IL-27 is elevated in acute lung injury and mediates inflammation

Role of IL-27 in COVID-19: A Thin Line between Protection and Disease Promotion

Cytokine storm is usually described as one of the main reasons behind COVID-associated mortality. Cytokines are essential protein molecules engaged in immune responses; they play a critical role in protection against infections. However, they also contribute to inflammatory reactions and tissue damage, becoming a double-edged sword in the context of COVID-19. Recent studies have suggested various cytokines and chemokines that play a crucial role in the immune response to SARS-CoV-2 infection. One such cytokine is interleukin 27 (IL-27), which has been found to be elevated in the blood plasma of patients with COVID-19. Within this study, we will explore the role of IL-27 in immune responses and analyze both the existing literature and our own prior research findings on this cytokine in the context of COVID-19. It affects a wide variety of immune cells. Regardless of the pathological process it is involved in, IL-27 is critical for upholding the necessary balance between tissue damage and cytotoxicity against infectious agents and/or tumors. In COVID-19, it is involved in multiple processes, including antiviral cytotoxicity via CD8+ cells, IgG subclass switching, and even the activation of Tregs.

Advances of mesenchymal stem cells and their derived extracellular vesicles as a promising therapy for acute respiratory distress syndrome: from bench to clinic

Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury characterized by diffuse alveolar damage. The period prevalence of ARDS was 10.4% of ICU admissions in 50 countries. Although great progress has been made in supportive care, the hospital mortality rate of severe ARDS is still up to 46.1%. Moreover, up to now, there is no effective pharmacotherapy for ARDS and most clinical trials focusing on consistently effective drugs have met disappointing results. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have spawned intense interest of a wide range of researchers and clinicians due to their robust anti-inflammatory, anti-apoptotic and tissue regeneration properties. A growing body of evidence from preclinical studies confirmed the promising therapeutic potential of MSCs and their EVs in the treatment of ARDS. Based on the inspiring experimental results, clinical trials have been designed to evaluate safety and efficacy of MSCs and their EVs in ARDS patients. Moreover, trials exploring their optimal time window and regimen of drug administration are ongoing. Therefore, this review aims to present an overview of the characteristics of mesenchymal stem cells and their derived EVs, therapeutic mechanisms for ARDS and research progress that has been made over the past 5 years.

Immune profiles to distinguish hospitalized versus ambulatory COVID-19 cases in older patients

A fraction of patients with COVID-19 develops severe disease requiring hospitalization, while the majority, including high-risk individuals, experience mild symptoms. Severe disease has been associated with higher levels of antibodies and inflammatory cytokines but often among patients with diverse demographics and comorbidity status. This study evaluated hospitalized vs. ambulatory patients with COVID-19 with demographic risk factors for severe COVID-19: median age of 63, >80% male, and >85% black and/or Hispanic. Sera were collected four to 243 days after symptom onset and evaluated for binding and functional antibodies as well as 48 cytokines and chemokines. SARS-CoV-2-specific antibody levels and functions were similar in ambulatory and hospitalized patients. However, a strong correlation between anti-S2 antibody levels and the other antibody parameters, along with higher IL-27 levels, was observed in hospitalized but not ambulatory cases. These data indicate that antibodies against the relatively conserved S2 spike subunit and immunoregulatory cytokines such as IL-27 are potential immune determinants of COVID-19.

Unpacking COVID-19 Systems Biology in Lung and Whole Blood with Transcriptomics and miRNA Regulators

COVID-19 is a systemic disease affecting tissues and organs, including and beyond the lung. Apart from the current pandemic context, we also have vastly inadequate knowledge of consequences of repeated exposures to SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus causing COVID-19, in multiple organ systems and the whole organism scales when the disease evolves from a pandemic to an endemic state. This calls for a systems biology and systems medicine approach and unpacking the effects of COVID-19 in lung as well as other tissues. We report here original findings from transcriptomics analyses and differentially expressed genes (DEGs) in lung samples from 60 patients and 27 healthy controls, and in whole blood samples from 255 patients and 103 healthy individuals. A total of 11 datasets with RNA-seq transcriptomic data were obtained from the Gene Expression Omnibus and the European Nucleotide Archive. The identified DEGs were used to construct protein interaction and functional networks and to identify related pathways and miRNAs. We found 35 DEGs common between lung and the whole blood, and importantly, 2 novel genes, namely CYP1B1 and TNFAIP6, which have not been previously implicated with COVID-19. We also identified four novel miRNA potential regulators, hsa-mir-192-5p, hsa-mir-221-3p, hsa-mir-4756-3p, and hsa-mir-10a-5p, implicated in lung or other diseases induced by coronaviruses. In summary, these findings offer new molecular leads and insights to unpack COVID-19 systems biology in a whole organism context and might inform future antiviral drug, diagnostics, and vaccine discovery efforts.

Time-Dependent Increase in Susceptibility and Severity of Secondary Bacterial Infections During SARS-CoV-2

Secondary bacterial infections can exacerbate SARS-CoV-2 infection, but their prevalence and impact remain poorly understood. Here, we established that a mild to moderate infection with the SARS-CoV-2 USA-WA1/2020 strain increased the risk of pneumococcal (type 2 strain D39) coinfection in a time-dependent, but sex-independent, manner in the transgenic K18-hACE2 mouse model of COVID-19. Bacterial coinfection increased lethality when the bacteria was initiated at 5 or 7 d post-virus infection (pvi) but not at 3 d pvi. Bacterial outgrowth was accompanied by neutrophilia in the groups coinfected at 7 d pvi and reductions in B cells, T cells, IL-6, IL-15, IL-18, and LIF were present in groups coinfected at 5 d pvi. However, viral burden, lung pathology, cytokines, chemokines, and immune cell activation were largely unchanged after bacterial coinfection. Examining surviving animals more than a week after infection resolution suggested that immune cell activation remained high and was exacerbated in the lungs of coinfected animals compared with SARS-CoV-2 infection alone. These data suggest that SARS-CoV-2 increases susceptibility and pathogenicity to bacterial coinfection, and further studies are needed to understand and combat disease associated with bacterial pneumonia in COVID-19 patients.

[A pilot study of plasma interleukin-6 and interleukin-27 in differential diagnosis of acute respiratory distress syndrome and neonatal respiratory distress syndrome in preterm infants]

OBJECTIVES

To study the significance of interleukin-6 (IL-6) and interleukin-27 (IL-27) in the differential diagnosis of acute respiratory distress syndrome (ARDS) and neonatal respiratory distress syndrome (NRDS) in preterm infants.

METHODS

The preterm infants with the manifestation of respiratory distress who were treated in the Neonatal Diagnosis and Treatment Center, Children's Hospital of Chongqing Medical University, from March to November 2021, were enrolled in this prospective study. According to the diagnosis results, they were divided into two groups: ARDS group (n=18) and NRDS group (n=20). ELISA was used to measure the plasma levels of IL-6 and IL-27. The receiver operating characteristic (ROC) curve was used to analyze the value of each index in the diagnosis of ARDS.

RESULTS

The ARDS group had significantly higher plasma levels of IL-6 and IL-27 than the NRDS group (P<0.05). The ROC curve analysis showed that IL-6 had an area under the ROC curve (AUC) of 0.867 for the diagnosis of ARDS, with a sensitivity of 61.1% and a specificity of 95.0% at the cut-off value of 56.21 pg/mL. The ROC curve analysis also showed that IL-27 had an AUC of 0.881 for the diagnosis of ARDS, with a sensitivity of 83.3% and a specificity of 80.0% at the cut-off value of 135.8 pg/mL.

CONCLUSIONS

Plasma IL-6 and IL-27 can be used as biological indicators for early differential diagnosis of ARDS and NRDS in preterm infants.

Time-Dependent Increase in Susceptibility and Severity of Secondary Bacterial Infection during SARS-CoV-2 Infection

Secondary bacterial infections can exacerbate SARS-CoV-2 infection, but their prevalence and impact remain poorly understood. Here, we established that a mild to moderate SARS-CoV-2 infection increased the risk of pneumococcal coinfection in a time-dependent, but sexindependent, manner in the transgenic K18-hACE mouse model of COVID-19. Bacterial coinfection was not established at 3 d post-virus, but increased lethality was observed when the bacteria was initiated at 5 or 7 d post-virus infection (pvi). Bacterial outgrowth was accompanied by neutrophilia in the groups coinfected at 7 d pvi and reductions in B cells, T cells, IL-6, IL-15, IL-18, and LIF were present in groups coinfected at 5 d pvi. However, viral burden, lung pathology, cytokines, chemokines, and immune cell activation were largely unchanged after bacterial coinfection. Examining surviving animals more than a week after infection resolution suggested that immune cell activation remained high and was exacerbated in the lungs of coinfected animals compared with SARS-CoV-2 infection alone. These data suggest that SARS-CoV-2 increases susceptibility and pathogenicity to bacterial coinfection, and further studies are needed to understand and combat disease associated with bacterial pneumonia in COVID-19 patients.

Exosomes from adipose-derived mesenchymal stem cells alleviate sepsis-induced lung injury in mice by inhibiting the secretion of IL-27 in macrophages

Acute lung injury (ALI) represents a frequent sepsis-induced inflammatory disorder. Mesenchymal stromal cells (MSCs) elicit anti-inflammatory effects in sepsis. This study investigated the mechanism of exosomes from adipose-derived MSCs (ADMSCs) in sepsis-induced ALI. The IL-27r^-/- (WSX-1 knockout) or wild-type mouse model of sepsis was established by cecal ligation and puncture (CLP). The model mice and lipopolysaccharide (LPS)-induced macrophages were treated with ADMSC-exosomes. The content of Dil-labeled exosomes in pulmonary macrophages, macrophages CD68⁺ F4/80⁺ in whole lung tissues, and IL-27 content in macrophages were detected. The mRNA expression and protein level of IL27 subunits P28 and EBI3 in lung tissue and the levels of IL-6, TNF-α, and IL-1β were measured. The pulmonary edema, tissue injury, and pulmonary vascular leakage were measured. In vitro, macrophages internalized ADMSC-exosomes, and ADMSC-exosomes inhibited IL-27 secretion in LPS-induced macrophages. In vivo, IL-27 knockout attenuated CLP-induced ALI. ADMSC-exosomes suppressed macrophage aggregation in lung tissues and inhibited IL-27 secretion. ADMSC-exosomes decreased the contents of IL-6, TNF-α, and IL-1β, reduced pulmonary edema and pulmonary vascular leakage, and improved the survival rate of mice. Injection of recombinant IL-27 reversed the protective effect of ADMSC-exosomes on sepsis mice. Collectively, ADMSC-exosomes inhibited IL-27 secretion in macrophages and alleviated sepsis-induced ALI in mice.

Serum IL-27 predicts the severity and prognosis in patients with community-acquired pneumonia: a prospective cohort study

Background: The previous studies have revealed that IL-27 was involved in the pathophysiology of pulmonary inflammatory diseases. However, the role of IL-27 in community-acquired pneumonia (CAP) was unclear. The goal of this research was to explore the associations of serum IL-27 with the severity and prognosis among CAP patients through a prospective cohort study. Methods: The whole of 239 healthy population and 239 CAP patients were enrolled. Fasting blood samples were collected. Inflammatory cytokines were detected using enzyme linked immunosorbent assay (ELISA). Demographic characteristics and clinical information were analyzed. Results: Serum IL-27 on admission was significantly risen in CAP patients compared with control subjects. Besides, serum IL-27 was gradually increased in line with CAP severity scores. Correlative analysis suggested that serum IL-27 was associated with blood routine indices, renal function, liver function, myocardial function and inflammatory cytokines. Linear and logistic regression analyses revealed that serum IL-27 was positively correlated with CAP severity scores. Logistic regression analysis demonstrated that serum higher IL-27 on admission elevated the risks of vasoactive agent usage and longer hospital stay during hospitalization among CAP patients. Conclusions: Serum IL-27 is markedly and positively associated with the severity and poor prognosis among CAP patients, indicating that IL-27 may involve in the pathophysiological process of CAP. Serum IL-27 may be used as a biomarker for diagnosis and prognosis in CAP patients.

IL-27 Mediates Th1 Cells Infiltration in Fetal Membranes in Preterm Labor

The objective of this study is to investigate the effect of IL-27 on Th1 cells infiltration in human fetal membranes (FMs) in preterm labor (PL). The expression of Th1 cells specific transcription factor (T-bet), Th1 cells infiltration related molecules (CXCL9, CXCL10, CXCL11, and ICAM-1), and IL-27 receptor α subunit (IL-27Rα) was compared in human FMs from pregnant women in PL group and term labor (TL) group. In vitro, rhIL-27 was added to the culture medium of amniotic epithelial cells (WISH cells) to detect the expression of CXCL9, CXCL10, CXCL11, and ICAM-1. Furthermore, the underlying signaling pathway was detected by single-sample gene set enrichment analysis and western blot analysis. The expression of T-bet and CXCL9, CXCL10, CXCL11, and ICAM-1 as well as IL-27Rα was higher in human FMs from PL group than TL group. In vitro, rhIL-27 could upregulate the expression of CXCL9, CXCL10, CXCL11, and ICAM-1 in WISH cells. Using gene-set enrichment analysis of FMs, JAK/STAT signaling pathway was found to be activated by IL-27 signaling in PL. Using western blot analysis, JAK2/STAT1/STAT3 signaling pathway was confirmed to be enhanced in rhIL-27 treated WISH cells. In addition, AG490 (JAK2 inhibitor) could inhibit the secretion of CXCL9, CXCL10, and CXCL11 in WISH cells stimulated by rhIL-27. Our results suggested that IL-27 may promote Th1 cells infiltration in human FMs in PL, by promoting the expression of CXCL9, CXCL10, and CXCL11 at least partly through JAK2/STAT1/STAT3 signaling pathway.

Interleukin-27 and Its Diverse Effects on Bacterial Infections

Innate and adaptive immune responses against pathogens are known to be carefully orchestrated by specific cytokines that initiate and down regulate immune cell functions from the initial infection through tissue repair and homeostasis. However, some cytokines, including interleukin-27, are expressed at multiple phases of the infection, such that their pro and anti-inflammatory functions have been difficult to interpret. As elucidation of specific cytokine functions throughout infection is central to our understanding of protective vs. susceptible immunity and return to homeostasis vs. prolonged inflammation leading to septic shock, here we review the literature on IL-27 signaling and the various functions of this heterodimeric ligand member of the IL-12 cytokine family. Canonically, IL-27 is produced by antigen-presenting cells, and is thought of as an immunostimulatory cytokine due to its capacity to induce Th1 differentiation. However, many studies have also identified various immunosuppressive effects of IL-27 signaling, including suppression of Th17 differentiation and induction of co-inhibitory receptors on T cells. Thus, the exact role of IL-27 in the context of infectious diseases remains a topic of debate and active research. Additionally, as recent interest has focused on clinical management of acute vs. chronic infections, and life-threatening “cytokine storm” from sepsis, we propose a hypothetical model to explain the biphasic role of IL-27 during the early and late phases of immune responses to reconcile its known pro and anti-inflammatory functions, which could be therapeutically regulated to improve patient outcomes of infection.

Coronavirus disease 2019 (COVID-19): cytokine storms, hyper-inflammatory phenotypes, and acute respiratory distress syndrome

Coronavirus Disease 2019 (COVID-19) was first identified in China at the end of 2019. Acute respiratory distress syndrome (ARDS) represents the most common and serious complication of COVID-19. Cytokine storms are a pathophysiological feature of COVID-19 and play an important role in distinguishing hyper-inflammatory subphenotypes of ARDS. Accordingly, in this review, we focus on hyper-inflammatory host responses in ARDS that play a critical role in the differentiated development of COVID-19. Furthermore, we discuss inflammation-related indicators that have the potential to identify hyper-inflammatory subphenotypes of COVID-19, especially for those with a high risk of ARDS. Finally, we explore the possibility of improving the quality of monitoring and treatment of COVID-19 patients and in reducing the incidence of critical illness and mortality via better distinguishing hyper- and hypo-inflammatory subphenotypes of COVID-19.

IL-27 regulation of innate immunity and control of microbial growth

IL-27 is a pleiotropic cytokine capable of influencing both innate and adaptive immune responses. With anti- and pro-inflammatory activity, IL-27 exerts its opposing effects in a cell-dependent and infectious context-specific manner. Upon pathogenic stimuli, IL-27 regulates innate immune cells, such as monocytes, dendritic cells, macrophages and neutrophils. Immune responses involving these innate cells that are negatively regulated by IL-27 signaling include inflammatory cytokine production, phagolysosomal acidification following phagocytosis, oxidative burst and autophagy. IL-27 signaling is crucial in maintaining the subtle balance between Th1 and Th2 immunity, in which protective inflammation is upregulated within the early stages of infection and subsequently downregulated once microbial growth is controlled. The immunomodulatory effects of IL-27 provide promising therapeutic targets for multiple disease types.

A primary role of IL-27 is to communicate between various immune cells to initiate different immune responses. Among these responses are those involved with destroying and eliminating microbial pathogens and then turning off inflammatory responses when the infectious threat has been resolved. IL-27 possesses both anti- and pro-inflammatory activity that varies with context, immune cell and pathogen stimulus. Depending on the precise formula of these details, there are important implications for IL-27 in disease outcomes. As such, harnessing or opposing IL-27 activity may have the potential to treat a variety of infectious diseases.

Elevated Levels of Interleukin-27 in Early Life Compromise Protective Immunity in a Mouse Model of Gram-Negative Neonatal Sepsis

Neonates are at increased risk for bacterial sepsis. We established that the immune-suppressive cytokine interleukin-27 (IL-27) is elevated in neonatal mice. Similarly, human cord blood-derived macrophages express IL-27 genes and secrete more cytokine than macrophages from adults. In the present work, we hypothesized that increased levels of IL-27 predispose neonatal mice to more severe infection during Gram-negative sepsis. Serum IL-27 levels continued to rise during infection.

Neonates are at increased risk for bacterial sepsis. We established that the immune-suppressive cytokine interleukin-27 (IL-27) is elevated in neonatal mice. Similarly, human cord blood-derived macrophages express IL-27 genes and secrete more cytokine than macrophages from adults. In the present work, we hypothesized that increased levels of IL-27 predispose neonatal mice to more severe infection during Gram-negative sepsis. Serum IL-27 levels continued to rise during infection. Peripheral tissue analysis revealed systemic IL-27 expression, while myeloid cell profiling identified Gr-1- and F4/80-expressing cells as the most abundant producers of IL-27 during infection. Increased IL-27 levels were consistent with increased mortality that was improved in IL-27 receptor α (IL-27Rα)^−/− mice that lack a functional IL-27 receptor. Infected IL-27Rα^−/− pups also exhibited improved weight gain and reduced morbidity. This was consistent with reduced bacterial burdens and more efficient bacterial killing by Ly6B.2⁺ myeloid cells and macrophages compared to WT neonates. Live animal imaging further supported a more severe and disseminated infection in WT neonates. This is the first report to describe the impact of elevated early-life IL-27 on the host response in a neonatal infection model while also defining the cell and tissue sources of cytokine. IL-27 is frequently associated with suppressed inflammation. In contrast, our findings demonstrate that IL-27 indirectly promotes an inflammatory cytokine response during neonatal sepsis by directly compromising control of bacteria that drive the inflammatory response. Collectively, our results suggest that IL-27 represents a therapeutic target to limit susceptibility and improve infectious outcomes in neonatal sepsis.

IL-27 is elevated in sepsis with acute hepatic injury and promotes hepatic damage and inflammation in the CLP model

BACKGROUND

Immuno-inflammation plays an important role in the pathophysiological process of sepsis-associated acute hepatic injury (AHI). Interleukin 27 (IL-27) is an important inflammatory regulator; however, its role in this condition is not clear.

METHODS

The clinical data and IL-27 serum levels in sepsis patients with or without AHI were analysed. Classical caecal ligation puncture (CLP) models were established in wild-type (WT) and IL-27 receptor (WSX-1)-deficient (IL-27R^-/-) mice. In addition, exogenous IL-27 was injected into these mice, and the levels of IL-27, IL-6, and tumour necrosis factor alpha (TNF-α) in the serum and liver were then measured by enzyme-linked immunoassay (ELISA), quantitative PCR, and Western blotting. The severity of liver damage was evaluated by haematoxylin and eosin staining of liver tissue, TUNEL assay and evaluation of alanine aminotransferase (ALT) and aspartate transaminase (AST) serum levels. Furthermore, the effects of IL-27 on the levels of phosphorylated c-Jun N-terminal kinase (JNK) in macrophages were assessed by Western blotting, and the effects of IL-27 on the expression of IL-6 and TNF-α in macrophages were assessed by ELISA.

RESULTS

IL-27 was elevated in sepsis patients with acute hepatic injury, which correlated with the Acute Physiologic Assessment and Chronic Health Evaluation II (APACHEII) scores, Sequential Organ Failure Assessment (SOFA) scores, and procalcitonin, C-reactive protein, IL-6, and TNF-α expression. In the CLP-WT group, IL-27 was highly expressed in the serum and liver, which correlated with the elevated content of ALT, AST, TNF-α, IL-6, and p-JNK in the serum and liver and the pathological injury of the liver. In CLP-IL-27R^-/- group, however, the levels of ALT, AST, TNF-α, IL-6, and p-JNK in the serum and liver and the pathological injury of the liver were decreased. Treatment with exogenous IL-27 led to a further increase in these cytokines in WT mice after CLP. IL-27 treatment and lipopolysaccharide stimulation in vitro increased the expression of p-JNK, IL-6, and TNF-α in macrophages, and these changes were decreased by a JNK signalling pathway inhibitor.

CONCLUSION

IL-27 is elevated in sepsis patients, especially those with acute hepatic injury. In addition, IL-27 can promote inflammatory reactions in the CLP-induced hepatic injury mice model.

IL-35 interferes with splenic T cells in a clinical and experimental model of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening critical care syndrome with uncontrolled inflammation that is a central issue. Its main characteristic is inflammatory mediators and cytokines as well as agglutinating chemokines that injure target cells. Interleukin (IL)-35 is a newly identified IL-12 cytokine family member with structural similarities to other IL-12, IL-23, and IL-27 cytokines but unique immunological functions. How IL-35 functions in ARDS is unclear. The purpose of our study was to determine what role IL-35 played in the development of ARDS. Here we found serum IL-35 concentrations were significantly elevated in patients with ARDS relative to healthy people. Moreover, we established a mouse model of lipopolysaccharide- and cecal ligation and puncture-induced ARDS treated with neutralizing antibodies (anti-IL-35 Ebi3 or anti-IL-35 P35); the results showed that lung injury occurred more often than in untreated models and the inflammatory cytokines CXCL-1, tumor necrosis factor alpha, IL-6, and IL-17A increased significantly after neutralizing antibody treatment in bronchoalveolar lavage fluid and serum. Therefore IL-35 can protect against the development of ARDS. Even more interesting in our study was that we discovered IL-35 expression differed between lung and spleen across different ARDS models, which further demonstrated that the spleen likely has an important role in extrapulmonary ARDS model only, improving the ratio of CD4⁺/CD4⁺CD25⁺Foxp3⁺(Tregs). Meanwhile in our clinical work, we also found that the concentration of IL-35 and the ratio of CD4⁺/Treg in the serum are higher and the mortality is lower than those with the spleen deficiency in patients with extrapulmonary ARDS. Therefore, IL-35 is protective in ARDS by promoting the ratio of splenic CD4⁺/Tregs in extrapulmonary ARDS, and as such, may be a therapeutic target.

Interleukin-27 Is a Potential Rescue Therapy for Acute Severe Colitis Through Interleukin-10-Dependent, T-Cell-Independent Attenuation of Colonic Mucosal Innate Immune Responses

BACKGROUND

If treatment with intravenous steroids fail, inflammatory bowel disease patients with acute severe colitis face systemic anti-tumor necrosis factor biologic rescue therapy or colectomy. Interleukin (IL)-27 is a cytokine with an immunosuppressive role in adaptive immune responses. However, the IL-27 receptor complex is also expressed on innate immune cells, and there is evidence that IL-27 can impact the function of innate cell subsets, although this particular functionality in vivo is not understood. Our aim was to define the efficacy of IL-27 in acute severe colitis and characterize novel IL-27-driven mechanisms of immunosuppression in the colonic mucosa.

METHODS

We assessed oral delivery of Lactococcus lactis expressing an IL-27 hyperkine on the innate immune response in vivo in a genetically intact, noninfective, acute murine colitis model induced by intrarectal instillation of 2,4,6-trinitrobenzenesulfonic acid in SJL/J mice.

RESULTS

IL-27 attenuates acute severe colitis through the reduction of colonic mucosal neutrophil infiltrate associated with a decreased CXC chemokine gradient. This suppression was T cell independent and IL-10 dependent, initially featuring enhanced mucosal IL-10. IL-27 was associated with a reduction in colonic proinflammatory cytokines and induced a multifocal, strong, positive nuclear expression of phosphorylated STAT-1 in mucosal epithelial cells.

CONCLUSION

We have defined novel mechanisms of IL-27 immunosuppression toward colonic innate immune responses in vivo. Mucosal delivery of IL-27 has translational potential as a novel therapeutic for inflammatory bowel disease, and it is a future mucosal directed rescue therapy in acute severe inflammatory bowel disease.

Lethal concentration of perfluoroisobutylene induces acute lung injury in mice mediated via cytokine storm, oxidative stress and apoptosis

Perfluoroisobutylene (PFIB) is a highly toxic gas that targets the lungs. Low-level inhalation of the gas can lead to acute lung injury (ALI), pulmonary edema and even death. No specific anti-PFIB drugs are currently available and the pathogenesis of PFIB-induced ALI is not fully understood. Early direct oxidative injury and a secondary hyper-inflammatory response are recognized as the primary mechanisms of PFIB-induced ALI. In the present study, our data demonstrate for the first time that a cytokine storm is associated with PFIB-induced ALI. Levels of 10 pro-inflammatory cytokines and one anti-inflammatory cytokine were significantly increased in lung tissues of PFIB-exposed mice. PFIB inhalation additionally led to significant oxidative stress in lung tissue. Inflammation-associated CD11b⁺Ly6G⁺Ly6C^int neutrophils and CD11b⁺Ly6G^-Ly6C^hi monocytes were significantly increased in blood in association with PFIB-induced ALI. Bcl-2/Bax-mediated lung cell apoptosis was significantly increased at 1 h, followed by a sustained decrease after 1 h, which was significant at 4-8 h in PFIB-exposed mice. This suppression of apoptosis is possibly associated with the Akt-signaling pathway.

Estimating the probability of bacterial infection using a novel biomarker among pediatric patients in the emergency department

CONTEXT

IL-27 is a novel biomarker to identify bacterial infection in children.

OBJECTIVE

IL-27 was evaluated among pediatric emergency department (ED) patients and compared with procalcitonin (PCT).

METHODS AND RESULTS

Children undergoing blood, urine, or cerebrospinal fluid cultures had IL-27 and PCT assays performed. Bacterial infection was defined as a positive culture or a clinical diagnosis based on chart review. IL-27 and PCT were increased among patients with bacterial infection and demonstrated comparable AUC's (0.62 versus 0.61). A decision tree incorporating IL-27, PCT, and white blood cell count improved the AUC (0.80).

CONCLUSION

IL-27 is a viable candidate biomarker to identify bacterial infection among ED patients and is comparable with PCT.

Andrographolide Restores Steroid Sensitivity To Block Lipopolysaccharide/IFN-γ-Induced IL-27 and Airway Hyperresponsiveness in Mice

LPS and IFN-γ alone or in combination have been implicated in the development of steroid resistance. Combined LPS/IFN-γ strongly upregulates IL-27 production, which has been linked to steroid-resistant airway hyperresponsiveness (AHR). Andrographolide, a bioactive molecule isolated from the plant Andrographis paniculata, has demonstrated anti-inflammatory and antioxidant properties. The present study investigated whether andrographolide could restore steroid sensitivity to block LPS/IFN-γ-induced IL-27 production and AHR via its antioxidative property. The mouse macrophage cell line Raw 264.7, mouse primary lung monocytes/macrophages, and BALB/c mice were treated with LPS/IFN-γ, in the presence and absence of dexamethasone and/or andrographolide. Levels of IL-27 in vitro and in vivo were examined and mouse AHR was assessed. Dexamethasone alone failed to inhibit LPS/IFN-γ-induced IL-27 production and AHR in mice. Andrographolide significantly restored the suppressive effect of dexamethasone on LPS/IFN-γ-induced IL-27 mRNA and protein levels in the macrophage cell line and primary lung monocytes/macrophages, mouse bronchoalveolar lavage fluid and lung tissues, and AHR in mice. LPS/IFN-γ markedly reduced the nuclear level of histone deacetylase (HDAC)2, an essential epigenetic enzyme that mediates steroid anti-inflammatory action. LPS/IFN-γ also decreased total HDAC activity but increased the total histone acetyltransferase/HDAC activity ratio in mouse lungs. Andrographolide significantly restored nuclear HDAC2 protein levels and total HDAC activity, and it diminished the total histone acetyltransferase/HDAC activity ratio in mouse lungs exposed to LPS/IFN-γ, possibly via suppression of PI3K/Akt/HDAC2 phosphorylation, and upregulation of the antioxidant transcription factor NF erythroid-2-related factor 2 level and DNA binding activity. Our data suggest that andrographolide may have therapeutic value in resensitizing steroid action in respiratory disorders such as asthma.

IL-27 enhances innate immunity of human pulmonary fibroblasts and epithelial cells through upregulation of TLR4 expression

Lung tissue cells play an active role in the pathogenesis of pulmonary inflammatory diseases by releasing a variety of cytokines and chemokines. However, how lung tissue cells respond to microbial stimuli during pulmonary infections remains unclear. In this study, we found that patients with community-acquired pneumonia displayed increased IL-27 levels in bronchoalveolar lavage fluid and serum. We subsequently examined the immunopathological mechanisms for the activation of primary human lung fibroblasts and bronchial epithelial cells by IL-27. We demonstrated that IL-27 priming enhanced LPS-induced production of IL-6 and IL-8 from lung fibroblasts and bronchial epithelia cells via upregulating Toll-like receptor-4 (TLR4) expression. IL-27 upregulated TLR4 expression in lung fibroblasts through activation of Janus-activated kinase (JAK) and Jun NH2-terminal kinase (JNK) signaling pathways, and inhibition of the JAK pathway could partially decrease IL-27-induced TLR4 expression, while inhibition of JNK pathway could completely suppress IL-27-induced TLR4 expression. Our data suggest that IL-27 modulates innate immunity of lung tissue cells through upregulating TLR4 expression during pulmonary infections.

Eosinophil-derived IL-10 supports chronic nematode infection

Eosinophilia is a feature of the host immune response that distinguishes parasitic worms from other pathogens, yet a discrete function for eosinophils in worm infection has been elusive. The aim of this study was to clarify the mechanism(s) underlying the striking and unexpected observation that eosinophils protect intracellular, muscle-stage Trichinella spiralis larvae against NO-mediated killing. Our findings indicate that eosinophils are specifically recruited to sites of infection at the earliest stage of muscle infection, consistent with a local response to injury. Early recruitment is essential for larval survival. By producing IL-10 at the initiation of infection, eosinophils expand IL-10(+) myeloid dendritic cells and CD4(+) IL-10(+) T lymphocytes that inhibit inducible NO synthase (iNOS) expression and protect intracellular larvae. The results document a novel immunoregulatory function of eosinophils in helminth infection, in which eosinophil-derived IL-10 drives immune responses that eventually limit local NO production. In this way, the parasite co-opts an immune response in a way that enhances its own survival.

Biological therapies in the acute respiratory distress syndrome

INTRODUCTION

The acute respiratory distress syndrome (ARDS) is characterised by life-threatening respiratory failure requiring mechanical ventilation, and multiple organ failure. It has a mortality of up to 30 - 45% and causes a long-term reduction in quality of life for survivors, with only approximately 50% of survivors able to return to work 12 months after hospital discharge.

AREAS COVERED

In this review we discuss the complex pathophysiology of ARDS, describe the mechanistic pathways implicated in the development of ARDS and how these are currently being targeted with novel biological therapies. These include therapies targeted against inflammatory cytokines, mechanisms mediating increased alveolar permeability and disordered coagulation, as well as the potential of growth factors, gene therapy and mesenchymal stem cells.

EXPERT OPINION

Although understanding of the pathophysiology of ARDS has improved, to date there are no effective pharmacological interventions that target a specific mechanism, with the only potentially effective therapies to date aiming to limit ventilator-associated lung injury. However, we believe that through this improved mechanistic insight and better clinical trial design, there is cautious optimism for the future of biological therapies in ARDS, and expect current and future biological compounds to provide treatment options to clinicians managing this devastating condition.