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.

Paeoniflorin ameliorates chronic colitis via the DR3 signaling pathway in group 3 innate lymphoid cells

Inhibiting the death receptor 3(DR3)signaling pathway in group 3 innate lymphoid cells(ILC3s)presents a promising approach for promoting mucosal repair in individuals with ulcerative colitis(UC).Paeoniflorin,a prominent component of Paeonia lactiflora Pall.,has demonstrated the ability to restore barrier function in UC mice,but the precise mechanism remains unclear.In this study,we aimed to delve into whether paeoniflorin may promote intestinal mucosal repair in chronic colitis by inhibiting DR3 signaling in ILC3s.C57BL/6 mice were subjected to random allocation into 7 distinct groups,namely the control group,the 2%dextran sodium sulfate(DSS)group,the paeoniflorin groups(25,50,and 100 mg/kg),the anti-tumor necrosis factor-like ligand 1A(anti-TL1A)antibody group,and the IgG group.We detected the expression of DR3 signaling pathway proteins and the proportion of ILC3s in the mouse colon using Western blot and flow cytometry,respectively.Meanwhile,DR3-overexpressing MNK-3 cells and 2%DSS-induced Rag1^(-/-)mice were used for verification.The results showed that paeoniflorin alleviated DSS-induced chronic colitis and repaired the intestinal mucosal barrier.Simultaneously,paeoniflorin inhibited the DR3 signaling pathway in ILC3s and regulated the content of cytokines(interleukin-17A,granulocyte-macrophage colony stimulating factor,and interleukin-22).Alternatively,paeoniflorin directly inhibited the DR3 signaling pathway in ILC3s to repair mucosal damage independently of the adaptive immune system.We additionally confirmed that paeoniflorin-conditioned medium(CM)restored the expression of tight junctions in Caco-2 cells via coculture.In conclusion,paeoniflorin ameliorates chronic colitis by enhancing the intestinal barrier in an ILC3-dependent manner,and its mechanism is associated with the inhibition of the DR3 signaling pathway.

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.

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.

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).

Involvement of Dectin-2 in the Innate Inflammatory Response Triggered by Influenza Virus Hemagglutinin

C-type lectin receptors (CLRs) are representative pattern recognition receptors that recognize microbial polysaccharides expressed on antigen-presenting cells. In the present study, we carried out further detailed analysis on the involvement of Dectin-2, a CLR that senses high mannose polysaccharide, in innate immune responses induced by influenza virus hemagglutinin (HA). Treatment of HA with periodate or PNGase F induced lower interleukin (IL)-12p40 secretion by conventional dendritic cells (DCs) compared with the untreated group. In contrast, treatment with O-glycosidase did not affect cytokine production. Green fluorescent protein expression in canonical Dectin-2-transducing cells was approximately 3% - 12% following HA stimulation, except with the A/H1N1pdm09 subtype HA. This expression was markedly reduced in cells possessing mutated amino acids in the carbohydrate recognition domain of Dectin-2, especially following stimulation with HA derived from the A/H3N2 subtype. Interferon (IFN)-α production from CD11c+Siglec-H+PDCA-1+ plasmacytoid DCs was significantly increased in Dectin-2 knockout mice compared with wild-type mice upon stimulation with HA except for the B/Yamagata lineage HA. These results suggested that Dectin-2 is involved in initiating inflammatory responses via mannose polysaccharide on HA. However, other mechanisms may function in the antiviral response, including the type I IFN axis.

The origin and role of innate lymphoid cells in the lung

Innate lymphoid cells(ILCs),a newly identified member of the lymphoid population,play a critical role in the transition from innate to adaptive immunity in host defense.ILCs are important in mucosal barrier immunity,tissue homeostasis,and immune regulation throughout the body.Significant alterations in ILC responses in lung diseases have been observed and reported.Emerging evidence has shown that ILCs are importantly involved in the pathogenesis and development of a variety of lung diseases,i.e.,helminth infections,allergic airway inflammation,and airway hyper-responsiveness.However,as a tissue-resident cell population,the role of ILCs in the lung remains poorly characterized.In this review,we discuss the role of ILCs in lung diseases,the mechanisms underlying the ILCmediated regulation of immunity,and the therapeutic potential of modulating ILC responses.

Complement and its role in innate and adaptive immune responses

The complement system plays a crucial role in the innate defense against common pathogens. Activation of complement leads to robust and efficient proteolytic cascades, which terminate in opsonization and lysis of the pathogen as well as in the generation of the classical inflammatory response through the production of potent proinflammatory molecules. More recently, however, the role of complement in the immune response has been expanded due to observations that link complement activation to adaptive immune responses. It is now appreciated that complement is a functional bridge between innate and adaptive immune responses that allows an integrated host defense to pathogenic challenges. As such, a study of its functions allows insight into the molecular underpinnings of host-pathogen interactions as well as the organization and orchestration of the host immune response. This review attempts to summarize the roles that complement plays in both innate and adaptive immune responses and the consequences of these interactions on host defense.

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.

Roles of liver innate immune cells in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease in the United States and other developed countries and is expected to increase in the next few years. Emerging data suggest that some patients with NAFLD may progress to nonalcoholic steatohepatitis (NASH), cirrhosis and even hepatocellular carcinoma. NAFLD can also promote the development and progression of disease in other organ systems, such as the cardiovascular and endocrine (i.e. diabetes) systems. Thus, understanding the pathogenesis of NAFLD is of great clinical importance and is critical for the prevention and treatment of the disease. Although the "two-hit hypothesis" is generally accepted, the exact pathogenesis of NAFLD has not been clearly established. The liver is an important innate immune organ with large numbers of innate immune cells, including Kupffer cells (KCs), natural killer T (NKT) cells and natural killer (NK) cells. Recent data show that an imbalance in liver cytokines may be implicated in the development of fatty liver disease. For example, Th1 cytokine excess may be a common pathogenic mechanism for hepatic insulin resistance and NASH. Innate immune cells in the liver play important roles in the excessive production of hepatic Th1 cytokines in NAFLD. In addition, liver innate immune cells participate in the pathogenesis of NAFLD in other ways. For example, activated KCs can generate reactive oxygen species, which induce liver injury. This review will focus primarily on the possible effect and mechanism of KCs, NKT cells and NK cells in the development of NAFLD.

Innate immunity in inflammatory bowel disease

The human intestinal tract is home to an enormous bacterial flora. The host defense against microorganisms can be divided into innate and adaptive immunity. The former is the most immediate line of response to immunologic challenges presented by bacteria, viruses, and fungi. The mucosal immune system has evolved to balance the need to respond to pathogens while co-existing with commensal bacteria and food antigens. In inflammatory bowel disease （IBD）, this hyporesponsiveness or tolerance breaks down and inflammation supervenes driven by the intestinal microbial flora. Bacteria contain compounds and are recognized by a variety of receptors, including Toll-like receptors （TLRs） and NODs （a family of intracellular bacterial sensors） and are potent stimuli of innate immune responses. Several mutations in these receptors have been associated with development of IBD.

Inflammatory bowel disease requires the interplay between innate and adaptive immune signals

Inflammatory bowl disease （IBD） is a type 1 T helper cell （Th1）-mediated autoimmune disease. Various studies have revealed that environmental pathogens also play a significant role in the initiation and progression of this disease. Interestingly, the pathogenesis of IBD has been shown to be related to nitric oxide （NO） released from innate immune cells. Although NO is known to be highly toxic to the gut epithelia, there is very little information about the regulation of NO production, One major question in the etiology of IBD is how Thl cells and pathogens interact in the induction of IBD. In present study, we focused on the regulation of NO. We show that macrophages require both interferon-γ, （IFN-γ）-mediated and TLR4-mediated signals for the production of NO, which causes inflammation in the intestine and subsequently IBD. Thus, IBD is the result of concerted actions of innate immune signals, such as the binding of LPS to TLR-4, and adaptive immune signals, such as IFN-γ produced by Thl cells.

Role of innate immunity in the development of hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is the most common form of liver cancer worldwide.It is caused by a variety of risk factors,most common ones being infection with hepatitis viruses,alcohol,and obesity.HCC often develops in the background of underlying cirrhosis,and even though a number of interventional treatment methods are currently in use,recurrence is fairly common among patients who have had a resection.Therefore,whole liver transplantation remains the most practical treatment option for HCC.Due to the growing incidence of HCC,intense research efforts are being made to understand cellular and molecular mechanisms of the disease so that novel therapeutic strategies can be developed to combat liver cancer.In recent years,it has become clear that innate immunity plays a critical role in the development of a number of liver diseases,including HCC.In particular,the activation of Toll-like receptor signaling results in the generation of immune responses that often results in the production of proinflammatory cytokines and chemokines,and could cause acute inflammation in the liver.In this review,the current knowledge on the role of innate immune responses in the development and progression of HCC is examined,and emerging therapeutic strategies based on molecular mechanisms of HCC are discussed.

Innate immune targets of hepatitis B virus infection

Approximately 400 million people are chronically infected with hepatitis B virus(HBV) globally despitethe widespread immunization of HBV vaccine and the development of antiviral therapies. The immunopathogenesis of HBV infection is initiated and driven by complexed interactions between the host immune system and the virus. Host immune responses to viral particles and proteins are regarded as the main determinants of viral clearance or persistent infection and hepatocyte injury. Innate immune system is the first defending line of host preventing from virus invasion. It is acknowledged that HBV has developed active tactics to escape innate immune recognition or actively interfere with innate immune signaling pathways and induce immunosuppression, which favor their replication. HBV reduces the expression of pattern-recognition receptors in the innate immune cells in humans. Also, HBV may interrupt different parts of antiviral signaling pathways, leading to the reduced production of antiviral cytokines such as interferons that contribute to HBV immunopathogenesis. A full comprehension of the mechanisms as to how HBV inactivates various elements of the innate immune response to initiate and maintain a persistent infection can be helpful in designing new immunotherapeutic methods for preventing and eradicating the virus. In this review, we aimed to summarize different branches the innate immune targeted by HBV infection. The review paper provides evidence that multiple components of immune responses should be activated in combination with antiviral therapy to disrupt the tolerance to HBV for eliminating HBV infection.

Crosstalk between innate and adaptive immunity in hepatitis B virus infection

Hepatitis B virus(HBV) infection is a major public healthproblem worldwide. HBV is not directly cytotoxic to infected hepatocytes; the clinical outcome of infection results from complicated interactions between the virus and the host immune system. In acute HBV infection, initiation of a broad, vigorous immune response is res-ponsible for viral clearance and self-limited inflammatory liver disease. Effective and coordinated innate and adaptive immune responses are critical for viral clearance and the development of long-lasting immunity. Chronic hepatitis B patients fail to mount efficient innate and adaptive immune responses to the virus. In particular, HBV-specific cytotoxic T cells, which are crucial for HBV clearance, are hyporesponsiveness to HBV infection. Accumulating experimental evidence obtained from the development of animal and cell line models has highlighted the importance of innate immunity in the early control of HBV spread. The virus has evolved immune escape strategies, with higher HBV loads and HBV protein concentrations associated with increasing impairment of immune function. Therefore, treatment of HBV infection requires inhibition of HBV replication and protein expression to restore the suppressed host immunity. Complicated interactions exist not only between innate and adaptive responses, but also among innate immune cells and different components of adaptive responses. Improved insight into these complex interactions are important in designing new therapeutic strategies for the treatment HBV infection. In this review, we summarize the current knowledge regarding the cross-talk between the innate and adaptive immune responses and among different immunocytes in HBV infection.

Interplay between hepatitis B virus and the innate immune responses:implications for new therapeutic strategies

Hepatitis B virus(HBV) infection is still a worldwide health problem;however,the current antiviral therapies for chronic hepatitis B are limited in efficacy.The outcome of HBV infection is thought to be the result of complex interactions between the HBV and the host immune system.While the role of the adaptive immune responses in the resolution of HBV infection has been well characterized,the contribution of innate immune mechanisms remains elusive until recent evidence implicates that HBV appears to activate the innate immune response and this response is important for controlling HBV infection.Here,we review our current understanding of innate immune responses to HBV infection and the multifaceted evasion by the virus and discuss the potential strategies to combat chronic HBV infection via induction and restoration of host innate antiviral responses.

Innate immunity and hepatocarcinoma:Can toll-likereceptors open the door to oncogenesis?

Hepatocarcinoma(HCC) is a highly prevalent cancer worldwide and its inflammatory background was established long ago.Recent studies have shown that innate immunity is closely related to the HCC carcinogenesis.An effective innate immunity response relies on the tolllike receptors(TLR) found in several different liver cells which,through different ligands and many signaling pathways can elicit,not only a pro-inflammatory but also an oncogenic or anti-oncogenic response.Our aim was to study the role of TLRs in the liver oncogenesis and as a consequence their value as potential therapeutic targets.We performed a systematic review of PubMed searching for original articles studying the relationship between HCC and TLRs until March 2015.TLR2 appears to be a fundamental stress-sensor as its absence reveals an augmented tendency to accumulate DNAdamages and to cell survival.However,pathways are still not fully understood as TLR2 up-regulation was also associated to enhanced tumorigenesis.TLR3 has a wellknown protective role influencing crucial processes like angiogenesis,cell growth or proliferation.TLR4 works as an interesting epithelial-mesenchymal transition's inducer and a promoter of cell survival probably inducing HCC carcinogenesis even though an anti-cancer role has already been observed.TLR9's influence on carcinogenesis is also controversial and despite a potential anticancer capacity,a pro-tumorigenic role is more likely.Genetic polymorphisms in some TLRs have been found and its influence on the risk of HCC has been reported.As therapeutic targets,TLRs are already in use and have a great potential.In conclusion,TLRs have been shown to be an interesting influence on the HCCs microenvironment,with TLR3 clearly determining an antitumour influence.TLR4 and TLR9 are considered to have a positive relationship with tumour development even though,in each of them anti-tumorigenic signals have been described.TLR2 presents a more ambiguous role,possibly depending on the stage of the inflammationHCC axis.

Innate lymphoid cells in tissue homeostasis and diseases

Innate lymphoid cells(ILCs) are the most recently discovered family of innate immune cells. They are a part of the innate immune system, but develop from the lymphoid lineage. They lack pattern-recognition receptors and rearranged receptors, and therefore cannot directly mediate antigen specific responses. The progenitors specifically associated with the ILCs lineage have been uncovered, enabling the distinction between ILCs and natural killer cells. Based on the requirement of specific transcription factors and their patterns of cytokine production, ILCs are categorized into three subsets(ILC1, ILC2 and ILC3). First observed in mucosal surfaces, these cell populations interact with hematopoietic and non-hematopoietic cells throughout the body during homeostasis and diseases, promoting immunity, commensal microbiota tolerance, tissue repair and inflammation. Over the last 8 years, ILCs came into the spotlight as an essential cell type able to integrate diverse host immune responses. Recently, it became known that ILC subsets play a key role in immune responses at barrier surfaces, interacting with the microbiota, nutrients and metabolites. Since the liver receives the venous blood directly from the intestinal vein, the intestine and liver are essential to maintain tolerance and can rapidly respond to infections or tissue damage. Therefore, in this review, we discuss recent findings regarding ILC functions in homeostasis and disease, with a focus on the intestine and liver.

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.

Gut epithelial barrier dysfunction in humanimmunodeficiency virus-hepatitis C virus coinfectedpatients:Influence on innate and acquired immunity

Even in cases where viral replication has been controlled by antiretroviral therapy for long periods of time, human immunodeficiency virus(HIV)-infected patients have several non-acquired immunodeficiency syndrome(AIDS) related co-morbidities, including liver disease, cardiovascular disease and neurocognitive decline, which have a clear impact on survival. It has been considered that persistent innate and acquired immune activation contributes to the pathogenesis of these non-AIDS related diseases. Immune activation has been related with several conditions, remarkably with the bacterial translocation related with the intestinal barrier damage by the HIV or by hepatitis C virus(HCV)-related liver cirrhosis. Consequently, increased morbidity and mortality must be expected in HIV-HCV coinfected patients. Disrupted gut barrier lead to an increased passage of microbial products and to an activation of the mucosal immune system and secretion of inflammatory mediators, which in turn might increase barrier dysfunction. In the present review, the intestinal barrier structure, measures of intestinal barrier dysfunction and the modifications of them in HIV monoinfection and in HIV-HCV coinfection will be considered. Both pathogenesis and the consequences for the progression of liver disease secondary to gut microbial fragment leakage and immune activation will be assessed.