Absence of toll-like receptor 7 ameliorates survival and reduces intestinal injury in mice after Clostridium difficile infection.

Clostridioides difficile (CD) is a major cause of antibiotic-associated diarrhea and pseudomembranous enteritis. C. difficile infection (CDI) is increasingly present in the community and represents a significant burden on the healthcare system. Identification of novel immune-based therapeutic targets from a better understanding of their molecular pathogenesis is urgently required. Toll-like receptor 7 (TLR7) is an important pattern recognition receptor and function as an immune sensor that can trigger host defenses against pathogens, but the relationship between TLR7 and CDI remains unknown. Here, we reported that the expression levels of TLR7 increased significantly in patients and mice with CDI. Absence of TLR7 in mice with CDI demonstrated enhanced bacterial clearance of intestinal contents and reduced intestinal inflammation, edema, injury and prolonged the survival. TLR7 loss decreased the concentrations of tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IFN-α1 in the intestine and improved tissue damage and inflammation. Flow cytometry and immunofluorescence results indicated that TLR7 enhanced leukocyte recruitment in the infected intestine. In-vitro results have shown that TLR7 impairs the phagocytosis and killing ability of macrophages to CD, prompts reactive oxygen species (ROS) production and accelerates apoptosis. To our knowledge, our study first identified TLR7 as a critical factor that contributes to the immunopathology of CDI, suggesting that targeting TLR7 might serve as a potential treatment for CDI.

The comprehensive role of apoptosis inhibitor of macrophage (AIM) in pathological conditions.

CD5L/AIM (apoptosis inhibitor of macrophage), as an important component in maintaining tissue homeostasis and inflammation, is mainly produced and secreted by macrophages but partially dissociated and released from blood AIM-IgM. AIM plays a regulatory role in intracellular physiological mechanisms, including lipid metabolism and apoptosis. AIM not only increases in autoimmune diseases, directly targets liver cells in liver cancer and promotes cell clearance in acute kidney injury, but also causes arteriosclerosis and cardiovascular events, and aggravates inflammatory reactions in lung diseases and sepsis. Obviously, AIM plays a pleiotropic role in the body. However, to date, studies have failed to decipher the mechanisms behind its different roles (beneficial or harmful) in inflammatory regulation. The inflammatory response is a "double-edged sword," and maintaining balance is critical for effective host defense while minimizing the adverse side effects of acute inflammation. Enhancing the understanding of AIM function could provide the theoretical basis for new therapies in these pathological settings. In this review, we discuss recent studies on the roles of AIM in lipid metabolism, autoimmune diseases and organic tissues, such as liver cancer, myocardial infarction, and kidney disease.

Progranulin aggravates lethal Candida albicans sepsis by regulating inflammatory response and antifungal immunity.

Candida albicans is the most frequent pathogen of fungal sepsis associated with substantial mortality in critically ill patients and those who are immunocompromised. Identification of novel immune-based therapeutic targets from a better understanding of its molecular pathogenesis is required. Here, we reported that the production of progranulin (PGRN) levels was significantly increased in mice after invasive C.albicans infection. Mice that lacked PGRN exhibited attenuated kidney injury and increased survival upon a lethal systemic infection with C. albicans. In mice, PGRN deficiency protected against systemic candidiasis by decreasing aberrant inflammatory reactions that led to renal immune cell apoptosis and kidney injury, and by enhancing antifungal capacity of macrophages and neutrophils that limited fungal burden in the kidneys. PGRN in hematopoietic cell compartment was important for this effect. Moreover, anti-PGRN antibody treatment limited renal inflammation and fungal burden and prolonged survival after invasive C. albicans infection. In vitro, PGRN loss increased phagocytosis, phagosome formation, reactive oxygen species production, neutrophil extracellular traps release, and killing activity in macrophages or neutrophils. Mechanistic studies demonstrated that PGRN loss up-regulated Dectin-2 expression, and enhanced spleen tyrosine kinase phosphorylation and extracellular signal-regulated kinase activation in macrophages and neutrophils. In summary, we identified PGRN as a critical factor that contributes to the immunopathology of invasive C.albicans infection, suggesting that targeting PGRN might serve as a novel treatment for fungal infection.

CXCL14 Protects against Polymicrobial Sepsis by Enhancing Antibacterial Functions of Macrophages.

Rapid and effective control of bacterial infection is critical for the treatment of bacterial sepsis. CXCL14 (CXC motif ligand 14) is an important chemokine involved in infection and immunity, which can bind to CXCR4. However, the contribution of the CXCL14/CXCR4 chemokine axis to bacterial clearance in sepsis remains unknown. Here, the impact of CXCL14/CXCR4 blockade or CXCL14 administration on sepsis was assessed using murine and cell models, as well as human samples. CXCL14 protein concentrations were elevated in mice after cecal ligation and puncture (CLP)-induced sepsis. In vivo, CXCL14 blockade using anti-CXCL14 antibody or CXCL14 knockdown by adeno-associated virus carrying-CXCL14 shRNA significantly increased mortality and bacterial burden, which was paralleled by significantly decreased macrophage influx and M2 macrophage polarization at the site of infection after CLP. Therapeutic administration of CXCL14 improved mortality and bacterial clearance after CLP in a CXCR4-dependent manner, and macrophages, but not neutrophils, were important for the protective effect of CXCL14 in sepsis. In vitro, CXCL14 directly enhanced bacterial phagocytosis and killing of macrophages, and it also increased phagosome formation and reactive oxygen species production in macrophages. Furthermore, inhibiting the activation of PI3K/Akt and NF-κB signaling pathways, but not STAT1 (signal transducer and activator of transcription 1), abrogated the enhanced antibacterial effects of CXCL14 on macrophages. Finally, circulating CXCL14 concentrations were significantly upregulated in patients with sepsis. CXCL14 could enhance bacterial phagocytosis and killing in human monocyte-derived macrophages, which was dependent on CXCR4. Therefore, our results indicate a previously undescribed role of the CXCL14/CXCR4 axis and suggest CXCL14 as a potential adjunct therapy in bacterial sepsis.

Elevated serum level of human epididymal protein 4 (HE4) predicts poor prognosis in the critically ill with sepsis: A prospective observational cohort study.

OBJECTIVE: Human epididymal protein 4 (HE4) has been widely used as an important clinical tumor biomarker for epithelial ovarian cancer. HE4 has recently been suggested to be an inflammatory biomarker and we hypothesized that the serum HE4 level upon intensive care unit (ICU) admission might predict prognosis in septic patients. We hypothesized that serum HE4 level upon intensive care unit (ICU) admission could predict prognosis in septic patients. METHODS: Serum levels of HE4, procalcitonin (PCT), C-reactive protein (CRP), IL-6 and IL-8 were quantified, and sequential organ failure assessment (SOFA) scores were recorded on day one of admission to ICU. The area under the receiver operating characteristic (ROC) curve (AUC) analysis of HE4, IL-6, PCT and SOFA at ICU admission for 28-day mortality was used to evaluate the ability of HE4 in predicting 28-day mortality of sepsis. Multivariate regression analysis was used to identify the independent risk factors for 28-day mortality. RESULTS: A total of 1289 patients were recruited, and 117 patients were included for final analysis. On day of ICU admission, septic patients had significantly higher levels of serum HE4 than those with infection without sepsis, those with ovarian cancer, or healthy controls. Compared with septic survivors, septic non-survivors presented with significantly higher serum HE4 concentrations. Serum levels of HE4 correlated with disease severity scores and cytokine levels (IL-6 and IL-8). Upon ICU admission, the AUC for HE4 level association with 28-day mortality was 0.881, higher than the AUC for SOFA (0.713), IL-6 (0.589), and PCT (0.567). A regression analysis showed that HE4 was an independent mortality predictor. CONCLUSION: HE4 can predict poor prognosis in septic patients, which may help to identify a group of septic patients at high risk of death.

Il-34 regulates MAPKs, PI3K/Akt, JAK and NF-κB pathways and induces the expression of inflammatory factors in RA-FLS.

OBJECTIVES: To explore the role of interleukin 34 (IL-34) in rheumatoid arthritis (RA) and its related signalling pathways as well as the expression levels of IL-34 in collagen-induced arthritis (CIA) modelling mice. METHODS: Recombination IL-34 was used to stimulate cultured RA fibroblast-like synoviocytes (RA-FLS). The expression levels of inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA), and the levels of phosphorylation signalling molecules were detected by western blotting assay (WB). After the establishment of the CIA model, paw indexes and serum IL-34 expression levels of mice were evaluated. RESULTS: IL-34 significantly increased the secretion of IL-8 and TNF-α but had no significant effect on IL-6, and this effect could be impaired by signal inhibitors. At the same time, IL-34 activated multiple signalling pathways, whereas treating with inhibitors could reduce phosphorylation intensity. In animal experiments, mice in the model group had lost weight, and their paws were obviously swollen, ulcerous, and even stiffened. The hyperplasia of synovial tissue, infiltration of many inflammatory cells, and destruction of bone and cartilage from the typical pannus formation were also apparently observed. CONCLUSIONS: IL-34 can mediate the production and secretion of IL-8 and TNF-α in RA-FLS cells through MAPKs, PI3K/Akt, JAK and NF-κB signalling pathways, while the expression of serum IL-34 in collagen-induced arthritis mice is also upregulated.

Apoptosis inhibitor of macrophage/CD5L is associated with disease activity in rheumatoid arthritis.

OBJECTIVES: To investigate the association between apoptosis inhibitor of macrophage (AIM) and disease activity in patients with rheumatoid arthritis (RA). METHODS: In this study, concentrations of serum AIM in 110 RA patients, 38 patients with osteoarthritis (OA) and 50 sex- and age-matched control subjects were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum AIM concentrations in RA patients were dramatically higher than those from patients with OA or healthy controls. The levels of synovial fluid AIM displayed a significant increase as compared with OA patients. More importantly, AIM levels were significantly correlated with RA disease activity features such as ESR, CRP and DAS28. The predictive value of AIM on high disease activity was superior to those of CRP and ESR. A noteworthy correlation in our study was observed between the serum AIM levels and laboratory parameters, particularly serum lipids. Furthermore, serum AIM levels could be significantly down-regulated after effective integrative treatment. CONCLUSIONS: AIM may serve as a novel sensitive biomarker to assist disease activity assessment and monitor therapeutic effects in active RA patients.

Risk of Clostridium tetani infection in an elderly patient following hemorrhoid ligation.

Tetanus after gastrointestinal surgery is an extremely rare but very dangerous disease caused by infection with Clostridium tetani. Tetanus can occur due to bacterial infection during surgery or dressing change, or the bacteria may exist in the patient's intestines and be discharged with feces. This report describes a 71-year-old woman who developed tetanus 3 days after a hemorrhoidal ligation. Clinicians need to be aware of symptoms of C. tetani infection that might present in patients who have undergone gastrointestinal procedures.

The correlation of HCV RNA and HCV core antigen in different genotypes of HCV.

BACKGROUND: To analyze the correlation of HCV RNA and HCV core antigen (HCV cAg) in different genotypes of HCV. METHODS: One hundred and six patients who were diagnosed with HCV infection by HCV RNA test were included in the study. HCV genotypes were detected by PCR fluorescent probe. Detected HCV cAg's expression in serum quantitatively and qualitatively with chemiluminescent micro-particle immuno assay (CMIA) and enzyme-linked immunosorbent assay (ELISA), respectively, and compared positive rates. Analyzed the correlation of HCV RNA and HCV cAg in different genotypes. RESULTS: Distribution of HCV genotypes in 106 HCV infected patients were as follows: 1b genotype 46 (43.4%); 2a genotype 7 (6.6%); 3a genotype 18 (17.0%); 3b genotype 3 (2.8%); 6a genotype 9 (8.5%); 1b/3b mixed type 13 (12.3%); and unidentified type 10 (9.4%). Positive rates of HCV cAg detected by CMIA and ELISA were 100% and 56%, respectively, with statistical significance (χ2  = 60.38, P = 0.000). HCV cAg in 1b genotype group was higher than that in 3b and 1b/3b genotype groups, with statistical significance (U = 3.0, P = 0.006, U = 165, P = 0.014). HCV RNA and HCV cAg in genotype 1b demonstrated a positive correlation (r = 0.894, P = 0.04). CONCLUSION: Major genetic subtype of HCV genotype was 1b. Compared with ELISA, detection of HCV cAg by CMIA increased the positive rate and facilitated early diagnosis and treatment of HCV-infected patients. With the increase in HCV RNA load and the expression of HCV cAg, HCV cAg could be an early indicator for the diagnosis of HCV infection in 1b genotype.

Serum Interleukin-34 Levels Are Elevated in Patients with Systemic Lupus Erythematosus.

Interleukin-34 (IL-34) was initially identified as an alternative ligand for the colony-stimulating factor-1 receptor (CSF-1R) to mediate the biology of mononuclear phagocytic cells. Recently, IL-34 was found to be associated with chronic inflammation, such as in rheumatoid arthritis (RA). Both RA and systemic lupus erythematosus (SLE) are multifactorial autoimmune diseases and are characterized by excessive immune and inflammatory responses. Thus, we investigated whether IL-34 is involved in the pathogenesis of SLE. In all, 78 SLE patients and 53 healthy controls were enrolled in the research. Enzyme-linked immunosorbent assay (ELISA) was employed to measure the concentrations of serological IL-34. Then serum IL-34 levels between the SLE group and healthy controls were analyzed by the Mann-Whitney U test. Meanwhile, the correlations between the serum IL-34 levels and disease activity indexes and other established serum markers were assessed. Furthermore, the serum IL-34 levels of 20 active SLE patients were reevaluated when diseases were in the remission stage from corticosteroids or immunosuppressive drugs. Serum IL-34 levels were significantly higher in SLE patients compared to healthy controls. Their levels were remarkably associated with accumulation of the clinical features of SLE. Additionally, IL-34 titers were positively correlated with the SLE disease activity indexes, anti-double-stranded DNA antibody (anti-dsDNA) titers and C-reactive protein (CRP) levels, and inversely with complement3 (C3) levels. Moreover, serum IL-34 levels were significantly decreased after successful treatment of SLE. Serum IL-34 could be a candidate biomarker for SLE as there are elevated serum levels in treatment-naive SLE patients and we saw a significant decrease after effective treatment.

Hepatic expression profile of forkhead transcription factor genes in normal Balb/c mice and their dynamic changes after bile duct ligation.

Dysregulation of Forkhead box (Fox) transcription factor family genes was previously shown to lead to congenital disorders, diabetes mellitus, and carcinogenesis, and recent reports suggested that several Fox genes play important roles in the pathogenesis of liver fibrosis. The present study was initiated to determine the expression profiles of the Fox genes in normal Balb/c mouse liver and their dynamic expression changes during fibrogenesis induced by experimental bile duct ligation (BDL). RT-PCR was employed to detect 18 FOX family members including FOXO1, FOXO3, FOXM1, and FOXL1 in normal mouse liver. FQ-PCR was performed to analyze the dynamic mRNA expression changes of nine inflammation- or proliferation-related FOX family genes in BDL mice. Results showed that all the 18 Fox genes were expressed in the normal mouse liver, among which the expression of FOXO1 and FOXO3 were found to be the highest. The inflammation and proliferation-related FOX family genes were found to be dynamically changed during BDL-induced liver injury with reduced FOXO1 and enhanced FOXOL1 and FOXM1, indicating their potential involvement in the pathogenesis of liver fibrosis. This is the first systematic evaluation of hepatic expression of FOX genes in both normal and BDL mice.