Fecal microbiota transplant rescues mice from human pathogen mediated sepsis by restoring systemic immunity

Multienzyme Active Nanozyme for Efficient Sepsis Therapy through Modulating Immune and Inflammation Inhibition

Sepsis, a life-threatening condition caused by a dysregulated immune response to infection, leads to systemic inflammation, immune dysfunction, and multiorgan damage. Various oxidoreductases play a very important role in balancing oxidative stress and modulating the immune response, but they are stored inconveniently, environmentally unstable, and expensive. Herein, we develop multifunctional artificial enzymes, CeO2 and Au/CeO2 nanozymes, exhibiting five distinct enzyme-like activities, namely, superoxide dismutase, catalase, glutathione peroxidase, peroxidase, and oxidase. These artificial enzymes have been used for the biocatalytic treatment of sepsis via inhibiting inflammation and modulating immune responses. These nanozymes significantly reduce reactive oxygen species and proinflammatory cytokines, achieving multiorgan protection. Notably, CeO2 and Au/CeO2 nanozymes with enzyme-mimicking activities can be particularly effective in restoring immunosuppression and maintaining homeostasis. The redox nanozyme offers a promising dual-protective strategy against sepsis-induced inflammation and organ dysfunction, paving the way for biocatalytic-based immunotherapies for sepsis and related inflammatory diseases.

NHH promotes Sepsis-associated Encephalopathy with the expression of AQP4 in astrocytes through the gut-brain Axis

Sepsis-associated encephalopathy (SAE) is a significant cause of mortality in patients with sepsis. Despite extensive research, its exact cause remains unclear. Our previous research indicated a relationship between non-hepatic hyperammonemia (NHH) and SAE. This study aimed to investigate the relationship between NHH and SAE and the potential mechanisms causing cognitive impairment. In the in vivo experimental results, there were no significant abnormalities in the livers of mice with moderate cecal ligation and perforation (CLP); however, ammonia levels were elevated in the hippocampal tissue and serum. The ELISA study suggest that fecal microbiota transplantation in CLP mice can reduce ammonia levels. Reduction in ammonia levels improved cognitive dysfunction and neurological impairment in CLP mice through behavioral, neuroimaging, and molecular biology studies. Further studies have shown that ammonia enters the brain to regulate the expression of aquaporins-4 (AQP4) in astrocytes, which may be the mechanism underlying brain dysfunction in CLP mice. The results of the in vitro experiments showed that ammonia up-regulated AQP4 expression in astrocytes, resulting in astrocyte damage. The results of this study suggest that ammonia up-regulates astrocyte AQP4 expression through the gut-brain axis, which may be a potential mechanism for the occurrence of SAE.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Regulatory effects of mangiferin on LPS-induced inflammatory responses and intestinal flora imbalance during sepsis

Studies suggest that mangiferin (MAF) has good therapeutic effects on chronic bronchitis and hepatitis. Also, it is one of the antiviral ingredients in Anemarrhena asphodeloides Bunge. However, its effect on the LPS-induced inflammation and intestinal flora during sepsis remains unclear yet. In the present study, LPS-stimulated inflammation RAW264.7 cells and LPS-induced sepsis mice were used to evaluate the efficacy of MAF in vitro and in vivo. 16S rDNA sequencing was performed to analyze the characteristics of intestinal flora of the sepsis mice. It has been demonstrated that MAF (12.5 and 25 μg/mL) significantly inhibited protein expressions of TLR4, MyD88, NF-κB, and TNF-α in the LPS-treated cells and reduced the supernatant TNF-α and IL-6 levels. In vivo, MAF (20 mg/kg) markedly protected the sepsis mice and reduced the serum TNF-α and IL-6 levels. Also, MAF significantly downregulated the protein expressions of TLR4, NF-κB, and MyD88 in the livers. Importantly, MAF significantly attenuated the pathological injuries of the livers and small intestines. Further, MAF significantly increased proportion of Bacteroidota and decreased the proportions of Firmicutes, Desulfobacterota, Actinobacteriota, and Proteobacteria at phylum level, and it markedly reduced the proportions of Escherichia-Shigella, Pseudoalteromonas, Staphylococcus at genus level. Moreover, MAF affects some metabolism-related pathways such as citrate cycle (TCA cycle), lipoic acid metabolism, oxidative phosphorylation, bacterial chemotaxis, fatty acid biosynthesis, and peptidoglycan biosynthesis of the intestinal flora. Thus, it can be concluded that MAF as a treatment reduces the inflammatory responses in vitro and in vivo by inhibiting the TLR4/ MyD88/NF-κB pathway, and corrects intestinal flora imbalance during sepsis to some degree.

IRF3 function and immunological gaps in sepsis

Lipopolysaccharide (LPS) induces potent cell activation via Toll-like receptor 4/myeloid differentiation protein 2 (TLR4/MD-2), often leading to septic death and cytokine storm. TLR4 signaling is diverted to the classical acute innate immune, inflammation-driving pathway in conjunction with the classical NF-κB pivot of MyD88, leading to epigenetic linkage shifts in nuclear pro-inflammatory transcription and chromatin structure-function; in addition, TLR4 signaling to the TIR domain-containing adapter-induced IFN-β (TRIF) apparatus and to nuclear pivots that signal the association of interferons alpha and beta (IFN-α and IFN-β) with acute inflammation, often coupled with oxidants favor inhibition or resistance to tissue injury. Although the immune response to LPS, which causes sepsis, has been clarified in this manner, there are still many current gaps in sepsis immunology to reduce mortality. Recently, selective agonists and inhibitors of LPS signals have been reported, and there are scattered reports on LPS tolerance and control of sepsis development. In particular, IRF3 signaling has been reported to be involved not only in sepsis but also in increased pathogen clearance associated with changes in the gut microbiota. Here, we summarize the LPS recognition system, main findings related to the IRF3, and finally immunological gaps in sepsis.

Engineering Strategies to Modulate the Gut Microbiome and Immune System

The gut microbiota, predominantly residing in the colon, is a complex ecosystem with a pivotal role in the host immune system. Dysbiosis of the gut microbiota has been associated with various diseases, and there is an urgent need to develop new therapeutics that target the microbiome and restore immune functions. This Brief Review discusses emerging therapeutic strategies that focus on oral delivery systems for modulating the gut microbiome. These strategies include genetic engineering of probiotics, probiotic-biomaterial hybrids, dietary fibers, and oral delivery systems for microbial metabolites, antimicrobial peptides, RNA, and antibiotics. Engineered oral formulations have demonstrated promising outcomes in reshaping the gut microbiome and influencing immune responses in preclinical studies. By leveraging these approaches, the interplay between the gut microbiota and the immune system can be harnessed for the development of novel therapeutics against cancer, autoimmune disorders, and allergies.

Gut microbiome dynamics and associations with mortality in critically ill patients

BACKGROUND

Critical illness and care within the intensive care unit (ICU) leads to profound changes in the composition of the gut microbiome. The impact of such changes on the patients and their subsequent disease course remains uncertain. We hypothesized that specific changes in the gut microbiome would be more harmful than others, leading to increased mortality in critically ill patients.

METHODS

This was a prospective cohort study of critically ill adults in the ICU. We obtained rectal swabs from 52 patients and assessed the composition the gut microbiome using 16 S rRNA gene sequencing. We followed patients throughout their ICU course and evaluated their mortality rate at 28 days following admission to the ICU. We used selbal, a machine learning method, to identify the balance of microbial taxa most closely associated with 28-day mortality.

RESULTS

We found that a proportional ratio of four taxa could be used to distinguish patients with a higher risk of mortality from patients with a lower risk of mortality (p = .02). We named this binarized ratio our microbiome mortality index (MMI). Patients with a high MMI had a higher 28-day mortality compared to those with a low MMI (hazard ratio, 2.2, 95% confidence interval 1.1-4.3), and remained significant after adjustment for other ICU mortality predictors, including the presence of the acute respiratory distress syndrome (ARDS) and the Acute Physiology and Chronic Health Evaluation (APACHE II) score (hazard ratio, 2.5, 95% confidence interval 1.4-4.7). High mortality was driven by taxa from the Anaerococcus (genus) and Enterobacteriaceae (family), while lower mortality was driven by Parasutterella and Campylobacter (genera).

CONCLUSIONS

Dysbiosis in the gut of critically ill patients is an independent risk factor for increased mortality at 28 days after adjustment for clinically significant confounders. Gut dysbiosis may represent a potential therapeutic target for future ICU interventions.

The role of faecal microbiota transplantation in chronic noncommunicable disorders

The gut microbiome plays a key role in influencing several pathways and functions involved in human health, including metabolism, protection against infection, and immune regulation. Perturbation of the gut microbiome is recognised as a pathogenic factor in several gastrointestinal and extraintestinal disorders, and is increasingly considered as a therapeutic target in these conditions. Faecal microbiota transplantation (FMT) is the transfer of the microbiota from healthy screened stool donors into the gut of affected patients, and is a well-established and highly effective treatment for recurrent Clostridioides difficile infection. Despite the mechanisms of efficacy of FMT not being fully understood, it has been investigated in several chronic noncommunicable disorders, with variable results. This review aims to give an overview of mechanisms of efficacy of FMT in chronic noncommunicable disorders, and to paint the current landscape of its investigation in these medical conditions, including inflammatory bowel disease (IBD), chronic liver disorders, and also extraintestinal autoimmune conditions.

Fuzi decoction treats chronic heart failure by regulating the gut microbiota, increasing the short-chain fatty acid levels and improving metabolic disorders

Fuzi decoction (FZD) is clinically used to treat chronic heart failure (CHF) in China, but the mechanism underlying FZD treatment in CHF remains unclear. Here, we investigated the potential mechanism underlying FZD treatment of CHF in rats. First, the compounds in FZD-containing serum of rats were identified, and 16 S rRNA sequencing and GC-MS-based untargeted metabolomics analysis were then performed. The levels of fecal short-chain fatty acids (SCFAs) were determined and compared, and fecal microbiota transplantation (FMT) was used to verify the role of the gut microbiota. Our results identified 27 in FD-containing serum. FZD increased the Firmicutes-to-Bacteroidetes ratio and the Lactobacillus abundance and affected the β diversity of the gut microbiota in rats with CHF. Differential species analysis showed that Lactobacillus and Prevotella were biomarkers of FZD treatment of CHF. Untargeted metabolomics analysis revealed that FZD affected valine, leucine and isoleucine biosynthesis; galactose metabolism; and aminoacyl-tRNA biosynthesis in rats with CHF. Furthermore, FZD significantly increased the acetic acid, propionic acid, butyric acid and isopentanoic acid levels in the feces of rats with CHF. Correlation analysis showed that the butyric acid and Lactobacillus levels had the strongest correlation in the control, sham and high-dose FZD (HFZD) groups, and many microbiota components were closely related to differentially abundant metabolites. FMT revealed that the fecal microbiota obtained from the HFZD group changed the heart rate; the brain natriuretic peptide (BNP), acetic acid, propionic acid, butyric acid, and metabolite levels; and the gut microbiota in rats with CHF. In summary, our study revealed that the mechanism of action of FZD in CHF treatment may be related to improvements in the gut microbiota, elevations in the SCFA content and the regulation of valine, leucine, and isoleucine biosynthesis; galactose metabolism; and other metabolic pathways.

Gut Microbiome-Based Therapeutics in Critically Ill Adult Patients-A Narrative Review

The gut microbiota plays a crucial role in the human microenvironment. Dysbiosis of the gut microbiota is a common pathophysiological phenomenon in critically ill patients. Therefore, utilizing intestinal microbiota to prevent complications and improve the prognosis of critically ill patients is a possible therapeutic direction. The gut microbiome-based therapeutics approach focuses on improving intestinal microbiota homeostasis by modulating its diversity, or treating critical illness by altering the metabolites of intestinal microbiota. There is growing evidence that fecal microbiota transplantation (FMT), selective digestive decontamination (SDD), and microbiota-derived therapies are all effective treatments for critical illness. However, different treatments are appropriate for different conditions, and more evidence is needed to support the selection of optimal gut microbiota-related treatments for different diseases. This narrative review summarizes the curative effects and limitations of microbiome-based therapeutics in different critically ill adult patients, aiming to provide possible directions for gut microbiome-based therapeutics for critically ill patients such as ventilator-associated pneumonia, sepsis, acute respiratory distress syndrome, and COVID-19, etc.

Nobiletin protects against ferroptosis to alleviate sepsis-associated acute liver injury by modulating the gut microbiota

Nobiletin (NOB), a plant-based polymethoxyflavone, is a promising protective agent against sepsis; yet the mechanisms were not fully elucidated. The gut microbiota is found to be strongly associated with sepsis-associated acute liver injury (SALI). Here, our study aimed to evaluate the protective effect of NOB on SALI and explore the underlying molecular mechanisms. Cecal ligation and puncture (CLP) was used to induce SALI in mice. NOB was administered by gavage for 7 days before CLP induction. The 16S rRNA gene sequencing and fecal microbiota transplantation (FMT) were performed to verify the function of the gut microbiota. The markers of ferroptosis, inflammation, gut microbiota composition, and liver injury were determined. NOB administration significantly alleviated hepatic ferroptosis and inflammation in septic mice. Meanwhile, NOB upregulated the expression levels of nuclear factor E2-related factor 2 (Nrf2) and its downstream protein heme oxygenase-1 (HO-1). The protective effect of NOB administration against ferroptosis in SALI mice was reversed by the Nrf2 inhibitor ML385. Additionally, increased abundances of Ligilactobacillus, Akkermansia, and Lactobacillus, and decreased abundances of Dubosiella and Bacteroides in the gut were observed under NOB administration, suggesting that NOB might modulate the gut microbiota composition of septic mice. Furthermore, gut microbiota ablation by antibiotic treatment partly reversed the protective effects of NOB on sepsis. FMT also confirmed that NOB inhibited ferroptosis and activated Nrf2 signalling in SALI mice by modulating the gut microbiota. These results revealed that, by modulating the gut microbiota, NOB attenuated ferroptosis in septic liver injury through upregulating Nrf2-Gpx4. Our findings provide novel insights into microbiome-based therapeutic approaches for sepsis.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.

Lactobacillus gasseri LGV03 isolated from the cervico-vagina of HPV-cleared women modulates epithelial innate immune responses and suppresses the growth of HPV-positive human cervical cancer cells

Persistent human papillomavirus (HPV) infections is necessary for the development of cervical cancers. An increasing number of retrospective studies have found the depletion of Lactobacillus microbiota in the cervico-vagina facilitate HPV infection and might be involved in viral persistence and cancer development. However, there have been no reports confirming the immunomodulatory effects of Lactobacillus microbiota isolated from cervico-vaginal samples of HPV clearance in women. Using cervico-vaginal samples from HPV persistent infection and clearance in women, this study investigated the local immune properties in cervical mucosa. As expected, type I interferons, such as IFN-α and IFN-β, and TLR3 globally downregulated in HPV+ persistence group. Luminex cytokine/chemokine panel analysis revealed that L. jannaschii LJV03, L. vaginalis LVV03, L. reuteri LRV03, and L. gasseri LGV03 isolated from cervicovaginal samples of HPV clearance in women altered the host's epithelial immune response, particularly L. gasseri LGV03. Furthermore, L. gasseri LGV03 enhanced the poly (I:C)-induced production of IFN by modulating the IRF3 pathway and attenuating poly (I:C)-induced production of proinflammatory mediators by regulating the NF-κB pathway in Ect1/E6E7 cells, indicating that L. gasseri LGV03 keeps the innate system alert to potential pathogens and reduces the inflammatory effects during persistent pathogen infection. L. gasseri LGV03 also markedly inhibited the proliferation of Ect1/E6E7 cells in a zebrafish xenograft model, which may be attributed to an increased immune response mediated by L. gasseri LGV03.

Vascular traffic control of neutrophil recruitment to the liver by microbiota-endothelium crosstalk

During bloodstream infections, neutrophils home to the liver as part of an intravascular immune response to eradicate blood-borne pathogens, but the mechanisms regulating this crucial response are unknown. Using in vivo imaging of neutrophil trafficking in germ-free and gnotobiotic mice, we demonstrate that the intestinal microbiota guides neutrophil homing to the liver in response to infection mediated by the microbial metabolite D-lactate. Commensal-derived D-lactate augments neutrophil adhesion in the liver independent of granulopoiesis in bone marrow or neutrophil maturation and activation in blood. Instead, gut-to-liver D-lactate signaling primes liver endothelial cells to upregulate adhesion molecule expression in response to infection and promote neutrophil adherence. Targeted correction of microbiota D-lactate production in a model of antibiotic-induced dysbiosis restores neutrophil homing to the liver and reduces bacteremia in a model of Staphylococcus aureus infection. These findings reveal long-distance traffic control of neutrophil recruitment to the liver by microbiota-endothelium crosstalk.

Gut-muscle axis and sepsis-induced myopathy: The potential role of gut microbiota

Sepsis is described as an immune response disorder of the host to infection in which microorganisms play a non-negligible role. Most survivors of sepsis experience ICU-acquired weakness, also known as septic myopathy, characterized by skeletal muscle atrophy, weakness, and irreparable damage/regenerated or dysfunctional. The mechanism of sepsis-induced myopathy is currently unclear. It has been believed that this state is triggered by circulating pathogens and their related harmful factors, leading to impaired muscle metabolism. Sepsis and its resulting alterations in the intestinal microbiota are associated with sepsis-related organ dysfunction, including skeletal muscle wasting. There are also some studies on interventions targeting the flora, including fecal microbiota transplants, the addition of dietary fiber and probiotics in enteral feeding products, etc., aiming to improve sepsis-related myopathy. In this review, we critically assess the potential mechanisms and therapeutic prospects of intestinal flora in the development of septic myopathy.

Interplay between Phytochemicals and the Colonic Microbiota

Phytochemicals are natural compounds found in food ingredients with a variety of health-promoting properties. Phytochemicals improve host health through their direct systematic absorption into the circulation and modulation of the gut microbiota. The gut microbiota increases the bioactivity of phytochemicals and is a symbiotic partner whose composition and/or diversity is altered by phytochemicals and affects host health. In this review, the interactions of phytochemicals with the gut microbiota and their impact on human diseases are reviewed. We describe the role of intestinal microbial metabolites, including short-chain fatty acids, amino acid derivatives, and vitamins, from a therapeutic perspective. Next, phytochemical metabolites produced by the gut microbiota and the therapeutic effect of some selected metabolites are reviewed. Many phytochemicals are degraded by enzymes unique to the gut microbiota and act as signaling molecules in antioxidant, anti-inflammatory, anticancer, and metabolic pathways. Phytochemicals can ameliorate diseases by altering the composition and/or diversity of the gut microbiota, and they increase the abundance of some gut microbiota that produce beneficial substances. We also discuss the importance of investigating the interactions between phytochemicals and gut microbiota in controlled human studies.

Jinhong decoction protects sepsis-associated acute lung injury by reducing intestinal bacterial translocation and improving gut microbial homeostasis

Background: Currently no specific treatments are available for sepsis and the associated syndromes including acute lung injury (ALI). Jinhong Decoction (JHD) is a traditional Chinese prescription, and it has been applied clinically as an efficient and safe treatment for sepsis, but the underlying mechanism remains unknown. The aim of the study was to explore the potential mechanisms of JHD ameliorating sepsis and concurrent ALI.

Methods: The cecum ligation puncture (CLP)- induced murine sepsis model was established for determining the efficacy of JHD protecting CLP and ALI. The role of gut microbiota involved in the efficacy of JHD was evaluated by 16S rRNA sequencing and fecal microbiota transplantation (FMT). Translocation of intestinal Escherichia coli (E. coli) to lungs after CLP was verified by qPCR and in vivo-imaging. Intestinal permeability was analyzed by detecting FITC-dextran leakness. Junction proteins were evaluated by Western blotting and immunofluorescence.

Results: JHD treatment remarkably increased survival rate of septic mice and alleviated sepsis-associated lung inflammation and injury. FMT suggested that the protective role for JHD was mediated through the regulation of gut microbiota. We further revealed that JHD administration partially restored the diversity and configuration of microbiome that was distorted by CLP operation. Of interest, the intestinal bacteria, E. coli particularly, was found to translocate into the lungs upon CLP via disrupting the intestinal mucosal barrier, leading to the inflammatory response and tissue damage in lungs. JHD impeded the migration and hence lung accumulation of intestinal E. coli, and thereby prevented severe ALI associated with sepsis. This effect is causatively related with the ability of JHD to restore intestinal barrier by up-regulating tight junctions.

Conclusion: Our study unveils a mechanism whereby the migration of gut bacteria leads to sepsis-associated ALI, and we demonstrate the potential of JHD as an effective strategy to block this bacterial migration for treating sepsis and the associated immunopathology in the distal organs.

Leveraging the microbiome in the treatment of sepsis: potential pitfalls and new perspectives

PURPOSE OF REVIEW

This review aims to provide an overview of the current knowledge about microbiota-targeted therapies in sepsis, and calls out - despite recent negative studies - not to halt our efforts of translating these tools into regular medical practice.

RECENT FINDINGS

The intestinal microbiome has an important role in shaping our immune system, and microbiota-derived metabolites prime innate and adaptive inflammatory responses to infectious pathogens. Microbiota composition is severely disrupted during sepsis, which has been linked to increased risk of mortality and secondary infections. However, efforts of using these microbes as a tool for prognostic or therapeutic purposes have been unsuccessful so far, and recent trials studying the impact of probiotics in critical illness did not improve patient outcomes. Despite these negative results, researchers must continue their attempts of harnessing the microbiome to improve sepsis survival in patients with a high risk of clinical deterioration. Promising research avenues that could potentially benefit sepsis patients include the development of next-generation probiotics, use of the microbiome as a theranostic tool to direct therapy, and addressing the restoration of microbial communities following ICU discharge.

SUMMARY

Although research focused on microbiome-mediated therapy in critically ill patients has not yielded the results that were anticipated, we should not abandon our efforts to translate promising preclinical findings into clinical practice.

Gut Microbiome in Sepsis

Abstract The gut has been hypothesized to be the "motor" of multiple organ dysfunction in sepsis. Although there are multiple ways in which the gut can drive systemic inflammation, increasing evidence suggests that the intestinal microbiome plays a more substantial role than previously appreciated. An English language literature review was performed to summarize the current knowledge of sepsis-induced gut microbiome dysbiosis. Conversion of a normal microbiome to a pathobiome in the setting of sepsis is associated with worsened mortality. Changes in microbiome composition and diversity signal the intestinal epithelium and immune system resulting in increased intestinal permeability and a dysregulated immune response to sepsis. Clinical approaches to return to microbiome homeostasis may be theoretically possible through a variety of methods including probiotics, prebiotics, fecal microbial transplant, and selective decontamination of the digestive tract. However, more research is required to determine the efficacy (if any) of targeting the microbiome for therapeutic gain. The gut microbiome rapidly loses diversity with emergence of virulent bacteria in sepsis. Restoring normal commensal bacterial diversity through various therapies may be an avenue to improve sepsis mortality.

Fecal microbiota transplantation affects the recovery of AD-skin lesions and enhances gut microbiota homeostasis

BACKGROUND

Accumulating evidence has shown that gut microbiota plays a key role in the progression of atopic dermatitis (AD). Fecal microbiota transplantation (FMT), as an effective method to restore gut microbiota homeostasis, has been successfully applied for treating many inflammatory diseases. However, the therapeutic effect of FMT on AD remains unclear. The following study examined the effect and mechanism of FMT on AD-skin lesions in an AD mouse model.

METHODS

In this study, we exposed the shaved back skin of BALB/c mice to calcipotriol (MC903) to induce AD model. Mice were then treated with FMT, which was performed with gut microbiota from healthy mice. The gut microbiota of treated mice was tracked by 16S rRNA gene sequencing. Mice skin tissues were examined by histopathology and inflammatory cytokines change in serum by ELISA.

RESULTS

FMT had a faster trend on the reversion of the increases in skin epidermal layer thicknesses and suppressed some of the representative inflammatory cytokines. The gut microbial community in the natural recovery process varied significantly in the FMT group at day 7 (ANOSIM P = 0.0229, r = 0.2593). Notably, FMT had a long-lasting and beneficial impact on the gut microbial compositions of AD mice by increasing the ratio of Firmicutes to Bacteroidetes and the amount of butyric-producing bacteria (BPB), including Erysipelotrichaceae, Lactobacillaceae, and Eubacteriacea. Furthermore, the relative abundances of gut microbiota-mediated functional pathways involved in the cell growth and death, amino acid, energy, lipid, and carbohydrate metabolisms, and immune system increased after FMT treatment.

CONCLUSION

FMT modulated the gut microbiota homeostasis and affected the recovery from AD-related inflammations, suggesting that it could be used as a treatment strategy for AD patients in the clinic.

What Is the Microbiome? A Description of a Social Network

The gut microbiome has coevolved with its hosts over the years, forming a complex and symbiotic relationship. It is formed by what we do, what we eat, where we live, and with whom we live. The microbiome is known to influence our health by training our immune system and providing nutrients for the human body. However, when the microbiome becomes out of balance and dysbiosis occurs, the microorganisms within can cause or contribute to diseases. This major influencer on our health is studied intensively, but it is unfortunately often overlooked by the surgeon and in surgical practice. Because of that, there is not much literature about the microbiome and its influence on surgical patients or procedures. However, there is evidence that it plays a major role, showing that it needs to be a topic of interest for the surgeon. This review is written to show the surgeon the importance of the microbiome and why it should be taken into consideration when preparing or treating patients.

Effect of Enrofloxacin on the Microbiome, Metabolome, and Abundance of Antibiotic Resistance Genes in the Chicken Cecum

Enrofloxacin is an important antibiotic for the treatment of Salmonella infections in livestock and poultry. However, the effects of different concentrations of enrofloxacin on the bacterial and metabolite compositions of the chicken gut and changes in the abundance of resistance genes in cecum contents remain unclear. To investigate the effects of enrofloxacin on chickens, we orally administered different concentrations of enrofloxacin to 1-day-old chickens and performed 16S rRNA gene sequencing to assess changes in the gut microbiomes of chickens after treatment. The abundance of fluoroquinolone (FQ) resistance genes was measured using quantitative PCR. Metabolomics techniques were used to examine the cecal metabolite composition. We found that different concentrations of enrofloxacin had different effects on cecum microorganisms, with the greatest effect on cecum microbial diversity in the low-concentration enrofloxacin group at day 7. Enrofloxacin use reduced the abundance of beneficial bacteria such as Lactobacillaceae and Oscillospira. Furthermore, cecum microbial diversity was gradually restored as the chickens grew. In addition, enrofloxacin increased the abundance of resistance genes, and there were differences in the changes in abundance among different antibiotic resistance genes. Moreover, enrofloxacin significantly affected linoleic acid metabolism, amino acid metabolism, and signaling pathways. This study helps improve our understanding of how antibiotics affect host physiological activities and provides new insights into the rational use of drugs in poultry farming. The probiotics and metabolites that we identified could be used to modulate the negative effects of antibiotics on the host, which requires further study. IMPORTANCE In this study, we investigated changes in the cecum flora, metabolites, and abundances of fluoroquinolone antibiotic resistance genes in chickens following the use of different concentrations of enrofloxacin. These results were used to determine the effects of enrofloxacin on chick physiology and the important flora and metabolites that might contribute to these effects. In addition, these results could help in assessing the effect of enrofloxacin concentrations on host metabolism. Our findings could help guide the rational use of antibiotics and mitigate the negative effects of antibiotics on the host.

Fecal microbiota transplantation and short-chain fatty acids reduce sepsis mortality by remodeling antibiotic-induced gut microbiota disturbances

Objective

Sepsis is the leading cause of death in critically ill patients. The gastrointestinal tract has long been thought to play an important role in the pathophysiology of sepsis. Antibiotic therapy can reduce a patient's commensal bacterial population and raise their risk of developing subsequent illnesses, where gut microbiota dysbiosis may be a key factor.

Methods

In this study, we analyzed the 16S rRNA of fecal samples from both healthy people and patients with sepsis to determine if alterations in gut bacteria are associated with sepsis. Then, we developed a mouse model of sepsis using cecal ligation and puncture (CLP) in order to examine the effects of fecal microbiota transplantation (FMT) and short-chain fatty acids (SCFAs) on survival rate, systemic inflammatory response, gut microbiota, and mucosal barrier function.

Results

Sepsis patients' gut microbiota composition significantly differed from that of healthy people. At the phylum level, the amount of Proteobacteria in the intestinal flora of sepsis patients was much larger than that of the control group, whereas the number of Firmicutes was significantly lower. Mice with gut microbiota disorders (ANC group) were found to have an elevated risk of death, inflammation, and organ failure as compared to CLP mice. However, all of these could be reversed by FMT and SCFAs. FMT and SCFAs could regulate the abundance of bacteria such as Firmicutes, Proteobacteria, Escherichia Shigella, and Lactobacillus, restoring them to levels comparable to those of healthy mice. In addition, they increased the expression of the Occludin protein in the colon of mice with sepsis, downregulated the expression of the NLRP3 and GSDMD-N proteins, and reduced the release of the inflammatory factors IL-1β and IL-18 to inhibit cell pyroptosis, ultimately playing a protective role in sepsis.

Disccusion

FMT and SCFAs provide a microbe-related survival benefit in a mouse model of sepsis, suggesting that they may be a viable treatment for sepsis.

Multicompartmental traumatic injury and the microbiome: Shift to a pathobiome

BACKGROUND

Previous animal models have demonstrated altered gut microbiome after mild traumatic injury; however, the impact of injury severity and critical illness is unknown. We hypothesized that a rodent model of severe multicompartmental injuries and chronic stress would demonstrate microbiome alterations toward a "pathobiome" characterized by an overabundance of pathogenic organisms, which would persist 1 week after injury.

METHODS

Male Sprague-Dawley rats (n = 8 per group) were subjected to either multiple injuries (PT) (lung contusion, hemorrhagic shock, cecectomy, and bifemoral pseudofractures), PT plus daily chronic restraint stress for 2 hours (PT/CS), or naive controls. Fecal microbiome was measured on days 0, 3, and 7 using high-throughput 16S rRNA sequencing and Quantitative Insights Into Microbial Ecology 2 bioinformatics analysis. Microbial α diversity was assessed using Chao1 and Shannon indices, and β diversity with principle coordinate analysis. Intestinal permeability was evaluated by plasma occludin; ileum and descending colon tissues were reviewed for injury. Analyses were performed in GraphPad (GraphPad Software, La Jolla, CA) and R (R Foundation for Statistical Computing, Vienna, Austria), with significance defined as p < 0.05.

RESULTS

There were significant alterations in β diversity at day 3 and between all groups. By day 3, both PT and PT/CS demonstrated significantly depleted bacterial diversity (Chao1) ( p = 0.01 and p = 0.001, respectively) versus naive, which persisted up to day 7 in PT/CS only ( p = 0.001). Anaerostipes and Rothia dominated PT and Lactobacillus bloomed in PT/CS cohorts by day 7. Plasma occludin was significantly elevated in PT/CS compared with naive ( p = 0.04), and descending colon of both PT and PT/CS showed significantly higher injury compared with naive ( p = 0.005, p = 0.006).

CONCLUSIONS

Multiple injuries with and without chronic stress induces significant alterations in microbiome diversity and composition within 3 days; these changes are more prominent and persist for 1 week postinjury with stress. This rapid and persistent transition to a "pathobiome" phenotype represents a critical phenomenon that may influence outcomes after severe trauma and critical illness.

The central role of the gut in intensive care

Critically ill patients undergo early impairment of their gut microbiota (GM) due to routine antibiotic therapies and other environmental factors leading to intestinal dysbiosis. The GM establishes connections with the rest of the human body along several axes representing critical inter-organ crosstalks that, once disrupted, play a major role in the pathophysiology of numerous diseases and their complications. Key players in this communication are GM metabolites such as short-chain fatty acids and bile acids, neurotransmitters, hormones, interleukins, and toxins. Intensivists juggle at the crossroad of multiple connections between the intestine and the rest of the body. Harnessing the GM in ICU could improve the management of several challenges, such as infections, traumatic brain injury, heart failure, kidney injury, and liver dysfunction. The study of molecular pathways affected by the GM in different clinical conditions is still at an early stage, and evidence in critically ill patients is lacking. This review aims to describe dysbiosis in critical illness and provide intensivists with a perspective on the potential as adjuvant strategies (e.g., nutrition, probiotics, prebiotics and synbiotics supplementation, adsorbent charcoal, beta-lactamase, and fecal microbiota transplantation) to modulate the GM in ICU patients and attempt to restore eubiosis.

Immunopathophysiology of human sepsis

Sepsis is an ill-defined syndrome yet is a leading cause of morbidity and mortality worldwide. The most recent consensus defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection. However, this definition belies the complexity and breadth of immune mechanisms involved in sepsis, which are characterized by simultaneous hyperinflammation and immune suppression. In this review, we describe the immunopathogenesis of sepsis and highlight some recent pathophysiological findings that have expanded our understanding of sepsis. Sepsis endotypes can be used to divide sepsis patients in different groups with distinct immune profiles and outcomes. We also summarize evidence on the role of the gut microbiome in sepsis immunity. The challenge of the coming years will be to translate our increasing knowledge about the molecular mechanisms underlying sepsis into therapies that improve relevant patient outcomes.

The gut–liver axis in sepsis: interaction mechanisms and therapeutic potential

Sepsis is a potentially fatal condition caused by dysregulation of the body's immune response to an infection. Sepsis-induced liver injury is considered a strong independent prognosticator of death in the critical care unit, and there is anatomic and accumulating epidemiologic evidence that demonstrates intimate cross talk between the gut and the liver. Intestinal barrier disruption and gut microbiota dysbiosis during sepsis result in translocation of intestinal pathogen-associated molecular patterns and damage-associated molecular patterns into the liver and systemic circulation. The liver is essential for regulating immune defense during systemic infections via mechanisms such as bacterial clearance, lipopolysaccharide detoxification, cytokine and acute-phase protein release, and inflammation metabolic regulation. When an inappropriate immune response or overwhelming inflammation occurs in the liver, the impaired capacity for pathogen clearance and hepatic metabolic disturbance can result in further impairment of the intestinal barrier and increased disruption of the composition and diversity of the gut microbiota. Therefore, interaction between the gut and liver is a potential therapeutic target. This review outlines the intimate gut–liver cross talk (gut–liver axis) in sepsis.

Bioinformatics Analysis Identifies TNFRSF1A as a Biomarker of Liver Injury in Sepsis TNFRSF1A is a Biomarker for Septic Liver Injury

Sepsis is a severe disease with high mortality, and liver injury is an independent risk factor for sepsis morbidity and mortality. We analyzed co-differentially expressed genes (co-DEGs) to explore potential biomarkers and therapeutic targets for sepsis-related liver injury. Three gene expression datasets (GSE60088, GSE23767, and GSE71530) were downloaded from the Gene Expression Omnibus (GEO). DEGs were screened between sepsis and control samples using GEO2R. The association of these DEGs with infection and liver disease was analyzed by using the CTD database. GO functional analysis, KEGG pathway enrichment analysis, and protein-protein interaction (PPI) network analysis were performed to elucidate the potential molecular mechanism of DEGs. DEGs of different tissues in GSE60088 were analyzed again to obtain specific markers of septic liver injury. Mouse model of sepsis was also established by cecal ligation and puncture (CLP), and the expression of specific markers in liver, lung, and kidney tissues was analyzed using Western blot. Here, we identified 21 DEGs in three datasets with 8 hub genes, all of which showed higher inference scores in liver diseases than bacterial infections. Among them, only TNFRSF1A had a liver-specific differential expression. TNFRSF1A was also confirmed to be specifically reduced in septic liver tissues in mice. Therefore, TNFRSF1A may serve as a potential biomarker for septic liver injury.

Critical roles of sepsis-reshaped fecal virota in attenuating sepsis severity

Because studies on all fecal organisms (bacteria, fungi, and viruses) in sepsis are rare and bacteriophages during sepsis might have adapted against gut bacteria with possible pathogenicity, cecal ligation and puncture (CLP; a sepsis mouse model) was evaluated. In fecal bacteriome, sepsis increased Bacteroides and Proteobacteria but decreased Firmicutes, while fecal virome demonstrated increased Podoviridae when compared with sham feces. There was no difference in the fungal microbiome (predominant Ascomycota in both sham and CLP mice) and the abundance of all organisms between sepsis and control groups. Interestingly, the transfers of feces from CLP mice worsened sepsis severity when compared with sham fecal transplantation, as evaluated by mortality, renal injury (serum creatinine and histology), liver damage (liver enzyme and histology), spleen apoptosis, serum cytokines, endotoxemia, and bacteremia. In contrast, the transfers of fecal viral particles from sepsis mice, but not from sham mice, attenuated inflammation in CLP sepsis possibly through the decrease in several fecal pathogenic bacteria (such as Proteobacteria, Gammaproteobacteria, and Prevotellaceae) as evaluated by fecal microbiome analysis. Perhaps the isolation of favorable bacteriophages in sepsis feces and increased abundance ex vivo before oral treatment in a high concentration are beneficial.

Sex differences associate with late microbiome alterations after murine surgical sepsis

BACKGROUND

Sepsis-induced gut microbiome alterations contribute to sepsis-related morbidity and mortality. Given evidence for improved postsepsis outcomes in females compared with males, we hypothesized that female mice maintain microbiota resilience versus males.

METHODS

Mixed-sex C57BL/6 mice underwent cecal ligation and puncture (CLP) with antibiotics, saline resuscitation, and daily chronic stress and were compared with naive (nonsepsis/no antibiotics) controls. For this work, the results of young (3-5 months) and old (18-22 months) adult mice were analyzed by sex, independent and dependent of age. Mice were sacrificed at days 7 and 14, and 16S rRNA gene sequencing was performed on fecal bacterial DNA. α and β diversity were determined by Shannon index and Bray-Curtis with principal coordinate analysis, respectively. False discovery rate (FDR) correction was implemented to account for potential housing effect.

RESULTS

In control mice, there was no difference in α or β diversity between male and female mice (FDR, 0.76 and 0.99, respectively). However, male mice that underwent CLP with daily chronic stress had a decrease in microbiota α diversity at 7 days post-CLP (Shannon FDR, 0.005), which was sustained at 14 days post-CLP (Shannon FDR, 0.001), compared with baseline. In addition, male mice maintained differences in β diversity even at day 14 compared with controls (FDR, <0.0001). In contrast, female mice had a decreased microbiota α diversity (Shannon FDR, 0.03) and β diversity (FDR, 0.02) 7 days post-CLP but recovered their α and β diversity by post-CLP day 14 (Shannon FDR, 0.5, and FDR, 0.02, respectively). Further analysis of females revealed that only young female mice were not different (β diversity) post-CLP day 14 to controls.

CONCLUSION

Although sepsis-induced perturbations of the intestinal microbiota occur initially in both male and female C57BL/6 mice, females demonstrate different microbiota by day 14. This may be seen primarily in younger females. This difference in recovery may play a role in outcome differences between sexes after sepsis.

Indole-3-Propionic Acid as a Potential Therapeutic Agent for Sepsis-Induced Gut Microbiota Disturbance

The effects of using gut microbiota metabolites instead of live microorganisms to modulate sepsis-induced gut dysbiosis remain largely unknown. We assessed the effects of microbiota metabolite indole-3-propionic acid (IPA) on gut microbiota in mice during sepsis. Sepsis models were constructed by cecal ligation and puncture (CLP) methods. Fecal microbiota composition analysis was performed to characterize the gut microbiota composition. Fecal microbiota transplantation was performed to validate the roles of gut microbiota on sepsis progression. IPA-treated mice exhibited lower serum inflammatory mediator levels and a higher survival rate than those of saline-treated mice after modeling of sepsis, which were negated in the presence of antibiotics. Compared with saline-treated mice after modeling, IPA-treated mice showed a markedly different intestinal microbiota composition, with an enrichment of Bifidobacteriaceae family and a depletion of Enterobacteriaceae family. Mice gavaged with postoperative feces from IPA-treated animals displayed better survival than mice gavaged with feces from saline-treated animals. Overall, these data suggest that IPA offers a microbe-modulated survival advantage in septic mice, indicating that some microbiota metabolites could replace live microorganisms as potential options for regulation of sepsis-induced gut dysbiosis. IMPORTANCE The role of gut microbiota in the pathophysiology of sepsis is gaining increasing attention and developing effective and safe sepsis therapies targeting intestinal microorganisms is promising. Given the safety of probiotic supplementation or fecal microbiota transplantation in critically ill patients, identifying an abiotic agent to regulate the intestinal microbiota of septic patients is of clinical significance. This study revealed that IPA, a microbiota-generated tryptophan metabolite, ameliorated sepsis-induced mortality and decreased the serum levels of proinflammatory cytokines by modulating intestinal microbiota. Although IPA did not increase the abundance and diversity of the microbiota of septic mice, it significantly decreased the number of Enterobacteriaceae family. These findings indicate that a specific microbiota metabolite (e.g., IPA) can mediate the intestinal microbiota apart from FMT or probiotics.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

Sodium butyrate reverses lipopolysaccharide-induced mitochondrial dysfunction in lymphoblasts

Butyrate is a short-chain fatty acid that is produced by commensal microbes within the intestinal microbiome through fermentation of dietary fibre. Microbial-derived butyrate has been shown to promote immunologic and metabolic homeostasis, in part through its beneficial effects on mitochondrial function, and thus has been proposed as a possible anti-inflammatory therapy. We tested the hypothesis that butyrate could mitigate the decrease in mitochondrial respiration in immune cells under septic conditions as a preliminary step towards better understanding the potential for butyrate as a novel therapy in sepsis. Mitochondrial respiration and content (measured as citrate synthase activity) were compared within four Epstein-Barr virus-transformed lymphoblast (LB) cell lines exposed to either control media or lipopolysaccharide (LPS) 100 ng/ml. Both co-incubation of LBs with LPS + butyrate and treatment with butyrate after LPS stimulation reversed the decrease in mitochondrial respiration observed in LBs exposed to LPS without butyrate. Neither LPS nor butyrate led to significant changes in citrate synthase activity. The preliminary findings support further investigation of a potential mitochondrial-based mechanism through which butyrate may help to mitigate the immuno-inflammatory response in sepsis.

Intestinal Microbiota Regulate Certain Meat Quality Parameters in Chicken

Growing evidence of intestinal microbiota-muscle axis provides a possibility to improve meat quality of broilers through regulating intestinal microbiota. Water-holding capacity is a crucial factor to evaluate the meat quality. High quality of water-holding capacity is usually described as a low drip-losing rate. This study aimed to explore the relationship between intestinal microbiota and water-holding capacity of muscle in broilers. According to our results, two native breeds of broilers (the Arbor Acres broilers and the Beijing-You broilers) exhibited remarkable differences in microbiota composition. However, the regular of gut bacteria compositions gradually became similar when the two breeds of broiler were raised in a same feeding environment. Therefore, this similar regular of intestinal microbiota induced similar water-holding capacity of the muscle from the two breeds. In subsequent fecal microbiota transplantation (FMT) experiments, the intestinal microbiota community of the Arbor Acres broilers was remodeling by oral gavage of bacterial suspension that was derived from the Beijing-You broilers. Then, not only body weight and abdominal fat rate were increased, but also drip loss of muscle was decreased in the Arbor Acres broilers. Additionally, muscle fiber diameter of biceps femoris muscle and expression of MyoD1 were notably enlarged. Muscle fiber diameter and related genes were deemed as important elements for water-holding capacity of muscle. Simultaneously, we screened typical intestinal bacteria in both the two native breeds of broilers by 16S rDNA sequencing. Lachnoclostridium was the only bacteria genus associated with drip-losing rate, meat fiber diameter, body weight, and abdominal fat rate.

Long-distance relationships - regulation of systemic host defense against infections by the gut microbiota

Despite compartmentalization within the lumen of the gastrointestinal tract, the gut microbiota has a far-reaching influence on immune cell development and function throughout the body. This long-distance relationship is crucial for immune homeostasis, including effective host defense against invading pathogens that cause systemic infections. Herein, we review new insights into how commensal microbes that are spatially restricted to the gut lumen can engage in long-distance relationships with innate and adaptive immune cells at systemic sites to fortify host defenses against infections. In addition, we explore the consequences of intestinal dysbiosis on impaired host defense and immune-mediated pathology during infections, including emerging evidence linking dysbiosis with aberrant systemic inflammation and immune-mediated organ damage in sepsis. As such, therapeutic modification of the gut microbiota is an emerging target for interventions to prevent and/or treat systemic infections and sepsis by harnessing the long-distance relationships between gut microbes and systemic immunity.

An Engineered Bacteria-Hybrid Microrobot with the Magnetothermal Bioswitch for Remotely Collective Perception and Imaging-Guided Cancer Treatment

Microrobots driven by multiple propelling forces hold great potential for noninvasively targeted delivery in the physiologic environment. However, the remotely collective perception and precise propelling in a low Reynold's number bioenvironment remain the major challenges of microrobots to achieve desired therapeutic effects in vivo. Here, we reported a biohybrid microrobot that integrated with magnetic, thermal, and hypoxia sensitivities and an internal fluorescent protein as the dual reporter of thermal and positioning signals for targeted cancer treatment. There were three key elements in the microrobotic system, including the magnetic nanoparticle (MNP)-loaded probiotic Escherichia coli Nissle1917 (EcN@MNP) for spatially magnetic and hypoxia perception, a thermal-logic circuit engineered into the bacteria to control the biosynthesis of mCherry as the temperature and positioning reporter, and NDH-2 enzyme encoded in the EcN for enhanced anticancer therapy. According to the fluorescent-protein-based imaging feedback, the microrobot showed good thermal sensitivity and active targeting ability to the tumor area in a collective manner under the magnetic field. The cancer cell apoptosis was efficiently triggered in vitro and in vivo by the hybrid microrobot coupled with the effects of magnetothermal ablation and NDH-2-induced reactive oxygen species (ROS) damage. Our study demonstrates that the biohybrid EcN microrobot is an ideal platform to integrate the physical, biological, and chemical properties for collective perception and propelling in targeted cancer treatment.

Fecal Microbiota Transplantation Derived from Alzheimer's Disease Mice Worsens Brain Trauma Outcomes in Wild-Type Controls

Traumatic brain injury (TBI) causes neuroinflammation and neurodegeneration, both of which increase the risk and accelerate the progression of Alzheimer's disease (AD). The gut microbiome is an essential modulator of the immune system, impacting the brain. AD has been related with reduced diversity and alterations in the community composition of the gut microbiota. This study aimed to determine whether the gut microbiota from AD mice exacerbates neurological deficits after TBI in control mice. We prepared fecal microbiota transplants from 18 to 24 month old 3×Tg-AD (FMT-AD) and from healthy control (FMT-young) mice. FMTs were administered orally to young control C57BL/6 (wild-type, WT) mice after they underwent controlled cortical impact (CCI) injury, as a model of TBI. Then, we characterized the microbiota composition of the fecal samples by full-length 16S rRNA gene sequencing analysis. We collected the blood, brain, and gut tissues for protein and immunohistochemical analysis. Our results showed that FMT-AD administration stimulates a higher relative abundance of the genus Muribaculum and a decrease in Lactobacillus johnsonii compared to FMT-young in WT mice. Furthermore, WT mice exhibited larger lesion, increased activated microglia/macrophages, and reduced motor recovery after FMT-AD compared to FMT-young one day after TBI. In summary, we observed gut microbiota from AD mice to have a detrimental effect and aggravate the neuroinflammatory response and neurological outcomes after TBI in young WT mice.

Maintenance of glutamine synthetase expression alleviates endotoxin-induced sepsis via alpha-ketoglutarate-mediated demethylation

Glutamine synthetase (Glul) is the enzyme that synthesizes endogenous glutamine, which is responsible for critical metabolic pathways and the immune system. However, the role of Glul in regulating endotoxin (lipopolysaccharide, LPS)-induced sepsis remains unclear. Here, we found that Glul expression in macrophages was significantly inhibited in endotoxemia, and that Glul deletion induced macrophages to differentiate into the pro-inflammatory type and aggravated sepsis in mice. Mechanistically, TLR4/NF-κB-induced alpha-ketoglutarate (α-KG) depletion inhibits Glul expression through H3K27me3-mediated methylation in septic mice. Both Glul overexpression with adeno-associated virus (AAV) and restoration by replenishing α-KG can alleviate the severity of sepsis. In conclusion, the study demonstrated that Glul can regulate LPS-induced sepsis and provides a novel strategy for the treatment of this disease.

An integrative understanding of the large metabolic shifts induced by antibiotics in critical illness

Antibiotics are commonly used in the Intensive Care Unit (ICU); however, several studies showed that the impact of antibiotics to prevent infection, multi-organ failure, and death in the ICU is less clear than their benefit on course of infection in the absence of organ dysfunction. We characterized here the compositional and metabolic changes of the gut microbiome induced by critical illness and antibiotics in a cohort of 75 individuals in conjunction with 2,180 gut microbiome samples representing 16 different diseases. We revealed an "infection-vulnerable" gut microbiome environment present only in critically ill treated with antibiotics (ICU⁺). Feeding of Caenorhabditis elegans with Bifidobacterium animalis and Lactobacillus crispatus, species that expanded in ICU⁺ patients, revealed a significant negative impact of these microbes on host viability and developmental homeostasis. These results suggest that antibiotic administration can dramatically impact essential functional activities in the gut related to immune responses more than critical illness itself, which might explain in part untoward effects of antibiotics in the critically ill.

Gut-Lung Crosstalk in Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common acute and severe cases of the respiratory system with complicated pathogenesis and high mortality. Sepsis is the leading indirect cause of ALI/ARDS in the intensive care unit (ICU). The pathogenesis of septic ALI/ARDS is complex and multifactorial. In the development of sepsis, the disruption of the intestinal barrier function, the alteration of gut microbiota, and the translocation of the intestinal microbiome can lead to systemic and local inflammatory responses, which further alter the immune homeostasis in the systemic environment. Disruption of homeostasis may promote and propagate septic ALI/ARDS. In turn, when ALI occurs, elevated levels of inflammatory cytokines and the shift of the lung microbiome may lead to the dysregulation of the intestinal microbiome and the disruption of the intestinal mucosal barrier. Thus, the interaction between the lung and the gut can initiate and potentiate sepsis-induced ALI/ARDS. The gut–lung crosstalk may be a promising potential target for intervention. This article reviews the underlying mechanism of gut-lung crosstalk in septic ALI/ARDS.

Mechanism of the Gut Microbiota Colonization Resistance and Enteric Pathogen Infection

The mammalian gut microbial community, known as the gut microbiota, comprises trillions of bacteria, which co-evolved with the host and has an important role in a variety of host functions that include nutrient acquisition, metabolism, and immunity development, and more importantly, it plays a critical role in the protection of the host from enteric infections associated with exogenous pathogens or indigenous pathobiont outgrowth that may result from healthy gut microbial community disruption. Microbiota evolves complex mechanisms to restrain pathogen growth, which included nutrient competition, competitive metabolic interactions, niche exclusion, and induction of host immune response, which are collectively termed colonization resistance. On the other hand, pathogens have also developed counterstrategies to expand their population and enhance their virulence to cope with the gut microbiota colonization resistance and cause infection. This review summarizes the available literature on the complex relationship occurring between the intestinal microbiota and enteric pathogens, describing how the gut microbiota can mediate colonization resistance against bacterial enteric infections and how bacterial enteropathogens can overcome this resistance as well as how the understanding of this complex interaction can inform future therapies against infectious diseases.

Sepsis-Induced Myopathy and Gut Microbiome Dysbiosis: Mechanistic Links and Therapeutic Targets

ABSTRACT

Sepsis is currently defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. The skeletal muscle system is among the host organ systems compromised by sepsis. The resulting neuromuscular dysfunction and impaired regenerative capacity defines sepsis-induced myopathy and manifests as atrophy, loss of strength, and hindered regeneration after injury. These outcomes delay recovery from critical illness and confer increased vulnerability to morbidity and mortality. The mechanisms underlying sepsis-induced myopathy, including the potential contribution of peripheral organs, remain largely unexplored. The gut microbiome is an immunological and homeostatic entity that interacts with and controls end-organ function, including the skeletal muscle system. Sepsis induces alterations in the gut microbiota composition, which is globally termed a state of "dysbiosis" for the host compared to baseline microbiota composition. In this review, we critically evaluate existing evidence and potential mechanisms linking sepsis-induced myopathy with gut microbiota dysbiosis.

The potential utility of fecal (or intestinal) microbiota transplantation in controlling infectious diseases

The intestinal microbiota is recognized to play a role in the defense against infection, but conversely also acts as a reservoir for potentially pathogenic organisms. Disruption to the microbiome can increase the risk of invasive infection from these organisms; therefore, strategies to restore the composition of the gut microbiota are a potential strategy of key interest to mitigate this risk. Fecal (or Intestinal) Microbiota Transplantation (FMT/IMT), is the administration of minimally manipulated screened healthy donor stool to an affected recipient, and remains the major 'whole microbiome' therapeutic approach at present. Driven by the marked success of using FMT in the treatment of recurrent Clostridioides difficile infection, the potential use of FMT in treating other infectious diseases is an area of active research. In this review, we discuss key examples of this treatment based on recent findings relating to the interplay between microbiota and infection, and potential further exploitations of FMT/IMT.

Effects of faecal microbiota transplantation on the growth performance, intestinal microbiota, jejunum morphology and immune function of laying-type chicks

Context Recent studies have indicated that the early stage of growth is a critical window for intestinal microbiota manipulation to optimise the immunity and body growth. Faecal microbiota transplantation (FMT) is often used to regulate intestinal microbiota colonisation. Aims The aim of this study was to explore the effect of FMT on the growth performance, intestinal microbiota, jejunum morphology and immune function of newly hatched laying-type chicks. Methods The chicks (Hy-line Brown) were randomly divided into the control group (CON) and FMT group (FMT), which were treated with sterile saline and faecal microbiota suspension of Hy-line Brown breeder hens on Days 1, 3 and 5 respectively. For each group, there were five replications of 12 birds each for 4 weeks. This study investigated the body weight, tibia length, intestinal microflora, jejunum morphology and immune indexes of the chicks. Key results The results showed that the body weight and tibia length of birds in the FMT group were significantly increased at 7, 14 and 21 days of age (P < 0.01). Furthermore, we found that FMT altered the intestinal microbiota community of the birds and improved the richness, evenness, diversity and stability of their intestinal microbiota (P < 0.05). The faecal microbiota of the donor hens and birds that received the transplantation were very similar. The villus height and the ratio of the villus to crypt of the birds in the FMT group were significantly (P < 0.0001) higher than those in the control group. In addition, Spearman’s correlation analysis showed that the villus height of the FMT group showed positive correlation with Bacteroides (P < 0.05), and the villus height and the ratio of the villus to crypt in the FMT group showed positive correlations with Megasphaera (P < 0.05). The birds in the FMT group had no significant difference in intestinal length, immune organ indexes, serum β-defensin and IgA concentrations. Conclusions In summary, FMT can promote the early growth performance and jejunum morphology of laying-type chicks and improve the intestinal microbiota. FMT has no significant effect on the immune function of chicks. Implications FMT may be a potential method to improve the health of chicks to enhance the poultry industry.

Impact of the Age of Cecal Material Transfer Donors on Alzheimer’s Disease Pathology in 5xFAD Mice

Alzheimer’s disease is a progressive neurodegenerative disorder affecting around 30 million patients worldwide. The predominant sporadic variant remains enigmatic as the underlying cause has still not been identified. Since efficient therapeutic treatments are still lacking, the microbiome and its manipulation have been considered as a new, innovative approach. 5xFAD Alzheimer’s disease model mice were subjected to one-time fecal material transfer after antibiotics-treatment using two types of inoculation: material derived from the caecum of age-matched (young) wild type mice or from middle aged, 1 year old (old) wild type mice. Mice were profiled after transfer for physiological parameters, microbiome, behavioral tasks, and amyloid deposition. A single time transfer of cecal material from the older donor group established an aged phenotype in the recipient animals as indicated by elevated cultivatable fecal Enterobacteriaceae and Lactobacillaceae representative bacteria, a decreased Firmicutes amount as assessed by qPCR, and by increased levels of serum LPS binding protein. While behavioral deficits were not accelerated, single brain regions (prefrontal cortex and dentate gyrus) showed higher plaque load after transfer of material from older animals. We could demonstrate that the age of the donor of cecal material might affect early pathological hallmarks of Alzheimer’s disease. This could be relevant when considering new microbiome-based therapies for this devastating disorder.

Impact of gastrointestinal surgery upon the gut microbiome: A systematic review

BACKGROUND

There is evidence from preclinical models that the gut microbiome may impact outcomes from gastrointestinal surgery, and that surgery may alter the gut microbiome. However, the extent to which gastrointestinal surgery modulates the gut microbiome in clinical practice is currently poorly defined. This systematic review aims to evaluate the changes observed in the gut microbiome after gastrointestinal surgery.

METHODS

A systematic review and meta-analysis were conducted according to the PRISMA guidelines by screening EMBASE, MEDLINE/PubMed, Web of Science, and CENTRAL for comparative studies meeting the predetermined inclusion criteria. The primary outcome was the difference between pre and postoperative bacterial taxonomic composition and diversity metrics among patients receiving gastrointestinal surgery.

RESULTS

In total, 33 studies were identified including 6 randomized controlled trials and 27 prospective cohort studies reporting a total of 968 patients. Gastrointestinal surgery was associated with an increase in α diversity and a shift in β diversity postoperatively. Multiple bacterial taxa were identified to consistently trend toward an increase or decrease postoperatively. A difference in microbiota across geographic provenance was also observed. There was a distinct lack of studies showing correlation with clinical outcomes or performing microbiome functional analysis. Furthermore, there was a lack of standardization in sampling, analytical methodology, and reporting.

CONCLUSION

This review highlights changes in bacterial taxa associated with gastrointestinal surgery. There is a need for standardization of microbial analysis methods and reporting of results to allow interstudy comparison. Further adequately powered multicenter studies are required to better assess variation in microbial changes and its potential associations with clinical outcomes.

Gut microbiota and sepsis: from pathogenesis to novel treatments

PURPOSE OF REVIEW

This review summarizes recent progress in our understanding of the role of the gut microbiota in sepsis pathogenesis and outlines the potential role of microbiota-targeted therapies.

RECENT FINDINGS

The composition of the gut microbiome is profoundly distorted during sepsis, with a loss of commensal bacteria and an overgrowth of potential pathogenic micro-organisms. These alterations also extend to nonbacterial intestinal inhabitants. Disruptions of these intestinal communities are associated with both an increased susceptibility to develop sepsis, as well as a higher risk of adverse outcomes. Preclinical studies have characterized the effects of several microbiota-derived metabolites (such as D-lactate, butyrate, and deoxycholic acid) on enhancing the host immune response during critical illness. Microbiota-targeted therapies (e.g. probiotics or fecal microbiota transplantation) might be of benefit, but can also be associated with increased risks of bloodstream infections.

SUMMARY

Emerging evidence display an important role of gut micro-organisms (including bacteria, fungi, eukaryotic viruses, and bacteriophages) and their derived metabolites in both the susceptibility to, as well as outcomes of sepsis. Despite recent progress in the mechanistic understanding of microbiota-mediated protection, clinical breakthroughs in the development of microbiota-based prognostic tools or therapies are thus far lacking in the field of sepsis.

Crosstalk between gut microbiota and sepsis

Sepsis is an overwhelming inflammatory response to microbial infection. Sepsis management remains a clinical challenge. The role of the gut microbiome in sepsis has gained some attention. Recent evidence has demonstrated that gut microbiota regulate host physiological homeostasis mediators, including the immune system, gut barrier function and disease susceptibility pathways. Therefore, maintenance or restoration of microbiota and metabolite composition might be a therapeutic or prophylactic target against critical illness. Fecal microbiota transplantation and supplementation of probiotics are microbiota-based treatment methods that are somewhat limited in terms of evidence-based efficacy. This review focuses on the importance of the crosstalk between the gastrointestinal ecosystem and sepsis to highlight novel microbiota-targeted therapies to improve the outcomes of sepsis treatment.

Gut Microbiota Contributes to Host Defense Against Klebsiella pneumoniae-Induced Liver Abscess

Purpose

Klebsiella pneumoniae-induced liver abscess (KLA) is a type of pyogenic liver abscess (PLA), which is a distinct invasive syndrome that has been increasingly reported worldwide over the past two decades. The intestinal microbiota is increasingly recognized as an important modulator that can promote and maintain host immune homeostasis. However, its precise role in liver abscess is unknown. We aimed to investigate the function of the gut microbiota in the host defense against K. pneumoniae infection.

Methods

We constructed C57BL/6J mice with KLA and analyzed the diversity and richness of the intestinal microflora by 16S rRNA sequencing. Next, to create a microbiota-depleted (MD) mouse model, we administered multiple broad-spectrum antibiotics and validated the model using 16S rRNA sequencing. At 48 h after K. pneumoniae infection, we assessed the general health condition, liver injury, bacterial loads, and inflammatory factor levels in MD+KLA mice. Additionally, fecal microbiota transplantation (FMT) was conducted in another group of MD+KLA mice prior to K. pneumoniae infection, and we assessed whether the transplantation changed the outcomes.

Results

The diversity of the intestinal flora was significantly changed in KLA mice compared to control mice, with a decrease in beneficial bacteria and an increase in harmful bacteria. The MD+KLA mice exhibited impaired antimicrobial capacity, reduced survival, increased inflammation and liver damage at 48 h after K. pneumoniae infection compared to the KLA mice. However, FMT normalized the inflammatory cytokine levels, reduced liver damage, and increased survival.

Conclusion

This study identified the gut microbiota as a protective factor against K. pneumoniae infection. The role of FMT in KLA should be investigated in future clinical studies.

Procedures for Fecal Microbiota Transplantation in Murine Microbiome Studies

Fecal microbiota transplantation (FMT) has been widely recognized as an approach to determine the microbiome’s causal role in gut dysbiosis-related disease models and as a novel disease-modifying therapy. Despite potential beneficial FMT results in various disease models, there is a variation and complexity in procedural agreement among research groups for performing FMT. The viability of the microbiome in feces and its successful transfer depends on various aspects of donors, recipients, and lab settings. This review focuses on the technical practices of FMT in animal studies. We first document crucial factors required for collecting, handling, and processing donor fecal microbiota for FMT. Then, we detail the description of gut microbiota depletion methods, FMT dosages, and routes of FMT administrations in recipients. In the end, we describe assessments of success rates of FMT with sustainability. It is critical to work under the anaerobic condition to preserve as much of the viability of bacteria. Utilization of germ- free mice or depletion of recipient gut microbiota by antibiotics or polyethylene glycol are two common recipient preparation approaches to achieve better engraftment. Oral-gastric gavage preferred by most researchers for fast and effective administration of FMT in mice. Overall, this review highlights various methods that may lead to developing the standard and reproducible protocol for FMT.