Selective intestinal decontamination with norfloxacin enhances a regulatory T cell-mediated inflammatory control mechanism in cirrhosis

Antibiotic-Induced Immunosuppression-A Focus on Cellular Immunity

Antibiotics are the fundamental treatment for bacterial infections. However, they are associated with numerous side effects. Their adverse effects on the immune system are increasingly recognised, with several mechanisms identified. In this review, we focus on their direct effects on cellular immunity. We review the effects of antibiotics on mitochondrial function and how they impair specific immune cell functions including chemotaxis, phagocytosis, cytokine production, antigen presentation, and lymphocyte proliferation. Findings are described in a multitude of in vivo and in vitro models. However, their impact on patient immunity and clinical outcomes requires further research. Awareness of the potential adverse effects of antibiotics may improve antimicrobial stewardship. The use of therapeutic drug monitoring may help to reduce dose-dependent effects, which warrants further research.

Mitigative Effects of Topical Norfloxacin on an Imiquimod-Induced Murine Model of Psoriasis

Psoriasis is a chronic, inflammatory dermatosis characterized by thickened, reddened, and scaly skin lesions. Norfloxacin is a fluoroquinolone antibiotic with enhanced antioxidant, anti-inflammatory, and immunomodulatory bioactivities. The aim of this study was to figure out the possible impact of topical norfloxacin on an imiquimod-induced model of psoriasis in mice. Thirty albino-type mice were split into five distinct groups of six animals each. The control group included healthy mice that had not received any treatment. The induction group was given the vehicle 2 h after the topical imiquimod, once daily for 8 days. Two hours after receiving topical imiquimod, the treatment groups including calcipotriol, norfloxacin 2.5%, and norfloxacin 5% were given topical ointments containing calcipotriol 0.005%, norfloxacin 2.5%, and norfloxacin 5%, for 8 days. Topical norfloxacin ointment significantly reduced the severity of imiquimod-exacerbated psoriatic lesions including erythema, shiny-white scaling, and acanthosis and fixed histological abnormalities. Furthermore, imiquimod-subjected mice treated with a higher concentration of norfloxacin ointment exhibited dramatically lower skin levels of inflammation-related biomarkers like IFN-γ, TNF-α, IL-6, IL-17A, IL-23, and TGF-β but higher levels of IL-10. They also demonstrated a notable decrease in angiogenesis parameters such as VEGF and IL-8, a substantial reduction in oxidative indicators like MDA and MPO, and a considerable rise in antioxidant enzymes like SOD and CAT. This study offers novel evidence that norfloxacin may assist in controlling inflammatory dermatoses like psoriasis by minimizing the severity of psoriatic plaques, correcting histological alterations, and diminishing the production of inflammatory, oxidative, and angiogenetic parameters.

The Mechanisms of Systemic Inflammatory and Immunosuppressive Acute-on-Chronic Liver Failure and Application Prospect of Single-Cell Sequencing

Acute-on-chronic liver failure (ACLF) is a complex clinical syndrome, and patients often have high short-term mortality. It occurs with intense systemic inflammation, often accompanied by a proinflammatory event (such as infection or alcoholic hepatitis), and is closely related to single or multiple organ failure. Liver inflammation begins when innate immune cells (such as Kupffer cells (KCs)) are activated by binding of pathogen-associated molecular patterns (PAMPs) from pathogenic microorganisms or damage-associated molecular patterns (DAMPs) of host origin to their pattern recognition receptors (PRRs). Activated KCs can secrete inflammatory factors as well as chemokines and recruit bone marrow-derived cells such as neutrophils and monocytes to the liver to enhance the inflammatory process. Bacterial translocation may contribute to ACLF when there are no obvious precipitating events. Immunometabolism plays an important role in the process (including mitochondrial dysfunction, amino acid metabolism, and lipid metabolism). The late stage of ACLF is mainly characterized by immunosuppression. In this process, the dysfunction of monocyte and macrophage is reflected in the downregulation of HLA-DR and upregulation of MER tyrosine kinase (MERTK), which weakens the antigen presentation function and reduces the secretion of inflammatory cytokines. We also describe the specific function of bacterial translocation and the gut-liver axis in the process of ACLF. Finally, we also describe the transcriptomics in HBV-ACLF and the recent progress of single-cell RNA sequencing as well as its potential application in the study of ACLF in the future, in order to gain a deeper understanding of ACLF in terms of single-cell gene expression.

Clostridioides difficile Infection in Liver Cirrhosis: A Concise Review

Clostridium difficile is a Gram-positive bacillus with fecal-oral transmission and is currently one of the most common nosocomial infections worldwide, which was renamed Clostridioides difficile in 2016. Clostridioides difficile infection (CDI) is a prevalent infection in cirrhosis and negatively affects prognosis. This study aimed to provide a concise review with clinical practice implications. The prevalence of CDI in cirrhotic patients increases, while the associated mortality decreases. Multiple groups of risk factors increase the likelihood of CDI in patients with cirrhosis, such as antibiotic use, the severity of cirrhosis, some comorbidities, and demographic aspects. Treatment in the general population is currently described in the latest guidelines. In patients with cirrhosis, rifaximin and lactulose have been shown to reduce CDI risk due to their modulatory effects on the intestinal flora, although conflicting results exist. Fecal microbiota transplantation (FMT) as a treatment for the second or subsequent CDI recurrences has demonstrated a good safety and efficacy in cirrhosis and CDI. Future validation in more prospective studies is needed. Screening of asymptomatic patients appears to be discouraged for the prevention currently, with strict hand hygiene and cleaning of the ward and medical equipment surfaces being the cornerstone of minimizing transmission.

The Risk of Clostridioides difficile Infection in Cirrhotic Patients Receiving Norfloxacin for Secondary Prophylaxis of Spontaneous Bacterial Peritonitis-A Real Life Cohort

Background and Objectives: Spontaneous bacterial peritonitis (SBP) is a life-threatening complication of liver cirrhosis. Antibiotic prophylaxis is effective but can lead to an increased incidence of Clostridioides difficile infection (CDI). The aim of this study was to evaluate the incidence of CDI and the risk factors in cirrhotic patients with a previous episode of SBP receiving norfloxacin as secondary prophylaxis. Materials and Methods: We performed a prospective, cohort study including patients with liver cirrhosis and SBP, successfully treated over a 2-year period in a tertiary university hospital. All the patients received secondary prophylaxis for SBP with norfloxacin 400 mg/day. Results: There were 122 patients with liver cirrhosis and SBP included (mean age 57.5 ± 10.8 years, 65.5% males). Alcoholic cirrhosis was the major etiology accounting for 63.1% of cases. The mean MELD score was 19.7 ± 6.1. Twenty-three (18.8%) of all patients developed CDI during follow-up, corresponding to an incidence of 24.8 cases per 10,000 person-years. The multivariate Cox regression analysis demonstrated that alcoholic LC etiology (HR 1.40, 95% CI 1.104-2.441, p = 0.029) and Child-Pugh C class (HR 2.50, 95% CI 1.257-3.850, p = 0.034) were independent risk factors for CDI development during norfloxacin secondary prophylaxis. The development of CDI did not influence the mortality rates in cirrhotic patients with SBP receiving norfloxacin. Conclusions: Cirrhotic patients with SBP and Child-Pugh C class and alcoholic liver cirrhosis had a higher risk of developing Clostridioides difficile infection during norfloxacin secondary prophylaxis. In patients with alcoholic Child-Pugh C class liver cirrhosis, alternative prophylaxis should be evaluated as SBP secondary prophylaxis.

Targeting the gut-liver-immune axis to treat cirrhosis

Cirrhotic portal hypertension is characterised by development of the decompensating events of ascites, encephalopathy, portal hypertensive bleeding and hepatorenal syndrome, which arise in a setting of cirrhosis-associated immune dysfunction (CAID) and define morbidity and prognosis. CAID describes the dichotomous observations that systemic immune cells are primed and display an inflammatory phenotype, while failing to mount robust responses to pathogen challenge. Bacterial infections including spontaneous bacterial peritonitis are common complications of advanced chronic liver disease and can precipitate variceal haemorrhage, hepatorenal syndrome and acute-on-chronic liver failure; they frequently arise from gut-derived organisms and are closely linked with dysbiosis of the commensal intestinal microbiota in advanced chronic liver disease.Here, we review the links between cirrhotic dysbiosis, intestinal barrier dysfunction and deficits of host-microbiome compartmentalisation and mucosal immune homoeostasis that occur in settings of advanced chronic liver disease. We discuss established and emerging therapeutic strategies targeted at restoring intestinal eubiosis, augmenting gut barrier function and ameliorating the mucosal and systemic immune deficits that characterise and define the course of decompensated cirrhosis.

Identification of Common Genes and Pathways in Eight Fibrosis Diseases

Acute and chronic inflammation often leads to fibrosis, which is also the common and final pathological outcome of chronic inflammatory diseases. To explore the common genes and pathogenic pathways among different fibrotic diseases, we collected all the reported genes of the eight fibrotic diseases: eye fibrosis, heart fibrosis, hepatic fibrosis, intestinal fibrosis, lung fibrosis, pancreas fibrosis, renal fibrosis, and skin fibrosis. We calculated the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment scores of all fibrotic disease genes. Each gene was encoded using KEGG and GO enrichment scores, which reflected how much a gene can affect this function. For each fibrotic disease, by comparing the KEGG and GO enrichment scores between reported disease genes and other genes using the Monte Carlo feature selection (MCFS) method, the key KEGG and GO features were identified. We compared the gene overlaps among eight fibrotic diseases and connective tissue growth factor (CTGF) was finally identified as the common key molecule. The key KEGG and GO features of the eight fibrotic diseases were all screened by MCFS method. Moreover, we interestingly found overlaps of pathways between renal fibrosis and skin fibrosis, such as GO:1901890-positive regulation of cell junction assembly, as well as common regulatory genes, such as CTGF, which is the key molecule regulating fibrogenesis. We hope to offer a new insight into the cellular and molecular mechanisms underlying fibrosis and therefore help leading to the development of new drugs, which specifically delay or even improve the symptoms of fibrosis.

Liver Sinusoidal Endothelial Cells Contribute to Hepatic Antigen-Presenting Cell Function and Th17 Expansion in Cirrhosis

Hepatic immune function is compromised during cirrhosis. This study investigated the immune features of liver sinusoidal endothelial cells (LSECs) in two experimental models of cirrhosis. Dendritic cells, hepatic macrophages, and LSECs were isolated from carbon tetrachloride and bile duct-ligated rats. Gene expression of innate receptors, bacterial internalization, co-stimulatory molecules induction, and CD4+ T cell activation and differentiation were evaluated. Induced bacterial peritonitis and norfloxacin protocols on cirrhotic rats were also carried out. LSECs demonstrated an active immunosurveillance profile, as shown by transcriptional modulation of different scavenger and cell-adhesion genes, and their contribution to bacterial internalization. LSECs significantly increased their expression of CD40 and CD80 and stimulated CD4+ T cell activation marker CD71 in both models. The pro-inflammatory Th17 subset was expanded in CCl₄-derived LSECs co-cultures. In the bile duct ligation (BDL) model, CD4+ T cell differentiation only occurred under induced bacterial peritonitis conditions. Differentiated pro-inflammatory Th cells by LSECs in both experimental models were significantly reduced with norfloxacin treatment, whereas Foxp3 tolerogenic Th CD4+ cells were expanded. Conclusion: LSECs’ participation in the innate-adaptive immune progression, their ability to stimulate pro-inflammatory CD4+ T cells expansion during liver damage, and their target role in norfloxacin-induced immunomodulation granted a specific competence to this cell population in cirrhosis.

Gut Microbiota Interventions With Clostridium butyricum and Norfloxacin Modulate Immune Response in Experimental Autoimmune Encephalomyelitis Mice

Gut microbiota has been proposed as an important environmental factor which can intervene and modulate central nervous system autoimmunity. Here, we altered the composition of gut flora with Clostridium butyricum and norfloxacin in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We found that appropriate C. butyricum (5.0 × 10⁶ CFU/mL intragastrically daily, staring at weaning period of age) and norfloxacin (5 mg/kg intragastrically daily, 1 week prior to EAE induction) treatment could both ameliorate EAE although there are obvious differences in gut microbiota composition between these two interventions. C. butyricum increased while norfloxacin decreased the abundance and diversity of the gut microbiota in EAE mice, and both of the treatments decreased firmicutes/bacteroidetes ratio. In the genus level, C. butyricum treatment increased the abundance of Prevotella while Akkermansia and Allobaculum increased in norfloxacin treatment. Moreover, both interventions reduced Desulfovibroneceae and Ruminococcus species. Although there was discrepancy in the gut microbiota composition with the two interventions, C. butyricum and norfloxacin treatment both reduced Th17 response and increased Treg response in the gastrointestinal tract and extra-gastrointestinal organ systems in EAE mice. And the reduced activity of p38 mitogen-activated kinase and c-Jun N-terminal kinase signaling in spinal cord could be observed in the two interventions. The results suggested that manipulation of gut microbiota interventions should take factors such as timing, duration, and dosage into consideration. The discrepancy in the gut microbiota composition and the similar protective T cells response of C. butyricum and norfloxacin implies that achieving intestinal microecology balance by promoting and/or inhibiting the gut microbiota contribute to the well-being of immune response in EAE mice.

Serum Angiopoietin-2 Predicts Mortality and Kidney Outcomes in Decompensated Cirrhosis

Acute kidney injury in decompensated cirrhosis has limited therapeutic options, and novel mechanistic targets are urgently needed. Angiopoietin-2 is a context-specific antagonist of Tie2, a receptor that signals vascular quiescence. Considering the prominence of vascular destabilization in decompensated cirrhosis, we evaluated Angiopoietin-2 to predict clinical outcomes. Serum Angiopoietin-2 was measured serially in a prospective cohort of hospitalized patients with decompensated cirrhosis and acute kidney injury. Clinical characteristics and outcomes were examined over a 90-day period and analyzed according to Angiopoietin-2 levels. Primary outcome was 90-day mortality. Our study included 191 inpatients (median Angiopoietin-2 level 18.2 [interquartile range 11.8, 26.5] ng/mL). Median Model for End-Stage Liver Disease (MELD) score was 23 [17, 30] and 90-day mortality was 41%. Increased Angiopoietin-2 levels were associated with increased mortality (died 21.9 [13.9, 30.3] ng/mL vs. alive 15.2 [9.8, 23.0] ng/mL; P < 0.001), higher Acute Kidney Injury Network stage (stage I 13.4 [9.8, 20.1] ng/mL vs. stage II 20.0 [14.1, 26.2] ng/mL vs. stage III 21.9 [13.0, 29.5] ng/mL; P = 0.002), and need for renal replacement therapy (16.5 [11.3, 23.6] ng/mL vs. 25.1 [13.3, 30.3] ng/mL; P = 0.005). The association between Angiopoietin-2 and mortality was significant in unadjusted and adjusted Cox regression models (P ≤ 0.001 for all models), and improved discrimination for mortality when added to MELD score (integrated discrimination increment 0.067; P = 0.001). Conclusion: Angiopoietin-2 was associated with mortality and other clinically relevant outcomes in a cohort of patients with decompensated cirrhosis with acute kidney injury. Further experimental study of Angiopoietin/Tie2 signaling is warranted to explore its potential mechanistic and therapeutic role in this population.

Unresolved issues in the prophylaxis of bacterial infections in patients with cirrhosis

Bacterial infections are highly prevalent and a frequent cause of hospitalization and short-term mortality in patients with cirrhosis. Due to their negative impact on survival, antibiotic prophylaxis for bacterial infections in high-risk subgroups of patients with cirrhosis has been the standard of care for decades. Patients with prophylaxis indications include those at risk for a first episode of spontaneous bacterial peritonitis (SBP) due to a low ascitic fluid protein count and impaired liver and kidney function, patients with a prior episode of SBP and those with an episode of gastrointestinal bleeding. Only prophylaxis due to gastrointestinal bleeding has a known and short-time duration. All other indications imply long-lasting exposure to antibiotics - once the threshold requirement for initiating prophylaxis is met - without standardized criteria for re-assessing antibiotic interruption. Despite the fact that the benefit of antibiotic prophylaxis in reducing bacterial infections episodes and mortality has been thoroughly reported, the extended use of antibiotics in patients with cirrhosis has also had negative consequences, including the emergence of multi-drug resistant bacteria. Currently, it is not clear whether restricting the use of broad and fixed antibiotic regimens, tailoring the choice of antibiotics to local bacterial epidemiology or selecting non-antibiotic strategies will be the preferred antibiotic prophylaxis strategy for patients with cirrhosis in the future.

Regulatory T Cells Restrict Permeability to Bacterial Antigen Translocation and Preserve Short-Chain Fatty Acids in Experimental Cirrhosis

Intestinal permeability to translocation of bacterial products is increased in cirrhosis. Regulatory T cells (Tregs) remain central to the interplay between the host and microbial milieu. We propose that Tregs are involved in promoting gut barrier integrity and a balanced interaction with gut microbiota–derived short‐chain fatty acids (SCFAs). Carbon tetrachloride cirrhosis was induced in wild‐type and recombination activating gene 1 (Rag1)^‐/‐ mice. Naive T cells and Treg cells were transferred into Rag1^‐/‐ mice. Intestinal permeability was assessed in vivo after lipopolysaccharide (LPS) oral administration, and bacterial DNA presence was evaluated in mesenteric lymph nodes. Transcript and protein levels of tight‐junction (TJ) proteins were measured in colonic tissue. Intestinal T helper profile in response to Escherichia coli (E. coli) was determined by flow cytometry. SCFAs were measured by gas chromatography–mass spectrometry in colonic content before and after E. coli challenge. Rag1^‐/‐ mice showed significantly increased permeability to LPS and bacterial DNA translocation rate compared with control mice. Naive T and Treg cotransfer significantly reduced gut permeability to bacterial antigen translocation and restored TJ protein expression in Rag1^‐/‐ mice. Naive T and Treg replenishment in Rag1^‐/‐ mice restrained proinflammatory differentiation of intestinal lymphocytes in response to E. coli. The main SCFA concentration resulted in significant reduction in Rag1^‐/‐ mice after E. coli administration but remained unaltered after naive T and Tregs cotransfer. The reduced expression of SCFA receptors induced by E. coli was reestablished following naive T and Treg reconstitution in Rag1^‐/‐ mice. Conclusion: The restriction of gut permeability, local inflammatory differentiation, and loss of bacteria‐derived SCFAs foster the value of Tregs in preventing bacterial translocation in cirrhosis.