Search Results (157)

Background: Punicalagin (Pg), a major ellagitannin derived from pomegranates, possesses antimicrobial, antioxidant, and immunomodulatory properties, suggesting its potential as an adjunctive therapy for sepsis. Objectives: This study investigated the synergistic effects of punicalagin and meropenem in a murine model of sublethal sepsis induced by cecal ligation and puncture (CLP). Methods: Mice were treated with punicalagin and meropenem, and multiple parameters were analyzed, including hematological indices, bacterial burden, lymphoid organ cellularity, cytokine profiles (IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, TNF-α), nitric oxide (NO) production, and organ histopathology. Results: Punicalagin enhanced NO-mediated antimicrobial responses, increased neutrophil migration, preserved lymphoid cellularity, and significantly reduced the bacterial translocation. Combined therapy with meropenem improved systemic IL-10 levels and mitigated histopathological damage in the liver, kidney, intestine, and lung. Importantly, punicalagin did not induce thrombocytopenia. Conclusions: These results support the potential of punicalagin as an adjunctive agent to antibiotics for sepsis treatment, offering both antimicrobial and immunoregulatory benefits. Further studies are required to explore its clinical applicability. Full article

Background:Salmonella Typhimurium is a major zoonotic pathogen, in which type 1 fimbriae play a crucial role in intestinal colonization and immune modulation. This study aimed to improve the protective immunity of a previously developed growth-deficient strain—a double auxotroph for D-glutamate and D-alanine—by engineering the inducible expression of type 1 fimbriae. Methods: P_tetA-driven expression of the fim operon was achieved by λ-Red mutagenesis. fimA expression was quantified by qRT-PCR, and fimbriation visualized by transmission electron microscopy. Adhesive properties were evaluated through FimH sequence analysis, yeast agglutination, mannose-binding/inhibition assays, and HT-29 cell adherence. BALB/c mice were immunized orogastrically with IRTA ΔΔΔ or IRTA ΔΔΔ P_tetA::fim. Safety and immunogenicity were assessed by clinical monitoring, bacterial load, fecal shedding, ELISA tests, and adhesion/blocking assays using fecal extracts. Protection was evaluated after challenging with wild-type and heterologous strains. Results: IRTA ΔΔΔ P_tetA::fim showed robust fimA expression, dense fimbrial coverage, a marked mannose-sensitive adhesive phenotype and enhanced HT-29 attachment. Fimbrial overexpression did not alter intestinal colonization or translocation to mesenteric lymph nodes (mLNs). Immunization elicited a mixed IgG1/IgG2a, significantly increased IgA and IgG against type 1 fimbriae-expressing Salmonella, and enhanced the ability of fecal extracts to inhibit the adherence of wild-type strains. Upon challenge (IRTA wild-type/20220258), IRTA ΔΔΔ P_tetA::fim reduced infection burden in the cecum (−1.46/1.47-log), large intestine (−1.35/2.17-log), mLNs (−1.32/0.98-log) and systemic organs more effectively than IRTA ΔΔΔ. Conclusions: Inducible expression of type 1 fimbriae enhances mucosal immunity and protection, supporting their inclusion in next-generation Salmonella vaccines. Future work should assess cross-protection and optimize FimH-mediated targeting for mucosal delivery. Full article

The COVID-19 pandemic has highlighted the complex interplay between the gut microbiota and systemic immune responses, particularly through the gut–lung axis. Disruptions in gut microbial diversity and function—commonly referred to as dysbiosis—have been increasingly implicated in the pathogenesis of SARS-CoV-2 infection. In this study, we assessed the gut bacteriome and permeability in SARS-CoV-2-infected patients using 16S sequencing and ELISA assays, respectively. We also measured blood inflammatory cytokines and fecal secretory IgA to evaluate systemic and mucosal immune responses. Significant alterations in both alpha and beta diversity metrics were observed in patients with COVID-19 (n = 79) and those with post-COVID-19 condition (n = 141) compared to the controls (n = 97). Differential abundance and taxonomic analyses revealed distinct microbial profiles in the infected groups. Increased plasma levels of IL-2, IL-6, IL-17A, IFN-γ, and zonulin were detected in patient samples. Some genera were elevated during acute infection, which was positively correlated with C-reactive protein, while Enterobacteriaceae and Escherichia-Shigella were associated with increased zonulin levels, indicating compromised intestinal barrier function. These findings suggest that gut dysbiosis may contribute to bacterial translocation and systemic inflammation. Overall, our results highlight the importance of the gut–lung axis and suggest that modulating the gut microbiota could support immune regulation in SARS-CoV-2 infection. Full article

Until recently, it was believed that bacterial translocation occurs as a result of leaky gut syndrome or sepsis. To confirm or exclude the process of bacterial translocation, biomarkers can be used. One such biomarker is defensins, which indicate immune activity, as defensins are cationic peptides with antibacterial properties produced by intestinal epithelial cells. Also, fatty acid-binding proteins (I-FABP and L-FABP) can serve as useful serological markers for intestinal epithelial damage, indicating impaired intestinal permeability or organ damage, as high concentrations of them are found in tissues and low concentrations in blood serum. In the context of obesity, the integrity of the intestinal barrier, which can be disrupted by dietary fat, leads to increased intestinal permeability. Since bacterial translocation and microbiota contribute to obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) associated with metabolic dysfunction, intestinal barrier markers can be used to study the role of the gut–liver axis. The aim of this study was to gain insight into the pathogenesis of MASLD and examine the impact of bacterial translocation markers and intestinal and hepatic fatty acid-binding proteins (I-FABP and L-FABP) in children with MASLD. Method: We examined 60 children with MASLD and overweight/obesity (MASLD was diagnosed based on increased liver echogenicity in ultrasound and elevated ALT activity), aged 14.5 years (range 8.5 to 15.8); 33 children with overweight/obesity without MASLD, aged 13.0 years (range 11.4 to 15.8); and 16 healthy controls aged 11.0 years (range 7.0 to 16.2). Defensin, I-FABP, and L-FABP levels were measured using commercial kits: ELISA kits (Drg Medtek) were used to assess α-5 and α-6 defensin concentrations (HBD5, HBD6). I-FABP and L-FABP concentrations were measured using commercial ELISA kits (Hycult Biotech Inc., Wayne, PA, USA). ANOVA analysis was used to compare results across the three study groups. Results: A significant difference was found for the following tests among children with MASLD, obesity, and healthy controls: defensin 6 (14.4 ng/mL vs. 6.13 ng/mL vs. 17.2 ng/mL, respectively), L-FABP (9168 pg/mL vs. 7954 pg/mL vs. 7620 pg/mL, respectively), and I-FABP (272 pg/mL vs. 321 pg/mL vs. 330 pg/mL, respectively). No differences were found in defensin 5 levels (median 567.2 pg/mL vs. 485.7 pg/mL vs. 601.8 pg/mL). No differences were observed in cholesterol levels (HDL, LDL) or triglyceride concentrations, as well as apolipoprotein levels. Conclusions: Based on our study, it was concluded that inflammation and intestinal barrier damage lead to increased L-FABP levels, as it is released from enterocytes in response to oxidative stress or tissue damage. Defensin 6 may indirectly affect L-FABP through microbiota regulation and protection of the intestinal barrier. Defensin 6 also exerts antimicrobial activity and may accompany liver inflammation, with its increased concentration in comparison to obesity explained by the activation of defense mechanisms. Full article

ACLF is a severe stage of liver cirrhosis, characterized by multiple organ failure, systemic inflammation, and high short-term mortality. The intestinal microbiota (IM) influences its pathophysiology; however, there are currently no studies in Latin American populations. Therefore, we analyzed IM and its relationships with sepsis, organ failure, and mortality. In parallel, we quantified serum lipopolysaccharides as a marker of bacterial translocation. Fecal samples from 33 patients and 20 healthy controls (HCs) were obtained. The IMs were characterized by 16S-rRNA amplicon sequencing, the metagenomic functional predictive profiles were analyzed by PICRUSt2, and LPS quantification was performed by ELISA. Patients with ACLF showed significant alterations in alpha and beta diversity compared to the HCs. A strong dominance index accurately predicted 28-day and 90-day mortalities. The IMs showed a polarization toward Proteobacteria associated with increased LPS. The LPS correlated with clinical severity, organ dysfunction, and higher pathogenic taxa. The Klebsiella/Faecalibacterium ratio showed good performance in identifying sepsis (AUROC = 0.83). Furthermore, Morganella, Proteus, and Klebsiella were enriched in patients with multiorgan failure. Lactobacillus, Escherichia/Shigella, Veillonella, and Ruminococcus gnavus exhibited potential in predicting 28- and 90-day mortalities. The IM alterations in ACLF may be useful as clinical biomarkers of poor prognosis, primarily for mortality and sepsis. These findings are representative of western Mexico. Full article

Background: Intestinal ischemia reperfusion injury (IRI) is a harmful process that occurs during intestinal infarction and intestinal transplantation (ITx). It is characterized by severe inflammation which disrupts the mucosal barrier, causing bacterial translocation and sepsis. Tranilast (N-[3,4-dimethoxycinnamoyl]-anthranilic acid) (TL) is a synthetic compound with powerful anti-inflammatory properties. Objective: To investigate the effect of pretreatment with TL in a validated rat model of intestinal IRI (60 min of ischemia). Methods: TL (650 mg/kg) was administered by oral gavage 24 and 2 h before the onset of ischemia. Experiment 1 examined 7-day survival in 3 study groups (sham, vehicle+IRI and TL+IRI, n = 10/group). In Experiment 2, the effects on the intestinal wall integrity and inflammation were studied after 60 min of reperfusion using 3 groups (sham, IRI and TL+IRI, n = 6/group). The following end-points were studied: L-lactate, intestinal fatty acid-binding protein (I-FABP), histology, intestinal permeability, endotoxin translocation, pro- and anti-inflammatory cytokines and heme oxygenase-1 (HO-1) levels. Experiment 3 examined the role of HO-1 upregulation in TL pretreatment, by blocking its expression using Zinc protoporphyrin (ZnPP) at 20 mg/kg vs. placebo (n = 6/group). Results: Intestinal IRI resulted in severe damage of the intestinal wall and a 10% 7-day survival. These alterations led to endotoxin translocation and upregulation of pro-inflammatory cytokines. TL pretreatment improved survival up to 50%, significantly reduced inflammation and protected the intestinal barrier. The HO-1 inhibitor ZnPP, abolished the protective effect of TL. Conclusions: TL pretreatment improves survival by protecting the intestinal barrier function, decreasing inflammation and endotoxin translocation, through upregulation of HO-1.This rat study of severe intestinal ischemia reperfusion injury demonstrates a novel role for Tranilast as a potential therapy. Administration of Tranilast led to a marked reduction in mortality, inflammation and intestinal permeability and damage. The study proved that Tranilast functions through upregulation of heme oxygenase-1. Full article

COVID-19 has caused millions of deaths globally; however, the characterization of molecular biomarkers of severe disease remains of great scientific importance. The aim of this study was to capture the transcriptional differences of the whole blood gene expression between COVID-19 patients with mild and severe disease, using Next Generation Sequencing technologies, on admission and after 7 days. The genes which were differentially expressed in severe compared to mild patients were used for Gene Ontology (GO) enrichment analysis. Gene expression data were used to estimate the cell abundance of 22 immune cell types via digital cytometry. GO terms related to the response to molecules of bacterial origin, such as intestine-derived lipopolysaccharide (LPS), were enriched, among other dysregulated pathways, which are well described as paramount mechanisms of severe manifestations of COVID-19. The neutrophil population increased in patients with severe disease, whereas the monocyte, CD8⁺ T cell, and activated Natural Killer (NK) cell populations were depleted. These cell population dynamics are also indicative of severe COVID-19 and intestinal bacterial translocation. This study elucidates the molecular basis of severe COVID-19 and highlights intestinal bacterial translocation as a potential driver of severe disease. Full article

The human immune system is closely linked to microbiota such as a complex symbiotic relationship during the coevolution of vertebrates and microorganisms. The transfer of microorganisms from the mother’s microbiota to the newborn begins before birth during gestation and is considered the initial phase of the intestinal microbiota (IM). The gut is an important site where microorganisms can establish colonies. The IM contains polymicrobial communities, which show complex interactions with diet and host immunity. The tendency towards dysbiosis of the intestinal microbiota is influenced by local but also extra-intestinal factors such as inflammatory processes, infections, or a septic state that can aggravate it. Pathogens could trigger an immune response, such as proinflammatory responses. In addition, changes in the host immune system also influence the intestinal community and structure with additional translocation of pathogenic and non-pathogenic bacteria. Finally, local intestinal inflammation has been found to be an important factor in the growth of pathogenic microorganisms, particularly in its role in sepsis. The aim of this article is to be able to detect the current knowledge of the mechanisms that can lead to dysbiosis of the intestinal microbiota and that can cause bacterial translocation with a risk of infection or septic state and vice versa. Full article

Background/Objectives: The aim of this study was to evaluate potential biomarkers of bacterial translocation (lipopolysaccharide-binding protein (LBP) and soluble CD14 subtype (sCD14-ST)) and intestinal wall damage (intestinal fatty acid binding protein (I-FABP), Zonulin, and regenerating islet-derived protein-3α (REG3α)) in patients with multiple organ dysfunction syndrome (MODS). Methods: The study involved 327 patients divided into two groups: Group 1 comprised 227 patients with MODS (main group), while Group 2 comprised 100 patients with identical pathologies but without MODS (control group). To examine these biomarkers in the blood, venous blood was taken in the control group on the day of admission to the hospital, in patients with MODS on the first day of MODS staging, and later on Days 3 and 7 of its development. Levels of these markers in blood serum were determined by enzyme-linked immunosorbent assays according to the manufacturers’ instructions. Results: In the control group, values of all the investigated markers were lower than in the group of MODS patients (p < 0.0001). In the main group, the mortality rate was 44.9% (n = 102). The values of sCD14-ST on Day 1 and of I-FABP and REG3α on Days 1 and 3 were higher in deceased MODS patients (p < 0.05), while LBP levels on Day 7 were conversely lower in the deceased patients (p = 0.006). SOFA and APACHE II scores were higher in the deceased patients (p < 0.0001). Conclusions: In MODS patients, the increased I-FABP, REG3α, and sCD14-ST but decreased LBP levels may indicate increased intestinal wall permeability and bacterial translocation, which may exacerbate the course of multiple organ dysfunction and increase the risk of mortality. Despite the limitations of this study, the studied potential biomarkers can be considered noteworthy candidates for identifying MODS patients at high risk of mortality. Full article

The role of gut microbiota (GM) and intestinal dysbiosis in triggering the onset and/or modulating the severity and progression of lupus nephritis (LN) has been the object of intense research over the last few years. Some alterations at the phyla level, such as the abundance of Proteobacteria and reduction in Firmicutes/Bacteroidetes (F/B) ratio and in α-diversity have been consistently reported in systemic lupus erythematosus (SLE), whereas a more specific role has been ascribed to some species (Bacteroides thetaiotaomicron and Ruminococcus gnavus) in LN. Underlying mechanisms include microbial translocation through a “leaky gut” and subsequent molecular mimicry, immune dysregulation (alteration of IFNγ levels and of balance between Treg and Th17 subsets), and epigenetic interactions. Levels of bacterial metabolites, such as butyrate and other short-chain fatty acids (SCFAs), appear to play a key role in modulating LN. Beyond bacterial components of GM, virome and mycobiome are also increasingly recognized as important players in the modulation of an immune response. On the other hand, microbiota-based therapy appears promising and includes diet, prebiotics, probiotics, symbiotics, and fecal microbiota transplantation (FMT). The modulation of microbiota could correct critical alterations, such as F/B ratio and Treg/Th17 imbalance, and blunt production of autoantibodies and renal damage. Despite current limits, GM is emerging as a powerful environmental factor that could be harnessed to interfere with key mechanisms leading to SLE, preventing flares and organ damage, including LN. The aim of this review is to provide a state-of-the-art analysis of the role of GM in triggering and modulating SLE and LN on the one hand, while exploring possible therapeutic manipulation of GM to control the disease on the other hand. Full article

This study evaluated the effect of a yeast β-glucan on the performance, gut health, liver function, and bacterial translocation of broiler chickens fed a diet contaminated with Fusarium mycotoxins. One-day-old male Ross broilers (n = 234) were divided into three treatments with six replicates each, and a cage containing 13 birds was the experimental unit. The animals were fed a maize–soybean-based control diet or maize–soybean diets naturally contaminated with Fusarium mycotoxins, where deoxynivalenol (DON) was the major mycotoxin (~3 mg/kg), followed by zearalenone (ZEN) (~0.5 mg/kg). The Fusarium-contaminated diet was either supplemented or not with a yeast β-glucan over 28 days. Dietary exposure to Fusarium mycotoxins did not affect production performance. On the other hand, Fusarium mycotoxin exposure significantly decreased jejunum villus height (VH) and crypt depth (CD) on d13, and this effect was counteracted by the yeast β-glucan. On d28, the jejunum VH:CD ratio was significantly higher in the broiler chickens that were fed the Fusarium-contaminated diet with yeast β-glucan (125 mg/kg diet) added to it. The ileal villus area was significantly decreased in the broiler chickens fed Fusarium-contaminated diet, regardless of the supplementation with yeast β-glucan. Dietary contamination caused intestinal oxidative stress and inflammation, probably affecting nutrient absorption on d28, and resulted in a significant increase in the translocation of Escherichia coli to the liver. Dietary supplementation with yeast β-glucan minimized these negative effects. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent chronic liver condition marked by excessive lipid accumulation in hepatic tissue. This disorder can lead to a range of pathological outcomes, including metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. Despite extensive research, the molecular mechanisms driving MASLD initiation and progression remain incompletely understood. Oxidative stress and lipid peroxidation are pivotal in the “multiple parallel hit model”, contributing to hepatic cell death and tissue damage. Gut microbiota plays a substantial role in modulating hepatic oxidative stress through multiple pathways: impairing the intestinal barrier, which results in bacterial translocation and chronic hepatic inflammation; modifying bile acid structure, which impacts signaling cascades involved in lipidic metabolism; influencing hepatocytes’ ferroptosis, a form of programmed cell death; regulating trimethylamine N-oxide (TMAO) metabolism; and activating platelet function, both recently identified as pathogenetic factors in MASH progression. Moreover, various exogenous factors impact gut microbiota and its involvement in MASLD-related oxidative stress, such as air pollution, physical activity, cigarette smoke, alcohol, and dietary patterns. This manuscript aims to provide a state-of-the-art overview focused on the intricate interplay between gut microbiota, lipid peroxidation, and MASLD pathogenesis, offering insights into potential strategies to prevent disease progression and its associated complications. Full article

Some strains of Enterococcus cecorum can cause spondylitis and bacterial osteomyelitis. Translocation and bacteremia are pivotal to the pathogenesis and clinical disease. Virulence typing to distinguish extra-intestinal disease of lesion from cloacal strains remains difficult. We investigated if organoids can be applied to differentiate between E. cecorum strains that are more or less virulent. Floating chicken intestinal organoids combine the complex cell system of the gut with an easily accessible apical-out orientation. The organoids were treated with four E. cecorum strains that differ in original isolation, lesion, or cloacal, and bacterial load was determined after 3 and 6 h by quantitative PCR and bacterial plating. Independent of the inoculum dose or time post inoculation, DNA levels of E. cecorum marginally differed between the strains. To determine if this was caused by adherence of bacteria to the epithelial cells, an invasion assay was developed. The organoids were inoculated with the different E. cecorum strains and after 3 or 6 h treated with an antimicrobial mixture, lysed, and quantified by bacterial plate counting. Significantly higher (p < 0.0001) numbers of bacteria isolated from lesions invaded the organoids compared to cloacal strains in a dose-dependent manner. Higher numbers of bacteria isolated from lesions invaded the organoids compared to cloacal strains in a dose-dependent manner. This study is a major step in the development of a model to study the interaction between E. cecorum and the chicken host and a model to test novel intervention strategies to prevent translocation of bacteria. Full article

Within mammalian cells, diverse endocytic mechanisms, including phagocytosis, pinocytosis, and receptor-mediated endocytosis, serve as gateways exploited by many bacterial pathogens and toxins. Among these, caveolae-mediated endocytosis is characterized by lipid-rich caveolae and dimeric caveolin proteins. Caveolae are specialized microdomains on cell surfaces that impact cell signaling. Caveolin proteins facilitate the creation of caveolae and have three members in vertebrates: caveolin-1, caveolin-2, and caveolin-3. Many bacterial pathogens hijack caveolin machinery to invade host cells. For example, the Gram-positive facultative model intracellular bacterial pathogen Listeria monocytogenes exploits caveolin-mediated endocytosis for efficient cellular entry, translocation across the intestinal barrier, and cell–cell spread. Caveolin facilitates the internalization of group A streptococci by promoting the formation of invaginations in the plasma membrane and avoiding fusion with lysosomes, thereby aiding intracellular survival. Caveolin plays a crucial role in internalizing and modulation of host immune responses by Gram-negative bacterial pathogens, such as Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium. Here, we summarize how bacterial pathogens manipulate the host’s caveolin system to facilitate bacterial entry and movement within and between host cells, to support intracellular survival, to evade immune responses, and to trigger inflammation. This knowledge enhances the intervention of new therapeutic targets against caveolin in microbial invasion and immune evasion processes. Full article

Obesity is a chronic, multifactorial disease characterized by persistent low-grade tissue and systemic inflammation. Fat accumulation in adipose tissue (AT) leads to stress and dysfunctional adipocytes, along with the infiltration of immune cells, which initiates and sustains inflammation. Neutrophils are the first immune cells to infiltrate AT during high-fat diet (HFD)-induced obesity. Emerging evidence suggests that the formation and release of neutrophil extracellular traps (NETs) play a significant role in the progression of obesity and related diseases. Additionally, obesity is associated with an imbalance in gut microbiota and increased intestinal barrier permeability, resulting in the translocation of live bacteria, bacterial deoxyribonucleic acid (DNA), lipopolysaccharides (LPS), and pro-inflammatory cytokines into the bloodstream and AT, thereby contributing to metabolic inflammation. Recent research has also shown that short-chain fatty acids (SCFAs), produced by gut microbiota, can influence various functions of neutrophils, including their activation, migration, and the generation of inflammatory mediators. This review comprehensively summarizes recent advancements in understanding the role of neutrophils and NET formation in the pathophysiology of obesity and related disorders while also focusing on updated potential therapeutic approaches targeting NETs based on studies conducted in humans and animal models. Full article