Interleukin-26 is overexpressed in human sepsis and contributes to inflammation, organ injury, and mortality in murine sepsis

Obeticholic acid ameliorates sepsis-induced renal mitochondrial damage by inhibiting the NF-κb signaling pathway

Acute kidney injury (AKI), a common complication of sepsis, might be caused by overactivated inflammation, mitochondrial damage, and oxidative stress. However, the mechanisms underlying sepsis-induced AKI (SAKI) have not been fully elucidated, and there is a lack of effective therapies for AKI. To this end, this study aimed to investigate whether obeticholic acid (OCA) has a renoprotective effect on SAKI and to explore its mechanism of action. Through bioinformatics analysis, our study confirmed that the mitochondria might be a critical target for the treatment of SAKI. Thus, a septic rat model was established by cecal ligation puncture (CLP) surgery. Our results showed an evoked inflammatory response via the NF-κB signaling pathway and NLRP3 inflammasome activation in septic rats, which led to mitochondrial damage and oxidative stress. OCA, an Farnesoid X Receptor (FXR) agonist, has shown anti-inflammatory effects in numerous studies. However, the effects of OCA on SAKI remain unclear. In this study, we revealed that pretreatment with OCA can inhibit the inflammatory response by reducing the synthesis of proinflammatory factors (such as IL-1β and NLRP3) via blocking NF-κB and alleviating mitochondrial damage and oxidative stress in the septic rat model. Overall, this study provides insight into the excessive inflammation-induced SAKI caused by mitochondrial damage and evidence for the potential use of OCA in SAKI treatment.

Characteristics and Risk Factors for Pediatric Sepsis

OBJECTIVE

Sepsis is considered a major cause of health loss in children and had high mortality and morbidity. Currently, there is no reliable model for predicting the prognosis of pediatric patients with sepsis. This study aimed to analyze the clinical characteristics of sepsis in children and assess the risk factors associated with poor prognosis in pediatric sepsis patients to identify timely interventions and improve their outcomes.

METHODS

This study analyzed the clinical indicators and laboratory results of septic patients hospitalized in the Pediatric Intensive Care Unit of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China, from January 1, 2019, to December 31, 2021. Risk factors for sepsis were identified by logistic regression analyses.

RESULTS

A total of 355 children with sepsis were enrolled, with 333 children (93.8%) in the good prognosis group, and 22 children (6.2%) in the poor prognosis group. Among them, there were 255 patients (71.8%) in the sepsis group, and 100 patients (28.2%) in the severe sepsis group. The length of hospital stay in the poor prognosis group was longer than that in the good prognosis group (P<0.01). The levels of interleukin 1β (IL-1β) in the poor prognosis group were higher than those in the good prognosis group (P>0.05), and the platelet (PLT), albumin (ALB), and hemoglobin (Hb) levels were lower in the poor prognosis group (P<0.01). The IL-8 levels in the severe sepsis group were higher than those in the sepsis group (P<0.05). Multiple logistic regression analysis suggested that lower Hb levels, ALB levels, peak PLT counts, and higher IL-1β levels were independent risk factors for poor prognosis in children with sepsis.

CONCLUSION

Lower Hb, ALB, and PLT counts and elevated IL-1β are independent risk factors for poor prognosis in children with sepsis.

Immunobiology of IL-26

T helper 17 (Th17) cells produce a set of cytokines that include IL-17 family members, IL-21, IL-22, and IL-26. These cytokines all contribute to the classic function of Th17 cells in combatting extracellular infection and promoting inflammation in autoimmune diseases. However, of the Th17 cytokines, only IL-26 has direct antimicrobial activity against microbes and can activate a broad range of immune cells through its ability to bind DNA and trigger pattern recognition receptors. It is noteworthy that IL-26 is produced by mammalian cells, including human Th17 cells, but is absent in rodents. As such, IL-26 is a potential therapeutic target to augment host immune responses against microbial pathogens but also to prevent inflammation and tissue damage in a variety of autoimmune diseases.

Clinical predictive value of the CRP-albumin-lymphocyte index for prognosis of critically ill patients with sepsis in intensive care unit: a retrospective single-center observational study

Background

Sepsis is a complex syndrome characterized by physiological, pathological, and biochemical abnormalities caused by infection. Its development is influenced by factors such as inflammation, nutrition, and immune status. Therefore, we combined C-reactive protein (CRP), albumin, and lymphocyte, which could reflect above status, to be the CRP-albumin-lymphocyte (CALLY) index, and investigated its association with clinical prognosis of critically ill patients with sepsis.

Methods

This retrospective observational study enrolled critically ill patients with sepsis who had an initial CRP, albumin, and lymphocyte data on the first day of ICU admission. All data were obtained from the Affiliated Hospital of Jiangsu University. The patients were divided into quartiles (Q1-Q4) based on their CALLY index. The outcomes included 30-/60-day mortality and acute kidney injury (AKI) occurrence. The association between the CALLY index and these clinical outcomes in critically ill patients with sepsis was evaluated using Cox proportional hazards and logistic regression analysis.

Results

A total of 1,123 patients (63.0% male) were included in the study. The 30-day and 60-day mortality rates were found to be 28.1 and 33.4%, respectively, while the incidence of AKI was 45.6%. Kaplan-Meier analysis revealed a significant association between higher CALLY index and lower risk of 30-day and 60-day mortality (log-rank p < 0.001). Multivariate Cox proportional hazards analysis indicated that the CALLY index was independently associated with 30-day mortality [HR (95%CI): 0.965 (0.935-0.997); p = 0.030] and 60-day mortality [HR (95%CI): 0.969 (0.941-0.997); p = 0.032]. Additionally, the multivariate logistic regression model showed that the CALLY index served as an independent risk predictor for AKI occurrence [OR (95%CI): 0.982 (0.962-0.998); p = 0.033].

Conclusion

The findings of this study indicated a significant association between the CALLY index and both 30-day and 60-day mortality, as well as the occurrence of AKI, in critically ill patients with sepsis. These findings suggested that the CALLY index may be a valuable tool in identifying sepsis patients who were at high risk for unfavorable outcomes.

Inhibition of Pyruvate Dehydrogenase Kinase 4 Attenuates Myocardial and Mitochondrial Injury in Sepsis-Induced Cardiomyopathy

BACKGROUND

Sepsis-induced cardiomyopathy (SIC) is a cardiac dysfunction caused by sepsis, with mitochondrial dysfunction being a critical contributor. Pyruvate dehydrogenase kinase 4 (PDK4) is a kinase of pyruvate dehydrogenase with multifaceted actions in mitochondrial metabolism. However, its role in SIC remains unknown.

METHODS

Serum PDK4 levels were measured and analyzed in 27 children with SIC, 30 children with sepsis, and 29 healthy children. In addition, for mice exhibiting SIC, the effects of PDK4 knockdown or inhibition on the function and structure of the myocardium and mitochondria were assessed.

RESULTS

The findings from the analysis of children with SIC revealed that PDK4 was significantly elevated and correlated with disease severity and organ injury. Nonsurvivors displayed higher serum PDK4 levels than survivors. Furthermore, mice with SIC benefited from PDK4 knockdown or inhibition, showing improved myocardial contractile function, reduced myocardial injury, and decreased mitochondrial structural injury and dysfunction. In addition, inhibition of PDK4 decreased the inhibitory phosphorylation of PDHE1α (pyruvate dehydrogenase complex E1 subunit α) and improved abnormal pyruvate metabolism and mitochondrial dysfunction.

CONCLUSIONS

PDK4 is a potential biomarker for the diagnosis and prognosis of SIC. In experimental SIC, PDK4 promoted mitochondrial dysfunction with increased phosphorylation of PDHE1α and abnormal pyruvate metabolism.

Preparation and immunogenicity evaluation of C-HapS-P6 fusion protein vaccine against nontypeable Haemophilus influenzae in mice

Nontypeable Haemophilus influenzae (NTHi) is the dominant pathogen in several infectious diseases. Currently the use of antibiotics is the main intervention to prevent NTHi infections, however with the emergence of drug resistant strains, it has compromised the treatment of respiratory infections with antibiotics. Therefore there is an urgent need to develop a safe and effective vaccine to prevent NTHi infections. We investigate the potential of C-HapS-P6 fusion protein as a vaccine for treating NTHi in murine models. PGEX-6P2/C-HapS-P6 fusion gene was constructed using overlap extension polymerase chain reaction. The recombined plasmid was transformed into Escherichia coli for protein expression. The mice were subjected to intraperitoneal immunization using purified antigens. Immunoglobulin (Ig) G in serum samples and IgA in nasal and lung lavage fluids were analyzed using enzyme-linked immunosorbent assay. Cytokine release and proliferation capacity of splenic lymphocytes in response to antigens were measured in vitro. The protective effect of the C-HapS-P6 protein against NTHi infection was evaluated by NTHi count and histological examination. The data showed that the C-HapS-P6 fusion protein increased significantly the levels of serum IgG and nasal and lung IgA, and promoted the release of interleukin (IL)-2, interferon-ϒ, IL-4, IL-5, and IL-17 and the proliferation of splenic lymphocytes compared with C-HapS or P6 protein treatment alone. Moreover, C-HapS-P6 effectively reduced the NTHi colonization in the nasopharynx and lungs of mice. In conclusion, our results demonstrated that the C-HapS-P6 fusion protein vaccine can significantly enhance humoral and cell immune responses and effectively prevent against NTHi infection in the respiratory tract in murine models.

Clinical predictive value of the initial neutrophils to lymphocytes and platelets ratio for prognosis of sepsis patients in the intensive care unit: a retrospective study

Background

Neutrophils to lymphocytes and platelets (N/LP) ratio has been confirmed as an indirect marker of inflammation. In this study, we aimed to further evaluate the prognostic significance of the N/LP ratio in sepsis patients admitted to the ICU.

Methods

Sepsis patients from the Affiliated Hospital of Jiangsu University were retrospectively enrolled from January 2015 and July 2023. The primary outcomes were 30/60 days mortality. The secondary outcomes included the incidence of AKI, vasoactive drug, CRRT, invasive ventilation, length of ICU stay, length of hospital stay and ICU mortality.

Results

A total of 1,066 sepsis patients were enrolled with a median age of 75.0 (66.0, 85.0) years, and 62.5% of them being male. The 30 days and 60 days mortality rates were found to be 28.7 and 34.0%, respectively, while the incidence of AKI was 45.2%. Based on their N/LP ratios, we classified the sepsis patients into three groups: low, middle, and high, consisting of 266, 534, and 266 patients, respectively. According the Cox proportional hazard model, the middle and high N/LP groups were associated with a 1.990/3.106-fold increase in 30 days mortality risk and a 2.066/3.046-fold increase in 60 days mortality risk compared with the low N/LP group. Besides, multivariate logistic regression model suggested that the risk of AKI occurrence increased 2.460 fold in the high group compared to the low group. However, through subgroup analyses, we observed substantial variations in the association between N/LP ratios and 30/60 days mortality rates as well as the incidence of AKI among different populations. Notably, the N/LP ratio measured at ICU admission exhibited a higher AUC for predicting 30/60 days mortality (0.684/0.687). Additionally, we observed a good predictive power for the occurrence of AKI (AUC: 0.645) using the N/LP ratio measured at sepsis prognosis. Regarding the other secondary outcomes, the N/LP ratio was associated with disease severity in sepsis patients, including the need for vasoactive drugs, length of ICU stay, and ICU mortality.

Conclusion

The N/LP ratio at ICU admission was found to have a significant independent association with 30/60 days mortality and the incidence of AKI in sepsis patients.

Interleukin-36 is overexpressed in human sepsis and IL-36 receptor deletion aggravates lung injury and mortality through epithelial cells and fibroblasts in experimental murine sepsis

BACKGROUND

Sepsis is defined as a life-threatening syndrome caused by an unbalanced host response to infection. The role of interleukin (IL)-36 cytokines binding to the IL-36 receptor (IL-36R) in host response during sepsis remains unknown.

METHODS

Serum IL-36 level was measured in 47 septic patients sampled on the day of intensive care unit (ICU) and emergency department admission, 21 non-septic ICU patient controls, and 21 healthy volunteers. In addition, the effects of IL-36R deletion on host inflammatory response in cecal ligation and puncture (CLP)-induced polymicrobial sepsis was determined.

RESULTS

On the day of ICU and emergency department admission, the patients with sepsis showed a significant increase in serum IL-36 levels compared with ICU patient controls and healthy volunteers, and the serum IL-36 levels were related to the severity of sepsis. Non-survivors of septic patients displayed significantly lower serum IL-36 levels compared with survivors. A high serum IL-36 level in ICU and emergency department admission was associated with 28-day mortality, and IL-36 was found to be an independent predictor of 28-day mortality in septic patients by logistic regression analysis. Furthermore, IL-36R deletion increased lethality in CLP-induced polymicrobial sepsis. Septic mice with IL-36R deletion had higher bacterial load and demonstrated more severe multiple organ injury (including lung, liver, and kidney) as indicated by clinical chemistry and histopathology. Mechanistically, IL-36R ligands released upon lung damage activated IL-36R+lung fibroblasts thereby inducing expression of the antimicrobial protein lipocalin 2. Moreover, they induced the apoptosis of lung epithelial cells.

CONCLUSIONS

Septic patients had elevated serum IL-36 levels, which may correlate with disease severity and mortality. In experimental sepsis, we demonstrated a previously unrecognized role of IL-36R deletion in increasing lethality.

PATHWAYS ASSOCIATED WITH POSITIVE SEPSIS SURVIVAL OUTCOMES IN AFRICAN AMERICAN/BLACK AND NON-HISPANIC WHITE PATIENTS WITH URINARY TRACT INFECTION

ABSTRACT

Urinary tract infections (UTIs) are a common cause of sepsis worldwide. Annually, more than 60,000 US deaths can be attributed to sepsis secondary to UTIs, and African American/Black adults have higher incidence and case-fatality rates than non-Hispanic White adults. Molecular-level factors that may help partially explain differences in sepsis survival outcomes between African American/Black and Non-Hispanic White adults are not clear. In this study, patient samples (N = 166) from the Protocolized Care for Early Septic Shock cohort were analyzed using discovery-based plasma proteomics. Patients had sepsis secondary to UTIs and were stratified according to self-identified racial background and sepsis survival outcomes. Proteomics results suggest patient heterogeneity across mechanisms driving survival from sepsis secondary to UTIs. Differentially expressed proteins (n = 122, false discovery rate-adjusted P < 0.05) in Non-Hispanic White sepsis survivors were primarily in immune system pathways, while differentially expressed proteins (n = 47, false discovery rate-adjusted P < 0.05) in African American/Black patients were mostly in metabolic pathways. However, in all patients, regardless of racial background, there were 16 differentially expressed proteins in sepsis survivors involved in translation initiation and shutdown pathways. These pathways are potential targets for prognostic intervention. Overall, this study provides information about molecular factors that may help explain disparities in sepsis survival outcomes among African American/Black and Non-Hispanic White patients with primary UTIs.

Interleukin 26 Induces Macrophage IL-9 Expression in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease with chronic inflammation, bone erosion, and joint deformation. Synovial tissue in RA patients is full of proinflammatory cytokines and infiltrated immune cells, such as T help (Th) 9, Th17, macrophages, and osteoclasts. Recent reports emphasized a new member of the interleukin (IL)-10 family, IL-26, an inducer of IL-17A that is overexpressed in RA patients. Our previous works found that IL-26 inhibits osteoclastogenesis and conducts monocyte differentiation toward M1 macrophages. In this study, we aimed to clarify the effect of IL-26 on macrophages linking to Th9 and Th17 in IL-9 and IL-17 expression and downstream signal transduction. Murine and human macrophage cell lines and primary culture cells were used and stimulated by IL26. Cytokines expressions were evaluated by flow cytometry. Signal transduction and transcription factors expression were detected by Western blot and real time-PCR. Our results show that IL-26 and IL-9 colocalized in macrophage in RA synovium. IL-26 directly induces macrophage inflammatory cytokines IL-9 and IL-17A expression. IL-26 increases the IL-9 and IL-17A upstream mechanisms IRF4 and RelB expression. Moreover, the AKT-FoxO1 pathway is also activated by IL-26 in IL-9 and IL-17A expressing macrophage. Blockage of AKT phosphorylation enhances IL-26 stimulating IL-9-producing macrophage cells. In conclusion, our results support that IL-26 promotes IL-9- and IL-17-expressing macrophage and might initiate IL-9- and IL-17-related adaptive immunity in rheumatoid arthritis. Targeting IL-26 may a potential therapeutic strategy for rheumatoid arthritis or other IL-9 plus IL-17 dominant diseases.

Fish Oil - Omega-3 Exerts Protective Effect in Oxidative Stress and Liver Dysfunctions Resulting from Experimental Sepsis

Background

Sepsis is a severe global health problem, with high morbidity and mortality. In sepsis, one of the main affected organs is the liver. Hepatic alterations characterize a negative prognostic. Omega-3 fatty acids (ω3), eicosapentaenoic acid, and docosahexaenoic acid, are part of the main families of polyunsaturated fatty acids. ω3 has been used in studies as sepsis treatment and as a treatment for non-alcoholic liver disease.

Aim

We aimed to evaluate the effects of treatment with fish oil (FO) rich in ω3 on liver changes and damage resulting from experimental sepsis.

Methodology

A model of severe sepsis in Wistar rats was used. Oxidative stress in the liver tissue was evaluated by means of tests of thiobarbituric acid reactive substances, 2,7-dihydrodichlorofluorescein diacetate , catalase, and glutathione peroxidase, in the serum TBARS, DCF, thiols and, to assess liver dysfunction, alanine aminotransferase and aspartate aminotransferase. Hepatic tissue damage was evaluated using H&E histology.

Results

In assessments of oxidative stress in liver tissue, a protective effect was observed in the tests of TBARS, DCF, CAT, and GPx, when compared the sepsis versus sepsis+ω3 groups. Regarding the oxidative stress in serum, a protective effect of treatment with ω3 was observed in the TBARS, DCF, and thiols assays, in the comparison between the sepsis and sepsis+ω3 groups. ω3 had also a beneficial effect on biochemical parameters in serum in the analysis of ALT, creatinine, urea, and lactate, observed in the comparison between the sepsis and sepsis+ω3 groups.

Conclusion

The results suggest ω3 as a liver protector during sepsis with an antioxidant effect, alleviating injuries and dysfunctions.

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.

Mucosal immunity of mannose-modified chitosan microspheres loaded with the nontyepable Haemophilus influenzae outer membrane protein P6 in BALB/c mice

Nontypeable Haemophilus influenzae (NTHi) is a common opportunistic pathogen that colonizes the nasopharynx. NTHi infections result in enormous global morbidity in two clinical settings: otitis media in children and acute exacerbation of chronic obstructive pulmonary disease (COPD) in adults. Thus, there is an urgent need to design and develop effective vaccines to prevent morbidity and reduce antibiotic use. The NTHi outer membrane protein P6, a potential vaccine candidate, is highly conserved and effectively induces protective immunity. Here, to enhance mucosal immune responses, P6-loaded mannose-modified chitosan (MC) microspheres (P6-MCMs) were developed for mucosal delivery. MC (18.75%) was synthesized by the reductive amination reaction method using sodium cyanoborohydride (NaBH₃CN), and P6-MCMs with an average size of 590.4±16.2 nm were successfully prepared via the tripolyphosphate (TPP) ionotropic gelation process. After intranasal immunization with P6-MCMs, evaluation of humoral immune responses indicated that P6-MCMs enhance both systemic and mucosal immune responses. Evaluation of cellular immune responses indicated that P6-MCMs enhance cellular immunity and trigger a mixed Th1/Th2-type immune response. Importantly, P6-MCMs also trigger a Th17-type immune response. They are effective in promoting lymphocyte proliferation and differentiation without toxicity in vitro. The results also demonstrate that P6-MCMs can effectively induce MHC class I- and II-restricted cross-presentation, promoting CD4⁺-mediated Th immune responses and CD8⁺-mediated cytotoxic T lymphocyte (CTL) immune responses. Evaluation of protective immunity indicated that immunization with P6-MCMs can reduce inflammation in the nasal mucosa and the lung and prevent NTHi infection. In conclusion, MCMs are a promising adjuvant-delivery system for vaccines against NTHi.

Interleukin-26 Expression in Inflammatory Bowel Disease and Its Immunoregulatory Effects on Macrophages

Background and Aim

Interleukin-26 (IL-26) has been implicated in several chronic inflammatory diseases. However, its role in inflammatory bowel disease (IBD) remains to be elucidated. We aimed to investigate IL-26 expression in IBD and its immunoregulatory effects on macrophages.

Methods

We assessed IL-26 expression in the intestinal mucosa and blood samples of IBD patients and healthy controls (HC). The associations between the clinical characteristics of IBD and IL-26 expression levels in serum and peripheral blood mononuclear cells (PBMCs) were investigated. In addition, the transcriptional changes in THP-1 macrophages exposed to IL-26 were determined by RNA sequencing and validated with qRT-PCR, ELISA and western blots.

Results

Compared with HC, in IBD patients, IL-26 expression levels were elevated in the inflamed intestinal mucosa, and reduced in serum and PBMCs. IL-26 mRNA levels in PBMCs, but not serum IL-26 levels, were inversely correlated with disease activity in IBD. Furthermore, IL-26 mRNA levels in PBMCs were significantly lower in patients with complicated Crohn's disease. A total of 1,303 differentially expressed protein-coding genes were identified between untreated and IL-26-treated macrophages. The up-regulated genes showed enrichment in some inflammatory and immune-related processes and pathways. Additionally, GSEA showed that neutrophil, monocyte, and lymphocyte chemotaxis was significantly enriched in IL-26-treated macrophages. Further validation revealed that IL-26 promotes the secretion of multiple inflammatory cytokines and chemokines and upregulates the expression of adhesion molecules, MMP-8, and MMP-9 while inhibiting MMP-1 in macrophages.

Conclusion

Compared with HC, in IBD patients, IL-26 levels were elevated in the inflamed intestinal mucosa, and reduced in the peripheral blood. The transcriptional changes in macrophages exposed to IL-26 suggest that IL-26 may amplify the aberrant immune response in IBD by activating macrophages.

IL-27 induces LL-37/CRAMP expression from intestinal epithelial cells: implications for immunotherapy of Clostridioides difficile infection

Clostridioides difficile infection is currently the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. Cathelicidins, a major group of natural antimicrobial peptides, have antimicrobial and immunomodulatory activities in Clostridioides difficile infection. Here, we have shown that cytokine IL-27 induced human cathelicidin antimicrobial peptide (LL-37) expression in primary human colonic epithelial cells. IL-27 receptor-deficient mice had impaired expression of cathelicidin-related antimicrobial peptide (CRAMP, mouse homolog for human LL-37) after Clostridioides difficile infection, and restoration of CRAMP improved Clostridium difficile clearance and reduced mortality in IL-27 receptor-deficient mice after Clostridioides difficile challenge. In clinical samples from 119 patients with Clostridioides difficile infection, elevated levels of IL-27 were positively correlated with LL-37 in the sera and stools. These findings suggest that IL-27 may be involved in host immunity against Clostridioides difficile infection via induction of LL-37/CRAMP. Therefore, IL-27-LL-37 axis may be a valuable pathway in the development of immune-based therapy.

A comprehensive review of IL-26 to pave a new way for a profound understanding of the pathobiology of cancer, inflammatory diseases and infections

Cytokines are considered vital mediators of the immune system. Down- or upregulation of these mediators is linked to several inflammatory and pathologic situations. IL-26 is referred to as an identified member of the IL-10 family and IL-20 subfamily. Due to having a unique cationic structure, IL-26 exerts diverse functions in several diseases. Since IL-26 is mainly secreted from Th17, it is primarily considered a pro-inflammatory cytokine. Upon binding to its receptor complex (IL-10R1/IL-20R2), IL-26 activates multiple signalling mediators, especially STAT1/STAT3. In cancer, IL-26 induces IL-22-producing cells, which consequently decrease cytotoxic T-cell functions and promote tumour growth through activating anti-apoptotic proteins. In hypersensitivity conditions such as rheumatoid arthritis, multiple sclerosis, psoriasis and allergic disease, this cytokine functions primarily as the disease-promoting mediator and might be considered a biomarker for disease prognosis. Although IL-26 exerts antimicrobial function in infections such as hepatitis, tuberculosis and leprosy, it has also been shown that IL-26 might be involved in the pathogenesis and exacerbation of sepsis. Besides, the involvement of IL-26 has been confirmed in other conditions, including graft-versus-host disease and chronic obstructive pulmonary disease. Therefore, due to the multifarious function of this cytokine, it is proposed that the underlying mechanism regarding IL-26 function should be elucidated. Collectively, it is hoped that the examination of IL-26 in several contexts might be promising in predicting disease prognosis and might introduce novel approaches in the treatment of various diseases.

Interleukin-26 Has Synergistic Catabolic Effects with Palmitate in Human Articular Chondrocytes via the TLR4-ERK1/2-c-Jun Signaling Pathway

The inflammatory cytokine interleukin-26 (IL-26) is highly expressed in the serum and synovial fluid of patients with inflammatory arthritis. The effect of IL-26 on human articular chondrocytes (HACs) remains unclear. Obesity is associated with disability of patients with rheumatoid arthritis and disease activity in those with ankylosing spondylitis. The saturated free fatty acid palmitate with IL-1β can synergistically induce catabolic effects in HACs. The aim of this study was to evaluate the effects of IL-26 and palmitate in HACs. In this study, palmitate markedly synergizes the IL-26-induced proinflammatory effects and matrix protease, including COX-2, IL-6, and MMP-1, in HACs via the toll-like receptor 4 (TLR4)-ERK1/2-c-Jun signal transduction pathway. The synergistic catabolic effects of palmitate and IL-26 were attenuated by inhibitors of TLR4 (TAK242), ERK1/2 (U0126), or c-Jun (SP600125) in HACs and cartilage matrix. In addition, metformin, a potential inhibitor of TLR4, also decreased expression of COX-2 and IL-6 induced by co-incubation with IL-26 and palmitate. IL-26 and palmitate synergistically induced expression of inflammatory and catabolic mediators, resulting in articular cartilage matrix breakdown. The present study also revealed a possible mechanism and therapeutic targets against articular cartilage degradation by increased saturated fatty acids in patients with inflammatory arthritis.

Prognostic and pathogenic role of CXC Motif Ligand 16 in sepsis

Chemokine CXC motif ligand 16 (CXCL16) is an important mediator that has been shown to participate in various human diseases. The role of CXCL16 in the immunopathology of sepsis remains unidentified. In this study, we found that human patients with sepsis had significantly higher soluble levels of serum CXCL16 than healthy volunteers on day of intensive care unit (ICU) admission. Soluble CXCL16 remained significantly up-regulated in the patients with sepsis, which correlated with disease severity. Furthermore, nonsurvivors displayed significantly higher admission levels of soluble CXCL16 compared with survivors of septic patients. Soluble CXCL16 levels revealed significant prognostic value for 28-day mortality, and CXCL16 was shown to be an independent predictor of 28-day mortality in the patients with sepsis. In a murine model of cecal ligation and puncture (CLP)-induced nonsevere sepsis, supplementation of recombinant CXCL16 protein could increase sepsis-induced mortality and tissue injury. Conversely, neutralizing CXCL16 by anti-CXCL16 monoclonal antibody could decrease mortality and tissue injury in CLP-induced severe sepsis. However, CXCL16 did not affect the ability of these mice to clear bacteria in CLP. Taken together, CXCL16 could be related to sepsis not only as a novel biomarker of prognosis, but also as a potential target for therapeutic intervention.

Interleukin-9 promotes intestinal barrier injury of sepsis: a translational research

Background

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Intestinal mucosal barrier injury is one of the important manifestations of sepsis. Interleukin-9 (IL-9) and IL-9-producing CD4(+) T cells were emerging pro-inflammatory mediators with development of intestinal injury. However, it is unclear whether IL-9 is related to the intestinal barrier injury of sepsis.

Methods

To investigate the roles of IL-9-producing CD4(+) T cells and IL-9 in the process of barrier injury in sepsis, serum IL-9-producing CD4(+) T cell percentages, IL-9, and D-lactate levels were measured in septic patients and controls. The markers of barrier function in serum and intestinal tissue were also collected in septic rats. Moreover, the barrier injury degree and survival rate of septic rats were also investigated after increasing or interfering with IL-9 expression.

Results

The serum IL-9-producing CD4(+) T cell percentages, IL-9, and D-lactate levels were significantly higher in septic patients or rats than those in controls. IL-9-producing CD4(+) T cells and IL-9 levels were positively correlated with D-lactate levels and had a high predictive value of 28-day mortality in septic patients. The non-survivors had significantly higher serum T cell percentages, IL-9, and D-lactate levels compared with survivors. In septic rats, IL-9 increased the expression levels of D-lactate, whereas that decreased the expression levels of zonula occludens 1. Moreover, the barrier injury was aggravated or alleviated by increasing or interfering with IL-9 expression, respectively. Survival rate analysis also showed that IL-9 decreased the 14-day survival rate of septic rats.

Conclusion

IL-9 is closely related to intestinal mucosal barrier injury and mortality in sepsis. IL-9 blockade has the potential to improve the barrier injury in sepsis.

Trial registration

The study was registered at ClinicalTrials.gov (ID: NCT03791866, Date: December 2018).

Anti-Interleukin-16 Neutralizing Antibody Treatment Alleviates Sepsis-Induced Cardiac Injury and Dysfunction via the Nuclear Factor Erythroid-2 Related Factor 2 Pathway in Mice

Several interleukin (IL) members have been reported to participate in sepsis. In this study, the effects of IL-16 on sepsis-induced cardiac injury and dysfunction were examined, and the related mechanisms were detected. IL-16 expression in septic mice was first measured, and the results showed that both cardiac and serum IL-16 expression levels were increased in mice with sepsis induced by LPS or cecal ligation and puncture (CLP) compared with control mice. Then, IL-16 was neutralized, and the effects on lipopolysaccharide- (LPS-) induced cardiac injury were detected. The results showed that an anti-IL-16 neutralizing antibody (nAb) significantly reduced mortality and increased serum lactate dehydrogenase (LDH), creatine kinase myocardial bound (CK-MB), and cardiac troponin T (cTnT) levels while improving cardiac function in mice with LPS-induced sepsis. Neutralization of IL-16 also increased the activation of antioxidant pathways and the expression of antioxidant factors in septic mice while decreasing the activation of prooxidant pathways and the expression of prooxidants. Treatment with the anti-IL-16 nAb increased mitochondrial apoptosis-inducing factor (AIF) expression, decreased nuclear AIF and cleaved poly-ADP-ribose polymerase (PARP) expression, and decreased TUNEL-positive cell percentages in LPS-treated mice. Additionally, treatment with CPUY192018, the nuclear factor erythroid-2 related factor 2 (Nrf2) pathway, significantly increased mortality and reversed the above effects in mice treated with LPS and the anti-IL-16 nAb. Our results showed that the anti-IL-16 nAb regulates oxidative stress through the Nrf2 pathway and participates in the regulation of cardiac injury in septic mice. Neutralization of IL-16 may be a beneficial strategy for the prevention of cardiac injury and dysfunction in sepsis patients.

Interleukin-37 as a biomarker of mortality risk in patients with sepsis

BACKGROUND

Sepsis is a serious syndrome that is caused by an unbalanced inflammatory response to infection and can cause high mortality. The role of interleukin-37 (IL-37) in estimating the mortality in patients with sepsis remains unknown. This study aims to reveal the clinical application of IL-37 as a potentially novel biomarker to predict mortality risk in patients with sepsis.

METHODS

The serum IL-37 level in 114 adult septic patient serum samples on the day of intensive care unit (ICU) admission, 56 non-sepsis ICU patients, and 56 healthy volunteers were measured and analyzed, and the 28-day survival status and sequential organ failure assessment (SOFA) scores of the participants were compared. Furthermore, the area under the receiver operating characteristic curve (AUC) of IL-37, IL-6, and SOFA at ICU admission for 28-day survival was used to evaluate the ability of IL-37 in predicting the mortality of sepsis.

RESULTS

The serum IL-37 level at admission was elevated in patients with sepsis. Moreover, the concentration of IL-37 in patients with sepsis was significantly higher than that in non-sepsis ICU patients and the healthy control group. In addition, the concentration of serum IL-37 in non-surviving patients with sepsis was significantly higher than that in survivors. In patients with sepsis on the day of ICU admission, the AUC associated with 28-day mortality was 0.67 (p = 0.0022;95% confidence interval [95% CI], 0.57-0.77) for IL-37, 0.75 (p < 0.0001; 95% CI, 0.66-0.84) for SOFA, and 0.62 (p = 0.0342; 95% CI, 0.51-0.72) for IL-6. IL-37 and SOFA scores on the day of ICU admission of the patients with sepsis were found to be independent predictors of 28-day mortality, whereas IL-6 was not. The risk of mortality in patients with sepsis and high serum IL-37 concentration (≥107.05pg/ml) was 4.6 times that of patients with sepsis and low serum concentration. The AUC of IL-37 combined with SOFA-estimated 28-day mortality in patients with sepsis increased from 0.67 (p = 0.0022; 95% CI, 0.57-0.77) to 0.80 (p < 0.0001; 95% CI, 0.711-0.879). In addition, patients with sepsis and high serum IL-37 concentrations (≥107.05pg/ml) had poorer survival rate than those with low serum concentrations (<107.05pg/ml).

CONCLUSION

IL-37 concentrations at ICU admission are valuable for predicting the 28-day mortality risk of patients with sepsis, suggesting that IL-37 may be a novel biomarker. These findings can be used as a basis for guiding early clinical decision-making in treating patients with sepsis.