Expression Of Innate Immune Receptors Research Articles

A microenvironment-modulating dressing with proliferative degradants for the healing of diabetic wounds.

Diabetic wounds are usually entangled in a disorganized and self-perpetuating microenvironment and accompanied by a prolonged delay in tissue repair. Sustained and coordinated microenvironment regulation and tissue regeneration are key to the healing process of diabetic wounds, yet they continue to pose a formidable challenge. Here we report a rational double-layered dressing design based on chitosan and a degradable conjugated polymer polydiacetylene, poly(deca-4,6-diynedioic acid) (PDDA), that can meet this intricate requirement. With an alternating ene-yne backbone, PDDA degrades when reacting with various types of reactive oxygen species (ROS), and more importantly, generates proliferative succinic acid as a major degradant. Inheriting from PDDA, the developed PDDA-chitosan double layer dressing (PCD) can eliminate ROS in the microenvironment of diabetic wounds, alleviate inflammation, and downregulate gene expression of innate immune receptors. PCD degradation also triggers simultaneous release of succinic acid in a sustainable manner, enabling long-term promotion on tissue regeneration. We have validated the biocompatibility and excellent performance of PCD in expediting the wound healing on both diabetic mouse and porcine models, which underscores the significant translational potential of this microenvironment-modulating, growth-promoting wound dressing in diabetic wounds care.

Bi-functional CpG-STAT3 decoy oligonucleotide triggers multilineage differentiation of acute myeloid leukemia in mice

Acute myeloid leukemia (AML) cells resist differentiation stimuli despite high expression of innate immune receptors, such as Toll-like receptor 9 (TLR9). We previously demonstrated that targeting Signal Transducer and Activator of Transcription 3 (STAT3) using TLR9-targeted decoy oligodeoxynucleotide (CpG-STAT3d) increases immunogenicity of human and mouse AML cells. Here, we elucidated molecular mechanisms of inv(16) AML reprogramming driven by STAT3-inhibition/TLR9-activation invivo. At the transcriptional levels, AML cells isolated from mice after intravenous administration of CpG-STAT3d or leukemia-targeted Stat3 silencing and TLR9 co-stimulation, displayed similar upregulation of myeloid cell differentiation (Irf8, Cebpa, Itgam) and antigen-presentation (Ciita, Il12a, B2m)-related genes with concomitant reduction of leukemia-promoting Runx1. Single-cell transcriptomics revealed that CpG-STAT3d induced multilineage differentiation of AML cells into monocytes/macrophages, erythroblastic and B cell subsets. As shown by an inducible Irf8 silencing invivo, IRF8 upregulation was critical for monocyte-macrophage differentiation of leukemic cells. TLR9-driven AML cell reprogramming was likely enabled by downregulation of STAT3-controlled methylation regulators, such as DNMT1 and DNMT3. In fact, the combination of DNA methyl transferase (DNMT) inhibition using azacitidine with CpG oligonucleotides alone mimicked CpG-STAT3d effects, resulting in AML cell differentiation, Tcell activation, and systemic leukemia regression. These findings highlight immunotherapeutic potential of bi-functional oligonucleotides to unleash TLR9-driven differentiation of leukemic cells by concurrent STAT3 and/or DNMT inhibition.

Innate immune receptors are differentially expressed in mice during experimental Schistosoma mansoni early infection.

The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

Impact of Psychological Distress on Immune Phenotype in CLL/SLL Patients Managed By Active Observation

Introduction: Asymptomatic patients with a new diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) are usually managed by active observation; however, many patients report elevated levels of distress and worry during the ‘watchful waiting’ phase. Psychological distress may have clinical implications given that natural killer [NK] and T cells are not only sensitive to distress, but also critical in controlling disease progression. Thus, the purpose of this study was to examine associations of psychological functioning and quality of life (QOL) with biomarker expression and functional activity of immune cells from peripheral blood of CLL/SLL patients being managed with surveillance. Methods: We conducted a multisite, prospective study in patients with indolent B-cell neoplasms who were managed with surveillance. Participants completed measures of perceived stress (Perceived Stress Scale), anxiety and depressive symptoms (Hospital Anxiety and Depression Scale) and quality of life (FACT-G) at study entry and then every 6 months for up to 2 years or disease progression (whichever occurred first). Blood samples were collected at study entry and every 6 months for immune phenotyping using multiparametric flow cytometry (up to 13-color). Biomarkers of activation, viability, proliferation, exhaustion, and receptor expression were assessed on subsets of T, NK, and myeloid cells, and mean fluorescence intensity or percentage of cells staining were determined. Results: Between April 2016 and November 2020, 233 patients were enrolled at two academic institutions in Philadelphia, including 111 with a diagnosis of CLL/SLL. Of these, 76 patients also had viable samples for immune phenotyping. Participants were predominantly male (60.5%) with a mean age of 63.7 years (SD=9.1 years). Approximately 5% self-reported their race as Black or African American and 4% were of Hispanic ethnicity. At enrollment, the median time since diagnosis was 10.6 months (median follow-up time = 23.6 months). Multivariable regression analyses revealed that increased depressive symptoms were associated with a significant shift from lower percentages of non-classical monocytes (NCM) to higher percentages of classical monocytes (CM; see Figure 1). Similar significant population shifts from reduced NCM toward increased CM were also observed with increased levels of stress and anxiety. These results suggest that patients reporting increased stress, anxiety, and depressive symptoms have fewer of the “patrolling” NCM and increased “sensing” CM in peripheral blood. We also assessed expression of numerous innate immune receptors, including DNAM-1, which can stimulate responses by NK and T cells toward tumors. We observed lower expression of DNAM-1 on CD4 + helper T cells and CD8 + cytotoxic T cells in patients with increased depressive symptoms (p< 0.05). Similarly, patients reporting lower QOL also expressed lower levels of DNAM-1 on CD4 + and CD8 + T cells, as well as cytotoxic CD56 dim NK cells (p<0.05). As DNAM-1 is important for antitumor responses, our data suggest that patients with higher depressive symptoms have T and NK cells with reduced capacity to respond to CLL/SLL tumor cells. NKp30, another activating receptor on NK and CD8+ T cells promoting cytotoxicity, was also expressed at lower levels on CD56 dim NK cells and T cells in the peripheral blood of patients reporting depressive symptoms. Patients who reported higher levels of depressive symptoms had lower levels of expression of the activation marker CD69 on CD4+ and CD8+ T cells. Finally, longitudinal analyses revealed that higher levels of depressive symptoms predicted lower levels of PD-L1 on CD56 dim NK cells over time ( p = 0.04). Conclusion: In CLL/SLL patients, psychological functioning is associated with differential patterns of monocyte distribution. Greater depressive symptoms and lower quality of life predicted lower expression of innate immune receptors, such as DNAM-1 on CD4 + helper T cells and CD8 + cytotoxic T cells. Future directions will investigate whether these measures are associated with disease progression or the occurrence of second primary cancers, given the importance of DNAM-1 and NKp30 in immune surveillance for cancers and reactivation of latent viruses. These findings may have direct translational relevance and enable the early identification of patients at-risk for poor outcomes.

304-OR: Proteomic Profile and Inflammatory Response of Islet Stressomes Released during Isolation

Purpose: Islets undergo enormous stress during isolation and peri-transplant periods which causes a significant release of stressomes (exosomes released during stress) . Uncovering the biological role of such vesicles is vital for long-term graft function and survival. Here, we sought to identify the global protein content and significance of stressomes isolated during isolation in autologous islet transplantation (AIT) . Methods: Post-transplant stress was mimicked in vitro by exposing human islets to hypoxia and cytokines (Cyt+Hyp) . Stressome protein contents were characterized by mass spectrometry and immunoblotting. Similar stressomes were also isolated from the islet infusion bag samples of AIT recipients (N=20) . The stressome protein levels were correlated with 1-year AIT outcomes. Finally, these islet stressomes were treated to another set of purified islets and macrophages to find their uptake and immune response. Results: The mass spectrometry analysis has revealed the islet stressomes contain DAMP proteins like histones (H2B, H3, and H4) . The canonical ER stress signal plays a crucial role in the biogenesis of islet stressomes induced by (Cyt+Hyp) . Exosomes isolated from the infusion bags showed an elevated histone level in the insulin-dependent (ID) group. Moreover, high levels of DAMP proteins were positively correlated with increased post-transplant recipients insulin requirements (p=0.029) . The fluorescent confocal microscopy analysis has revealed these stressomes were easily uptaken by the macrophages and also conferred an inflammatory phenotype. Instead, the stressome treated islets showed elevated expression of innate immune receptors like TLR2 and AGTR1. Conclusion: The study has identified the islet stressome global protein content and briefs its prospective to induce islet inflammation and graft loss in AIT. Disclosure P.Saravanan: None. J.Kalivarathan: None. M.F.Levy: Research Support; Vertex Pharmaceuticals Incorporated, Speaker's Bureau; AbbVie Inc., Sanofi Genzyme. M.A.Kanak: None.

Differencial expression of innate immune receptors in term placentas and extravillous cytotrofoblast cells infected with Zika virus

Differencial expression of innate immune receptors in term placentas and extravillous cytotrofoblast cells infected with Zika virus

Virulence of Trypanosoma cruzi Strains Is Related to the Differential Expression of Innate Immune Receptors in the Heart.

Resistance or susceptibility to T. cruzi infection is dependent on the host immunological profile. Innate immune receptors, such as Toll-like receptors (TLRs/TLR2, TLR4, TLR7, and TLR9) and Nod-like receptors (NLRs/NOD1 and NLRP3 inflammasome) are involved with the resistance against acute experimental T. cruzi infection. Here, we evaluated the impact of T. cruzi virulence on the expression of innate immune receptors and its products in mice. For that, we used six T. cruzi strains/isolates that showed low (AM64/TcIV and 3253/Tc-V), medium (PL1.10.14/TcIII and CL/TcVI), or high (Colombian/Tc-I and Y/TcII) virulence and pathogenicity to the vertebrate host and belonging to the six discrete typing units (DTUs)—TcI to TcVI. Parasitemia, mortality, and myocarditis were evaluated and correlated to the expression of TLRs, NLRs, adapter molecules, cytokines, and iNOS in myocardium by real time PCR. Cytokines (IL-1β, IL-12, TNF-α, and IFN-γ) were quantified in sera 15 days after infection. Our data indicate that high virulent strains of T. cruzi, which generate high parasitemia, severe myocarditis, and 100% mortality in infected mice, inhibit the expression of TLR2, TLR4, TLR9, TRIF, and Myd88 transcripts, leading to a low IL-12 production, when compared to medium and low virulent T. cruzi strains. On the other hand, the high virulent T. cruzi strains induce the upregulation of NLRP3, caspase-1, IL-1β, TNF-α, and iNOS mRNA in heart muscle, compared to low and medium virulent strains, which may contribute to myocarditis and death. Moreover, high virulent strains induce higher levels of IL-1β and TNF-α in sera compared to less virulent parasites. Altogether the data indicate that differential TLR and NLR expression in heart muscle is correlated with virulence and pathogenicity of T cruzi strains. A better knowledge of the immunological mechanisms involved in resistance to T. cruzi infection is important to understand the natural history of Chagas disease, can lead to identification of immunological markers and/or to serve as a basis for alternative therapies.

Hemeprotein amplifies the innate immune receptors of Ctenopharyngodon idellus kidney cells through NF-κB- and MAPK-dependent reactive oxygen species generation

Infectious bacterial and viral diseases that cause hemolysis are considered life-threatening to grass carp (Ctenopharyngodon idellus), which is a species used in aquaculture worldwide. After heme and hemeproteins (Hb) are released as a result of hemolysis, the effect of excess Hb and heme on tissues remains to be characterized. To decipher the mechanisms, after incubation with Hb, we showed that lipopolysaccharide (LPS), Hb, and heme increased the cytotoxicity and secretion of inflammatory cytokines such as interleukin (IL)-6, chemokine (C-C motif) ligand 1 (CCL1), tumor necrosis factor (TNF)-α, IL-6, and IL-1β in vitro, which was due to stimulation of the expression of innate immune receptors, such as nucleotide-binding oligomerization domain (NOD2), toll-like receptor 2 (TLR2), TLR 4, and TLR3. The formation of reactive oxygen species (ROS) and the activation of mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-κB were important for increasing the cytokine production to induce heme, Hb, and LPS. Moreover, we confirmed that after LPS, Hb, and heme challenge, superoxide dismutase (SOD) and glutathione (GSH) synthetase (GSS) also caused remarkable destruction. However, catalase (CAT) and heme oxygenase-1 (HO-1) were strongly activated. In summary, our research findings present a framework through which heme and Hb concentrations amplify the secretions of inflammatory cytokines, which are induced by pattern recognition receptor (PRR) activation and present possible paths for immune intervention during infection with viral diseases and hemolytic bacterial.

Pregnane X Receptor Activation Triggers Rapid ATP Release in Primed Macrophages That Mediates NLRP3 Inflammasome Activation.

The pregnane X receptor (PXR) is a ligand-activated nuclear receptor that acts as a xenobiotic sensor, responding to compounds of foreign origin, including pharmaceutical compounds, environmental contaminants, and natural products, to induce transcriptional events that regulate drug detoxification and efflux pathways. As such, the PXR is thought to play a key role in protecting the host from xenobiotic exposure. More recently, the PXR has been reported to regulate the expression of innate immune receptors in the intestine and modulate inflammasome activation in the vasculature. In the current study, we report that activation of the PXR in primed macrophages triggers caspase-1 activation and interleukin-1β release. Mechanistically, we show that this response is nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing 3-dependent and is driven by the rapid efflux of ATP and P2X purinoceptor 7 activation following PXR stimulation, an event that involves pannexin-1 gating, and is sensitive to inhibition of Src-family kinases. Our findings identify a mechanism whereby the PXR drives innate immune signaling, providing a potential link between xenobiotic exposure and the induction of innate inflammatory responses.

Downregulation of SP‐R210L Alters the Macrophage Epigenetic Chromatin Landscape Associated with Changes in Transcription Factor Binding

Alveolar macrophages are the first immune cells to come into contact with air‐borne pathogens such as influenza. Previous studies demonstrated that the surfactant protein A (SP‐A) receptor, SP‐R210, also known as MYO18A, regulates the immune functions of macrophages through the action of two isoforms; a long form SP‐R210L(L), and a short form SP‐R210S(S). Stable knockdown of L in RAW264.7 cells (abbreviated as DN) revealed alterations in mRNA expression of innate immune receptors and responsiveness to various inflammatory stimuli. To elucidate the intrinsic functions of the L isoform, the present study addressed the hypothesis that L modulates macrophage gene transcription through epigenetic modification of chromatin. We thus utilized chromatin immunoprecipitation and sequencing (ChIP‐seq) to determine the impact of L depletion on histone modification marks H3K4me3, H3K9me3, and H3K27me3 and binding of transcription factors PU.1 and NFκB subunit RelA, which regulate macrophage differentiationand inflammatory responses, respectively. Pulled‐down sequences were visualized on the UCSC genome browser to identify the spatial relation between enriched sequences. This analysis showed reduced PU.1 binding at genes associated with macrophage differentiation and intercellular communication between innate and adaptive immune cells, such as interleukin 18 (IL‐18) and colony‐stimulating factor receptors (CSF1R, CSF2RB) in DN cells. Additionally, differences in PU.1 binding were reflected in similar suppression of H3K4me3 marks in DN cells. Further analysis by ChIPpeakAnno and ChIPseeker and ingenuity pathway analysis, however, revealed enrichment in genes that regulate TNFα and interferon (IFN) signaling in DN cells. Collectively, these findings support the idea that the L isoform of SP‐R210 regulates chromatin architecture and accessibility of transcription factors at genes with discrete roles in macrophage differentiation and activation.Support or Funding InformationThis work was supported by HL128746, The Children's Miracle Network, and the Department of Pediatrics, Penn State University College of MedicineThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Innate immune response in patients with acute Zika virus infection.

Innate immunity receptors (Toll-like receptors/TLRs and RIG-like receptors/RLRs) are important for the initial recognition of Zika virus (ZIKV), modulation of protective immune response, and IFN-α and IFN-β production. Immunological mechanisms involved in protection or pathology during ZIKV infection have not yet been determined. In this study, we evaluated the mRNA expression of innate immune receptors (TLR3, TLR7, TLR8, TLR9, melanoma differentiation-associated protein 5/MDA-5, and retinoic acid inducible gene/RIG-1), its adapter molecules (Myeloid Differentiation Primary Response Gene 88/Myd88, Toll/IL-1 Receptor Domain-Containing Adaptor-Inducing IFN-β/TRIF), and cytokines (IL-6, IL-12, TNF-α, IFN-α, IFN-β, and IFN-γ) in the acute phase of patients infected by ZIKV using real-time PCR in peripheral blood. Patients with acute ZIKV infection had high expression of TLR3, IFN-α, IFN-β, and IFN-γ when compared to healthy controls. In addition, there was a positive correlation between TLR3 expression compared to IFN-α and IFN-β. Moreover, viral load is positively correlated with TLR8, RIG-1, MDA-5, IFN-α, and IFN-β. On the other hand, patients infected by ZIKV showed reduced expression of RIG-1, TLR8, Myd88, and TNF-α molecules, which are also involved in antiviral immunity. Similar expressions of TLR7, TLR9, MDA-5, TRIF, IL-6, and IL-12 were observed between the group of patients infected with ZIKV and control subjects. Our results indicate that acute infection (up to 5days after the onset of symptoms) by ZIKV in patients induces the high mRNA expression of TLR3 correlated to high expression of IFN-γ, IFN-α, and IFN-β, even though the high viral load is correlated to high expression of TLR8, RIG-1, MDA-5, IFN-α, and IFN-β in ZIKV patients.

Ca2+ and innate immune pathways are activated and differentially expressed in childhood asthma phenotypes.

Asthma is the most common chronic disease in children. Underlying immunologic mechanisms-in particular of different phenotypes-are still just partly understood. The objective of the study was the identification of distinct cellular pathways in allergic asthmatics (AA) and nonallergic asthmatics (NA) vs healthy controls (HC). Peripheral blood mononuclear cells (PBMCs) of steroid-naïve children (n(AA/NA/HC)=35/13/34)) from the CLARA study (n=275) were stimulated (anti-CD3/CD28, LpA) or kept unstimulated. Gene expression was investigated by transcriptomics and quantitative RT-PCR. Differentially regulated pathways between phenotypes were assessed after adjustment for sex and age (KEGG pathways). Networks based on correlations of gene expression were built using force-directed graph drawing. Allergic asthmatics vs NA and asthmatics overall vs HC showed significantly different expression of Ca2+ and innate immunity-associated pathways. PCR analysis confirmed significantly increased Ca2+ -associated gene regulation (ORMDL3 and ATP2A3) in asthmatics vs HC, most prominent in AA. Innate immunity receptors (LY75, TLR7), relevant for virus infection, were also upregulated in AA and NA compared to HC. AA and NA could be differentiated by increased ATP2A3 and FPR2 in AA, decreased CLEC4E in AA, and increased IFIH1 expression in NA following anti-CD3/28 stimulation vs unstimulated (fold change). Ca2+ regulation and innate immunity response pattern to viruses were activated in PBMCs of asthmatics. Asthma phenotypes were differentially characterized by distinct regulation of ATP2A3 and expression of innate immune receptors (FPR2, CLEC4E, IFIH1). These genes may present promising targets for future in-depth investigation with the long-term goal of more phenotype-specific therapeutic interventions in asthmatics.

Innate immune receptors over expression correlate with chronic chagasic cardiomyopathy and digestive damage in patients.

Chronic chagasic cardiomyopathy (CCC) is observed in 30% to 50% of the individuals infected by Trypanosoma cruzi and heart failure is the important cause of death among patients in the chronic phase of Chagas disease. Although some studies have elucidated the role of adaptive immune responses involving T and B lymphocytes in cardiac pathogenesis, the role of innate immunity receptors such as Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in CCC pathophysiology has not yet been determined. In this study, we evaluated the association among innate immune receptors (TLR1-9 and nucleotide-binding domain-like receptor protein 3/NLRP3), its adapter molecules (Myd88, TRIF, ASC and caspase-1) and cytokines (IL-1β, IL-6, IL-12, IL-18, IL-23, TNF-α, and IFN-β) with clinical manifestation, digestive and cardiac function in patients with different clinical forms of chronic Chagas disease. The TLR8 mRNA expression levels were enhanced in the peripheral blood mononuclear cells (PBMC) from digestive and cardiodigestive patients compared to indeterminate and cardiac patients. Furthermore, mRNA expression of IFN-β (cytokine produced after TLR8 activation) was higher in digestive and cardiodigestive patients when compared to indeterminate. Moreover, there was a positive correlation between TLR8 and IFN-β mRNA expression with sigmoid and rectum size. Cardiac and cardiodigestive patients presented higher TLR2, IL-12 and TNF-α mRNA expression than indeterminate and digestive patients. Moreover, cardiac patients also expressed higher levels of NLRP3, ASC and IL-1β mRNAs than indeterminate patients. In addition, we showed a negative correlation among TLR2, IL-1β, IL-12 and TNF-α levels with left ventricular ejection fraction, and positive correlation between NLRP3 with cardiothoracic index, and TLR2, IL-1β and IL-12 with left ventricular mass index. Together, our data suggest that high expression of innate immune receptors in cardiac and digestive patients may induce an enhancement of cytokine expression and participate of cardiac and digestive dysfunction.

Type I IFN signature in childhood-onset systemic lupus erythematosus: a conspiracy of DNA- and RNA-sensing receptors?

BackgroundChildhood-onset systemic lupus erythematosus (cSLE) is an incurable multi-systemic autoimmune disease. Interferon type I (IFN-I) plays a pivotal role in the pathogenesis of SLE. The objective of this study was to assess the prevalence of the IFN-I signature and the contribution of cytosolic nucleic acid receptors to IFN-I activation in a cohort of primarily white cSLE patients.MethodsThe IFN-I score (positive or negative), as a measure of IFN-I activation, was assessed using real-time quantitative PCR (RT-PCR) expression values of IFN-I signature genes (IFI44, IFI44L, IFIT1, Ly6e, MxA, IFITM1) in CD14+ monocytes of cSLE patients and healthy controls (HCs). Innate immune receptor expression was determined by RT-PCR and flow cytometry. To clarify the contribution of RNA-binding RIG-like receptors (RLRs) and DNA-binding receptors (DBRs) to IFN-I activation, peripheral blood mononuclear cells (PBMCs) from patients were treated with BX795, a TANK-binding kinase 1 (TBK1) inhibitor blocking RLR and DBR pathways.ResultsThe IFN-I signature was positive in 57% of cSLE patients and 15% of the HCs. Upregulated gene expression of TLR7, RLRs (IFIH1, DDX58, DDX60, DHX58) and DBRs (ZBP-1, IFI16) was observed in CD14+ monocytes of the IFN-I-positive cSLE patients. Additionally, RIG-I and ZBP-1 protein expression was upregulated in these cells. Spontaneous IFN-I stimulated gene (ISG) expression in PBMCs from cSLE patients was inhibited by a TBK1-blocker.ConclusionsIFN-I activation, assessed as ISG expression, in cSLE is associated with increased expression of TLR7, and RNA and DNA binding receptors, and these receptors contribute to IFN-I activation via TBK1 signaling. TBK1-blockers may therefore be a promising treatment target for SLE.

They Must Hold Tight: Junction Proteins, Microbiota And Immunity In Intestinal Mucosa.

Homeostasis of the immune system depends on several factors. The gastrointestinal tract plays an important role in maintaining our immune system. With this aim, the intestinal immune system interacts with epithelial barrier molecules, especially tight junction proteins, that are key molecules involved in controlling paracellular permeability to increase the protection barrier against external antigens or possibly to respond to commensal microorganisms. During intestinal inflammatory diseases, the expression of innate immune receptors in intestinal epithelial cells and infiltration of immune cells are related, but it is still unclear how the immune system induces modulation of paracellular permeability. In this review, we provide an overview of the understanding of how the immune system modulates the expression of tight junctions to maintain the mucosal immune system.

Characterization of Toll-like receptor-4 (TLR-4) in the spleen and thymus of Swiss albino mice and its modulation in experimental endotoxemia.

Expression of innate immune receptors varies among organs and species and within different strains among the same species; thus, periodic classification of different pattern recognition receptors in the available strains is necessary to initiate different therapeutic approaches to combat inflammation. On characterization of TLR-4 in spleen and thymus of Swiss albino mice—with no reports of TLR-4 expression—induced with endotoxemia, it was found that the mode of expression varied among the organs at both mRNA and protein level in a time-dependent manner. Their functionality was verified by measuring proinflammatory and anti-inflammatory cytokines. In the in vitro study using isolated macrophages and lymphocytes from the same organs, the expression of TLR-4 after a shorter period of LPS stimulation was verified. The results substantiated the potent role of macrophage on LPS challenge compared to lymphocytes. The diverse pattern of TLR-4 expression on different cell population indicated their distinct functional activity in LPS-endotoxemia. It may be hypothesized that the expression patterns of TLR-4 could be different based on the anatomical localization and the varying bacterial milieu or bacterial endotoxin encountered in each anatomical location. Thus, blocking TLR-4 or administering IL-6 or IL-10 might impart protection against endotoxemia in the clinical field.

The Ground State of Innate Immune Responsiveness Is Determined at the Interface of Genetic, Epigenetic, and Environmental Influences

Monocytes and macrophages form the major cellular component of the innate immune system, with roles in tissue development, homeostasis, and host defense against infection. Environmental factors were shown to play a significant part in determining innate immune responsiveness, and this included systemic conditions, such as circulating glucose levels, gut microflora, time of year, and even diurnal rhythm, which had a direct impact on innate immune receptor expression. Although the underlying molecular processes are just beginning to emerge, it is clear that environmental factors may alter epigenetic states of peripheral blood monocytes and resident tissue macrophages. We conclude that some measure of cellular ground state must become an essential part of the analysis of myeloid responsiveness or infectious susceptibility.

Innate Immune Receptor Expression in Peri‐Implant Tissues of Patients With Different Susceptibility to Periodontal Diseases

Although inflammation mediates the pathogenesis of periodontal diseases, the effects of innate immune responses on implant therapies have not been evaluated. Innate immune receptors, including toll-like-receptors (TLRs) and the receptor for advanced glycated end-products (RAGE), are upregulated within inflamed gingiva and are responsible for initiation of detrimental host responses. The aim of this study is to compare the expression of TLR2, TLR4, and RAGE in gingival tissues from participants susceptible to periodontitis and participants not susceptible to periodontitis before and after implant therapy. Periodontally healthy participants received implant therapy for non-periodontal edentulism. Participants susceptible to periodontitis were diagnosed with chronic periodontitis prior to implant therapy. Gingival biopsies were collected from edentulous ridges before implant installation and from peri-implant mucosa 2 months after treatment. Histology, real-time PCR, and Western blot were used to evaluate levels of inflammatory infiltrate, TLR2, TLR4, and RAGE expression. Before implant therapy, elevated levels of RAGE were detected in gingival tissues from participants susceptible to periodontitis when compared to those from participants with healthy periodontiums, whereas no differences in the expression of TLR2 or TLR4 were detected. After implant therapy, there was an upregulation of RAGE and TLR4 levels that coincided with a downregulation of TLR2 levels in biopsies from participants susceptible to periodontitis. Levels of RAGE and TLR4 remained unchanged in biopsies from participants with healthy periodontiums, whereas TLR2 levels were significantly upregulated. Histologically, post-implant biopsies from participants susceptible to periodontitis displayed higher levels of inflammatory infiltrate. Elevated levels of inflammatory potential were found after implant therapy in participants susceptible to periodontitis.

Innate Immune Deficiency of Extremely Premature Neonates Can Be Reversed by Interferon-γ

BackgroundBacterial sepsis is a major threat in neonates born prematurely, and is associated with elevated morbidity and mortality. Little is known on the innate immune response to bacteria among extremely premature infants.Methodology/Principal FindingsWe compared innate immune functions to bacteria commonly causing sepsis in 21 infants of less than 28 wks of gestational age, 24 infants born between 28 and 32 wks of gestational age, 25 term newborns and 20 healthy adults. Levels of surface expression of innate immune receptors (CD14, TLR2, TLR4, and MD-2) for Gram-positive and Gram-negative bacteria were measured in cord blood leukocytes at the time of birth. The cytokine response to bacteria of those leukocytes as well as plasma-dependent opsonophagocytosis of bacteria by target leukocytes was also measured in the presence or absence of interferon-γ. Leukocytes from extremely premature infants expressed very low levels of receptors important for bacterial recognition. Leukocyte inflammatory responses to bacteria and opsonophagocytic activity of plasma from premature infants were also severely impaired compared to term newborns or adults. These innate immune defects could be corrected when blood from premature infants was incubated ex vivo 12 hrs with interferon-γ.Conclusion/SignificancePremature infants display markedly impaired innate immune functions, which likely account for their propensity to develop bacterial sepsis during the neonatal period. The fetal innate immune response progressively matures in the last three months in utero. Ex vivo treatment of leukocytes from premature neonates with interferon-γ reversed their innate immune responses deficiency to bacteria. These data represent a promising proof-of-concept to treat premature newborns at the time of delivery with pharmacological agents aimed at maturing innate immune responses in order to prevent neonatal sepsis.

Innate immunity in the small intestine

This article reviews the most recent publications on innate immunity in the small intestine. We will go over the innate immune receptors that act as sensors of microbial presence or cell injury, Paneth cells as the main epithelial cell type that secrete antimicrobial peptides, and mucosal production of immunoglobulin A (IgA). In addition, we will give an update on examples of imbalance of the innate immune response resulting in clinical disease with the most relevant example being Crohn's disease. Toll-like receptors (TLRs) are involved in B-cell homing to the intestine, rejection of small intestinal allografts, and recruitment of mast cells. The TLR adaptor Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-β is necessary to activate innate immunity after Yersinia enterocolitica infection. Moreover, MyD88 is required to keep the intestinal microbiota under control and physically separated from the epithelium, and RegIIIγ is responsible for the bacterial segregation from the lining epithelial cells. In Crohn's disease, ATG16L1 T300A variant promotes a proinflammatory response; and miR-196 downregulates a protective immunity-related GTPase family M protein (IRGM) polymorphism leading to impaired clearance of adherent Escherichia coli in the intestine. The intestine is continuously exposed to dietary and microbial antigens. The host has to maintain intestinal homeostasis to keep the commensal and pathogenic bacteria under control. Some of the mechanisms to do so are by expression of innate immune receptors, production of antimicrobial peptides, secretion of IgA, or autophagy of intracellular bacteria. Unfortunately, in some cases the innate immune response fails to protect the host and chronic inflammation, transplant rejection, or other disorders may occur.