Macrophage Polarization Induced by Probiotic Bacteria: a Concise Review

Unveiling the immunomodulatory effect of the novel probiotic Akkermansia muciniphila and its protective effect in vitro

Akkermansia muciniphila, a bacterium found in the human microbiota, has gained interest due to its potential health benefits. Previous studies have linked its absence to inflammatory disorders, while also suggesting its role in maintaining a healthy gut barrier. However, there is limited information on its specific effects on the immune system. Therefore, the aim of this research was to analyze the in vitro response triggered by A. muciniphila employing RAW 264.7 macrophages. The study focused on investigating the production of cytokines and nitric oxide, along with evaluating the expression of inflammatory surface cellular markers. Additionally, we assessed its potential to protect against intestinal infections, using Salmonella enterica serovar Enteritidis as a model. Our findings reveal a modulation effect of A. muciniphila with pro-inflammatory features, including the release of pro-inflammatory cytokines and upregulation of CD40 and CD80 surface markers, in contrast with previous reported data. Importantly, A. muciniphila could protect against Salmonella infection by promoting macrophage activation, appearing as a promising probiotic candidate for the control of intestinal infections.

Studies of the Impact of the Bifidobacterium Species on Inducible Nitric Oxide Synthase Expression and Nitric Oxide Production in Murine Macrophages of the BMDM Cell Line

Bifidobacterium species are one of the most important probiotic microorganisms which are present in both, infants and adults. Nowadays, growing data describing their healthy properties arise, indicating they could act at the cellular and molecular level. However, still little is known about the specific mechanisms promoting their beneficial effects. Nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), is involved in the protective mechanisms in the gastrointestinal tract, where it can be provided by epithelial cells, macrophages, or bacteria. The present study explored whether induction of iNOS-dependent NO synthesis in macrophages stems from the cellular action of Bifidobacterium species. The ability of ten Bifidobacterium strains belonging to 3 different species (Bifidobacterium longum, Bifidobacterium adolescentis, and Bifidobacterium animalis) to activate MAP kinases, NF-κB factor, and iNOS expression in a murine bone-marrow-derived macrophages cell line was determined by Western blotting. Changes in NO production were determined by the Griess reaction. It was performed that the Bifidobacterium strains were able to induce NF-қB-dependent iNOS expression and NO production; however, the efficacy depends on the strain. The highest stimulatory activity was observed for Bifidobacterium animalis subsp. animals CCDM 366, whereas the lowest was noted for strains Bifidobacterium adolescentis CCDM 371 and Bifidobacterium longum subsp. longum CCDM 372. Both TLR2 and TLR4 receptors are involved in Bifidobacterium-induced macrophage activation and NO production. We showed that the impact of Bifidobacterium on the regulation of iNOS expression is determined by MAPK kinase activity. Using pharmaceutical inhibitors of ERK 1/2 and JNK, we confirmed that Bifidobacterium strains can activate these kinases to control iNOS mRNA expression. Concluding, the induction of iNOS and NO production may be involved in the protective mechanism of action observed for Bifidobacterium in the intestine, and the efficacy is strain-dependent.

Effects of folate-chicory acid liposome on macrophage polarization and TLR4/NF-κB signaling pathway in ulcerative colitis mouse

BACKGROUND

Chichoric acid (CA) is a major active ingredient found in chicory and Echinacea. As a derivative of caffeic acid, it has various pharmacological effects.

PURPOSE

Due to the unclear etiology and disease mechanisms, effective treatment methods for ulcerative colitis (UC) are currently lacking. The study investigated the therapeutic effects of the folate-chicory acid liposome on both LPS-induced macrophage inflammation models and dextran sulfate sodium (DSS)-induced mouse UC models.

METHODS

Folate-chicory acid liposome was prepared using the double emulsion ultrasonic method with the aim of targeting folate receptors specifically expressed on macrophages. The study investigated the therapeutic effects of the folate-chicory acid liposome on both LPS-induced macrophage inflammation models and DSS -induced mouse UC models. Furthermore, the effects of the liposomes on macrophage polarization and their underlying mechanisms in UC were explored.

RESULTS

The average particle size of folate-chicory acid liposome was 120.4 ± 0.46 nm, with an encapsulation efficiency of 77.32 ± 3.19 %. The folate-chicory acid liposome could alleviate macrophage apoptosis induced by LPS, decrease the expression of inflammatory factors in macrophages, enhance the expression of anti-inflammatory factors, inhibit macrophage polarization towards the M1 phenotype, and mitigate cellular inflammation in vetro. In vivo test, folate-chicory acid liposome could attenuate clinical symptoms, increased colon length, reduced DAI scores, CMDI scores, and alleviated the severity of colonic histopathological damage in UC mice. Furthermore, it inhibited the polarization of macrophages towards the M1 phenotype in the colon and downregulated the TLR4/NF-κB signaling pathway, thereby ameliorating UC in mice.

CONCLUSION

Folate-chicory acid liposome exhibited a uniform particle size distribution and high encapsulation efficiency. It effectively treated UC mice by inhibiting the polarization of macrophages towards the M1 phenotype in the colon and downregulating the TLR4/NF-κB signaling pathway.

Gut microbiota as a key regulator of intestinal mucosal immunity

Gut microbiota is a complex microbial community with the ability of maintaining intestinal health. Intestinal homeostasis largely depends on the mucosal immune system to defense external pathogens and promote tissue repair. In recent years, growing evidence revealed the importance of gut microbiota in shaping intestinal mucosal immunity. Therefore, according to the existing findings, this review first provided an overview of intestinal mucosal immune system before summarizing the regulatory roles of gut microbiota in intestinal innate and adaptive immunity. Specifically, this review delved into the gut microbial interactions with the cells such as intestinal epithelial cells (IECs), macrophages, dendritic cells (DCs), neutrophils, and innate lymphoid cells (ILCs) in innate immunity, and T and B lymphocytes in adaptive immunity. Furthermore, this review discussed the main effects of gut microbiota dysbiosis in intestinal diseases and offered future research prospects. The review highlighted the key regulatory roles of gut microbiota in intestinal mucosal immunity via various host-microbe interactions, providing valuable references for the development of microbial therapy in intestinal diseases.

Tolerogenic probiotics Lactobacillus delbrueckii and Lactobacillus rhamnosus promote anti-inflammatory profile of macrophages-derived monocytes of newly diagnosed patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is known as an autoimmune disorder that is characterized by the breakdown of self-tolerance, resulting in disease onset and progression. Macrophages have been implicated as a factor in the development of SLE through faulty phagocytosis of dead cells or an imbalanced M1/M2 ratio. The study aimed to investigate the immunomodulatory effects of Lactobacillus delbrueckii and Lactobacillus rhamnosus on M1 and M2 macrophages in new case lupus patients. For this purpose, blood monocytes were collected from lupus patients and healthy people and were cultured for 5 days to produce macrophages. For 48 h, the macrophages were then cocultured with either probiotics or lipopolysaccharides (LPS). Flow cytometry and real-time polymerase chain reaction were then used to analyze the expression of cluster of differentiation (CD) 14, CD80, and human leukocyte antigen - DR (HLADR) markers, as well as cytokine expression (interleukin [IL]1-β, IL-12, tumor necrosis factor α [TNF-α], IL-10, and transforming growth factor beta [TGF-β]). The results indicated three distinct macrophage populations, M0, M1, and M2. In both control and patient-derived macrophage-derived monocytes (MDMs), the probiotic groups showed a decrease in CD14, CD80, and HLADR expression compared to the LPS group. This decrease was particularly evident in M0 and M2 macrophages from lupus patients and M1 macrophages from healthy subjects. In addition, the probiotic groups showed increased levels of IL-10 and TGF-β and decreased levels of IL-12, IL1-β, and TNF-α in MDMs from both healthy and lupus subjects compared to the LPS groups. Although there was a higher expression of pro-inflammatory cytokines in lupus patients, there was a higher expression of anti-inflammatory cytokines in healthy subjects. In general, L. delbrueckii and L. rhamnosus could induce anti-inflammatory effects on MDMs from both healthy and lupus subjects.

Monitoring mRNA Expression Patterns in Macrophages in Response to Two Different Strains of Probiotics

As an initial study to elucidate the molecular mechanism of how probiotics modulate macrophage activity, we monitored mRNA expression patterns in peritoneal macrophages (PMs) treated with two different strains of probiotics. After treatment with either Weissella cibaria WIKIM28 or Latilactobacillus sakei WIKIM50, total RNAs from PMs were isolated and subjected into gene chip analyses. As controls, mRNAs from vehicle (phosphate-buffered saline, PBS)-treated PMs were also subjected to gene chip analysis. Compared to vehicle (PBS)-treated PMs, WIKIM28-treated and WIKIM50-treated PMs exhibited a total of 889 and 432 differentially expressed genes with expression differences of at least 4 folds, respectively. Compared to WIKIM28-treated PMs, WIKIM50-treated PMs showed 25 up-regulated genes and 21 down-regulated genes with expression differences of more than 2 folds. Interestingly, mRNA transcripts of M2 macrophage polarization marker such as anxa1, mafb, and sepp1 were increased in WIKIM50-treated PMs comparing to those in WIKIM28-treated PMs. Reversely, mRNA transcripts of M1 macrophage polarization marker such as hdac9, ptgs2, and socs3 were decreased in WIKIM50-treated PMs comparing to those in WIKIM28-treated PMs. In agreement with these observations, mRNA expression levels of tumor necrosis factor-α and interleukin-1α were significantly reduced in WIKIM50-treated macrophages compared to those in WIKIM28-treated macrophages. These results may indicate that probiotics can be classified as two different types depending on their ability to convert macrophages into M1 or M2 polarization.

Bacillus coagulans T4 and Lactobacillus paracasei TD3 Ameliorate Skeletal Muscle Oxidative Stress and Inflammation in High-Fat Diet-Fed C57BL/6J Mice

Background

This study aims to investigate the effects of Bacillus coagulans T4 and Lactobacillus paracasei TD3 probiotics on skeletal muscle inflammation and oxidative stress in C57BL/6J mice fed a high-fat diet (HFD).

Methods

Probiotics B. coagulans T4, and L. paracasei TD3 were administered to male C57BL/6J mice fed with HFD. The gene expression of macrophage infiltration markers, inflammatory cytokines, and oxidative stress indicators in the muscle tissue was investigated.

Results

Treatment with B. coagulans T4 and L. paracasei TD3 reduced macrophage infiltration, accompanied by a decrease in the expression of monocyte chemoattractant protein-1 (MCP-1) and an increase in the expression of interleukin (IL)-10. On the other hand, L. paracasei TD3 decreased malondialdehyde (MDA) while B. coagulans T4 decreased carbonyl and increased catalase activity.

Conclusions

Treatment with probiotics B. coagulans T4 and L. paracasei TD3 partially ameliorated obesity-induced skeletal muscle inflammation in HFD-fed mice.

The modulation of macrophage subsets in celiac disease pathogenesis

BACKGROUND

So far, limited studies have focused on the role of Macrophages (MQs) in the development or progression of celiac disease (CD). Researchers believe that increasing knowledge about the function of MQs in inflammatory disorders plays a critical role in finding a new treatment for these kinds of diseases.

MAIN BODY

CD is a permanent autoimmune intestinal disorder triggered by gluten exposure in predisposed individuals. This disorder happens due to the loss of intestinal epithelial barrier integrity characterized by dysregulated innate and adaptive immune responses. MQs are known as key players of the innate immune system that link innate and adaptive immunity. MQs of human intestinal lamina propria participate in maintaining tissue homeostasis, and also intestinal inflammation development. Previous studies suggested that gliadin triggers a proinflammatory phenotype (M1 MQ) in human primary MQs. Moreover, M2-related immunosuppressive mediators are also present in CD. In fact, CD patients present an impaired transition from pro-inflammatory to anti-inflammatory responses due to inappropriate responses to gliadin peptides.

CONCLUSION

The M1/M2 MQs polarization balancing regulators can be considered novel therapeutic targets for celiac disease.

Contribution of Lactobacilli on Intestinal Mucosal Barrier and Diseases: Perspectives and Challenges of Lactobacillus casei

The intestine barrier, the front line of normal body defense, relies on its structural integrity, microbial composition and barrier immunity. The intestinal mucosal surface is continuously exposed to a complex and dynamic community of microorganisms. Although it occupies a relatively small proportion of the intestinal microbiota, Lactobacilli has been discovered to have a significant impact on the intestine tract in previous studies. It is undeniable that some Lactobacillus strains present probiotic properties through maintaining the micro-ecological balance via different mechanisms, such as mucosal barrier function and barrier immunity, to prevent infection and even to solve some neurology issues by microbiota-gut-brain/liver/lung axis communication. Notably, not only living cells but also Lactobacillus derivatives (postbiotics: soluble secreted products and para-probiotics: cell structural components) may exert antipathogenic effects and beneficial functions for the gut mucosal barrier. However, substantial research on specific effects, safety and action mechanisms in vivo should be done. In clinical application of humans and animals, there are still doubts about the precise evaluation of Lactobacilli's safety, therapeutic effect, dosage and other aspects. Therefore, we provide an overview of central issues on the impacts of Lactobacillus casei (L. casei) and their products on the intestinal mucosal barrier and some diseases and highlight the urgent need for further studies.

Immunostimulatory Activity of Lactic Acid Bacteria Cell-Free Supernatants through the Activation of NF-κB and MAPK Signaling Pathways in RAW 264.7 Cells

Lactic acid bacteria (LAB) can improve host health and has strong potential for use as a health functional food. Specific strains of LAB have been reported to exert immunostimulatory effects. The primary goal of this study was to evaluate the immunostimulatory activities of novel LAB strains isolated from humans and foods and to investigate the probiotic properties of these strains. Cell-free supernatants (CFS) obtained from selected LAB strains significantly increased phagocytosis and level of nitric oxide (NO) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-6 in RAW264.7 macrophage cells. The protein expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, which are immunomodulators, was also upregulated by CFS treatment. CFS markedly induced the phosphorylation of nuclear factor-κB (NF-κB) and MAPKs (ERK, JNK, and p38). In addition, the safety of the LAB strains used in this study was demonstrated by hemolysis and antibiotic resistance tests. Their stability was confirmed under simulated gastrointestinal conditions. Taken together, these results indicate that the LAB strains selected in this study could be useful as probiotic candidates with immune-stimulating activity.

Lactiplantibacillus plantarum LOC1 Isolated from Fresh Tea Leaves Modulates Macrophage Response to TLR4 Activation

Previously, we demonstrated that Lactiplantibacillus plantarum LOC1, originally isolated from fresh tea leaves, was able to improve epithelial barrier integrity in in vitro models, suggesting that this strain is an interesting probiotic candidate. In this work, we aimed to continue characterizing the potential probiotic properties of the LOC1 strain, focusing on its immunomodulatory properties in the context of innate immunity triggered by Toll-like receptor 4 (TLR4) activation. These studies were complemented by comparative and functional genomics analysis to characterize the bacterial genes involved in the immunomodulatory capacity. We carried out a transcriptomic study to evaluate the effect of L. plantarum LOC1 on the response of murine macrophages (RAW264.7 cells) to the activation of TLR4. We demonstrated that L. plantarum LOC1 exerts a modulatory effect on lipopolysaccharide (LPS)-induced inflammation, resulting in a differential regulation of immune factor expression in macrophages. The LOC1 strain markedly reduced the LPS-induced expression of some inflammatory cytokines (IL-1β, IL-12, and CSF2) and chemokines (CCL17, CCL28, CXCL3, CXCL13, CXCL1, and CX3CL1), while it significantly increased the expression of other cytokines (TNF-α, IL-6, IL-18, IFN-β, IFN-γ, and CSF3), chemokines (IL-15 and CXCL9), and activation markers (H2-k1, H2-M3, CD80, and CD86) in RAW macrophages. Our results show that L. plantarum LOC1 would enhance the intrinsic functions of macrophages, promoting their protective effects mediated by the stimulation of the Th1 response without affecting the regulatory mechanisms that help control inflammation. In addition, we sequenced the LOC1 genome and performed a genomic characterization. Genomic comparative analysis with the well-known immunomodulatory strains WCSF1 and CRL1506 demonstrated that L. plantarum LOC1 possess a set of adhesion factors and genes involved in the biosynthesis of teichoic acids and lipoproteins that could be involved in its immunomodulatory capacity. The results of this work can contribute to the development of immune-related functional foods containing L. plantarum LOC1.

Lactobacillus acidophilus KBL409 reduces kidney fibrosis via immune modulatory effects in mice with chronic kidney disease

SCOPE

Intestinal dysbiosis has been reported to play an important role in the pathogenesis of various diseases, including chronic kidney disease (CKD). Here, we aimed to evaluate whether probiotic supplements can have protective effects against kidney injury in an animal model of CKD.

METHODS AND RESULTS

An animal model of CKD was established by feeding C57BL/6 mice a diet containing 0.2% adenine. These model mice were administered Lactobacillus acidophilus KBL409 daily for 4 weeks. Features of adenine-induce CKD (Ade-CKD) mice, such as prominent kidney fibrosis and higher levels of serum creatinine and albuminuria were improved by administration of KBL409. Ade-CKD mice also exhibited a disrupted intestinal barrier and elevated levels of TNF-α, IL-6, and 8-hydroxy-2'-deoxyguanosine. These changes were attenuated by KBL409. Administration of KBL409 significantly reduced macrophage infiltration and promoted a switch to the M2 macrophage phenotype and increasing regulatory T cells. Notably, the NLRP3 inflammasome pathway was activated in the kidneys of Ade-CKD and decreased by KBL409. In primary kidney tubular epithelial cells treated with p-cresyl sulfate, short-chain fatty acids significantly increased M2 macrophage polarization factors and decreased profibrotic markers.

CONCLUSIONS

These results demonstrate that supplementation with the probiotic KBL409 has beneficial immunomodulating effects and protects against kidney injury. This article is protected by copyright. All rights reserved.

Mechanical Stretch Promotes Macrophage Polarization and Inflammation via the RhoA-ROCK/NF-κB Pathway

Macrophages play an essential role in the pathogenesis of most inflammatory diseases. Recent studies have shown that mechanical load can influence macrophage function, leading to excessive and uncontrolled inflammation and even systemic damage, including cardiovascular disease and knee osteoarthritis. However, the molecular mechanism remains unclear. In this study, murine RAW264.7 cells were treated with mechanical stretch (MS) using the Flexcell-5000T Tension System. The expression of inflammatory factors and cytokine release were measured by RT-qPCR, ELISA, and Western blotting. The protein expression of NF-κB p65, Iκb-α, p-Iκb-α, RhoA, ROCK1, and ROCK2 was also detected by Western blotting. Then, Flow cytometry was used to detect the proportion of macrophage subsets. Meanwhile, Y-27632 dihydrochloride, a ROCK inhibitor, was added to knockdown ROCK signal transduction in cells. Our results demonstrated that MS upregulated mRNA expression and increased the secretion levels of proinflammatory factors iNOS, IL-1β, TNF-α, and IL-6. Additionally, MS significantly increased the proportion of CD11b+CD86+ and CD11b+CD206+ subsets in RAW264.7 macrophages. Furthermore, the protein expression of RhoA, ROCK1, ROCK2, NF-κB p65, and IκB-α increased in MS-treated RAW264.7 cells, as well as the IL-6 and iNOS. In contrast, ROCK inhibitor significantly blocked the activation of RhoA-ROCK and NF-κB pathway, decreased the protein expression of IL-6 and iNOS, reduced the proportion of CD11b+CD86+ cells subpopulation, and increased the proportion of CD11b+CD206+ cell subpopulation after MS. These data indicate that mechanical stretch can regulate the RAW264.7 macrophage polarization and enhance inflammatory responses in vitro, which may contribute to activation the RhoA-ROCK/NF-κB pathway.

Current Progress and Future Perspectives on the Use of Bacillus clausii

Bacillus clausii is a probiotic that benefits human health. Its key characteristics include the ability to form spores; the resulting tolerance to heat, acid, and salt ensures safe passage through the human gastrointestinal tract with no loss of cells. Although B. clausii has been widely used for many decades, the beneficial properties of other probiotics, such as Lactobacillus spp. and Bifidobacterium spp., are better disseminated in the literature. In this review, we summarize the physiological, antimicrobial, and immunomodulatory properties of probiotic B. clausii strains. We also describe findings from studies that have investigated B. clausii probiotics from the perspective of quality and safety. We highlight innovative properties based on biochemical investigations of non-probiotic strains of B. clausii, revealing that B. clausii may have further health benefits in other therapeutic areas.

Lactobacillus plantarum RS-09 Induces M1-Type Macrophage Immunity Against Salmonella Typhimurium Challenge via the TLR2/NF-κB Signalling Pathway

Lactobacillus plantarum can interact with macrophages against bacterial enteropathy due to its potential ability to modulate macrophage polarization. However, this mechanism is not completely understood. TLR2 can recognize microbial components and trigger macrophage cytokine responses to different gram-positive strains. The aim of this study was to investigate whether probiotic Lactobacillus plantarum RS-09 can induce macrophage polarization against Salmonella Typhimurium infection via TLR2 signalling. BALB/c mice were preadministered RS-09 continuously for 7 days and then infected with Salmonella Typhimurium ATCC14028. Mouse RAW264.7 mononuclear macrophages were stimulated with RS-09 and coincubated with ATCC14028 or PBS controls. The results of the in vivo study indicated that RS-09 could relieve S. Typhimurium-induced splenomegaly, body weight loss and death rate. RS-09 also limited the colonization and translocation of S. Typhimurium in the gastrointestinal tract and thereby protected against infection. We also observed that RS-09 upregulated the production of M1 macrophage characteristics (e.g., CD11c and IL-6) against S. Typhimurium. Furthermore, RS-09 induced the expression of TLR2 in macrophages. In an in vitro study, treatment of RAW264.7 cells with RS-09 either concurrently with or before S. Typhimurium challenge enhanced the secretion of Reactive oxygen species and Nitric oxide. This effect was related to TLR2 and NF-κB activation. Based on these findings, Lactobacillus plantarum RS-09 was shown to modulate M1 macrophage polarization and induce TLR2-linked NF-κB signalling activity in the innate immune response to S. Typhimurium infection.

Bifidobacterium animalis subsp. lactis lkm512 Attenuates Obesity-Associated Inflammation and Insulin Resistance Through the Modification of Gut Microbiota in High-Fat Diet-Induced Obese Mice

SCOPE

The impacts of longevity-promoting probiotic Bifidobacterium animalis subsp. lactis LKM512 (LKM512) on metabolic disease remain unclear. Here, the authors aim to explore the potential of LKM512 on the host physiological function and gut microbiota in high-fat diet-induced obese mice.

METHODS AND RESULTS

LKM512 are orally administrated for 12 weeks, and the effects of LKM 512 on systemic inflammation and insulin resistance, as well as gut microbiota, are investigated in high-fat (HF) diet-induced obese mice. LKM512 supplementation ameliorates hepatic lipid accumulation, attenuates hepatic and adipose tissue inflammation, and improves intestinal barrier function. These results are associated with improved insulin sensitivity and metabolic endotoxemia. Furthermore, the colonization of LKM512 induces an increase in polyamine metabolism and production, together with significant alternations in the composition and function of gut microbiota in obese mice, which are correlated with these improved metabolic phenotypes in the host.

CONCLUSION

The probiotic strain LKM512 may become a promising strategy to improve obesity and related metabolic disorders.

Photoacoustic probe of targeting intracellular Staphylococcus aureus infection with signal-enhanced by self-assembly

In this chapter, we introduce the photoacoustic imaging probe in detecting the infection of bacterial in host cells. We give detailed protocols for the synthesis and confirmation of a PA probe which response to caspase-1 and then self-assembly to enhance the signal. With this PA contrast agent, we may provide a new approach for an intracellular bacterial infection with the selective and sensitive diagnosis.

Elizabethkingia anophelis, an emerging pathogen, inhibits RAW 264.7 macrophage function

Elizabethkingia anophelis is a pathogen that can cause a life-threatening infection in immunocompromised patients. The first case of E. anophelis infection was reported in 2013; subsequently, an increase in its incidence has been reported globally. Additionally, a mortality rate of more than 30% was observed in the US outbreak of 2015. To date, the pathogenic mechanisms underlying E. anophelis infection, such as toxin production, remain unclear. Since tissue macrophages act as the first line of defense against pathogens, in the present study the interactions between E. anophelis and a macrophage-like cell line RAW 264.7 were examined. Although E. anophelis showed no cytotoxicity toward RAW 264.7 macrophages, the infection inhibited LPS-induced morphological changes and activation of differentiation markers for the polarization of RAW 264.7 macrophages toward an M1-like phenotype. However, when the cell contact was restricted using Transwell inserts or bacterial culture supernatants were used instead of live bacteria, no such inhibition was observed. Moreover, it was shown that E. anophelis evaded phagocytosis. Overall, the results suggest that E. anophelis infection inhibits the differentiation of RAW 264.7 macrophages to a pro-inflammatory phenotype in a contact-dependent manner.

Transcriptome Landscape of Intracellular Brucella ovis Surviving in RAW264.7 Macrophage Immune System

Brucella ovis infection results in genital damage and epididymitis in rams, placental inflammation and rare abortion in ewes, and neonatal mortality in lambs. However, the mechanism underlying B. ovis infection remains unclear. In the present study, we used prokaryotic transcriptome sequencing to identify the differentially expressed genes (DEGs) between wild-type B. ovis and intracellular B. ovis in RAW264.7 macrophages. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed, and quantitative reverse transcriptase PCR (qRT-PCR) was used to validate the top 10 upregulated and downregulated DEGs. The results showed that 212 genes were differentially expressed, including 68 upregulated and 144 downregulated genes, which were mainly enriched in 30 GO terms linked to biological process, cellular component, and molecular function. KEGG analysis showed that the DEGs were enriched in the hypoxia-inducible factor 1 (HIF-1) signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, beta-alanine metabolism, and quorum sensing pathway. BME_RS01160, BME_RS04270, BME_RS08185, BME_RS12880, BME_RS25875, predicted_RNA865, and predicted_RNA953 were confirmed with the transcriptome sequencing data. Hence, our findings not only reveal the intracellular parasitism of B. ovis in the macrophage immune system, but also help to understand the mechanism of chronic B. ovis infection.

Gut Microbiota and Chemical-Induced Acute Liver Injury

Background: Drug overdose or chemical exposures are the main causes of acute liver injury (ALI). Severe liver injury can develop into liver failure that is an important cause of liver-related mortality in intensive care units in most countries. Pharmacological studies have utilized a variety of comprehensive chemical induction models that recapitulate the natural pathogenesis of acute liver injury. Their mechanism is always based on redox imbalance-induced direct hepatotoxicity and massive hepatocyte cell death, which can trigger immune cell activation and recruitment to the liver. However, the pathogenesis of these models has not been fully stated. Many studies showed that gut microbiota plays a crucial role in chemical-induced liver injury. Hepatotoxicity is likely induced by imbalanced microbiota homeostasis, gut mucosal barrier damage, systemic immune activation, microbial-associated molecular patterns, and bacterial metabolites. Meanwhile, many preclinical studies have shown that supplementation with probiotics can improve chemical-induced liver injury. In this review, we highlight the pathogenesis of gut microorganisms in chemical-induced acute liver injury animal models and explore the protective mechanism of exogenous microbial supplements on acute liver injury.

Probiotic Bacteria can Modulate Murine Macrophage's Superoxide Production in Trichinella Spiralis Infection

The effect of probiotic strains (Enterococcus faecium EF55, E. faecium CCM7420, E. faecium CCM8558, E. durans ED26E/7, Lactobacillus fermentum CCM7421, L. plantarum 17L/1) on the production of superoxide anion (O₂^-) in peritoneal macrophages of Trichinella spiralis infected mice was examined. E. faecium EF55 and E. faecium CCM8558 strains increased the O₂^-production prior to parasitic infection,at the day7of application.A significant inhibition of the O₂^- production caused by T. spiralis infection on day 5 post infection (p.i.) was prevented by all examined strains. Lactobacilli stimulated metabolic activity of macrophages during intestinal and early muscular phase (from day 5 to 25 p.i.) of trichinellosis. Enterococci increased the O₂^- production in early intestinal phase (day 5 p.i.) and during the muscular phase of trichinellosis (days 25 and 32 p.i.). Respected increase in macrophage’s metabolic activity induced by probiotic treatment in the intestinal phase of trichinellosis augmented the host antiparasite defence (damage and killing of newborn larvae with reactive oxygen species from macrophages).