The role of innate immunity in diabetic nephropathy and their therapeutic consequences

Diabetic nephropathy (DN) is an enduring condition that leads to inflammation and affects a substantial number of individuals with diabetes worldwide. A gradual reduction in glomerular filtration and emergence of proteins in the urine are typical aspects of DN, ultimately resulting in renal failure. Mounting evidence suggests that immunological and inflammatory factors are crucial for the development of DN. Therefore, the activation of innate immunity by resident renal and immune cells is critical for initiating and perpetuating inflammation. Toll-like receptors (TLRs) are an important group of receptors that identify patterns and activate immune responses and inflammation. Meanwhile, inflammatory responses in the liver, pancreatic islets, and kidneys involve inflammasomes and chemokines that generate pro-inflammatory cytokines. Moreover, the activation of the complement cascade can be triggered by glycated proteins. This review highlights recent findings elucidating how the innate immune system contributes to tissue fibrosis and organ dysfunction, ultimately leading to renal failure. This review also discusses innovative approaches that can be utilized to modulate the innate immune responses in DN for therapeutic purposes.

MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants

Mitogen-activated protein kinase （MAPK） cascades play important roles in regulating plant innate immune responses. In a genetic screen to search for mutants with constitutive defense responses, we identified multiple alleles of mpk4 and mekkl that exhibit cell death and constitutive defense responses. Bimolecular fluorescence complemen- tation （BiFC） analysis showed that both MPK4 and MEKK1 interact with MKK1 and MKK2, two closely related MAPK kinases, mkkl and mkk2 single mutant plants do not have obvious mutant phenotypes. To test whether MKK1 and MKK2 function redundantly, mkkl mkk2 double mutants were generated. The mkkl mkk2 double mutant plants die at seedling stage and the seedling-lethality phenotype is temperature-dependent. Similar to the mpk4 and mekkl mutants, the mkkl mkk2 double mutant seedlings accumulate high levels of H202, display spontaneous cell death, constitutively express Pathogenesis Related （PR） genes and exhibit pathogen resistance. In addition, activation of MPK4 by fig22 is impaired in the mkkl mkk2 double mutants, suggesting that MKK1 and MKK2 function together with MPK4 and MEKK1 in a MAP kinase cascade to negatively regulate innate immune responses in plants.

Dysregulation of innate immunity in ulcerative colitis patients who fail anti-tumor necrosis factor therapy

AIM To study the innate immune function in ulcerative colitis(UC) patients who fail to respond to anti-tumor necrosis factor(TNF) therapy.METHODS Effects of anti-TNF therapy, inflammation and medications on innate immune function were assessed by measuring peripheral blood mononuclear cell(PBMC) cytokine expression from 18 inflammatory bowel disease patients pre- and 3 mo post-anti-TNF therapy. Toll-like receptor(TLR) expression and cytokine production post TLR stimulation was assessed in UC "responders"(n = 12) and "non-responders"(n = 12) and compared to healthy controls(n = 12). Erythrocyte sedimentation rate(ESR) and C-reactive protein(CRP) levels were measured in blood to assess disease severity/activity and inflammation. Pro-inflammatory(TNF, IL-1β, IL-6), immuno-regulatory(IL-10), Th1(IL-12, IFNγ) and Th2(IL-9, IL-13, IL-17A) cytokine expression was measured with enzyme-linked immunosorbent assay while TLR cellular composition and intracellular signalling was assessed with FACS.RESULTS Prior to anti-TNF therapy, responders and nonresponders had similar level of disease severity and activity. PBMC's ability to respond to TLR stimulation was not affected by TNF therapy, patient's severity of the disease and inflammation or their medication use. At baseline, non-responders had elevated innate but not adaptive immune responses compared to responders(P < 0.05). Following TLR stimulation, nonresponders had consistently reduced innate cytokine responses to all TLRs compared to healthy controls(P < 0.01) and diminished TNF(P < 0.001) and IL-1β(P < 0.01) production compared to responders. This innate immune dysfunction was associated with reduced number of circulating plasmacytoid dendritic cells(p DCs)(P < 0.01) but increased number of CD4+ regulatory T cells(Tregs)(P = 0.03) as well as intracellular accumulation of IRAK4 in non-responders following TLR-2,-4 and-7 activation(P < 0.001). CONCLUSION Reduced innate immunity in non-responders may explain reduced efficacy to anti-TNF therapy. These serological markers may prove useful in predicting the outcome of costly anti-TNF therapy.

Regulation of microRNA by hepatitis B virus infection and their possible association with control of innate immunity

Hepatitis B virus(HBV)chronically infects more than350 million people worldwide.HBV causes acute and chronic hepatitis,and is one of the major causes of cirrhosis and hepatocellular carcinoma.There exist complex interactions between HBV and the immune system including adaptive and innate immunity.Tolllike receptors(TLRs)and TLR-signaling pathways are important parts of the innate immune response in HBV infections.It is well known that TLR-ligands could suppress HBV replication and that TLRs play important roles in anti-viral defense.Previous immunological studies demonstrated that HBV e antigen(HBeAg)is more efficient at eliciting T-cell tolerance,including production of specific cytokines IL-2 and interferon gamma,than HBV core antigen.HBeAg downregulates cytokine production in hepatocytes by the inhibition of MAPK or NF-κB activation through the interaction with receptor-interacting serine/threonine protein kinase.MicroRNAs(miRNAs)are also able to regulate various biological processes such as the innate immune response.When the expressions of approximately 1000 miRNAs were compared between human hepatoma cells HepG2 and HepG2.2.15,which could produce HBV virion that infects chimpanzees,using real-time RT-PCR,we observed several different expression levels in miRNAs related to TLRs.Although we and others have shown that HBV modulates the host immune response,several of the miRNAs seem to be involved in the TLR signaling pathways.The possibility that alteration of these miRNAs during HBV infection might play a critical role in innate immunity against HBV infection should be considered.This article is intended to comprehensively review the association between HBV and innate immunity,and to discuss the role of miRNAs in the innate immune response to HBV infection.

Regulatory effects of dietary L-Arg supplementation on the innate immunity and antioxidant ability in broiler chickens

Here, we investigated the effect of dietary arginine（Arg） supplementation on innate immunity and the antioxidant ability of broiler chickens. The experiment was designed as a single-factorial arrangement（n=8 cages/treatment, six birds/cage）, and we used four dietary Arg concentrations（10.0, 15.0, 20.0 or 25.0 g kg–1）. On day 21, the birds were killed to obtain spleen, cecal tonsil and liver samples to determine the gene expression and antioxidant characteristics. Increasing the Arg concentration linearly decreased（P0.05） the m RNA expression of splenic interleukin-18（IL-18） and tumor necrosis factor-α（TNF-α）. Dietary Arg supplementation quadratically decreased（P0.05） the expression of interleukin-1b（IL-1b） and interferon-γ（IFN-γ） m RNA in the spleen. Increasing Arg concentrations linearly and quadratically reduced the expression of IL-18 m RNA in the spleen. Meanwhile, increasing dietary Arg supplementation linearly and quadratically increased the lymphotactin m RNA（P0.05） expression, and linearly increased the macrophage inflammatory protein-1β（MIP-1β） and toll-like receptor 15（TLR15） m RNA expression in the cecal tonsils. Dietary Arg supplementation linearly（P0.05） increased the glutathione peroxidase（GSH-Px）, catalase（CAT）, and lysozyme（LZM） activities in the liver. However, the malondialdehyde（MDA） activity in the liver was not influenced by the dietary Arg concentration（P0.05）. No significant（P0.05） effect was found on the activity of superoxide dismutase（SOD） in the liver. Thus high levels of Arg supplementation（20.0 g kg^（–1）） may potentially suppress the innate immunity of broiler chickens, and dietary Arg supplementation enhances the antioxidant activity in broiler chickens.

Innate immunity–the hallmark of Helicobacter pylori infection in pediatric chronic gastritis

BACKGROUND Innate immunity was found to be associated with both persistence of Helicobacter pylori(H.pylori)infection and increased risk of gastric cancer.AIM To identify the risk factors associated with H.pylori infection and to establish the role of TLR9 rs352140 in suppressing or promoting inflammation related to this infection in children.METHODS We performed a study of 155 children with digestive symptoms,who were divided into two groups according to the histopathological exam:Group 1–48 children with H.pylori-induced chronic gastritis,and Group 2–control group.RESULTS Rural area and poor living conditions were significantly associated with H.pylori chronic gastritis(P=0.0042/P<0.0001).Both positive immunoglobulin A anti H.pylori and the rapid urease test were significantly associated with H.pylori infection(P<0.0001).Significantly higher values of leukocytes and neutrophils within the peripheral blood were found in children with H.pylori chronic gastritis(P=0.111/P=0.284).We found a significant positive correlation between the variant TT genotype of TLR9 rs352140 polymorphism and both leucocytes and neutrophils(P=0.0225/P=0.0292).CONCLUSION Variant TT genotype carriers of the TLR9 rs352140 gene polymorphism might have a more severe degree of inflammation.

Dectin-1 agonist curdlan modulates innate immunity to Aspergillus fumigatus in human corneal epithelial cells

· AIM: To explore the immunomodulatory effects of curdlan on innate immune responses against Aspergillus fumigatus(A. fumigatus) in cultured human corneal epithelial cells(HCECs), and whether C-type lectin receptor Dectin-1 mediates the immunomodulatory effects of curdlan.·METHODS: The HCECs were stimulated by curdlan in different concentrations(50, 100, 200, 400 μg/m L) for various time. Then HCECs pretreated with or without laminarin(Dectin-1 blocker, 0.3 mg/m L) and curdlan were stimulated by A. fumigatus hyphae. The m RNA and protein production of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6) were determined by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The protein level of Dectin-1 was measured by Western blot.· RESULTS: Curdlan stimulated m RNA expression of TNF-α and IL-6 in a dose and time dependent manner in HCECs. Curdlan pretreatment before A. fumigatus hyphae stimulation significantly enhanced the expression of TNF-α and IL-6 at m RNA and protein levels compared with A. fumigatus hyphae stimulation group(P 【0.05).Both curdlan and A. fumigatus hyphae up-regulated Dectin-1 protein expression in HCECs, and Dectin-1expression was elevated to 1.5- to 2-fold by curdlan pretreatment followed hyphae stimulation. The Dectin-1blocker laminarin suppressed the m RNA expression and protein production of TNF-α and IL-6 induced by curdlan and hyphae(P 【0.05).· CONCLUSION: These findings demonstrated that curdlan pretreatment enhanced the inflammatory response induced by A. fumigatus hyphae in HCECs.Dectin-1 is essential for the immunomodulatory effectsof curdlan. Curdlan may have high clinical application values in fungal keratitis treatment.

Evaluation of fatty acid metabolism and innate immunity interactions between commercial broiler, F1 layer × broiler cross and commercial layer strains selected for different growth potentials

Background： The broiler industry has undergone intense genetic selection over the past 50 yr. resulting in improvements for growth and feed efficiency, however, significant variation remains for performance and growth traits. Production improvements have been coupled with unfavourable metabolic consequences, including immunological trade-offs for growth, and excess fat deposition. To determine whether interactions between fatty acid（FA） metabolism and innate immunity may be associated with performance variations commonly seen within commercial broiler flocks, total carcass lipid %, carcass and blood FA composition, as wel as genes involved with FA metabolism, immunity and cel ular stress were investigated in male birds of a broiler strain, layer strain and F1 layer × broiler cross at d 14 post hatch. Heterophil：lymphocyte ratios, relative organ weights and bodyweight data were also compared.Results： Broiler bodyweight（n = 12） was four times that of layers（n = 12） by d 14 and had significantly higher carcass fat percentage compared to the cross（n = 6; P = 0.002） and layers（P = 0.017） which were not significantly different from each other（P = 0.523）. The carcass and whole blood FA analysis revealed differences in the FA composition between the three groups indicating altered FA metabolism, despite al being raised on the same diet. Genes associated with FA synthesis andβ-oxidation were upregulated in the broilers compared to the layers indicating a net overal increase in FA metabolism,which may be driven by the larger relative liver size as a percentage of bodyweight in the broilers. Genes involved in innate immunity such as TLR2 and TLR4, as wel as organel e stress indicators ERN1 and XBP1 were found to be nonsignificant, with the exception of high expression levels of XBP1 in layers compared to the cross and broilers. Additional y there was no difference in heterophil： lymphocytes between any of the birds.Conclusions： The results provide evidence that genetic selection may be associated with altered metabolic processes between broilers, layers and their F1 cross. Whilst there is no evidence of interactions between FA metabolism, innate immunity or cel ular stress, further investigations at later time points as growth and fat deposition increase would provide useful information as to the effects of divergent selection on key metabolic and immunological processes.

Effects of retinoic acid receptor-γ on the Aspergillus fumigatus induced innate immunity response in human corneal epithelial cells

AIM： To explore the effects of retinoic acid receptor-γ （RARγ） on innate immune responses against Aspergillus fumigatus （A. fumigatus） in cultured human corneal epithelial cells （HCECs）. METHODS： The HCECs were stimulated with A. fumigatus hyphae for 0, 2, 4, 8, 12 and 16h. RARγ mRNA and protein levels were tested by quantitative real-time polymerase chain reaction （qRT-PCR） and Western blot. Then HCECs were pretreated with or without BMS961 （RARγ agonist, 1 μg/mL）. The mRNA and protein expression of Dectin-1 and the downstream cytokines （TNF-α and IL-6） were determined by qRT-PCR, Western blot and enzyme-linked immunosorbent assay （ELISA）. RESULTS： The expression of RARγ was upregulated after stimulation with A. fumigatus. RARγ mRNA began to rise at 4h and peaked at 8h （P〈0.001）. The protein of RARγ reached to the peak at 16h （P〈0.001）. Pretreated with BMS961 before A. fumigatus hyphae stimulation, expression of Dectin-1, TNF-α and IL-6 decreased dramatically at mRNA and protein levels. CONCLUSION： HCECs can express RARγ and A. fumigatus hyphae infection can increase RARγ expression. BMS961 can inhibit the expression of Dectin-1 and pro-inflammatory cytokines, and play an anti-inflammatory role in innate immune responses against A. fumigatus.

Mitochondrial Regulation of Macrophages in Innate Immunity and Diverse Roles of Macrophages During Cochlear Inflammation

Macrophages are essential components of the innate immune system and constitute a non-specific first line of host defense against pathogens and inflammation.Mitochondria regulate macrophage activation and innate immune responses in various inflammatory diseases,including cochlear inflammation.The distribution,number,and morphological characteristics of cochlear macrophages change significantly across different inner ear regions under various pathological conditions,including noise exposure,ototoxicity,and age-related degeneration.However,the exact mechanism underlying the role of mitochondria in macrophages in auditory function remains unclear.Here,we summarize the major factors and mitochondrial signaling pathways(e.g.,metabolism,mitochondrial reactive oxygen species,mitochondrial DNA,and the inflammasome)that influence macrophage activation in the innate immune response.In particular,we focus on the properties of cochlear macrophages,activated signaling pathways,and the secretion of inflammatory cytokines after acoustic injury.We hope this review will provide new perspectives and a basis for future research on cochlear inflammation.

Pharmacological Investigation on the Qi-Invigorating Action of Schisandrin B: Effects on Mitochondrial ATP Generation in Multiple Tissues and Innate/Adaptive Immunity in Mice

Schisandrae Fructus, containing schisandrin B (Sch B) as its main active component, is recognized in traditional Chinese medicine (TCM) for its Qi-invigorating properties in the five visceral organs. Our laboratory has shown that the Qi-invigorating action of Chinese tonifying herbs is linked to increased mitochondrial ATP generation and an enhancement in mitochondrial glutathione redox status. To explore whether Sch B can exert Qi-invigorating actions across various tissues, we investigated the effects of Sch B treatment on mitochondrial ATP generation and glutathione redox status in multiple mouse tissues ex vivo. In line with TCM theory, which posits that Zheng Qi generation relies on the Qi function of the visceral organs, we also examined Sch B’s impact on natural killer cell activity and antigen-induced splenocyte proliferation, both serving as indirect measures of Zheng Qi. Our findings revealed that Sch B treatment consistently enhanced mitochondrial ATP generation and improved mitochondrial glutathione redox status in mouse tissues. This boost in mitochondrial function was associated with stimulated innate and adaptive immune responses, marked by increased natural killer cell activity and antigen-induced T/B cell proliferation, potentially through the increased generation of Zheng Qi.

SARS-CoV-2 and innate immunity:the good,the bad,and the"goldilocks"

An ancient conflict between hosts and pathogens has driven the innate and adaptive arms of immunity.Knowledge about this interplay can not only help us identify biological mechanisms but also reveal pathogen vulnerabilities that can be leveraged therapeutically.The humoral response to SARS-CoV-2 infection has been the focus of intense research,and the role of the innate immune system has received significantly less attention.Here,we review current knowledge of the innate immune response to SARS-CoV-2 infection and the various means SARS-CoV-2 employs to evade innate defense systems.We also consider the role of innate immunity in SARS-CoV-2 vaccines and in the phenomenon of long COVID.

Role of innate immunity in SARS-CoV-2 infection

During severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2)infection,activated macrophages,dendritic cells(D.C.),neutrophils,and natural killer(N.K.)cells are the first defense against infection.These immune effectors trap and ingest the virus,kill infected epithelial cells,or produce anti‐viral cytokines.Evidence suggests that aging,obesity,and mental illness can lead to weakened innate immunity and,thus,are all associated with elevated infection and severe disease progression of coronavirus disease 2019(COVID‐19).Innate immune defense networks play a fundamental role in suppressing viral replication,infection establishment,and viral pathogenesis of SARS‐CoV‐2 and other respiratory viruses.

Differential Effects of Yin- and Yang-Chinese Tonifying Herbs on Innate and Adaptive Immunity

The present study investigated the effect of treatment with methanolic extracts of Yin- and Yang-Chinese tonifying herbs on concanavalin A (Con A)/lipopolysaccharide (LPS)-stimulated splenocyte proliferation (adaptive immunity) and natural killer (NK) cell activity (innate immunity) in an ex vivo mouse model. The results indicated that while treatment with most Yin herbal extracts potentiated the Con A/LPS-stimulated splenocyte proliferation, only Yang (but not Yin) herbal extracts stimulated NK cell activity. The differential effects of Yin- and Yang-Chinese tonifying herbs on innate and adaptive immunity are consistent with the Chinese medicine theory which depicts the Yin and Yang functional components of Zheng Qi (vital energy), with the Yang component being responsible for the first line of defense against invading microorganisms (i.e., innate immunity) and the Yin oner serving as a follow-up defensive response (adaptive immunity).

Unveiling the dynamic role of innate and adaptive immune cells in COPD pathogenesis induced by cigarette smoke

Chronic obstructive pulmonary disease(COPD)is a multifaceted syndrome characterized by a dysregulated inflammatory cascade within the respiratory system,primarily triggered by exposure to harmful particles and gases,notably from cigarette smoke.This inflammatory response is orchestrated by innate immune cells like macrophages and epithelial cells,which recognize danger signals released from damaged cells.Prolonged inflammation prompts an adaptive immune reaction mediated by dendritic cells,culminating in the formation of lymphoid follicles and involving a complex interplay of T and B cells,as well as cytotoxic activity.Additionally,both viral and bacterial infections exacerbate COPD by further igniting inflammatory pathways,perpetuating the chronic inflammatory state.This comprehensive review encapsulates the intricate interplay between innate and adaptive immunity in COPD,with a particular focus on the role of cigarette smoke in its pathogenesis and potential therapeutic targets.

BmMD-2A responds to 20-hydroxyecdysone and regulates Bombyx mori silkworm innate immunity in larva-to-pupa metamorphosis

20E-hydroxyecdysone(20E)plays important roles in larval molting and metamorphosis in insects and is also involved in the insect innate immune response.Insect metamorphosis is a highly successful strategy for environmental adaptation and is the most vulnerable stage during which the insect is susceptible to various pathogens.20E regulates a series of antimicrobial peptides(AMPs)through the immunodeficiency(IMD)pathway activation in Drosophila;nevertheless,whether other immune pathways are involved in 20E-regulated insect immunity is unknown.Our previous studies showed that BmMD-2A is a member of the MD-2-related lipid recognition(ML)family of proteins that are involved in the Bombyx mori innate immunity Toll signaling pathway.In this study,we further demonstrate that BmMD-2A is also positively regulated by 20E,and the BmMD-2A neutralization experiment suggested that 20E activates some downstream immune effect factors,the AMP genes against Escherichia coli and Staphylococcus aureus,through the regulation of BmMD-2A in larval metamorphosis,implying that B.mori may use the Toll-ML signaling pathway to maintain innate immune balance in the larval-pupal metamorphosis stage,which is a different innate immunity pathway regulated by 20E compared to the IMD pathway in Drosophila.

Role of Notch signaling in regulating innate immunity and inflammation in health and disease

The Notch signaling pathway is conserved from Drosophila to mammals and is critically involved in developmental processes. In the immune system, it has been established that Notch signaling regulates multiple steps of T and B cell development in both central and peripheral lymphoid organs. Relative to the well documented role of Notch signaling in lymphocyte development, less is known about its role in regulating myeloid lineage development and function, especially in the context of acute and chronic inflammation. In this review article, we will describe the evidence accumulated during the recent years to support a key regulatory role of the Notch pathway in innate immune and inflammatory responses and discuss the potential implications of such regulation for pathogenesis and therapy of inflammatory disorders.

Receptor-Like Kinases in Plant Innate Immunity

Plants employ a highly effective surveillance system to detect potential pathogens, which is critical for the success of land plants in an environment surrounded by numerous microbes. Recent efforts have led to the identification of a number of immune receptors and components of immune receptor complexes. It is now clear that receptor-like kinases （RLKs） and receptor-like proteins （RLPs） are key pattern-recognition receptors （PRRs） for microbe- and plant-derived molecular patterns that are associated with pathogen invasion. RLKs and RLPs involved in immune signaling belong to large gene families in plants and have undergone lineage specific expansion. Molecular evolution and population studies on phytopathogenic molecular signatures and their receptors have provided crucial insight into the co-evolution between plants and pathogens.

Plant pattern-recognition receptors controlling innate immunity

Plants are exposed to numerous potential pathogenic microbes. To counter the threat, plants have evolved diverse patternrecognition receptors(PRRs), which are receptor kinases(RKs) and receptor proteins(RPs) specialized to detect conserved pathogen/microbe-associated molecular patterns(PAMPs/MAMPs). Although only a handful of RKs and RPs are known PRRs,they belong to the receptor-like kinase(RLK) and receptor-like protein(RLP) superfamilies that undergo lineage-specific expansion, suggesting that many of these RLKs and RLPs are potential PRRs. Analyses of existing PRRs have uncovered ligand-induced RLK-RK or RLK-RP oligomerization as a common mechanism for immune activation. PRRs can recruit additional components to form dynamic receptor complexes, which mediate specific cellular responses. Detailed analyses of these components are shedding light on molecular mechanisms underlying the regulation of PRR activity and downstream signaling.

Long noncoding RNAs in innate immunity

Long noncoding RNAs （IncRNAs） have been shown to play important roles in immune cell development and immune responses through different mechanisms, such as dosage compensation, imprinting, enhancer function, and transcriptional regulation. Although the functions of most IncRNAs are unclear, some IncRNAs have been found to control transcriptional or post-transcriptional regulation of the innate and adaptive immune responses via new methods of protein-protein interactions or pairing with DNA and RNA. Interestingly, increasing evidence has elucidated the importance of IncRNAs in the interaction between hosts and pathogens. In this review, an overview of the IncRNAs modes of action, as well as the important and diversified roles of IncRNAs in immunity, are provided, and an emerging paradigm of IncRNAs in regulating innate immune responses is highlighted.