Cellular and molecular regulation of innate inflammatory responses

ECSIT: Biological function and involvement in diseases

Evolutionary conserved signaling intermediate in Toll pathways (ECSIT), a multi-functional protein, was first identified as a cytosolic adaptor protein in Toll-like receptors (TLRs) signaling-mediated innate immune responses. In the past two decades, studies have expanded the understanding of ECSIT. Nevertheless, there are still large knowledge gaps due to the inadequate number of studies regarding ECSIT, especially an overall review of ECSIT is lacking. Here, we first comprehensively summarize the biological functions of ECSIT with particular focus on innate immune responses and mitochondrial homeostasis. Cumulative studies have reinforced that ECSIT is involved in the regulation of innate immune responses through activating NF-κB signaling and potentiating the Retinoic acid-induced gene Ⅰ (RIG-Ⅰ)/ mitochondrial antiviral- signaling protein (MAVS) pathway-mediated innate antiviral immunity. In addition, ECSIT determines the mitochondrial morphology and function including mitochondrial complex Ⅰ (CⅠ) assembly, mitochondrial reactive oxygen species (mROS) production, mitochondrial membrane potential (MMP) maintenance and mitochondrial quality control. Owing to these distinct functions, ECSIT is involved in the etiology and pathology of human diseases including Alzheimer's disease (AD), cardiac hypertrophy, musculoskeletal disintegration, cancer, extranodal natural killer/T cell lymphoma (ENKTL) and ischemic stroke. Collectively, the roles and mechanisms of ECSIT under physiological and pathological conditions are critically discussed to provide a clearer view of the therapeutic potential of ECSIT.

The human disease-associated gene ZNFX1 controls inflammation through inhibition of the NLRP3 inflammasome

Inherited deficiency of zinc finger NFX1-type containing 1 (ZNFX1), a dsRNA virus sensor, is associated with severe familial immunodeficiency, multisystem inflammatory disease, increased susceptibility to viruses, and early mortality. However, limited treatments for patients with pathological variants of ZNFX1 exist due to an incomplete understanding of the diseases resulting from ZNFX1 mutations. Here, we demonstrate that ZNFX1 specifically inhibits the activation of the NLR family pyrin domain-containing protein 3 (NLRP3) inflammasome in response to NLRP3 activators both in vitro and in vivo. ZNFX1 retains NLRP3 in the cytoplasm and prevents its accumulation in the TGN38 + /TGN46+ vesicles in the resting state. Upon NLRP3 inflammasome activation, ZNFX1 is cleaved by caspase-1, establishing a feed-forward loop that promotes NLRP3 accumulation in the trans-Golgi network (TGN) and amplifies the activity of the downstream cascade. Expression of wild-type ZNFX1, but not of ZNFX1 with human pathogenic mutations, rescues the impairment of NLRP3 inflammasome inhibition. Our findings reveal a dual role of ZNFX1 in virus sensing and suppression of inflammation, which may become valuable for the development of treatments for ZNFX1 mutation-related diseases.

The role of infection in signalling root resorption: A narrative review

BACKGROUND

Root resorption consists of complex, multistep processes that involve cell signalling caused by inflammation and stromal cells, which promotes the secretion of receptor activator of nuclear factor κB ligand/ macrophage-colony stimulating factor (RANKL/M-CSF) resulting in a resorptive process.

OBJECTIVE

The aim of this narrative review was to analyse the literature related to root resorption resulting from microbial infection and to comparing it with non-microbial infection.

METHODS

An electronic literature search was performed using the PubMed database and applying keywords of articles published in English. Eligible papers were reviewed to reveal the descriptions of bone and root resorption processes. The abstracts were searched manually to identify articles about infection-stimulating bone and root resorption.

RESULTS

Three main types of root resorption were identified, two associated with primary bacterial infection and one secondary to bacterial infection. These include external inflammatory resorption, internal inflammatory resorption and external cervical (invasive) resorption.

DISCUSSION

The magnitude of cytokine involvement that promotes resorption and M-CSF/RANKL production depends on multiple factors, including pathogen virulence, site of infection and host genetic factors that activate the inflammation at the infection site. Two mechanisms activate the resorption mechanisms-the canonical and non-canonical pathways that can activate clastic cells independently of the RANKL/RANK canonical pathways.

CONCLUSIONS

Two pathways of root resorption co-exist in the body. When resorption is caused by infection, chronic inflammation due to bacterial infection prolongs the secretions of pro-inflammatory cytokines that intensify root and bone resorption. The second pathway is bacterial independent of the non-infection root resorption that is part of the wound healing process, which is limited in time due to its innate ability.

Protective immune response against Rhodococcus equi: An innate immunity-focused review

Rhodococcus equi causes pyogranulomatous pneumonia in foals and immunocompromised people. Despite decades of research efforts, no vaccine is available against this common cause of disease and death in foals. The purpose of this narrative review is to summarise the current understanding of interactions between R. equi and the host innate immune system, to describe features of the immune response that are associated with resistance or susceptibility to R. equi infection, and help guide strategies for developing novel approaches for preventing R. equi infections. Virulence of R. equi in foals has been attributed to the virulence associated protein A which allows intracellular survival in macrophages by preventing acidification of R. equi-containing vacuole. Additionally, foal susceptibility to R. equi infection is associated with immaturity and naivety of innate and adaptive immune systems, while adult horses with fully functional immune system are resistant to pneumonia. Specific interaction between R. equi and innate immune cells can result in bacterial survival or death; learning how to manipulate these responses to control infection is critical to prevent pneumonia in foals. Administration of live vaccines and stimulation of innate immune responses appears to improve foals' immune response and has the potential to overcome the challenges of foal active vaccination and elicit protection against pneumonia.

Host Factors Modulate Virus-Induced IFN Production via Pattern Recognition Receptors

Innate immunity is the first line of defense in the human body, and it plays an important role in defending against viral infection. Viruses are identified by different pattern-recognition receptors (PRRs) that activate the mitochondrial antiviral signaling protein (MAVS) or transmembrane protein 173 (STING), which trigger multiple signaling cascades that cause nuclear factor-κB (NF-κB) and interferon regulatory factor 3 (IRF3) to produce inflammatory factors and interferons (IFNs). PRRs play a pivotal role as the first step in pathogen induction of interferon production. Interferon elicits antiviral activity by inducing the transcription of hundreds of IFN-stimulated genes (ISGs) via the janus kinase (JAK) - signal transducer and activator of transcription (STAT) pathway. An increasing number of studies have shown that environmental, pathogen and host factors regulate the IFN signaling pathway. Here, we summarize the mechanisms of host factor modulation in IFN production via pattern recognition receptors. These regulatory mechanisms maintain interferon levels in a normal state and clear viruses without inducing autoimmune disease.

DEFB114 protein enhances host resistance to fungal infection through the NOD1/2-ATG16L1-NF-κB signaling pathway

The overuse of antibiotics has led to the enhanced resistance of many pathogenic bacteria, posing a threat to human health. Therefore, there is a need to develop green and safe alternatives to antibiotics. Beta-defensins play a crucial role in host defense against pathogens and have multifunctional properties, exerting key roles in innate and adaptive immunity, as well as non-immune processes. In this study, a 210 bp long cDNA sequence of yak DEFB114 gene was amplified and successfully expressed in a prokaryotic system. The DEFB114 protein exhibited significant inhibitory effects on the growth of Aspergillus fumigatus in vitro. When co-cultured with yak macrophages, DEFB114 protein enhanced macrophage phagocytic activity and increased nucleic acid fluorescence intensity (P < 0.05). DEFB114 protein also enhanced the activity of yak macrophages stimulated by inactivated Aspergillus fumigatus spores, increased the release of nitric oxide (NO), and promoted the expression of genes such as γ-actin, Lgals, Man2b, and Capg (P < 0.05). In mice experiments, DEFB114 protein promoted resistance against Aspergillus fumigatus infection, by regulating the NOD1/2-ATG16L1-NF-κB pathway to modulate the host immune response and exert its anti-infective effects. In summary, the yak DEFB114 protein could inhibit the growth of Aspergillus fumigatus and enhance the animal's resistance to pathogenic microorganisms, thereby having significant implications in the treatment and prevention of fungal infections.

The non-pathogenic protozoon Leishmania tarentolae interferes with the activation of NLRP3 inflammasome in human cells: new perspectives in the control of inflammation

Background

Innate immune responses against infectious agents can act as triggers of inflammatory diseases. On the other hand, various pathogens have developed mechanisms for the evasion of the immune response, based on an inhibition of innate immunity and inflammatory responses. Inflammatory diseases could thus be controlled through the administration of pathogens or pathogen-derived molecules, capable of interfering with the mechanisms at the basis of inflammation. In this framework, the NLRP3 inflammasome is an important component in innate antimicrobial responses and a major player in the inflammatory disease. Parasites of the genus Leishmania are master manipulators of innate immune mechanisms, and different species have been shown to inhibit inflammasome formation. However, the exploitation of pathogenic Leishmania species as blockers of NLRP3-based inflammatory diseases poses safety concerns.

Methods

To circumvent safety issues associated with pathogenic parasites, we focused on Leishmania tarentolae, a species of Leishmania that is not infectious to humans. Because NLRP3 typically develops in macrophages, in response to the detection and engulfment microorganisms, we performed our experiments on a monocyte-macrophage cell line (THP-1), either wild type or knockout for ASC, a key component of NLRP3 formation, with determination of cytokines and other markers of inflammation.

Results

L. tarentolae was shown to possess the capability of dampening the formation of NLRP3 inflammasome and the consequent expression of pro-inflammatory molecules, with minor differences compared to effects of pathogenic Leishmania species.

Conclusion

The non-pathogenic L. tarentolae appears a promising pro-biotic microbe with anti-inflammatory properties or a source of immune modulating cellular fractions or molecules, capable of interfering with the formation of the NLRP3 inflammasome.

When DNA-damage responses meet innate and adaptive immunity

When cells proliferate, stress on DNA replication or exposure to endogenous or external insults frequently results in DNA damage. DNA-Damage Response (DDR) networks are complex signaling pathways used by multicellular organisms to prevent DNA damage. Depending on the type of broken DNA, the various pathways, Base-Excision Repair (BER), Nucleotide Excision Repair (NER), Mismatch Repair (MMR), Homologous Recombination (HR), Non-Homologous End-Joining (NHEJ), Interstrand Crosslink (ICL) repair, and other direct repair pathways, can be activated separately or in combination to repair DNA damage. To preserve homeostasis, innate and adaptive immune responses are effective defenses against endogenous mutation or invasion by external pathogens. It is interesting to note that new research keeps showing how closely DDR components and the immune system are related. DDR and immunological response are linked by immune effectors such as the cyclic GMP-AMP synthase (cGAS)-Stimulator of Interferon Genes (STING) pathway. These effectors act as sensors of DNA damage-caused immune response. Furthermore, DDR components themselves function in immune responses to trigger the generation of inflammatory cytokines in a cascade or even trigger programmed cell death. Defective DDR components are known to disrupt genomic stability and compromise immunological responses, aggravating immune imbalance and leading to serious diseases such as cancer and autoimmune disorders. This study examines the most recent developments in the interaction between DDR elements and immunological responses. The DDR network's immune modulators' dual roles may offer new perspectives on treating infectious disorders linked to DNA damage, including cancer, and on the development of target immunotherapy.

IFI16 Positively Regulates RIG-I-Mediated Type I Interferon Production in a STING-Independent Manner

Previous studies have shown that interferon gene-stimulating protein (STING) is essential for IFN-γ-inducible protein 16 (IFI16) as the DNA sensor and RNA sensor to induce transcription of type I interferon (IFN-I) and is essential for IFI16 to synergize with DNA sensor GMP-AMP (cGAMP) synthase (cGAS) in induction of IFN-I transcription. While other and our previous studies have shown that IFI16 enhanced retinoic acid-inducible gene I (RIG-I)-, which was an RNA sensor, and mitochondrial antiviral signaling (MAVS)-, which was the adaptor protein of RIG-I, induced production of IFN-I, so we wonder whether IFI16 regulates the signal pathway of RNA-RIG-I-MAVS-IFN-I in a STING-dependent manner. We used HEK 293T cells, which did not express endogenous STING and were unable to mount an innate immune response upon DNA transfection and found that IFI16 could enhance RIG-I- and MAVS-mediated induction of IFN-I in a STING-independent way. Furthermore, we found that upregulation of the expression of NF-kappa-B essential modulator (NEMO) by IFI16 was not the mechanism that IFI16 regulated the induction of IFN-I. In conclusion, we found that IFI16 regulated the signal pathway of RNA-RIG-I-MAVS-IFN-I in a STING-independent manner.

Investigating the Nexus of NLRP3 Inflammasomes and COVID-19 Pathogenesis: Unraveling Molecular Triggers and Therapeutic Strategies

The coronavirus disease 2019 (COVID-19) global pandemic, caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has been marked by severe cases demonstrating a "cytokine storm", an upsurge of pro-inflammatory cytokines in the bloodstream. NLRP3 inflammasomes, integral to the innate immune system, are speculated to be activated by SARS-CoV-2 within host cells. This review investigates the potential correlation between NLRP3 inflammasomes and COVID-19, exploring the cellular and molecular mechanisms through which SARS-CoV-2 triggers their activation. Furthermore, promising strategies targeting NLRP3 inflammasomes are proposed to mitigate the excessive inflammatory response provoked by SARS-CoV-2 infection. By synthesizing existing studies, this paper offers insights into NLRP3 as a therapeutic target, elucidating the interplay between COVID-19 and its pathophysiology. It serves as a valuable reference for future clinical approaches in addressing COVID-19 by targeting NLRP3, thus providing potential avenues for therapeutic intervention.

Sodium humate ameliorates LPS-induced liver injury in mice by inhibiting TLR4/NF-κB and activating NRF2/HO-1 signaling pathways

BACKGROUND

Acute liver damage is a type of liver disease that has a significant global occurrence and a lack of successful treatment and prevention approaches. Sodium humate (HNa), a natural organic substance, has extensive applications in traditional Chinese medicine due to its antibacterial, anti-diarrheal, and anti-inflammatory characteristics. The purpose of this research was to examine the mitigating impacts of HNa on liver damage induced by lipopolysaccharide (LPS) in mice.

METHODS AND RESULTS

A total of 30 female mice were randomly assigned into Con, Mod, L-HNa, M-HNa, and H-HNa groups. Mice in the Con and Mod groups were gavaged with PBS, whereas L-HNa, M-HNa, and H-HNa groups mice were gavaged with 0.1%, 0.3%, and 0.5% HNa, daily. On day 21, Mod, L-HNa, M-HNa, and H-HNa groups mice were challenged with LPS (10 mg/kg). We discovered that pretreatment with HNa improved liver pathological damage and inflammation by inhibiting the toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) signaling pathway, enhancing the polarization of liver M2 macrophages, and reducing the levels of inflammatory cytokines. Our further study found that pretreatment with HNa enhanced the liver ability to combat oxidative stress and reduced hepatocyte apoptosis by activating the nuclear factor erythroid-2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) signaling pathway and enhancing the activities of antioxidant enzymes.

CONCLUSIONS

In conclusion, HNa could alleviate LPS-induced liver damage through inhibiting TLR4/NF-κB and activating NRF2/HO-1 signaling pathways. This study is the first to discover the therapeutic effects of HNa on liver damage induced by LPS.

Role of the Hippo pathway in autoimmune diseases

The immune system is an important defense against diseases, and it is essential to maintain the homeostasis of the body's internal environment. Under normal physiological conditions, the steady state of the immune system should be sustained to play normal immune response and immune function. Exploring the molecular mechanism of maintaining immune homeostasis under physiological and pathological conditions will provides understanding of the pathogenesis of autoimmune diseases, infections, metabolic disorders, and tumors, as well as new ideas and molecular targets for the prevention and treatment of these diseases. Hippo signaling pathway can not only regulate immune cells such as macrophages, T cells and dendritic cells, but also interact with immune-related signaling pathways such as NF-kB signaling pathway, TGF-β signaling pathway and Toll-like receptor signaling pathway, so as to resist the internal environment disorder caused by the invasion of exogenous pathogenic microorganisms and maintain the internal environment stability and physiological balance of the body. Hippo signaling pathway is also involved in the pathological process of immune system-related diseases such as rheumatoid arthritis, inflammatory bowel disease and psoriasis. Hippo pathway is closely related to organ development, stem cell biology, regeneration, and tumor biology. It affects cell differentiation by participating in extracellular and intracellular physiological signal reactions, sensing cell environment, and coordinating cell reactions. This pathway is crucial in maintaining immune homeostasis. This review summarizes the mechanism of Hippo pathway in different immune cells and some autoimmune diseases and the interaction between different immune signaling pathways and Hippo signaling pathway. It aims to explore the role of Hippo in autoimmune diseases and provide theoretical and practical basis for the treatment of autoimmune diseases through Hippo signaling pathway.

Protective effects of sodium humate on the intestinal barrier damage of Salmonella Typhimurium-challenged broilers

Salmonella Typhimurium (S. Typhimurium) infections can lead to severe intestinal damage and reduce growth performance in broilers. Thus, this study examined the potential mitigating impact of sodium humate (HNa) on intestinal barrier damage resulting from S. Typhimurium infection in broilers. A total of 320 1-day-old Arbor Acres broilers were randomly assigned into 5 treatments with 8 replicates. On d 22-24, broilers in the CON group were challenged with 1 ml of PBS, while broilers in the other groups were challenged with 1 ml of 3 × 109 CFU/ml S. Typhimurium, daily. Dietary administration with 4 g/kg of HNa increased (P < 0.05) the final body weight, jejunal secretory immunoglobulin A (sIgA), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), and catalase (CAT) levels as compared with the MOD group broilers. Furthermore, HNa alleviated intestinal barrier damage by increasing villus height (VH), upregulating protein expression of Occludin, Claudin-1, and zonula occludens-1 (ZO-1), inhibiting toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) signaling pathway activation, and decreasing the secretion of inflammatory cytokines (P < 0.05). Collectively, the present study showed that HNa mitigated intestinal barrier damage induced by S. Typhimurium infection in broilers.

Enterococcus faecium inhibits NF-κB/NLRP3/IL-1β signaling pathway and antagonizes Salmonella-mediated inflammatory response

Aim: This study explored the protective effect of Enterococcus faecium as a probiotic against Salmonella typhimurium infection. Materials & methods: The protective role of E. faecium against tissue damage by S. typhimurium infection and the expression of inflammatory cytokines and tight junction proteins were detected by histological observation, real-time quantitative PCR and immunohistochemical methods. Results: E. faecium demonstrated a regulatory function that affected the expression of Claudin-1 and enhanced tight junctions, suppressed the NF-κB/NLRP3/IL-1β signaling pathway and reduced the release of IL-6, TNF-α, IFN-γ, TLR4 and MYD88 and inflammatory damage to tissues by S. typhimurium in the duodenum, cecum and colon of mice. Conclusion: E. faecium antagonized S. Typhimurium alleviating inflammatory injury in mice through the NF-κB/NLRP3/IL-1β signaling pathway.

Microbial sensing in the intestine

The gut microbiota plays a key role in host health and disease, particularly through their interactions with the immune system. Intestinal homeostasis is dependent on the symbiotic relationships between the host and the diverse gut microbiota, which is influenced by the highly co-evolved immune-microbiota interactions. The first step of the interaction between the host and the gut microbiota is the sensing of the gut microbes by the host immune system. In this review, we describe the cells of the host immune system and the proteins that sense the components and metabolites of the gut microbes. We further highlight the essential roles of pattern recognition receptors (PRRs), the G protein-coupled receptors (GPCRs), aryl hydrocarbon receptor (AHR) and the nuclear receptors expressed in the intestinal epithelial cells (IECs) and the intestine-resident immune cells. We also discuss the mechanisms by which the disruption of microbial sensing because of genetic or environmental factors causes human diseases such as the inflammatory bowel disease (IBD).

The phenylalanine-28 is crucial for black carp RIG-I mediated antiviral signaling

Retinoic acid-inducible gene I (RIG-I) functions as a cytosolic sensor to recognize RNA products of the invading microorganisms and induce the production of type I interferons（IFNs）. In this study, two RIG-I variants, named as bcRIG-Ia and bcRIG-Ib, were characterized in black carp (Mylopharyngodon piceus) respectively. RNA pull-down assay revealed that both bcRIG-Ia and bcRIG-Ib could bind to synthetic poly(I:C) and the RD domain was crucial for RNA binding of these two molecules. However, over-expression of bcRIG-Ib, but not bcRIG-Ia, induced the transcription of IFN promoter, and led to the improved antiviral activity against both spring viremia of carp virus (SVCV) and grass carp reovirus (GCRV). And knockdown of bcRIG-I dampened the transcription of bcViperin and bcIFNb in host cells. Truncation mutation and site mutation analysis identified that phenylalanine (F)- 28 was crucial for bcRIG-Ib oligomerization and its mediated IFN signaling. Interestingly, F28 was conserved among teleost RIG-Is and site mutation analysis revealed that F28 was essential for RIG-I mediated IFN signaling in the cyprinid fish. Thus, our study concludes that F28 is crucial for black carp RIG-I mediated antiviral signaling and suggests F28 is also essential for the activation of IFN signaling by RIG-Is from other teleost fish.

NLRP3 is essential for neutrophil polarization and chemotaxis in response to leukotriene B4 gradient

Neutrophil recruitment to sites of infection and inflammation is an essential process in the early innate immune response. Upon activation, a subset of neutrophils rapidly assembles the multiprotein complex known as the NLRP3 inflammasome. The NLRP3 inflammasome forms at the microtubule organizing center, which promotes the formation of interleukin (IL)-1β and IL-18, essential cytokines in the immune response. We recently showed that mice deficient in NLRP3 (NLRP3-/-) have reduced neutrophil recruitment to the peritoneum in a model of thioglycolate-induced peritonitis. Here, we tested the hypothesis that this diminished recruitment could be, in part, the result of defects in neutrophil chemotaxis. We find that NLRP3-/- neutrophils show loss of cell polarization, as well as reduced directionality and velocity of migration toward increasing concentrations of leukotriene B4 (LTB4) in a chemotaxis assay in vitro, which was confirmed through intravital microscopy of neutrophil migration toward a laser-induced burn injury of the liver. Furthermore, pharmacologically blocking NLRP3 inflammasome assembly with MCC950 in vitro reduced directionality but preserved nondirectional movement, indicating that inflammasome assembly is specifically required for polarization and directional chemotaxis, but not cell motility per se. In support of this, pharmacological breakdown of the microtubule cytoskeleton via nocodazole treatment induced cell polarization and restored nondirectional cell migration in NLRP3-deficient neutrophils in the LTB4 gradient. Therefore, NLRP3 inflammasome assembly is required for establishment of cell polarity to guide the directional chemotactic migration of neutrophils.

Immunomodulatory response in an experimental model of brain death

Liver transplantation has come a long way and is now regarded as the gold standard treatment for end-stage liver failure. The great majority of livers utilized in transplantation come from brain-dead donors. A broad inflammatory response characterizes BD, resulting in multiorgan damage. This process is primarily mediated by cytokines, which increase the immunogenicity of the graft. In male Lewis rats, we evaluated the immune response in a BD liver donor and compared it to that of a control group. We studied two groups: Control and BD (rats subjected to BD by increasing intracranial pressure). After the induction of BD, there was an intense rise in blood pressure followed by a fall. There were no significant differences observed between the groups. Blood tissue and hepatic tissue analyzes showed an increase in plasma concentrations of liver enzymes (AST, ALT, LDH and ALP), in addition to pro-inflammatory cytokines and macrophages in liver tissue in animals submitted to BD. The current study found that BD is a multifaceted process that elicits both a systemic immune response and a local inflammatory response in liver tissue. Our findings strongly suggested that the immunogenicity of plasma and liver increased with time following BD.

Sodium Humate-Derived Gut Microbiota Ameliorates Intestinal Dysfunction Induced by Salmonella Typhimurium in Mice

Salmonella is a foodborne pathogen that is one of the main causes of gastroenteric disease in humans and animals. As a natural organic substance, sodium humate (HNa) possesses antibacterial, antidiarrheal, and anti-inflammatory properties. However, it is unclear whether the HNa and HNa-derived microbiota exert alleviative effects on Salmonella enterica serovar Typhimurium-induced enteritis. We found that treatment with HNa disrupted the cell wall of S. Typhimurium and decreased the virulence gene expression. Next, we explored the effect of HNa presupplementation on S. Typhimurium-induced murine enteritis. The results revealed that HNa ameliorated intestinal pathological damage. In addition, we observed that presupplementation with HNa enhanced intestinal barrier function via modulating gut microbiota, downregulating toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) and NOD-like receptor protein 3 (NLRP3) signaling pathways, regulating intestinal mucosal immunity, and enhancing tight junction protein expression. To further validate the effect of HNa-derived microbiota on S. Typhimurium-induced enteritis, we performed fecal microbiota transplantation and found that HNa-derived microbiota also alleviated S. Typhimurium-induced intestinal damage. It is noteworthy that both HNa and HNa-derived microbiota improved the liver injury caused by S. Typhimurium infection. Collectively, this is the first study to confirm that HNa could alleviate S. Typhimurium-induced enteritis in a gut microbiota-dependent manner. This study provides a new perspective on HNa as a potential drug to prevent and treat salmonellosis. IMPORTANCE Salmonella Typhimurium is an important zoonotic pathogen, widely distributed in nature. S. Typhimurium is one of the leading causes of foodborne illnesses worldwide, and more than 350,000 people died from Salmonella infection each year, which poses a substantial risk to public health and causes a considerable economic loss. Here, we found that the S. Typhimurium infection caused severe intestinal and liver damage. In addition, we first found that sodium humate (HNa) and HNa-derived gut microbiota can alleviate S. Typhimurium infection-induced intestinal damage. These findings extend the knowledge about the public health risk and pathogenic mechanisms of S. Typhimurium.

CSF neopterin, quinolinic acid and kynurenine/tryptophan ratio are biomarkers of active neuroinflammation

BACKGROUND

Defining the presence of acute and chronic brain inflammation remains a challenge to clinicians due to the heterogeneity of clinical presentations and aetiologies. However, defining the presence of neuroinflammation, and monitoring the effects of therapy is important given its reversible and potentially damaging nature. We investigated the utility of CSF metabolites in the diagnosis of primary neuroinflammatory disorders such as encephalitis and explored the potential pathogenic role of inflammation in epilepsy.

METHODS

Cerebrospinal fluid (CSF) collected from 341 paediatric patients (169 males, median age 5.8 years, range 0.1-17.1) were examined. The patients were separated into a primary inflammatory disorder group (n = 90) and epilepsy group (n = 80), who were compared with three control groups including neurogenetic and structural (n = 76), neurodevelopmental disorders, psychiatric and functional neurological disorders (n = 63), and headache (n = 32).

FINDINGS

There were statistically significant increases of CSF neopterin, kynurenine, quinolinic acid and kynurenine/tryptophan ratio (KYN/TRP) in the inflammation group compared to all control groups (all p < 0.0003). As biomarkers, at thresholds with 95% specificity, CSF neopterin had the best sensitivity for defining neuroinflammation (82%, CI 73-89), then quinolinic acid (57%, CI 47-67), KYN/TRP ratio (47%, CI 36-56) and kynurenine (37%, CI 28-48). CSF pleocytosis had sensitivity of 53%, CI 42-64). The area under the receiver operating characteristic curve (ROC AUC) of CSF neopterin (94.4% CI 91.0-97.7%) was superior to that of CSF pleocytosis (84.9% CI 79.5-90.4%) (p = 0.005). CSF kynurenic acid/kynurenine ratio (KYNA/KYN) was statistically decreased in the epilepsy group compared to all control groups (all p ≤ 0.0003), which was evident in most epilepsy subgroups.

INTERPRETATION

Here we show that CSF neopterin, kynurenine, quinolinic acid and KYN/TRP are useful diagnostic and monitoring biomarkers of neuroinflammation. These findings provide biological insights into the role of inflammatory metabolism in neurological disorders and provide diagnostic and therapeutic opportunities for improved management of neurological diseases.

FUNDING

Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, University of Sydney, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead. Prof Guillemin is funded by NHMRC Investigator grant APP 1176660 and Macquarie University.

USP39 Regulates NF-κB-Mediated Inflammatory Responses through Deubiquitinating K48-Linked IκBα

IκBα is a critical protein that inhibits NF-κB nuclear translocation and impairs NF-κB-mediated signaling. The abundance of IκBα determines the activation and restoration of the inflammatory response. However, posttranslational regulation of IκBα remains to be fully understood. In this study, we identified ubiquitin-specific protease 39 (USP39) as a negative regulator in the NF-κB inflammatory response by stabilizing basal IκBα. The expression of USP39 in macrophages was reduced under LPS-induced inflammation. Knockdown or knockout of USP39 in macrophages significantly increased the expression and secretion of proinflammatory cytokines upon exposure to LPS or Escherichia coli, whereas reexpression of exogenous USP39 in USP39-deficient macrophages rescued the effect. Moreover, USP39-defective mice were more sensitive to LPS or E. coli-induced systemic sepsis. Mechanistically, USP39 interacted with and stabilized IκBα by reducing K48-linked polyubiquination of IκBα. Taken together, to our knowledge, our study for the first time revealed the inhibitory function of USP39 in the NF-κB inflammatory response, providing a previously unknown mechanism for control of inflammatory cytokine induction in the cellular anti-inflammatory response.

Disulfiram Enhances the Antineoplastic Activity and Sensitivity of Murine Hepatocellular Carcinoma to 5-FU via Redox Management

The efficacy of anticancer drug 5-FU is suppressed due to various factors, including severe side effects and decreased insensitivity during prolonged chemotherapy. Elevated endogenous copper (Cu) levels are one of the prominent hallmark features of cancer cells. In the present investigation, this feature was targeted in diethyl nitrosamine-phenobarbital-induced hepatocellular carcinoma (HCC) in a rat model system by an established anticancer drug, 5-FU, co-administered with copper and its chelating agent, disulfiram. After treatment with the test chemicals in HCC-induced rats, blood and liver samples were subjected to biochemical, molecular, and histopathological analyses. The analysis revealed that reactive oxygen species-mediated oxidative stress is the crucial etiological reason for the pathogenesis of HCC in rats, as evidenced by the significantly compromised activity of major antioxidant enzymes and elevated levels of oxidative damaged products with major histological alterations compared to the control. However, the combination of 5-FU with DSF demonstrated a significant improvement in most of the parameters, followed by 5-FU-Cu in the combination-treated groups. The combination treatment improved the histological details and triggered apoptosis in the cancer cells to a remarkable extent, as the levels of cleaved PARP and caspase-3 were significantly higher than those in the HCC rats treated with the drug alone. The present study envisages that manipulating the Cu-level greatly enhances the antineoplastic activity of 5-FU and sensitizes cancer cells to the increased efficacy of the drug.

Piperine Reduces Neoplastic Progression in Cervical Cancer Cells by Downregulating the Cyclooxygenase 2 Pathway

Cervical cancer is the fourth-most common type of cancer in the world that causes death in women. It is mainly caused by persistent infection by human papillomavirus (HPV) that triggers a chronic inflammatory process. Therefore, the use of anti-inflammatory drugs is a potential treatment option. The effects of piperine, an amino alkaloid derived from Piper nigrum, are poorly understood in cervical cancer inflammation, making it a target of research. This work aimed to investigate the antitumor effect of piperine on cervical cancer and to determine whether this effect is modulated by the cyclooxygenase 2 (PTGS2) pathway using in vitro model of cervical cancer (HeLa, SiHa, CaSki), and non-tumoral (HaCaT) cell lines. The results showed that piperine reduces in vitro parameters associated with neoplastic evolution such as proliferation, viability and migration by cell cycle arrest in the G1/G0 and G2/M phases, with subsequent induction of apoptosis. This action was modulated by downregulation of cyclooxygenase 2 (PTGS2) pathway, which in turn regulates the secretion of cytokines and the expression of mitogen-activated protein kinases (MAPKs), metalloproteinases (MMPs), and their antagonists (TIMPs). These findings indicate the phytotherapeutic potential of piperine as complementary treatment in cervical cancer.

Yeast culture supplementation of sow diets regulates the immune performance of their weaned piglets under lipopolysaccharide stress

The aim of this study was to investigate the effect of dietary supplementation of sows with yeast cultures (XPC) during late gestation and lactation on the immune performance of their weaned offspring under lipopolysaccharide (LPS) stress. A total of 40 Landrace × Yorkshire sows (parity 3 to 7) with similar backfat thickness were selected and randomly divided into two treatment groups: a control group (basal diet) and a yeast culture group (basal diet + 2.0 g/kg XPC). The trial was conducted from day 90 of gestation to day 21 of lactation. At the end of the experiment, 12 piglets with similar weights were selected from each group and slaughtered 4 h after intraperitoneal injection with either saline or LPS. The results showed that the concentrations of interleukin-6 (IL-6) in the thymus and tumor necrosis factor-α in the liver increased significantly (P < 0.05) in weaned piglets after LPS injection. Maternal dietary supplementation with XPC significantly reduced the concentration of inflammatory factors in the plasma and thymus of weaned piglets (P < 0.05). LPS injection significantly upregulated the expression of some tissue inflammation-related genes, significantly downregulated the expression of intestinal tight junction-related genes, and significantly elevated the protein expression of liver phospho-nuclear factor kappa B (p-NF-κB), the phospho-inhibitory subunit of NF-κB (p-IκBα), phospho-c-Jun N-terminal kinase (p-JNK), Nuclear factor kappa-B (NF-κB), and the inhibitory subunit of NF-κB (IκBα) in weaned piglets (P < 0.05). Maternal dietary supplementation with XPC significantly downregulated the gene expression of IL-6 and interleukin-10 (IL-10) in the thymus and decreased the protein expression of c-Jun N-terminal kinase (JNK) in the liver of weaned piglets (P < 0.05). In summary, injection of LPS induced an inflammatory response in weaned piglets and destroyed the intestinal barrier. Maternal dietary supplementation of XPC improved the immune performance of weaned piglets by inhibiting inflammatory responses.

Atorvastatin-induced tolerogenic dendritic cells improve cardiac remodeling by suppressing TLR-4/NF-κB activation after myocardial infarction

OBJECTIVE

Myocardial infarction (MI) caused by ischemic cardiomyocyte necrosis induces inflammatory responses that strongly affect ventricular remodeling. Tolerogenic dendritic cells (tDCs) can suppress this effect on inflammatory responses. However, the precise role of atorvastatin-induced tDCs in ventricular remodeling after MI remains unclear.

METHODS

To explore the effect of necrotic cardiomyocytes (SNC) and/or atorvastatin on DC function, the expression of CD40, CD80, CD86, and MHC-II was determined using flow cytometry. The protein levels of TLR-4/NF-κB-related molecules were evaluated using western blotting. The infarct area after MI was determined via 2,3,5-triphenyltetrazolium chloride staining. The TUNEL assay was employed to evaluate the apoptosis of cardiomyocytes in heart sections. Masson's trichrome method was used to determine the extent of fibrosis.

RESULTS

Compared to the DCs co-cultured with PBS (control), cells co-cultured with Supernatant-IM or Supernatant-NH produced higher levels of inflammatory cytokines, including TNF-α, IL-1, IL-6, IL-12P40, and IL-8. This cytokine production was impaired by atorvastatin treatment. SNC treatment induced DC maturation and enhanced inflammatory cytokine secretion and oxidative stress through TLR-4/NF-κB pathway activation. Compared to that in the PBS-treated group, the left ventricular ejection fraction was significantly improved after tDC treatment. Additionally, compared to that in the PBS-treated group, tDC treatment reduced the left ventricular end-diastolic and end-systolic diameters in mice. Furthermore, treatment with tDCs improved the left ventricular systolic function, attenuated inflammatory cell infiltration, and reduced cardiomyocyte apoptosis, myocardial fibrosis, and infarct size compared to those in the control group.

CONCLUSIONS

Adoptive transfer of atorvastatin-induced tDCs alleviated post-infarction cardiomyocyte apoptosis and myocardial fibrosis in association with decreased inflammatory cell infiltration and inhibited oxidative stress, likely by suppressing TLR-4/NF-κB activation after myocardial infarction.

Molecular and functional characterization of zinc finger aspartate-histidine-histidine-cysteine (DHHC)-type containing 1, ZDHHC1 in Chinese perch Siniperca chuatsi

In the present study, the zinc finger aspartate-histidine-histidine-cysteine (DHHC)-type containing 1 (ZDHHC1) gene was identified in a commercial fish, the Chinese perch Siniperca chuatsi. The ZDHHC1 has five putative transmembrane motifs and conserved DHHC domain, showing high amino-acid identity with other teleost fish, and vertebrate ZDHHC1 loci are conserved from fish to human. In vivo expression analysis indicated that ZDHHC1 gene was constitutively transcribed in all the examined organs/tissues, and was induced following infectious spleen and kidney necrosis virus (ISKNV) infection. It is further observed that ZDHHC1 interacts with MITA and the overexpression of ZDHHC1 in cells resulted in the upregulated expression of ISGs, such as Mx, RSAD2, IRF3 and type I IFNs such as IFNh and IFNc, exhibiting its antiviral function in fish as reported in mammals.

Raising the Alarm: Environmental Factors in the Onset and Maintenance of Chronic (Low-Grade) Inflammation in the Gastrointestinal Tract

Chronic inflammatory disease of the gastrointestinal (GI) tract is defined by several pathophysiological characteristics, such as dysbiosis of the microbiota, epithelial barrier hyperpermeability, systemic dissemination of endotoxins and chronic inflammation. In addition to well-reported environmental factors in non-communicable disease, such as smoking, diet, and exercise, humans are frequently exposed to myriads more environmental factors, from pesticides to food additives. Such factors are ubiquitous across both our diet and indoor/outdoor environments. A major route of human exposure to these factors is ingestion, which frequently occurs due to their intentional addition (intentional food additives) and/or unintentional contamination (unintentional food contaminants) of food products-often linked to environmental pollution. Understanding how this persistent, diverse exposure impacts GI health is of paramount importance, as deterioration of the GI barrier is proposed to be the first step towards systemic inflammation and chronic disease. Therefore, we aim to evaluate the impact of ingestion of environmental factors on inflammatory processes in the GI tract. In this review, we highlight human exposure to intentional food additives (e.g. emulsifiers, bulking agents) and unintentional food contaminants (e.g. persistent organic pollutants, pesticides, microplastics), then present evidence for their association with chronic disease, modification of the GI microbiota, increased permeability of the GI barrier, systemic dissemination of endotoxins, local (and distal) pro-inflammatory signalling, and induction of oxidative stress and/or endoplasmic reticulum stress. We also propose a link to NLRP3-inflammasome activation. These findings highlight the contribution of common environmental factors towards deterioration of GI health and the induction of pathophysiology associated with onset and maintenance of chronic inflammation in the GI tract.

Novel insights into the regulation of cellular catabolic metabolism in macrophages through nuclear receptors

Regulation of cellular catabolic metabolism in immune cells has recently become a major concept for resolution of inflammation. Nuclear receptors (NRs), including peroxisome proliferator activator receptors (PPARs), 1,25-dihydroxyvitamin D(3) receptor (VDR), liver X receptors (LXRs), glucocorticoid receptors (GRs), estrogen-related receptor α (ERRα) and Nur77, have been identified as major modulators of inflammation, affecting innate immune cells, such as macrophages. Evidence emerges on how NRs regulate cellular metabolism in macrophages during inflammatory processes and contribute to the resolution of inflammation. This could have new implications for our understanding of how NRs shape immune responses and inform anti-inflammatory drug design. This review will highlight the recent developments about NRs and their role in cellular metabolism in macrophages.

MST4 negatively regulates type I interferons production via targeting MAVS-mediated pathway

BACKGROUND

Cytosolic RNA sensing can elicit immune responses against viral pathogens. However, antiviral responses must be tightly regulated to avoid the uncontrolled production of type I interferons (IFN) that might have deleterious effects on the host. Upon bacterial infection, the germinal center kinase MST4 can directly phosphorylate the adaptor TRAF6 to limit the inflammatory responses, thereby avoiding the damage caused by excessive immune activation. However, the molecular mechanism of how MST4 regulates virus-mediated type I IFN production remains unknown.

METHODS

The expression levels of IFN-β, IFIT1, and IFIT2 mRNA were determined by RT-PCR. The expression levels of p-IRF3, IRF3, RIG-I, MAVS, and MST4 proteins were determined by Western blot. The effect of secreted level of IFN-β was measured by ELISA. The relationship between MST4 and MAVS was investigated by immunofluorescence staining and coimmunoprecipitation.

RESULTS

In this study, we reported that MST4 can act as a negative regulator of type I IFN production. Ectopic expression of MST4 suppressed the Poly (I:C) (polyino-sinic-polycytidylic acid)- and Sendai virus (SeV)-triggered production of type I IFN, while the knockdown of MST4 enhanced the production of type I IFN. Mechanistically, upon SeV infection, the MST4 competed with TRAF3 to bind to the 360-540 domain of MAVS, thereby inhibiting the TRAF3/MAVS association. Additionally, MST4 facilitated the interaction between the E3 ubiquitin ligase Smurf1 and MAVS. This promoted the K48-linked ubiquitination of MAVS, thereby accelerating the ubiquitin-mediated proteasome degradation of MAVS.

CONCLUSIONS

Our findings showed that MST4 acted as a crucial negative regulator of RLR-mediated type I IFN production. Video Abstract.

Time-serial expression of toll-like receptor 4 signaling during polymicrobial sepsis in rats

Sepsis caused by aggressive infection is a severe clinical problem with an increasing incidence worldwide. Toll-like receptors and their common adapter myeloid differentiation factor 88 (MyD88) can activate immune responses by recognizing a foreign microbe’s product. This study aimed to identify the different time expression of TLR four signaling pathway in an experimental rodent model of polymicrobial sepsis. A randomized animal study was investigated in rats with septic peritonitis induced by cecal ligation and puncture (CLP). The expressions of MyD88-dependent pathway biomarkers, including MyD88, nuclear factor-κB (NF-κB), and serum tumor necrosis factor-α (TNF-α), were analyzed and compared to the sham controls at the different time points after CLP surgery. CLP-induced sepsis increased liver MyD88 mRNA expression and protein expression compared to the control groups at 2 h after surgery. The MyD88 mRNA and protein expressions in rats with CLP-induced sepsis marked increased at 4 and 6 h, and their NF-κB activities and serum TNF-α levels also increased at 4 h after CLP surgery (both p < .05). The different serial expression of MyD88-ependent pathway during sepsis may be used as biomarkers during sepsis. These results may provide further helpful information for using pro-inflammatory biomarkers of innate immunity such as MyD88 and TNF-α in clinical sepsis or related abdominal surgical emergency in the future.

Dietary Linolenic Acid Increases Sensitizing and Eliciting Capacities of Cow's Milk Whey Proteins in BALB/c Mice

α-Lactalbumin (BLA) and β-lactoglobulin (BLG) are the major whey proteins causing allergic reactions. Polyunsaturated fatty acids (PUFAs) stand among the extrinsic factors of the food matrix that can bind BLA and BLG and change their bioactivities, but their contribution to change the allergenic properties of these proteins has not been investigated. Here, we aimed to determine how PUFAs influence BLA and BLG to sensitize and trigger allergic responses in BALB/c mice. First, tricine-SDS-PAGE and spectroscopic assays identified that α-linolenic acid (ALA, as a proof-of-concept model) can induce BLA and BLG to form cross-linked complexes and substantially modify their conformation. Then, BALB/c mice (n = 10/group) were orally sensitized and challenged with BLA and BLG or ALA-interacted BLA and BLG, respectively. Allergic reactions upon oral challenge were determined by measuring clinical allergic signs, specific antibodies, levels of type-1/2 cytokines, the status of mast cell activation, and percentage of cell populations (B and T cells) in different tissues (PP, MLN, and spleen). Overall, systemic allergic reaction was promoted in mice gavage with ALA-interacted BLA and BLG by disrupting the Th1/Th2 balance toward a Th2 immune response with the decreased number of Tregs. Enhanced induction of Th2-related cytokines, as well as serum-specific antibodies and mast cell activation, was also observed. In this study, we validated that ALA in the food matrix promoted both the sensitization and elicitation of allergic reactions in BALB/c mice.

Modulation of Innate Antiviral Immune Response by Porcine Enteric Coronavirus

Host’s innate immunity is the front-line defense against viral infections, but some viruses have evolved multiple strategies for evasion of antiviral innate immunity. The porcine enteric coronaviruses (PECs) consist of porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), transmissible gastroenteritis coronavirus (TGEV), and swine acute diarrhea syndrome-coronavirus (SADS-CoV), which cause lethal diarrhea in neonatal pigs and threaten the swine industry worldwide. PECs interact with host cells to inhibit and evade innate antiviral immune responses like other coronaviruses. Moreover, the immune escape of porcine enteric coronaviruses is the key pathogenic mechanism causing infection. Here, we review the most recent advances in the interactions between viral and host’s factors, focusing on the mechanisms by which viral components antagonize interferon (IFN)-mediated innate antiviral immune responses, trying to shed light on new targets and strategies effective for controlling and eliminating porcine enteric coronaviruses.

Kirenol: A Potential Natural Lead Molecule for a New Drug Design, Development, and Therapy for Inflammation

Kirenol, a potential natural diterpenoid molecule, is mainly found in Sigesbeckia species. Kirenol has received a lot of interest in recent years due to its wide range of pharmacological actions. In particular, it has a significant ability to interact with a wide range of molecular targets associated with inflammation. In this review, we summarise the efficacy and safety of kirenol in reducing inflammation, as well as its potential mechanisms of action and opportunities in future drug development. Based on the preclinical studies reported earlier, kirenol has a good therapeutic potential against inflammation involved in multiple sclerosis, inflammatory bowel disorders, diabetic wounds, arthritis, cardiovascular disease, bone damage, and joint disorders. We also address the physicochemical and drug-like features of kirenol, as well as the structurally modified kirenol-derived molecules. The inhibition of pro-inflammatory cytokines, reduction in the nuclear factor kappa-B (NF-κB), attenuation of antioxidant enzymes, stimulation of heme-oxygenase-1 (HO-1) expression, and nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation are among the molecular mechanisms contributing to kirenol's anti-inflammatory actions. Furthermore, this review also highlights the challenges and opportunities to improve the drug delivery of kirenol for treating inflammation. According to the findings of this review, kirenol is an active molecule against inflammation in numerous preclinical models, indicating a path to using it for new drug discovery and development in the treatment of a wide range of inflammations.

Mechanism of MyD88S mediated signal termination

Background

A universal adaptor protein, MyD88, orchestrates the innate immune response by propagating signals from toll-like receptors (TLRs) and interleukin-1 receptor (IL-1R). Receptor activation seeds MyD88 dependent formation of a signal amplifying supramolecular organizing center (SMOC)—the myddosome. Alternatively spliced variant MyD88S, lacking the intermediate domain (ID), exhibits a dominant negative effect silencing the immune response, but the mechanistic understanding is limited.

Methods

Luciferase reporter assay was used to evaluate functionality of MyD88 variants and mutants. The dimerization potential of MyD88 variants and myddosome nucleation process were monitored by co-immunoprecipitation and confocal microscopy. The ID secondary structure was characterized in silico employing I-TASSER server and in vitro using nuclear magnetic resonance (NMR) and circular dichroism (CD).

Results

We show that MyD88S is recruited to the nucleating SMOC and inhibits its maturation by interfering with incorporation of additional components. Biophysical analysis suggests that important functional role of ID is not supported by a well-defined secondary structure. Mutagenesis identifies Tyr116 as the only essential residue within ID required for myddosome nucleation and signal propagation (NF-κB activation).

Conclusions

Our results argue that the largely unstructured ID of MyD88 is not only a linker separating toll-interleukin-1 receptor (TIR) homology domain and death domain (DD), but contributes intermolecular interactions pivotal in MyD88-dependent signaling. The dominant negative effect of MyD88S relies on quenching the myddosome nucleation and associated signal transduction.

Presence of two RIG-I-like receptors, MDA5 and LGP2, and their dsRNA binding capacity in a perciform fish, the snakehead Channa argus

Fish retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are critical RNA sensors in cytoplasm and are involved in antiviral innate immunity. However, some species of fish lack RIG-I gene, and the function of RLR members in RIG-I-absent fish is poorly understood. In the present study, MDA5, LGP2 and MAVS genes were identified in commercially important snakehead Channa argus. But, RIG-I gene was not found in this fish, and a systematic analysis of RLRs in available genome database of fish indicated the absence of RIG-I in the Acanthomorphata, Clupeiformes and Polypteriformes, suggesting that loss events of RIG-I gene may have occurred independently three times in the evolutionary history of fish. The MDA5, LGP2 and MAVS in snakehead have conserved protein domains and genomic location based on sequence, phylogenetic and syntenic analyses. These genes are constitutively expressed in healthy fish and can be induced by polyinosinic and polycytidylic acid (poly(I:C)) stimulation in vitro. It is further revealed that the snakehead MDA5 and LGP2 have binding capacity with dsRNA, such as poly(I:C), and MDA5 can interact with MAVS, implying the antiviral function of MDA5 in the RIG-I-absent fish.

Retroposition of the Long Transcript from Multiexon IFN-β Homologs in Ancestry Vertebrate Gave Rise to the Proximal Transcription Elements of Intronless IFN-β Promoter in Humans

IFN-β is a unique member of type I IFN in humans and contains four positive regulatory domains (PRDs), I-II-III-IV, in its promoter, which are docking sites for transcription factors IFN regulatory factor (IRF) 3/7, NF-κB, IRF3/7, and activating transcription factor 2/Jun proto-oncogene, respectively. In chicken IFN-β and zebrafish IFNφ1 promoters, a conserved PRD or PRD-like sequences have been reported. In this study, a type I IFN gene, named as xl-IFN1 in the amphibian model Xenopus laevis, was found to contain similar PRD-like sites, IV-III/I-II, in its promoter, and these PRD-like sites were proved to be functionally responsive to activating transcription factor 2/Jun proto-oncogene, IRF3/IRF7, and p65, respectively. The xl-IFN1, as IFNφ1 in zebrafish, was transcribed into a long and a short transcript, with the long transcript containing all of the transcriptional elements, including PRD-like sites and TATA box in its proximal promoter. A retroposition model was then proposed to explain the transcriptional conservation of IFNφ1, xl-IFN1, and IFN-β in chicken and humans.

Walking down Skeletal Muscle Lane: From Inflammasome to Disease

Over the last decade, innate immune system receptors and sensors called inflammasomes have been identified to play key pathological roles in the development and progression of numerous diseases. Among them, the nucleotide-binding oligomerization domain (NOD-), leucine-rich repeat (LRR-) and pyrin domain-containing protein 3 (NLRP3) inflammasome is probably the best characterized. To date, NLRP3 has been extensively studied in the heart, where its effects and actions have been broadly documented in numerous cardiovascular diseases. However, little is still known about NLRP3 implications in muscle disorders affecting non-cardiac muscles. In this review, we summarize and present the current knowledge regarding the function of NLRP3 in diseased skeletal muscle, and discuss the potential therapeutic options targeting the NLRP3 inflammasome in muscle disorders.

Adipocyte inflammation and pathogenesis of viral pneumonias: an overlooked contribution

Epidemiological evidence establishes obesity as an independent risk factor for increased susceptibility and severity to viral respiratory pneumonias associated with H1N1 influenza and SARS-CoV-2 pandemics. Given the global obesity prevalence, a better understanding of the mechanisms behind obese susceptibility to infection is imperative. Altered immune cell metabolism and function are often perceived as a key causative factor of dysregulated inflammation. However, the contribution of adipocytes, the dominantly altered cell type in obesity with broad inflammatory properties, to infectious disease pathogenesis remains largely ignored. Thus, skewing of adipocyte-intrinsic cellular metabolism may lead to the development of pathogenic inflammatory adipocytes, which shape the overall immune responses by contributing to either premature immunosenescence, delayed hyperinflammation, or cytokine storm in infections. In this review, we discuss the underappreciated contribution of adipocyte cellular metabolism and adipocyte-produced mediators on immune system modulation and how such interplay may modify disease susceptibility and pathogenesis of influenza and SARS-CoV-2 infections in obese individuals.

Monocyte Chemotactic Protein-Induced Protein 1 (MCPIP-1): A Key Player of Host Defense and Immune Regulation

Inflammatory response is a host-protective mechanism against tissue injury or infections, but also has the potential to cause extensive immunopathology and tissue damage, as seen in many diseases, such as cardiovascular diseases, neurodegenerative diseases, metabolic syndrome and many other infectious diseases with public health concerns, such as Coronavirus Disease 2019 (COVID-19), if failure to resolve in a timely manner. Recent studies have uncovered a superfamily of endogenous chemical molecules that tend to resolve inflammatory responses and re-establish homeostasis without causing excessive damage to healthy cells and tissues. Among these, the monocyte chemoattractant protein-induced protein (MCPIP) family consisting of four members (MCPIP-1, -2, -3, and -4) has emerged as a group of evolutionarily conserved molecules participating in the resolution of inflammation. The focus of this review highlights the biological functions of MCPIP-1 (also known as Regnase-1), the best-studied member of this family, in the resolution of inflammatory response. As outlined in this review, MCPIP-1 acts on specific signaling pathways, in particular NFκB, to blunt production of inflammatory mediators, while also acts as an endonuclease controlling the stability of mRNA and microRNA (miRNA), leading to the resolution of inflammation, clearance of virus and dead cells, and promotion of tissue regeneration via its pleiotropic effects. Evidence from transgenic and knock-out mouse models revealed an involvement of MCPIP-1 expression in immune functions and in the physiology of the cardiovascular system, indicating that MCPIP-1 is a key endogenous molecule that governs normal resolution of acute inflammation and infection. In this review, we also discuss the current evidence underlying the roles of other members of the MCPIP family in the regulation of inflammatory processes. Further understanding of the proteins from this family will provide new insights into the identification of novel targets for both host effectors and microbial factors and will lead to new therapeutic treatments for infections and other inflammatory diseases.

The epigenome: key to understanding and predicting gout flares

Gout is a form of arthritis, resulting from an inflammatory reaction to the deposition of monosodium urate (MSU) crystals in the synovial fluid of the joint space. It is characterised by periods of acute inflammation in the affected joint, or joints (known as gout flares), separated by asymptomatic periods. There seems to be substantial overlap between environmental triggers of gout flares and common environmental modifiers (diet, pharmaceuticals, and stress) of epigenetic markers (DNA methylation, histone modifications, and ncRNA). Very few studies have looked at whether environment is influencing gout through epigenetic mechanisms. The pathogenesis of gouty inflammation is well understood but understanding the variation of response to hyperuricaemia in terms of gout flare initiation is less well known. In this review, we will examine the potential of epigenomics in understanding how gout flares may occur, both in terms of development of hyperuricaemia and the inflammatory response. Looking at the epigenome and its intersection with lifestyle could help identify new targets and strategies for effective management of gout flares.

ARGEOS: A New Bioinformatic Tool for Detailed Systematics Search in GEO and ArrayExpress

Conduct a reanalysis of transcriptome data for studying intracellular signaling or solving other experimental problems is becoming increasingly popular. Gene expression data are archived as microarray or RNA-seq datasets mainly in two public databases: Gene Expression Omnibus (GEO) and ArrayExpress (AE). These databases were not initially intended to systematically search datasets, making it challenging to conduct a secondary study. Therefore, we have created the ARGEOS service, which has the following advantages that facilitate the search: (1) Users can simultaneously send several requests that are supposed to be used for systematic searches, and it is possible to correct the requests; (2) advanced analysis of information about the dataset is available. The service collects detailed protocols, information on the number of datasets, analyzes the availability of raw data, and provides other reference information. All this contributes to both rapid data analysis with the search for the most relevant datasets and to the systematic search with detailed analysis of the information of the datasets. The efficiency of the service is shown in the example of analyzing transcriptome data of activated (polarized) cells. We have performed a systematic search of studies of cell polarization (when cells are exposed to different immune stimuli). The web interface for ARGEOS is user-friendly and straightforward. It can be used by a person who is not familiar with database searching.

Traditional Chinese Medicine is an Alternative Therapeutic Option for Treatment of Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is an opportunistic pathogen causing life-threatening infections in cystic fibrosis patients and immunocompromised individuals, and it is a leading cause of nosocomial infections associated with significant morbidity and mortality. Treatment of P. aeruginosa infections is challenging due to the antibiotic resistance to most of the conventional antibiotics. Development of alternative therapeutic options is urgently demanded for the patients who have antibiotic-resistant infections. Traditional Chinese medicine (TCM) has a clinical history of thousands of years for prevention and treatment of infectious diseases in China, taking advantages of improving clinical outcomes, producing less side effects, inhibiting pathogen, and modulating host immunity. Recent research has revealed a variety of natural products derived from TCM showing significant antimicrobial effects on antibiotic-resistant strains of P. aeruginosa alone or combined with antibiotics in vitro or in animal models, suggesting that TCM is a promising complementary and alternative therapeutic approach for treatment of chronic P. aeruginosa infections. This review summarizes the recent findings attempting to dissect the mechanisms of TCM combating P. aeruginosa infections and highlights the molecular targets of TCM on P. aeruginosa and host.

Therapeutic Targeting of Inflammatory Pathways with Emphasis on NLRP3 Inflammasomes by Natural Products: A Novel Approach for the Treatment of Inflammatory Eye Diseases

There is an increase in the incidence of inflammatory eye diseases worldwide. Several dysregulated inflammatory pathways, including the NOD-like receptor protein 3 (NLRP3) inflammasome, have been reported to contribute significantly to the pathogenesis and progression of ophthalmic diseases. Although the available allopathic/conventional medicine has demonstrated effectiveness in managing eye diseases, there is an ongoing global demand for alternative therapeutics with minimal adverse drug reactions, easy availability, increase in patient-compliance, and better disease outcome. Therefore, several studies are investigating the utilization of natural products and herbal formulations in impeding inflammatory pathways, including the NLRP3 inflammasome, in order to prevent or manage eye diseases. In the present review, we highlight the recently reported inflammatory pathways with special emphasis on NLRP3 Inflammasomes involved in the development of eye diseases. Furthermore, we present a variety of natural products and phytochemicals that were reported to interfere with these pathways and their underlying mechanisms of action. These natural products represent potential therapeutic applications for the treatment of several inflammatory eye diseases.

Role of Immunoglobulins in Muscular Dystrophies and Inflammatory Myopathies

Muscular dystrophies and inflammatory myopathies are heterogeneous muscular disorders characterized by progressive muscle weakness and mass loss. Despite the high variability of etiology, inflammation and involvement of both innate and adaptive immune response are shared features. The best understood immune mechanisms involved in these pathologies include complement cascade activation, auto-antibodies directed against muscular proteins or de-novo expressed antigens in myofibers, MHC-I overexpression in myofibers, and lymphocytes-mediated cytotoxicity. Intravenous immunoglobulins (IVIGs) administration could represent a suitable immunomodulator with this respect. Here we focus on mechanisms of action of immunoglobulins in muscular dystrophies and inflammatory myopathies highlighting results of IVIGs from pre-clinical and case reports evidences.

Role of DAMPs in respiratory virus-induced acute respiratory distress syndrome-with a preliminary reference to SARS-CoV-2 pneumonia

When surveying the current literature on COVID-19, the "cytokine storm" is considered to be pathogenetically involved in its severe outcomes such as acute respiratory distress syndrome, systemic inflammatory response syndrome, and eventually multiple organ failure. In this review, the similar role of DAMPs is addressed, that is, of those molecules, which operate upstream of the inflammatory pathway by activating those cells, which ultimately release the cytokines. Given the still limited reports on their role in COVID-19, the emerging topic is extended to respiratory viral infections with focus on influenza. At first, a brief introduction is given on the function of various classes of activating DAMPs and counterbalancing suppressing DAMPs (SAMPs) in initiating controlled inflammation-promoting and inflammation-resolving defense responses upon infectious and sterile insults. It is stressed that the excessive emission of DAMPs upon severe injury uncovers their fateful property in triggering dysregulated life-threatening hyperinflammatory responses. Such a scenario may happen when the viral load is too high, for example, in the respiratory tract, "forcing" many virus-infected host cells to decide to commit "suicidal" regulated cell death (e.g., necroptosis, pyroptosis) associated with release of large amounts of DAMPs: an important topic of this review. Ironically, although the aim of this "suicidal" cell death is to save and restore organismal homeostasis, the intrinsic release of excessive amounts of DAMPs leads to those dysregulated hyperinflammatory responses-as typically involved in the pathogenesis of acute respiratory distress syndrome and systemic inflammatory response syndrome in respiratory viral infections. Consequently, as briefly outlined in this review, these molecules can be considered valuable diagnostic and prognostic biomarkers to monitor and evaluate the course of the viral disorder, in particular, to grasp the eventual transition precociously from a controlled defense response as observed in mild/moderate cases to a dysregulated life-threatening hyperinflammatory response as seen, for example, in severe/fatal COVID-19. Moreover, the pathogenetic involvement of these molecules qualifies them as relevant future therapeutic targets to prevent severe/ fatal outcomes. Finally, a theory is presented proposing that the superimposition of coronavirus-induced DAMPs with non-virus-induced DAMPs from other origins such as air pollution or high age may contribute to severe and fatal courses of coronavirus pneumonia.

Gold nanoclusters treat intracellular bacterial infections: Eliminating phagocytic pathogens and regulating cellular immune response

Intracellular bacterial infection is underlying many serious human disorders, leading to high morbidity and mortality. The development of safe and efficient therapeutic agents is the most effective solutions to combat intracellular bacterial infections. Recently, ultrasmall gold nanoclusters (AuNCs) have emerged as an innovative nanoantibiotics against multidrug-resistant bacterial infections due to their inherent antibacterial activity. However, the therapeutic effects of AuNCs on intracellular bacterial infections and their effects on host cells still remain unvisited. Here, we demonstrate the therapeutic potential of 4,6-diamino-2-mercaptopyrimidine-functionalized AuNCs (AuDAMP) for intracellular multidrug-resistant infections in a co-culture model of macrophages and methicillin-resistant Staphylococcus aureus (MRSA). The AuNCs were found to show a superior intracellular antibacterial capability, which can eliminate most of the MRSA phagocytosed by macrophages, and without exhibiting obvious cytotoxicity on host RAW 264.7 macrophages at tested concentrations. More importantly, treatment of AuDAMP exerts critical roles on enhancing the innate immune response to defend against pathogens invading inside the host cells and alleviating the bacterial infection-induced inflammatory response to avoid pyroptosis by up-regulating significantly xenophagy level in macrophages. Taken together, our results suggest that AuNCs hold great potential for the treatment of intracellular bacterial infections.

Exosomes Released From Human Bone Marrow-Derived Mesenchymal Stem Cell Attenuate Acute Graft-Versus-Host Disease After Allogeneic Hematopoietic Stem Cell Transplantation in Mice

Objective

Mesenchymal stromal cell–derived exosomes have been applied for the treatment of several immune diseases. This study aimed to explore the effect of human bone marrow–derived mesenchymal stem cell (hBMSC)–derived exosomes on acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT).

Methods

hBMSC were cultured, and the culture supernatants were then collected to prepare exosomes using total exosome isolation reagent from Invitrogen. Mouse aGVHD model was established by allogeneic cell transplantation and injected with hBMSC-derived exosomes (Msc-exo) via tail vein. Exosomes from human fibroblast (Fib-exo) were used as the treatment control. The effects of Msc-exo on dendritic cells, CD4⁺, and CD8⁺ T cells in aGVHD mice were analyzed through flow cytometry. The impact on inflammatory cytokines was tested by ELISA. Besides, the body weight, survival rate, and clinical score of treated mice were monitored.

Results

Msc-exo were successfully prepared. aGVHD mice injected with Msc-exo led to 7–8-fold increase of the CD8α⁺ conventional dendritic cells (cDCs) and CD11b⁺ cDCs compared with the controls. In addition, Msc-exo altered the T help and Treg subpopulation, and decreased the cytotoxicity and proliferation of cytotoxic T cells to favor inflammatory inhibition in aGVHD mice. Mice that received Msc-exo exhibited decreased weight loss and reduced aGVHD clinical score in a time-dependent manner as well as reduced lethality compared with Fib-exo treated or untreated control. Furthermore, the levels of IL-2, TNF-α, and IFN-γ were decreased, as well as the level of IL-10 was increased after Msc-exo treatment in vivo and in vitro.

Conclusion

hBMSC-derived exosomes could attenuate aGVHD damage and promote the survival of aGVHD mice by regulating the DC and T-cell subpopulation and function, and lead to inhibited inflammatory response in aGVHD mice.

Exosome-inflammasome crosstalk and their roles in inflammatory responses

Inflammasome is a complex of multiple proteins found in cytoplasm of the cells activated by infectious and/or non-infectious stimuli. This complex involves caspase-1 activation, leading to unconventional secretion of interleukin-1β (IL-1β) and IL-18 and inflammatory cascade. Exosome is the nanoscale membrane-bound extracellular vesicle that plays significant roles in intercellular communications by carrying bioactive molecules, e.g., proteins, RNAs, microRNAs (miRNAs), DNAs, from one cell to the others. In this review, we provide the update information on the crosstalk between exosome and inflammasome and their roles in inflammatory responses. The effects of inflammasome activation on exosomal secretion are summarized. On the other hand, the (dual) effects of exosomes on inhibiting and promoting inflammasome activation are discussed. Finally, perspectives on therapeutic roles of exosomes in human diseases and future direction of the research on exosome-inflammasome crosstalk are provided.