0.019). LPS reduced BT in the CON group (p < 0.01), but LPS-TM birds bypassed hypothermia. LPS significantly reduced BW (p < 0.001), while TM had no significant effect. These findings demonstrate TM's enduring influence on gut microbiota and stress resilience, highlighting its potential to reduce antibiotic reliance and mitigate antimicrobial resistance (AMR) in poultry production.

Metagenomic analysis reveals microbial drivers of heat resistance in dairy cattle

Heat stress poses a significant challenge to dairy cattle, leading to adverse physiological effects, reduced milk yield, impaired reproduction performance and economic losses. This study investigates the role of the rumen microbiome in mediating heat resistance in dairy cows. Using the entropy-weighted TOPSIS method, we classified 120 dairy cows into heat-resistant (HR) and heat-sensitive (HS) groups based on physiological and biochemical markers, including rectal temperature (RT), respiratory rate (RR), salivation index (SI) and serum levels of potassium ion (K+), heat shock protein 70 (HSP70) and cortisol. Metagenomic sequencing of rumen fluid samples revealed distinct microbial compositions and functional profiles between the two groups. HR cows exhibited a more cohesive and functionally stable microbiome, dominated by taxa such as Ruminococcus flavefaciens and Succiniclasticum, which are key players in fiber degradation and short-chain fatty acid production. Functional analysis highlighted the enrichment of the pentose phosphate pathway (PPP) in HR cows, suggesting a metabolic adaptation that enhances oxidative stress management. In contrast, HS cows showed increased activity in the tricarboxylic acid (TCA) cycle, pyruvate metabolism and other energy-intensive pathways, indicating a higher metabolic burden under heat stress. These findings underscore the critical role of the rumen microbiome in modulating heat resistance and suggest potential microbiome-based strategies for improving dairy cattle resilience to climate change.

Maternal Roughage Sources Influence the Gastrointestinal Development of Goat Kids by Modulating the Colonization of Gastrointestinal Microbiota

During pregnancy and lactation, maternal nutrition is linked to the full development of offspring and may have long-term or lifelong effects. However, the influence of the doe's diet on the gastrointestinal (GI) tract of young kids remains largely unexplored. Therefore, we investigated the effects of doe roughage sources (alfalfa hay, AH, or corn straw, CS) during pregnancy and lactation on kid growth, GI morphology, barrier function, metabolism, immunity, and microbiome composition. The results indicate that, compared with the CS group, does fed an AH diet had significantly higher feed intake (p < 0.01). However, CS-fed does exhibited higher neutral detergent fiber (NDF) digestibility (p < 0.05). There were no significant differences in animal (doe or kid) weight among the groups (p > 0.05). In the rumen of goat kids, the AH group exhibited a higher papillae width and increased levels of interleukin-10 (IL-10) compared with the CS group (p < 0.05). In the jejunum of goat kids, the AH group showed a higher villus-height-to-crypt-depth (VH/CD) ratio, as well as elevated levels of secretory immunoglobulin A (SIgA), immunoglobulin G (IgG), IL-10, acetate, and total volatile fatty acids (TVFAs), when compared with the CS group (p < 0.05). Transcriptome analysis revealed that the source of roughage in does was associated with changes in the GI transcriptome of the kids. Differentially expressed genes (DEGs) in the rumen were mainly associated with tissue development and immune regulation, while the DEGs in the jejunum were mainly associated with the regulation of transferase activity. Spearman correlation analyses indicated significant associations between GI DEGs and phenotypic indicators related to GI development, immunity, and metabolism. LEfSe analysis identified 14 rumen microbial biomarkers and 6 jejunum microbial biomarkers. Notably, these microorganisms were also enriched in the rumen or day 28 milk of the does. Further microbial composition analysis revealed significant correlations between the rumen and milk microbiomes of does and the rumen or jejunum microbiomes of kids. Association analyses indicated that microbial biomarkers interact with host genes, thereby affecting the development and function of the GI system. Additionally, correlation analyses revealed significant association between milk metabolites and the rumen and jejunum microbiomes of kids. This study demonstrated that maternal diet significantly influences the development of microbial ecosystems in offspring by modulating microbial communities and metabolite composition. The early colonization of GI microorganisms is crucial for the structural development, barrier function, immune capacity, and microbial metabolic activity of the GI system.

Strontium Attenuates LPS-Induced Inflammation via TLR4/MyD88/NF-κB Pathway in Bovine Ruminal Epithelial Cells

Subacute ruminal acidosis (SARA) is a common nutritional metabolic disease in ruminants that causes significant economic losses to dairy farming. Strontium (Sr) is known to be involved in bone metabolism and exhibits potent anti-inflammatory effects. To evaluate the effect of Sr on inflammation in bovine ruminal epithelial cells, a model of LPS-induced inflammation was established in this study, and the cell viability of bovine ruminal epithelial cells was measured using CCK-8. The production of pro-inflammatory cytokines was measured by ELISA and real-time PCR, respectively. The related proteins of the TLR4/MyD88/NF-κB pathway were assayed through Western blotting, and the fluorescence of p-p65 and p-IκB were assayed by immunofluorescence. Molecular docking of Sr and TLR4/MyD88/NF-κB pathway-related proteins was performed using MIB2 ( http://bioinfo.cmu.edu.tw/MIB2/ ). Results showed that after treatment for 24 h, the cell viability was decreased at the high concentration of Sr (≥ 10 mmol/L). Sr significantly decreased the production of TNF-α, IL-1β, and IL-6, downregulated the related proteins expression of the TLR4/MyD88/NF-κB pathway, and reduced the fluorescence levels of p-p65 and p-IκB. The NF-κB pathway inhibitor PDTC and molecular docking further revealed that Sr reduced LPS-induced pro-inflammatory cytokines production via the TLR4/MyD88/NF-κB pathway. These results suggest that Sr reduces LPS-induced pro-inflammatory cytokines production via the TLR4/MyD88/NF-κB pathway, thereby exerting an anti-inflammatory effect in bovine ruminal epithelial cells, providing a basis for Sr in the treatment of bovine rumen acidosis disease.

Ochratoxin A induces abnormal tryptophan metabolism in the intestine and liver to activate AMPK signaling pathway

BACKGROUND

Ochratoxin A (OTA) is a mycotoxin widely present in raw food and feed materials and is mainly produced by Aspergillus ochraceus and Penicillium verrucosum. Our previous study showed that OTA principally induces liver inflammation by causing intestinal flora disorder, especially Bacteroides plebeius (B. plebeius) overgrowth. However, whether OTA or B. plebeius alteration leads to abnormal tryptophan-related metabolism in the intestine and liver is largely unknown. This study aimed to elucidate the metabolic changes in the intestine and liver induced by OTA and the tryptophan-related metabolic pathway in the liver.

MATERIALS AND METHODS

A total of 30 healthy 1-day-old male Cherry Valley ducks were randomly divided into 2 groups. The control group was given 0.1 mol/L NaHCO3 solution, and the OTA group was given 235 μg/kg body weight OTA for 14 consecutive days. Tryptophan metabolites were determined by intestinal chyme metabolomics and liver tryptophan-targeted metabolomics. AMPK-related signaling pathway factors were analyzed by Western blotting and mRNA expression.

RESULTS

Metabolomic analysis of the intestinal chyme showed that OTA treatment resulted in a decrease in intestinal nicotinuric acid levels, the downstream product of tryptophan metabolism, which were significantly negatively correlated with B. plebeius abundance. In contrast, OTA induced a significant increase in indole-3-acetamide levels, which were positively correlated with B. plebeius abundance. Simultaneously, OTA decreased the levels of ATP, NAD+ and dipeptidase in the liver. Liver tryptophan metabolomics analysis showed that OTA inhibited the kynurenine metabolic pathway and reduced the levels of kynurenine, anthranilic acid and nicotinic acid. Moreover, OTA increased the phosphorylation of AMPK protein and decreased the phosphorylation of mTOR protein.

CONCLUSION

OTA decreased the level of nicotinuric acid in the intestinal tract, which was negatively correlated with B. plebeius abundance. The abnormal metabolism of tryptophan led to a deficiency of NAD+ and ATP in the liver, which in turn activated the AMPK signaling pathway. Our results provide new insights into the toxic mechanism of OTA, and tryptophan metabolism might be a target for prevention and treatment.

Invited review: Rumen modifiers in today's dairy rations

Our aim was to review feed additives that have a potential ruminal mechanism of action when fed to dairy cattle. We discuss how additives can influence ruminal fermentation stoichiometry through electron transfer mechanisms, particularly the production and usage of dihydrogen. Lactate accumulation should be avoided, especially when acidogenic conditions suppress ruminal neutral detergent fiber digestibility or lead to subclinical acidosis. Yeast products and other probiotics are purported to influence lactate uptake, but growing evidence also supports that yeast products influence expression of gut epithelial genes promoting barrier function and resulting inflammatory responses by the host to various stresses. We also have summarized methane-suppressing additives for potential usage in dairy rations. We focused on those with potential to decrease methane production without decreasing fiber digestibility or milk production. We identified some mitigating factors that need to be addressed more fully in future research. Growth factors such as branched-chain volatile fatty acids also are part of crucial cross-feeding among groups of microbes, particularly to optimize fiber digestibility in the rumen. Our developments of mechanisms of action for various rumen-active modifiers should help nutrition advisors anticipate when a benefit in field conditions is more likely.

Gut dysbiosis induces the development of mastitis through a reduction in host anti-inflammatory enzyme activity by endotoxemia

BACKGROUND

Mounting experimental evidence has shown that the gut microbiota plays a significant role in the pathogenesis of mastitis, and clinical investigations have found that the occurrence of mastitis is correlated with ruminal dysbiosis. However, the underlying mechanism by which the ruminal microbiota participates in the development of mastitis remains unknown.

RESULTS

In the present study, we found that cows with clinical mastitis had marked systemic inflammation, which was associated with significant ruminal dysbiosis, especially enriched Proteobacteria in the rumen. Ruminal microbiota transplantation from mastitis cows (M-RMT) to mice induced mastitis symptoms in recipient mice along with increased mammary proinflammatory signature activation of the TLR4-cGAS-STING-NF-κB/NLRP3 pathways. M-RMT also induced mucosal inflammation and impaired intestinal barrier integrity, leading to increased endotoxemia and systemic inflammation. Moreover, we showed that M-RMT mirrored ruminal microbiota disruption in the gut of recipient mice, as evidenced by enriched Proteobacteria and similar bacterial functions, which were correlated with most proinflammatory parameters and serum lipopolysaccharide (LPS) levels in mice. Recurrent low-grade LPS treatment mirrored gut dysbiosis-induced endotoxemia and caused severe mastitis in mice. Furthermore, we found that gut dysbiosis-derived LPS reduced host alkaline phosphatase activity by activating neuraminidase (Neu), which facilitates low-grade LPS exposure and E. coli-induced mastitis in mice. Conversely, treatment with calf intestinal alkaline phosphatase or the Neu inhibitor zanamivir alleviated low-grade LPS exposure and E. coli-induced mastitis in mice.

CONCLUSIONS

Our results suggest that ruminal dysbiosis-derived low-grade endotoxemia can cause mastitis and aggravate pathogen-induced mastitis by impairing host anti-inflammatory enzymes, which implies that regulating the ruminal or gut microbiota to prevent low-grade systemic inflammation is a potential strategy for mastitis intervention. Video Abstract.

In Vitro Gene Expression Responses of Bovine Rumen Epithelial Cells to Different pH Stresses

Ruminal acidosis often occurs in production, which greatly affects animal health and production efficiency. Subacute rumen acidosis (SARA) occurs when rumen pH drops rapidly to 5.5−5.8, and acute rumen acidosis (ARA) occurs when rumen pH drops below 5.0, but the molecular regulation mechanism of the rumen epithelium after the rapid decrease in pH is still unclear. Bovine rumen epithelial cells (BRECs) were cultured at pH = 7.4 (control), 5.5 (SARA), and 4.5 (ARA). Transcriptome and metabolomic methods were used to obtain the molecular-based response of BRECs to different pH treatments; pH = 4.5 can significantly induce apoptosis of BRECs. The RNA-seq experiments revealed 1381 differently expressed genes (DEGs) in the control vs. SARA groups (p < 0.05). Fibroblast growth factor (FGF) and tumor necrosis factor (TNF) were upregulated 4.25 and 6.86 fold, respectively, and TLR4 was downregulated 0.58 fold. In addition, 283 DEGs were identified in the control vs. ARA comparison (p < 0.05), and prostaglandin-endoperoxide synthase 2 (PSTG2) was downregulated 0.54 fold. Our research reveals that the MAPK/TNF signaling pathway regulates the inflammatory response of BRECs. Metabolomics identified 35 biochemical compounds that were significantly affected (p < 0.05) in control vs. SARA and 51 in control vs. ARA. Bioinformatics analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database revealed that drug metabolism-cytochrome P450 metabolic and alpha-linolenic acid metabolism changes occurred. These transcriptional and metabolic changes are related to the adaptation of BRECs to low-pH stresses. In conclusion, the combined data analyses presented a worthy strategy to characterize the cellular, transcriptomic, and metabonomic adaptation of BRECs to pH in vitro. We demonstrated transcriptional expression changes in BRECs under pH stress and activation of the molecular mechanisms controlling inflammation.

Effects of ruminal lipopolysaccharides on growth and fermentation end products of pure cultured bacteria

Elevated levels of ruminal lipopolysaccharides (LPS) have been linked to ruminal acidosis; however, they result in reduced endotoxicity compared to LPS derived from species like Escherichia coli. Additionally, there is a knowledge gap on the potential effect of LPS derived from ruminal microbiome on ruminal bacteria species whose abundance is associated with ruminal acidosis. The objective of this study was to evaluate the effects of LPS-free anaerobic water (CTRL), E. coli-LPS (E. COLI), ruminal-LPS (RUM), and a 1:1 mixture of E. coli and ruminal-LPS (MIX) on the growth characteristics and fermentation end products of lactate-producing bacteria (Streptococcus bovis JB1, Selenomonas ruminantium HD4) and lactate-utilizing bacterium (Megasphaera elsdenii T81). The growth characteristics were predicted based on the logistic growth model, the ammonia concentration was determined by the phenolic acid/hypochlorite method and organic acids were analyzed with high performance liquid chromatography. Results indicate that, compared to the CTRL, the maximum specific growth rate of S. bovis JB1 decreased by approximately 19% and 23% when RUM and MIX were dosed, respectively. In addition, acetate and lactate concentrations in Se. ruminantium HD4 were reduced by approximately 30% and 18%; respectively, in response to MIX dosing. Compared to CTRL, lactate concentration from S. bovis JB1 was reduced approximately by 31% and 22% in response to RUM and MIX dosing; respectively. In summary, RUM decreased the growth and lactate production of some lactate-producing bacteria, potentially mitigating the development of subacute ruminal acidosis by restricting lactate availability to some lactate-utilizing bacteria that metabolize lactate into VFAs thus further contributing to the development of acidosis. Also, RUM did not affect Megasphaera elsdenii T81 growth.

Phytogenic additive from Prosopis juliflora on populations of rumen ciliate protozoa and its correlation with nutrition of sheep

We evaluated the effect of phytogenic additive Prosopis juliflora on populations of ruminal ciliated protozoa and its correlation with variables related to sheep nutrition. In this experiment, five cannulated adult Santa Ines ewes were submitted to the additive intake. Each animal received 6 mL of the extract daily. The experimental design adopted was the Latin square 5 × 5 (five concentrations of additive 0, 200, 400, 600 and 800 mg/mL of water and five periods of 18 days). The additive quadratically reduces the number of large, small and total ciliating protozoa, without promoting changes in the number of medium protozoa in the rumen. Among the genera investigated, Isotricha and Dasytricha were the only ones affected by supplementation. Additionally, the concentration of ruminal protozoa correlates significantly with the variables related to the nutrition of the animal. The effects of the additive on these variables were particularly pronounced at concentrations around 600 mg/mL.

Siqueira MC, DiLorenzo N. Polyclonal antibody preparations from avian origin as a feed additive to beef cattle: Ruminal fermentation during the step-up transition diets

This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (40%, 35%, and 25% of the preparation, respectively) on ruminal fermentation [pH, ammonia-N (NH₃-N), lactate, and volatile fatty acids (VFA)] of beef steers during a 21-d step-up diet adaptation. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of body weight) were assigned in a crossover design to be transitioned from a diet containing ad libitum bermudagrass hay [Cynodon dactylon (L.) Pers.] plus 0.45 kg/d (as fed) of molasses with 0 (CON) or 3 g of PAP (PAP) to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet DM for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), ruminal fluid samples were obtained every 3 h for 24 h. Feeding 3 g of PAP daily increased (P < 0.01) average ruminal pH during STEP3 compared with CON steers (5.6 vs. 5.4 ± 0.05, respectively). During STEP1, NH₃-N concentration was greater (P < 0.01; 9.4 vs. 6.8 ± 0.74 mM, respectively), and time (min/d) and area (time × pH) of ruminal pH below or equal to 5.2 was lesser (P ≤ 0.03) for steers consuming PAP compared with steers assigned to CON treatment (33.4 vs. 73.3 ± 21.7 min/d and 187.4 vs. 406.3 ± 119.7 min × pH/d, respectively). Steers consuming PAP had greater acetate:propionate ratio at 0, 3, and 6 h relative to diet change compared with CON (2.42, 2.35, 2.29 vs. 1.66, 1.79, and 1.72 ± 0.17, respectively), whereas butyrate molar proportions increased (P = 0.02; 17.1 vs. 11 ± 1.58 mol/100 mol for CON and PAP, respectively) when PAP was not fed at STEP2. Total ruminal lactate concentrations were not affected by PAP feeding (P > 0.11). In conclusion, feeding 3 g/d of polyclonal antibody preparation against S. bovis, F. necrophorum, and lipopolysaccharides was effective in increasing ruminal pH, A:P ratio, and NH₃-N concentrations, possibly attenuating the risks of ruminal acidosis in steers during the step-up transition from forage to high-grain diets.

Ruminal bacteria lipopolysaccharides: an immunological and microbial outlook

Lipopolysaccharides (LPS) are outer membrane components of Gram-negative bacteria made of three regions: the O-antigen; the core oligosaccharide; and a glucosamine disaccharide linked to hydroxy fatty acids, which is named lipid A. The number phosphate groups, and hydroxy fatty acid chains is associated with the immunopotency and the immunomodulatory activity of LPS, where six-acyl chain lipid A with two phosphate groups is found in virulent strains and five- or four-acyl chain lipid A with one phosphate group are found in non-virulent bacteria strains. Ruminal bacteria are predominantly Gram-negative and their LPS have not been thoroughly investigated. In the rumen, LPS is comprised of mixed ruminal LPS. Drawing upon a body of theoretical and applied work, this paper aims to critically review the scientific literature regarding single-species and mixed ruminal bacteria LPS, highlighting the importance of ruminal LPS to the host. Lastly, future research directions are suggested in order to further our understanding of the roles of LPS in the rumen. Possible suggestions for further understanding ruminal LPS include (1) in silico evaluation of major bacteria contributing to ruminal LPS, (2) structural characterization of LPS from prominent ruminal bacteria species, such as ruminal selenomonads and Megasphaera elsdenii, and, (3) ruminal epithelial tissue immune response evaluation from single-species and mixed ruminal LPS. In conclusion, this review identifies numerous areas for future research, including setting the basis for future modeling and simulation of host microbiome interactions in ruminants.

Impact of gut permeability on the breast microbiome using a non-human primate model

We previously demonstrated in non-human primates (NHP) that Mediterranean diet consumption shifted the proportional abundance of Lactobacillus in the breast and gut. This data highlights a potential link about gut-breast microbiome interconnectivity. To address this question, we compared bacterial populations identified in matched breast and faecal samples from our NHP study. Dietary pattern concurrently shifted two species in both regions; Streptococcus lutetiensis and Ruminococcus torques. While we observe similar trends in Lactobacillus abundances in the breast and gut, the species identified in each region vary; Mediterranean diet increased Lactobacillus_unspecified species in breast but regulated L. animalis and L. reuteri in the gut.We also investigated the impact of gut permeability on the breast microbiome. Regardless of dietary pattern, subjects that displayed increased physiological measures of gut permeability (elevated plasma lipopolysaccharide, decreased villi length, and decreased goblet cells) displayed a significantly different breast microbiome. Gut barrier dysfunction was associated with increased α-diversity and significant different β-diversity in the breast tissue. Taken together our data supports the presence of a breast microbiome influenced by diet that largely varies from the gut microbiome population but is, however, sensitive to gut permeability.

Transcriptome Analysis Reveals Catabolite Control Protein A Regulatory Mechanisms Underlying Glucose-Excess or -Limited Conditions in a Ruminal Bacterium, Streptococcus bovis

Ruminants may suffer from rumen acidosis when fed with high-concentrate diets due to the higher proliferation and overproduction of lactate by Streptococcus bovis. The catabolite control protein A (CcpA) regulates the transcription of lactate dehydrogenase (ldh) and pyruvate formate-lyase (pfl) in S. bovis, but its role in response to different carbon concentrations remains unclear. To characterize the regulatory mechanisms of CcpA in S. bovis S1 at different levels of carbon, herein, we analyzed the transcriptomic and physiological characteristics of S. bovis S1 and its ccpA mutant strain grown in glucose-excess and glucose-limited conditions. A reduced growth rate and a shift in fermentation pattern from homofermentation to heterofermentation were observed under glucose-limited condition as compared to glucose-excess condition, in S. bovis S1. Additionally, the inactivation of ccpA significantly affected the growth and end metabolites in both conditions. For the glycolytic intermediate, fructose 1,6-bisphosphate (FBP), the concentration significantly reduced at lower glucose conditions; its concentration decreased significantly in the ccpA mutant strain. Transcriptomic results showed that about 46% of the total genes were differentially transcribed between the wild-type strain and ccpA mutant strain grown in glucose-excess conditions; while only 12% genes were differentially transcribed in glucose-limited conditions. Different glucose concentrations led to the differential expression of 38% genes in the wild-type strain, while only half of these were differentially expressed in the ccpA-knockout strain. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that the substrate glucose concentration significantly affected the gene expression in histidine metabolism, nitrogen metabolism, and some carbohydrate metabolism pathways. The deletion of ccpA affected several genes involved in carbohydrate metabolism, such as glycolysis, pyruvate metabolism, fructose and mannose metabolism, as well as in fatty acid biosynthesis pathways in bacteria grown in glucose-excess conditions; this effect was attenuated under glucose-limited conditions. Overall, these findings provide new information on gene transcription and metabolic mechanisms associated with substrate glucose concentration and validate the important role of CcpA in the regulation of carbon metabolism in S. bovis S1 at differential glucose availability.

The impact of the gut microbiome on toxigenic bacteria

Millions of symbiotic and pathogenic microorganisms known as microbiota colonize the host body. The microbiome plays an important role in human health and colonizes hundreds of different species of multicellular organisms so that they are introduced as the metaorganisms. Changes in the microbial population of the gut microbiome may cause resistance to pathogenic bacteria-induced infection. Understanding the principles of Host-Microbiota Interactions (HMIs) is important because it clarifies our insight towards the mechanisms of infections established in the host. Interactions between the host and the microbiota help answer the question of how a microorganism can contribute to the health or disease of the host. Microbiota can increase host resistance to colonization of pathogenic species. Studying the HMIs network can in several ways delineate the pathogenic mechanisms of pathogens and thereby help to increase useful and novel therapeutic pathways. For example, the potentially unique microbial effects that target the distinct host or interfere with the endogenous host interactions can be identified. In addition, the way mutations in essential proteins in the host and/or in the microbes can influence the interactions between them may be determined. Furthermore, HMIs help in identifying host cell regulatory modules.

Angelica polysaccharide attenuates LPS-induced inflammation response of primary dairy cow claw dermal cells via NF-κB and MAPK signaling pathways

Background

Laminitis, an inflammation of the claw laminae, is one of the major causes of bovine lameness, which can lead to enormous economic losses and animal welfare problems in dairy farms. Angelica polysaccharide (AP) is proved to possess anti-inflammatory properties. But the role of AP on inflammatory response of the claw dermal cells has not been reported. The aim of this study was to investigate the anti-inflammatory effects of AP on lipopolysaccharide (LPS)-induced primary claw dermal cells of dairy cow and clarify the potential mechanisms. In the current research, the primary claw dermal cells were exposed to gradient concentrations of AP (10, 50, 100 µg/mL) in the presence of 10 µg/mL LPS. The levels of cytokines and nitric oxide (NO) were detected with ELISA and Griess colorimetric method. The mRNA expressions of TLR4, MyD88 and chemokines were measured with qPCR. The activation of NF-κB and MAPK signaling pathways was detected with western blotting.

Results

The results indicated that AP reduced the production of inflammatory mediators (TNF-α, IL-1β, IL-6 and NO), downregulated the mRNA expression of TLR4, MyD88 and some pro-inflammatory chemokines (CCL2, CCL20, CXCL2, CXCL8, CXCL10), and suppressed the NF-κB and MAPK signaling pathways evidenced by inhibition of the phosphorylation of IκBα, p65 and ERK, JNK, p38.

Conclusions

Our results demonstrated that AP may exert its anti-inflammatory effects on claw dermal cells of dairy cow by regulating the NF-κB and MAPK signaling pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02952-4.

Using neural networks to mine text and predict metabolic traits for thousands of microbes

Microbes can metabolize more chemical compounds than any other group of organisms. As a result, their metabolism is of interest to investigators across biology. Despite the interest, information on metabolism of specific microbes is hard to access. Information is buried in text of books and journals, and investigators have no easy way to extract it out. Here we investigate if neural networks can extract out this information and predict metabolic traits. For proof of concept, we predicted two traits: whether microbes carry one type of metabolism (fermentation) or produce one metabolite (acetate). We collected written descriptions of 7,021 species of bacteria and archaea from Bergey's Manual. We read the descriptions and manually identified (labeled) which species were fermentative or produced acetate. We then trained neural networks to predict these labels. In total, we identified 2,364 species as fermentative, and 1,009 species as also producing acetate. Neural networks could predict which species were fermentative with 97.3% accuracy. Accuracy was even higher (98.6%) when predicting species also producing acetate. Phylogenetic trees of species and their traits confirmed that predictions were accurate. Our approach with neural networks can extract information efficiently and accurately. It paves the way for putting more metabolic traits into databases, providing easy access of information to investigators.

Ruminal Lipopolysaccharides Analysis: Uncharted Waters with Promising Signs

Simple Summary

Lipopolysaccharide (LPS) is a component of the outer membranes of Gram-negative bacterial cell wall made of three covalently linked regions: the O-antigen, the core oligosaccharide, and the endotoxin lipid A moiety, which carries the endotoxic activity of LPS. Among Gram-negative bacteria there is significant structural diversity in the lipid A region. Specifically, the number of lipid A acyl chains directly correlates with the ability to induce cytokine production whereas the hexa-acylated forms usually are the most immunostimulant ones, contrary to penta- or tetra- acylated forms that result in weak inflammatory host responses. Ruminal bacteria are predominantly Gram-negative, and their respective LPS presence has been suggested to be associated with ruminal acidosis, a metabolic disorder of cattle with negative effects on health and production. In the rumen, the most predominant phylum is Bacteroidetes which exhibit weak host immunological response compared to widely used Escherichia coli LPS. This review aims to present accumulated knowledge regarding ruminal LPS, pointing out the differences in ruminal LPS compared to widely known LPS, and introduce hypotheses that could contribute to further understanding and planning strategies to tackle ruminal acidosis.

Abstract

The objective of this review is to present the need for the development of a comprehensive ruminal lipopolysaccharide (LPS) extraction, purification and analysis protocol and state hypotheses that could contribute to planning novel strategies against ruminal acidosis. Lipopolysaccharide is an immunostimulatory molecule of Gram-negative bacterial outer membranes and has been reported to contribute to ruminal acidosis in cattle. Bacterial death and lysis are normal processes, and thus LPS is normally present in ruminal fluid. However, ruminal LPS concentration is much greater during subacute ruminal acidosis (SARA). Contrary to the widely known LPSs, ruminal LPS seems to be composed of a variety of LPS chemotypes that may interact with each other resulting in an LPS “mixture”. Hypotheses regarding the influence of each specific ruminal bacterial specie to innate immunity during SARA, and the representativeness of the exclusive use of the Escherichia coli LPS to rumen epithelial tissue challenges, could expand our knowledge regarding SARA. In addition, possible correlation between the monomeric Toll-like Receptor 4 (TRL4) and the antagonistic penta-acylated lipid A of LPS could contribute to novel strategies to tackle this nutrition disorder.

Ruminal acidosis, bacterial changes, and lipopolysaccharides

Acute and subacute ruminal acidosis (SARA) are common nutritional problems in both beef and dairy cattle. Therefore, the objective of this review is to describe how ruminal Gram-negative bacteria could contribute to the pathogenesis of ruminal acidoses, by releasing lipopolysaccharides (LPS; a component of their cell wall) in the ruminal fluid. When cattle consume excessive amounts of highly fermentable carbohydrates without prior adaptation, normal fermentation become disrupted. The fermentation of these carbohydrates quickly decreases ruminal pH due to the accumulation of short-chain fatty acids and lactate in the rumen. As a consequence, ruminal epithelium may be damaged and tissue function could be impaired, leading to a possible translocation of pathogenic substances from the rumen into the bloodstream. Such changes in fermentation are followed by an increase in Gram-positive bacteria while Gram-negative bacteria decrease. The lyses of Gram-negative bacteria during ruminal acidosis increase LPS concentration in the ruminal fluid. Because LPS is a highly proinflammatory endotoxin in the circulatory system, past studies have raised concerns regarding ruminal LPS contribution to the pathogenesis of ruminal acidosis. Although animals that undergo these disorders do not always have an immune response, recent studies showed that different Gram-negative bacteria have different LPS composition and toxicity, which may explain the differences in immune response. Given the diversity of Gram-negative bacteria in the rumen, evaluating the changes in the bacterial community during ruminal acidosis could be used as a way to identify which Gram-negative bacteria are associated with LPS release in the rumen. By identifying and targeting ruminal bacteria with possible pathogenic LPS, nutritional strategies could be created to overcome, or at least minimize, ruminal acidosis.