Interleukin-10 down-regulates MHC class II alphabeta peptide complexes at the plasma membrane of monocytes by affecting arrival and recycling

Phenotype and function of IL-10 producing NK cells in individuals with malaria experience

Plasmodium falciparum infection can trigger high levels of inflammation that lead to fever and sometimes severe disease. People living in malaria-endemic areas gradually develop resistance to symptomatic malaria and control both parasite numbers and the inflammatory response. We previously found that adaptive natural killer (NK) cells correlate with reduced parasite load and protection from symptoms. We also previously found that murine NK cell production of IL-10 can protect mice from experimental cerebral malaria. Human NK cells can also secrete IL-10, but it was unknown what NK cell subsets produce IL-10 and if this is affected by malaria experience. We hypothesize that NK cell immunoregulation may lower inflammation and reduce fever induction. Here, we show that NK cells from subjects with malaria experience make significantly more IL-10 than subjects with no malaria experience. We then determined the proportions of NK cells that are cytotoxic and produce interferon gamma and/or IL-10 and identified a signature of adaptive and checkpoint molecules on IL-10-producing NK cells. Lastly, we find that co-culture with primary monocytes, Plasmodium -infected RBCs, and antibody induces IL-10 production by NK cells. These data suggest that NK cells may contribute to protection from malaria symptoms via IL-10 production.

Interleukin-22 suppresses major histocompatibility complex II in mucosal epithelial cells

Major histocompatibility complex (MHC) II is dynamically expressed on mucosal epithelial cells and is induced in response to inflammation and parasitic infections, upon exposure to microbiota, and is increased in chronic inflammatory diseases. However, the regulation of epithelial cell-specific MHC II during homeostasis is yet to be explored. We discovered a novel role for IL-22 in suppressing epithelial cell MHC II partially via the regulation of endoplasmic reticulum (ER) stress, using animals lacking the interleukin-22-receptor (IL-22RA1), primary human and murine intestinal and respiratory organoids, and murine models of respiratory virus infection or with intestinal epithelial cell defects. IL-22 directly downregulated interferon-γ-induced MHC II on primary epithelial cells by modulating the expression of MHC II antigen A α (H2-Aα) and Class II transactivator (Ciita), a master regulator of MHC II gene expression. IL-22RA1-knockouts have significantly higher MHC II expression on mucosal epithelial cells. Thus, while IL-22-based therapeutics improve pathology in chronic disease, their use may increase susceptibility to viral infections.

Mycobacterium tuberculosis impairs human memory CD4+ T cell recognition of M2 but not M1-like macrophages

Direct recognition of Mycobacterium tuberculosis (Mtb)-infected cells is required for protection by CD4+ T cells. While impaired T cell recognition of Mtb-infected macrophages was demonstrated in mice, data are lacking for humans. Using T cells and monocyte-derived macrophages (MDMs) from individuals with latent Mtb infection (LTBI), we quantified the frequency of memory CD4+ T cell activation in response to autologous MDMs infected with virulent Mtb. We observed robust T cell activation in response to Mtb infection of M1-like macrophages differentiated using GM-CSF, while M2-like macrophages differentiated using M-CSF were poorly recognized. However, non-infected GM-CSF and M-CSF MDMs loaded with exogenous antigens elicited similar CD4+ T cell activation. IL-10 was preferentially secreted by infected M-CSF MDMs, and neutralization improved T cell activation. These results suggest that preferential infection of macrophages with an M2-like phenotype limits T cell-mediated protection against Mtb. Vaccine development should focus on T cell recognition of Mtb-infected macrophages.

Cytokines as Biomarkers for Evaluating Physical Exercise in Trained and Non-Trained Individuals: A Narrative Review

Physical activity and exercise training have numerous health benefits, including the prevention and management of chronic diseases, improvement of cardiovascular health, and enhancement of mental well-being. However, the effectiveness of training programs can vary widely among individuals due to various factors, such as genetics, lifestyle, and environment. Thus, identifying reliable biomarkers to evaluate physical training effectiveness and personalize training programs is crucial. Cytokines are signaling molecules produced by immune cells that play a vital role in inflammation and tissue repair. In recent years, there has been increasing interest in the potential use of cytokines as biomarkers for evaluating training effectiveness. This review article aims to provide an overview of cytokines, their potential as biomarkers, methods for measuring cytokine levels, and factors that can affect cytokine levels. The article also discusses the potential benefits of using cytokines as biomarkers, such as monitoring muscle damage and inflammation, and the potential for personalized training programs based on cytokine responses. We believe that the use of cytokines as biomarkers holds great promise for optimizing training programs and improving overall health outcomes.

The Bowel-Associated Arthritis-Dermatosis Syndrome (BADAS): A Systematic Review

Bowel-associated arthritis-dermatosis syndrome (BADAS) is a rare neutrophilic dermatosis that was first described in 1971 in patients who underwent bypass surgery for obesity. Over the years, the number of reported cases associated with medical gastroenterological conditions, particularly inflammatory bowel disease (IBD), has progressively increased. To date, there are no systematic reviews in the literature on BADAS. The design of an a priori protocol was based on PRISMA guidelines, and a search of PubMed and Scopus databases was conducted for articles published between 1971 and 2023 related to the topic. Fifty-one articles including 113 patients with BADAS were analyzed in this systematic review. Bariatric surgery and IBD were the most frequently reported causes of BADAS, accounting for 63.7% and 24.7% of all cases, respectively. A total of 85% of cases displayed the typical dermatological presentation, including urticarial maculopapular lesions centered by a vesicopustule, with the majority of lesions located on the upper limbs (73.5%). Polyarthralgia or localized arthritis were always present. Atypical presentations included cellulitis-like, erythema-nodosum-like, Sweet-syndrome-like and pyoderma-gangrenosum-like manifestations. Gastrointestinal symptoms were frequently observed in IBD-related cases (67.9%). The histopathology showed a neutrophilic infiltrate (96.6%). The most commonly used treatment regimens consisted of systemic corticosteroids, metronidazole and tetracyclines, either alone or in combination. A relapsing-remitting course was observed in 52.1% of patients. In conclusion, BADAS is a neutrophilic dermatosis that presents with a wide variety of cutaneous manifestations, both typical and atypical. Gastrointestinal symptoms are frequently observed, particularly in cases related to IBD. The histopathology is clear but not specific compared with other neutrophilic dermatoses. The diagnosis can be challenging, but the relapsing-remitting course and the strong association with polyarthralgia and gastrointestinal disease can aid in the diagnosis.

Canine Distemper Virus Alters Defense Responses in an Ex Vivo Model of Pulmonary Infection

Canine distemper virus (CDV), belonging to the genus Morbillivirus, is a highly contagious pathogen. It is infectious in a wide range of host species, including domestic and wildlife carnivores, and causes severe systemic disease with involvement of the respiratory tract. In the present study, canine precision-cut lung slices (PCLSs) were infected with CDV (strain R252) to investigate temporospatial viral loads, cell tropism, ciliary activity, and local immune responses during early infection ex vivo. Progressive viral replication was observed during the infection period in histiocytic and, to a lesser extent, epithelial cells. CDV-infected cells were predominantly located within the bronchial subepithelial tissue. Ciliary activity was reduced in CDV-infected PCLSs, while viability remained unchanged when compared to controls. MHC-II expression was increased in the bronchial epithelium on day three postinfection. Elevated levels of anti-inflammatory cytokines (interleukin-10 and transforming growth factor-β) were observed in CDV-infected PCLSs on day one postinfection. In conclusion, the present study demonstrates that PCLSs are permissive for CDV. The model reveals an impaired ciliary function and an anti-inflammatory cytokine response, potentially fostering viral replication in the lung during the early phase of canine distemper.

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR^-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

Exercise Restores Hypothalamic Health in Obesity by Reshaping the Inflammatory Network

Obesity and overnutrition induce inflammation, leptin-, and insulin resistance in the hypothalamus. The mediobasal hypothalamus responds to exercise enabling critical adaptions at molecular and cellular level that positively impact local inflammation. This review discusses the positive effect of exercise on obesity-induced hypothalamic dysfunction, highlighting the mechanistic aspects related to the anti-inflammatory effects of exercise. In HFD-fed animals, both acute and chronic moderate-intensity exercise mitigate microgliosis and lower inflammation in the arcuate nucleus (ARC). Notably, this associates with restored leptin sensitivity and lower food intake. Exercise-induced cytokines IL-6 and IL-10 mediate part of these positive effect on the ARC in obese animals. The reduction of obesity-associated pro-inflammatory mediators (e.g., FFAs, TNFα, resistin, and AGEs), and the improvement in the gut-brain axis represent alternative paths through which regular exercise can mitigate hypothalamic inflammation. These findings suggest that the regular practice of exercise can restore a proper functionality in the hypothalamus in obesity. Further analysis investigating the crosstalk muscle-hypothalamus would help toward a deeper comprehension of the subject.

The role of the canonical nf-κb signaling pathway in the development of acute liver failure

As a clinical emergency with a high mortality rate, the treatment of acute liver failure has been paid attention to by society. At present, liver transplantation is the most effective treatment for acute liver failure, but there is still an insufficient supply of liver sources and a poor prognosis. In view of the current therapeutic development of this disease, more researchers have turned their attention to the research of drugs related to the NF-κB pathway. The NF-κB canonical pathway has been proven to play a role in a variety of diseases, regulating inflammation, apoptosis, and other physiological processes. More and more evidence shows that the NF-κB canonical pathway regulates the pathogenesis of acute liver failure. In this review, we will summarize the regulation process of the NF-κB canonical pathway on acute liver failure, and develop a new way to treat acute liver failure by targeting the components of the pathway.

Extracellular vesicles produced by the human gut commensal bacterium Bacteroides thetaiotaomicron elicit anti-inflammatory responses from innate immune cells

Bacterial extracellular vesicles (BEVs) produced by gut commensal bacteria have been proposed to play an important role in maintaining host homeostasis via interactions with the immune system. Details of the mediators and pathways of BEV-immune cell interactions are however incomplete. In this study, we provide evidence for the anti-inflammatory and immunomodulatory properties of extracellular vesicles produced by the prominent human gut commensal bacterium Bacteroides thetaiotaomicron (Bt BEVs) and identify the molecular mechanisms underlying their interaction with innate immune cells. Administration of Bt BEVs to mice treated with colitis-inducing dextran sodium sulfate (DSS) ameliorates the symptoms of intestinal inflammation, improving survival rate and reducing weight loss and disease activity index scores, in association with upregulation of IL-10 production in colonic tissue and in splenocytes. Pre-treatment (conditioning) of murine bone marrow derived monocytes (BMDM) with Bt BEVs resulted in higher ratio of IL-10/TNFα production after an LPS challenge when compared to LPS pre-conditioned or non-conditioned BMDM. Using the THP-1 monocytic cell line the interactions between Bt BEVs and monocytes/macrophages were shown to be mediated primarily by TLR2. Histone (H3K4me1) methylation analysis showed that Bt BEVs induced epigenetic reprogramming which persisted after infectious challenge, as revealed by increased levels of H3K4me1 in Bt BEV-conditioned LPS-challenged BMDM. Collectively, our findings highlight the important role of Bt BEVs in maintaining host immune homeostasis and raise the promising possibility of considering their use in immune therapies.

Increased frequency of CD14+HLA-DR-/low cells in type 2 diabetes patients with poor glycemic control

AIMS

Type 2 diabetes (T2DM) is associated with alterations of the immune response and T2DM patients have an increased risk for infections and certain sorts of cancers. Although CD14⁺HLA-DR^-/low cells have emerged as important mediators of immunosuppression in several pathologies, including cancer and non-malignant diseases, the presence of these cells in T2DM is not fully characterized.

METHODS

In this study, we evaluated the frequency of CD14⁺HLA-DR^-/low cells in non-obese T2DM patients and their association with glycemic control. Peripheral blood mononuclear cells were isolated from healthy controls (HC, n = 24) and non-obese T2DM patients (n = 25), the population was evaluated by flow cytometry, and an analysis of correlation between cell frequencies and clinical variables was performed.

RESULTS

CD14⁺HLA-DR^-/low monocytes were expanded in patients with T2DM compared to HC regardless of weight. Among the subjects with T2DM, the frequency of CD14⁺HLA-DR^-/low was higher in patients with poor glycemic control (HbA1c > 9%) compared to those with better glycemic control (HbA1c < 9%) and, positively correlated with the years since the diagnosis of T2DM, the age of the patients and the glycemic index.

CONCLUSIONS

An increased frequency of CD14⁺HLA-DR^-/low cells in the blood of T2DM patients was recorded. The influence of hyperglycemia seems to be independent of obesity, but related to glycemic control and age.

MHCII Expression on Peripheral Blood Monocytes in Canine Lymphoma: An Impact of Glucocorticoids

Simple Summary

Loss or decreased expression of human leukocyte antigen—D-related (HLA-DR) on the surface of monocytes is related to the dysfunction of the immune system and was reported in human neoplasia, including lymphoma. Canine lymphoma is frequently presented as a valuable comparative model for studies on human non-Hodgkin’s lymphoma. However, there are no studies on the expression of analogue proteins—MHCII antigens—on monocytes in canine lymphoma. In this study, we have evaluated the changes in the expression of MHCII on monocytes in the blood of dogs with lymphoma before any treatment and in dogs that had previously received glucocorticoids. Glucocorticoids are often used by clinicians as first drugs after diagnosis for immediate health improvement and are known to impact monocyte number. We have shown an increase in the percentage of MHCII− monocytes, regardless of treatment. However, only in dogs that had received glucocorticoids were changes in the proportion of MHCII+ and MHCII− monocytes reflected also by the changes in the number of MHCII− monocytes in the blood, which was significantly higher. Evaluating the changes in canine monocytes might be helpful in the diagnosis of various tumor types, monitoring of the treatment or assessing the immune status of dogs.

Abstract

An increase in the percentage of monocytes with reduced HLA-DR expression and immunosuppressive properties has been reported in numerous human neoplastic diseases, including lymphoma. However, there are no analogous studies on phenotypical variations in the peripheral blood monocytes in dogs with lymphoma. The aim of this study was to determine the difference in the expression of the MHCII molecule on peripheral blood monocytes in dogs with lymphoma before any treatment (NRG) and in dogs that had previously received glucocorticoids (RG) in comparison to healthy dogs. Flow cytometry immunophenotyping of peripheral blood leukocytes was performed using canine-specific or cross-reactive antibodies against CD11b, CD14 and MHCII. In the blood of dogs with lymphoma (NRG and RG), compared to that of healthy ones, the MHCII+ and MHCII− monocytes ratio was changed due to an increase in the percentage of MHCII− monocytes. The number of MHCII− monocytes was significantly higher only in RG dogs compared to healthy ones, which might result from the release of these cells from the blood marginal pool due to the action of glucocorticoids. Our results encourage further studies to assess if changes in MHCII expression affect immune status in dogs with lymphoma.

Unravelling the sex-specific diversity and functions of adrenal gland macrophages

Despite the ubiquitous function of macrophages across the body, the diversity, origin, and function of adrenal gland macrophages remain largely unknown. We define the heterogeneity of adrenal gland immune cells using single-cell RNA sequencing and use genetic models to explore the developmental mechanisms yielding macrophage diversity. We define populations of monocyte-derived and embryonically seeded adrenal gland macrophages and identify a female-specific subset with low major histocompatibility complex (MHC) class II expression. In adulthood, monocyte recruitment dominates adrenal gland macrophage maintenance in female mice. Adrenal gland macrophage sub-tissular distribution follows a sex-dimorphic pattern, with MHC class II^low macrophages located at the cortico-medullary junction. Macrophage sex dimorphism depends on the presence of the cortical X-zone. Adrenal gland macrophage depletion results in altered tissue homeostasis, modulated lipid metabolism, and decreased local aldosterone production during stress exposure. Overall, these data reveal the heterogeneity of adrenal gland macrophages and point toward sex-restricted distribution and functions of these cells.

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Adrenal glands contain multiple macrophage populations

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Macrophage sex dimorphism depends on the presence of the cortical X zone

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Embryonic and monocyte-derived macrophages co-exist in adrenal glands

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Adrenal gland macrophage depletion alters tissue lipid metabolism

RNASE2 Mediates Age-Associated B Cell Expansion Through Monocyte Derived IL-10 in Patients With Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is characterized by the production of pathogenic autoantibodies. Ribonuclease A family member 2 (RNase2) is known to have antiviral activity and immunomodulatory function. Although RNASE2 level has been reported to be elevated in SLE patients based on mRNA microarray detection, its pathologic mechanism remains unclear. Here, we confirmed that RNASE2 was highly expressed in PBMCs from SLE patients and associated with the proportion of CD11c⁺T-bet⁺ B cells, a class of autoreactive B cells also known as age-associated B cells (ABCs). We showed that reduction of RNASE2 expression by small interfering RNA led to the decrease of ABCs in vitro, accompanied by total IgG and IL-10 reduction. In addition, we demonstrated that both RNASE2 and IL-10 in peripheral blood of lupus patients were mainly derived from monocytes. RNASE2 silencing in monocytes down-regulated IL-10 production and consequently reduced ABCs numbers in monocyte-B cell co-cultures, which could be restored by the addition of recombinant IL-10. Based on above findings, we concluded that RNASE2 might induce the production of ABCs via IL-10 secreted from monocytes, thus contributing to the pathogenesis of SLE.

Histidine-rich glycoprotein (HRGP): Pleiotropic and paradoxical effects on macrophage, tumor microenvironment, angiogenesis, and other physiological and pathological processes

Histidine-rich glycoprotein (HRGP) is a relatively less known glycoprotein, but it is abundant in plasma with a multidomain structure, which allows it to interact with many ligands and regulate various biological processes. HRGP ligands includes heme, Zn²⁺, thrombospondin, plasmin/plasminogen, heparin/heparan sulfate, fibrinogen, tropomyosin, IgG, FcγR, C1q. In many conditions, the histidine-rich region of HRGP strengthens ligand binding following interaction with Zn²⁺ or exposure to low pH, such as sites of tissue injury or tumor growth. The multidomain structure and diverse ligand binding attributes of HRGP indicates that it can act as an extracellular adaptor protein, connecting with different ligands, especially on cell surfaces. Also, HRGP can selectively target IgG, which blocks the production of soluble immune complexes. The most common cell surface ligand of HRGP is heparan sulfate proteoglycan, and the interaction is also potentiated by elevated Zn²⁺ concentration and low pH. Recent reports have shown that HRGP can modulate macrophage polarization and possibly regulate other physiological processes such as angiogenesis, anti-tumor immune response, fibrinolysis and coagulation, soluble immune complex clearance and phagocytosis of apoptotic/necrosis cells. In addition, it has also been reported that HRGP has antibacterial and anti-HIV infection effects and may be used as a novel clinical biomarker accordingly. This review outlines the molecular, structural and biological properties of HRGP as well as presenting an update on the function of HRGP in various physiological processes.

Early IL-10 promotes vasculature-associated CD4+ T cells unable to control Mycobacterium tuberculosis infection

Cytokine-producing CD4⁺ T cells play a crucial role in the control of Mycobacterium tuberculosis infection; however, there is a delayed appearance of effector T cells in the lungs following aerosol infection. The immunomodulatory cytokine IL-10 antagonizes control of M. tuberculosis infection through mechanisms associated with reduced CD4⁺ T cell responses. Here, we show that IL-10 overexpression only before the onset of the T cell response impaired control of M. tuberculosis growth; during chronic infection, IL-10 overexpression reduced the CD4⁺ T cell response without affecting the outcome of infection. IL-10 overexpression early during infection did not, we found, significantly impair the kinetics of CD4⁺ T cell priming and effector differentiation. However, CD4⁺ T cells primed and differentiated in an IL-10–enriched environment displayed reduced expression of CXCR3 and, because they did not migrate into the lung parenchyma, their ability to control infection was limited. Importantly, these CD4⁺ T cells maintained their vasculature phenotype and were unable to control infection, even after adoptive transfer into low IL-10 settings. Together our data support a model wherein, during M. tuberculosis infection, IL-10 acts intrinsically on T cells, impairing their parenchymal migratory capacity and ability to engage with infected phagocytic cells, thereby impeding control of infection.

Upregulation of type 1 conventional dendritic cells implicates antigen cross-presentation in multisystem inflammatory syndrome

Background

Multisystem inflammatory syndrome in children (MIS-C) is an acute, febrile, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated syndrome, often with cardiohemodynamic dysfunction. Insight into mechanism of disease is still incomplete.

Objective

Our objective was to analyze immunologic features of MIS-C patients compared to febrile controls (FC).

Methods

MIS-C patients were defined by narrow criteria, including having evidence of cardiohemodynamic involvement and no macrophage activation syndrome. Samples were collected from 8 completely treatment-naive patients with MIS-C (SARS-CoV-2 serology positive), 3 patients with unclassified MIS-C–like disease (serology negative), 14 FC, and 5 MIS-C recovery (RCV). Three healthy controls (HCs) were used for comparisons of normal range. Using spectral flow cytometry, we assessed 36 parameters in antigen-presenting cells (APCs) and 29 in T cells. We used biaxial analysis and uniform manifold approximation and projection (UMAP).

Results

Significant elevations in cytokines including CXCL9, M-CSF, and IL-27 were found in MIS-C compared to FC. Classic monocytes and type 2 dendritic cells (DCs) were downregulated (decreased CD86, HLA-DR) versus HCs; however, type 1 DCs (CD11c⁺CD141⁺CLEC9A⁺) were highly activated in MIS-C patients versus FC, expressing higher levels of CD86, CD275, and atypical conventional DC markers such as CD64, CD115, and CX3CR1. CD169 and CD38 were upregulated in multiple monocyte subtypes. CD56^dim/CD57⁻/KLRG^hi/CD161⁺/CD38⁻ natural killer (NK) cells were a unique subset in MIS-C versus FC without macrophage activation syndrome.

Conclusion

Orchestrated by complex cytokine signaling, type 1 DC activation and NK dysregulation are key features in the pathophysiology of MIS-C. NK cell findings may suggest a relationship with macrophage activation syndrome, while type 1 DC upregulation implies a role for antigen cross-presentation.

Exercise tolls the bell for key mediators of low-grade inflammation in dysmetabolic conditions

Metabolic conditions share a common low-grade inflammatory milieu, which represents a key-factor for their ignition and maintenance. Exercise is instrumental for warranting systemic cardio-metabolic balance, owing to its regulatory effect on inflammation. This review explores the effect of physical activity in the modulation of sub-inflammatory framework characterizing dysmetabolic conditions. Regular exercise suppresses plasma levels of TNFα, IL-1β, FFAs and MCP-1, in dysmetabolic subjects. In addition, a single session of training increases the anti-inflammatory IL-10, IL-1 receptor antagonist (IL-1ra), and muscle-derived IL-6, mitigating low-grade inflammation. Resting IL-6 levels are decreased in trained-dysmetabolic subjects, compared to sedentary. On the other hand, the acute release of muscle-IL-6, after exercise, seems to exert a regulatory effect on the metabolic and inflammatory balance. In fact, muscle-released IL-6 is presumably implicated in fat loss and boosts plasma levels of IL-10 and IL-1ra. The improvement of adipose tissue functionality, following regular exercise, is also critical for the mitigation of sub-inflammation. This effect is likely mediated by muscle-released IL-15 and IL-6 and partly relies on the brown-shifting of white adipocytes, induced by exercise. In obese-dysmetabolic subjects, moderate training is shown to restore gut-microbiota health, and this mitigates the translocation of bacterial-LPS into bloodstream. Finally, regular exercise can lower plasma advanced glycated endproducts. The articulated physiology of circulating mediators and the modulating effect of the pathophysiological background, render the comprehension of the exercise-regulatory effect on sub-inflammation a key issue, in dysmetabolism.

Uptake, recognition and responses to peptidoglycan in the mammalian host

Microbiota, and the plethora of signalling molecules that they generate, are a major driving force that underlies a striking range of inter-individual physioanatomic and behavioural consequences for the host organism. Among the bacterial effectors, one finds peptidoglycan, the major constituent of the bacterial cell surface. In the steady-state, fragments of peptidoglycan are constitutively liberated from bacterial members of the gut microbiota, cross the gut epithelial barrier and enter the host system. The fate of these peptidoglycan fragments, and the outcome for the host, depends on the molecular nature of the peptidoglycan, as well the cellular profile of the recipient tissue, mechanism of cell entry, the expression of specific processing and recognition mechanisms by the cell, and the local immune context. At the target level, physiological processes modulated by peptidoglycan are extremely diverse, ranging from immune activation to small molecule metabolism, autophagy and apoptosis. In this review, we bring together a fragmented body of literature on the kinetics and dynamics of peptidoglycan interactions with the mammalian host, explaining how peptidoglycan functions as a signalling molecule in the host under physiological conditions, how it disseminates within the host, and the cellular responses to peptidoglycan.

Extracellular Vesicles Secreted by Tumor Cells Promote the Generation of Suppressive Monocytes

Monocytes are among the first cells to infiltrate the tumor microenvironment. The conversion of monocytes to suppressor cells in the tumor microenvironment is crucial in evasion of the immune response and tumor maintenance. Tumor cells may secrete products that promote the conversion of monocytes to suppressor cells. Cells secrete extracellular vesicles (EVs) containing cargos of genetic materials and proteins as a way to communicate with neighboring cells. During pathologic conditions like cancers, tumor cells increase their EVs production containing microRNA, RNA, and proteins that may affect the immune cell response, contributing to the immunosuppressive microenvironment. Our studies show that EVs secreted by a wide range of murine tumor cells, including osteosarcoma, glioma, colon carcinoma, sarcoma, and melanoma, can be taken up by bone marrow-derived monocytes. The monocytes that took up the EVs secreted by tumor cells matured toward an immune-suppressive phenotype by upregulating the expression of suppressive cytokines and effector molecules. The monocytes also downregulated MHC class II and costimulatory molecules while increasing the expression of PD-L1 on their surface after taking up EVs from tumor cells. Most importantly, monocytes exposed to EVs secreted by tumor cells suppressed activated Ag-specific CD4+ T cells. These results show that tumor cells from several different tumor types secrete EVs which promote the conversion of monocytes into suppressor cells, thus promoting immune evasion. These studies suggest that EVs secreted by tumors are potentially a new target for future cancer therapy.

IgG Epitopes Processed and Presented by IgG+ B Cells Induce Suppression by Human Thymic-Derived Regulatory T Cells

We described a human regulatory T cell (Treg) population activated by IgG⁺ B cells presenting peptides of the heavy C region (Fc) via processing of the surface IgG underlying a model for B cell-Treg cooperation in the human immune regulation. Functionally, Treg inhibited the polarization of naive T cells toward a proinflammatory phenotype in both a cognate and a noncognate fashion. Their fine specificities were similar in healthy donors and patients with rheumatoid arthritis, a systemic autoimmune disease. Four immunodominant Fc peptides bound multiple HLA class II alleles and were recognized by most subjects in the two cohorts. The presentation of Fc peptides that stimulate Treg through the processing of IgG by dendritic cells (DC) occurred in myeloid DC classical DC 1 and classical DC 2. Different routes of Ag processing of the IgG impacted Treg expansion in rheumatoid arthritis patients.

Surgical Site Infections and Perioperative Optimization of Host Immunity by Selection of Anesthetics

Surgical site infections are significant health care issues, and efforts to mitigate their occurrence have been ongoing worldwide, mainly focusing to reduce the spillage of microbes to the otherwise sterile tissues. Optimization of host immunity has been also recognized including temperature regulation (normothermia), adequate oxygenation, and glucose management. A number of papers have described the role of anesthetics in host immunity. The role of anesthetics in postoperative outcomes including surgical site infections has been also studied. We will review the current literature and propose the importance of anesthetic selection to potentially mitigate surgical site infections.

Modulating Th2 Cell Immunity for the Treatment of Asthma

It is estimated that more than 339 million people worldwide suffer from asthma. The leading cause of asthma development is the breakdown of immune tolerance to inhaled allergens, prompting the immune system's aberrant activation. During the early phase, also known as the sensitization phase, allergen-specific T cells are activated and become central players in orchestrating the subsequent development of allergic asthma following secondary exposure to the same allergens. It is well-established that allergen-specific T helper 2 (Th2) cells play central roles in developing allergic asthma. As such, 80% of children and 60% of adult asthma cases are linked to an unwarranted Th2 cell response against respiratory allergens. Thus, targeting essential components of Th2-type inflammation using neutralizing antibodies against key Th2 modulators has recently become an attractive option for asthmatic patients with moderate to severe symptoms. In addition to directly targeting Th2 mediators, allergen immunotherapy, also known as desensitization, is focused on redirecting the allergen-specific T cells response from a Th2-type profile to a tolerogenic one. This review highlights the current understanding of the heterogeneity of the Th2 cell compartment, their contribution to allergen-induced airway inflammation, and the therapies targeting the Th2 cell pathway in asthma. Further, we discuss available new leads for successful targeting pulmonary Th2 cell responses for future therapeutics.

Suppressive Effects of a Truncated Inhibitor K562 Protein-Derived Peptide on Two Proinflammatory Cytokines, IL-17 and TNF-α

Inhibitor K562 (IK) protein was first isolated from the culture medium of K562 cells, a leukemia cell line, and is an inhibitory regulator of interferon-γ-induced major histocompatibility complex class II expression. Recently, exogenous truncated IK (tIK) protein showed potential as a therapeutic agent for inflammation-related diseases. In this study, we designed a novel putative anti-inflammatory peptide derived from tIK protein based on homology modeling of the human interleukin-10 (hIL-10) structure, and investigated whether the peptide exerted inhibitory effects against proinflammatory cytokines such as IL-17 and tumor necrosis factor-α (TNF-α). The peptide contains key residues involved in binding hIL-10 to the IL-10 receptor, and exerted strong inhibitory effects on IL- 17 (43.8%) and TNF-α (50.7%). In addition, we used circular dichroism spectroscopy to confirm that the peptide is usually present in a random coil configuration in aqueous solution. In terms of toxicity, the peptide was found to be biologically safe. The mechanisms by which the short peptide derived from human tIK protein exerts inhibitory effects against IL-17 and TNF-α should be explored further. We also evaluated the feasibility of using this novel peptide in skincare products.

High PD-L1/CD274 Expression of Monocytes and Blood Dendritic Cells Is a Risk Factor in Lung Cancer Patients Undergoing Treatment with PD1 Inhibitor Therapy

Simple Summary

Tumor cells can evade destruction via immune cells by expressing coinhibitory membrane molecules, which suppress antitumoral immune responses. Immune checkpoint inhibitor therapy acts by blocking these inhibitory pathways. Although this type of immunotherapy has shown promising results for selected cancer patients during recent years, an important challenge remains to identify baseline characteristics of patients who will mostly benefit from such therapy. The aim of our study was to assess the expression of the coinhibitory molecule PD-L1/CD274 on different antigen-presenting cells (monocytes and dendritic cell subsets) in the peripheral blood of 35 patients with nonsmall cell lung cancer undergoing checkpoint inhibitor therapy. CD274 expression correlated with therapy response and the survival of patients. Tumor patients with high CD274 expression levels of antigen-presenting cells in blood rarely responded to checkpoint inhibitor therapy. Our results implicate that a high CD274 expression in monocytes and dendritic cell subsets is a risk factor for therapy response.

Abstract

The aim of this study was to investigate the expression of the coinhibitory molecule PD-L1/CD274 in monocytes and dendritic cells (DC) in the blood of lung cancer patients undergoing PD1 inhibitor therapy and to correlate data with patient’s outcome. PD-L1/CD274 expression of monocytes, CD1c⁺ myeloid DC (mDC) and CD303⁺ plasmacytoid DC (pDC) was determined by flow cytometry in peripheral blood at immunotherapy onset. The predictive value of the PD-L1/CD274-expression data was determined by patients’ survival analysis. Patients with a high PD-L1/CD274 expression of monocytes and blood DC subpopulations rarely responded to PD1 inhibitor therapy. Low PD-L1/CD274 expression of monocytes and DC correlated with prolonged progression-free survival (PFS) as well as overall survival (OS). The highest PD-L1/CD274 expression was found in CD14⁺HLA-DR⁺⁺CD16⁺ intermediate monocytes. Whereas the PD-L1/CD274 expression of monocytes and DC showed a strong positive correlation, only the PD-L1/CD274 expression of DC inversely correlated with DC amounts and lymphocyte counts in peripheral blood. Our results implicate that a high PD-L1/CD274 expression of blood monocytes and DC subtypes is a risk factor for therapy response and for the survival of lung cancer patients undergoing PD1 inhibitor therapy.

Suppression of Cisplatin-Induced Hepatic Injury in Rats Through Alarmin High-Mobility Group Box-1 Pathway by Ganoderma lucidum: Theoretical and Experimental Study

Purpose

Drug-induced liver injury (DILI) is the most common cause of acute liver failure. The aim of this study was to investigate the molecular mechanisms by which Ganoderma lucidum mushroom (GLM) may ameliorate cisplatin (CP)-induced hepatotoxicity theoretically and experimentally.

Materials and Methods

Thirty-six male Sprague-Dawley (SD) rats were divided into six groups, two of them are normal and Ganoderma lucidum control groups. Liver injury was induced by a single dose of CP (12 mg/kg i.p) in four groups, one of them is CP control group. Besides cisplatin injection in day 1, rats in groups (4–6) were subjected to GLM (500 mg/kg/day) either every other day or daily oral dose or via i.p injection for 10 consecutive days.

Results

In this study, GLM supplementation caused significant reduction of elevated high-mobility group box-1 (HMGB-1) with a concurrent decline in TNF-α and upregulation of IL-10 compared to the CP group (P<0.05). The histopathological and fibrosis evaluation significantly confirmed the improvement upon simultaneous treatment with GLM. Moreover, immunohistochemical examination also confirmed the recovery following GLM treatment indicated by downregulation of NF-κB, p53 and caspase-3 along with upsurge of B-cell lymphoma 2 (Bcl-2) expression (P<0.05). GLM treatment significantly decreased serum levels of hepatic injury markers; ALT, AST, T. bilirubin as well as oxidative stress markers; MDA and H₂O₂ with a concomitant increase in hepatic GSH and SOD. Also, the performed docking simulation of ganoderic acid exhibited good fitting and binding with HMGB-1 through hydrogen bond formation with conservative amino acids which gives a strong evidence for its hepatoprotective effect and may interpret the effect of Ganoderma lucidum.

Conclusion

GLM attenuated hepatic injury through downregulation of HMGB-1/NF-kB and caspase-3 resulted in modulation of the induced oxidative stress and the subsequent cross-talk between the inflammatory and apoptotic cascade indicating its promising role in DILI.

The role of neutrophil chemotaxis activity as an immunologic biomarker to predict mortality in critically-ill patients with severe sepsis

BACKGROUND

Innate immunity is an important host response to infection. However, the role of innate immunity as a prognostic biomarker in severe sepsis is still unknown. This study is to evaluate the discriminatory characteristics of these biomarkers on clinical outcome.

MATERIALS AND METHODS

Retrospective study was conducted in critically ill patients with severe sepsis. Neutrophil function was assessed by neutrophil chemotaxis activity and CD-11b expression. Monocyte function was assessed by measurement of mHLA-DR expression and presepsin level. The primary end point was 28 day-mortality.

RESULTS

A total of 136 participants were enrolled. Patients were classified into 2 groups as survivors (n = 63, 46.3%) and non-survivors (n = 73, 53.7%). Neutrophil chemotaxis activity was significantly higher in survivors (46.7% vs. 41.2%, p = .023). There was no difference in the remaining biomarker levels between survivors and non-survivors. Only decreased neutrophil chemotaxis activity was associated with 28-day mortality. Combining neutrophil chemotaxis activity with mHLA-DR, CD-11b expression, presepsin, and SOFA score provided the highest AUC of 0.90 (0.84-0.96) in predicting 28-day mortality.

CONCLUSION

Neutrophil chemotaxis activity appears to be a promising novel immunologic biomarker in predicting clinical outcome in patients with severe sepsis.

Curcumin Nanoparticles Enhance Mycobacterium bovis BCG Vaccine Efficacy by Modulating Host Immune Responses

Tuberculosis (TB) is one of the deadliest diseases, causing ∼2 million deaths annually worldwide. Mycobacterium bovis bacillus Calmette-Guérin (BCG), the only TB vaccine in common use, is effective against disseminated and meningeal TB in young children but is not effective against adult pulmonary TB.

Tuberculosis (TB) is one of the deadliest diseases, causing ∼2 million deaths annually worldwide. Mycobacterium bovis bacillus Calmette-Guérin (BCG), the only TB vaccine in common use, is effective against disseminated and meningeal TB in young children but is not effective against adult pulmonary TB. T helper 1 (Th1) cells producing interferon gamma (IFN-γ) and Th17 cells producing interleukin-17 (IL-17) play key roles in host protection against TB, whereas Th2 cells producing IL-4 and regulatory T cells (Tregs) facilitate TB disease progression by inhibiting protective Th1 and Th17 responses. Furthermore, the longevity of vaccine efficacy critically depends on the magnitude of long-lasting central memory T (T_CM) cell responses. Hence, immunomodulators that promote T_CM responses of the Th1 and Th17 cell lineages may improve BCG vaccine efficacy. Here, we show that curcumin nanoparticles enhance various antigen-presenting cell (APC) functions, including autophagy, costimulatory activity, and the production of inflammatory cytokines and other mediators. We further show that curcumin nanoparticles enhance the capacity of BCG to induce T_CM cells of the Th1 and Th17 lineages, which augments host protection against TB infection. Thus, curcumin nanoparticles hold promise for enhancing the efficacy of TB vaccines.

Antigen processing and presentation

Dendritic cells are at the center of immune responses. They are defined by their ability to sense the environment, take up and process antigen, migrate to secondary lymphoid organs, where they present antigens to the adaptive immune system. In particular, they present lipids and proteins from pathogens, which they encountered in peripheral tissues, to T cells in order to induce a specific effector immune response. These complex antigens need to be broken down into peptides of a certain length in association with Major Histocompatibility Complex (MHC) molecules. Presentation of MHC/antigen complexes alongside costimulatory molecules and secretion of proinflammatory cytokines will induce an appropriate immune response. This interaction between dendritic cells and T cells takes place at defined locations within secondary lymphoid organs. In this review, we discuss the current knowledge and recent advances on the cellular and molecular mechanisms that underlie antigen processing and the subsequent presentation to T lymphocytes.

The CD14+HLA-DRlo/neg Monocyte: An Immunosuppressive Phenotype That Restrains Responses to Cancer Immunotherapy

Recent successes in cancer immunotherapy have been tempered by sub-optimal clinical responses in the majority of patients. The impaired anti-tumor immune responses observed in these patients are likely a consequence of immune system dysfunction contributed to by a variety of factors that include, but are not limited to, diminished antigen presentation/detection, leukopenia, a coordinated network of immunosuppressive cell surface proteins, cytokines and cellular mediators. Monocytes that have diminished or no HLA-DR expression, called CD14⁺HLA-DR^lo/neg monocytes, have emerged as important mediators of tumor-induced immunosuppression. These cells have been grouped into a larger class of suppressive cells called myeloid derived suppressor cells (MDSCs) and are commonly referred to as monocytic myeloid derived suppressor cells. CD14⁺HLA-DR^lo/neg monocytes were first characterized in patients with sepsis and were shown to regulate the transition from the inflammatory state to immune suppression, ultimately leading to immune paralysis. These immunosuppressive monocytes have also recently been shown to negatively affect responses to PD-1 and CTLA-4 checkpoint inhibition, CAR-T cell therapy, cancer vaccines, and hematopoietic stem cell transplantation. Ultimately, the goal is to understand the role of these cells in the context of immunosuppression not only to facilitate the development of targeted therapies to circumvent their effects, but also to potentially use them as a biomarker for understanding disparate responses to immunotherapeutic regimens. Practical aspects to be explored for development of CD14⁺HLA-DR^lo/neg monocyte detection in patients are the standardization of flow cytometric gating methods to assess HLA-DR expression, an appropriate quantitation method, test sample type, and processing guidances. Once detection methods are established that yield consistently reproducible results, then further progress can be made toward understanding the role of CD14⁺HLA-DR^lo/neg monocytes in the immunosuppressive state.

The supernatant of cervical carcinoma cells lines induces a decrease in phosphorylation of STAT-1 and NF-κB transcription factors associated with changes in profiles of cytokines and growth factors in macrophages derived from U937 cells

Macrophages are presents in the tumor microenvironment and acquire different phenotypic and functional characteristics in response to microenvironmental signals. Macrophages can be differentiated into two phenotypes: M1 or pro-inflammatory (classically activated), and M2 or anti-inflammatory macrophage (alternatively activated). In response to the microenvironment, macrophages activate transcription factors as STAT1 and NF-κB-p65 for M1 macrophages or STAT3 and STAT6 for M2 macrophages; activation impacts on the profile of cytokine, chemokines and growth factors secreted by macrophages. We evaluated the effect of the supernatant of cervical-derived carcinoma cell lines HeLa, SiHa, and C-33A on the phosphorylation of transcriptional factors STAT1, NF-κB-p65, and STAT6, and their impact in the profile of secretion of cytokines and growth factors by macrophages derived from the U937 cell line. The results show that in macrophages, these supernatants induce a decrease in the phosphorylation of NF-κB-p65 and STAT1 in U937-macrophages accompanied by an increase in the secretion of IL-10, IL-6, MCP-1, and IL-8, as well as GM-CSF, G-CSF, PDGF-AA, PDGF-BB, and VEGF. Our results suggest that HeLa, SiHa, and C-33A cell lines down-regulate the activation of transcription factors characteristic of M1 macrophages (STAT1, NF-κB-p65) and induce the secretion of factors that favor tumor growth.

Diabetes alters immune response patterns to acute melioidosis in humans

Diabetes mellitus (DM) is a serious global health problem currently affecting over 450 million people worldwide. Defining its interaction with major global infections is an international public health priority. Melioidosis is caused by Burkholderia pseudomallei, an exemplar pathogen for studying intracellular bacterial infection in the context of DM due to the 12‐fold increased risk in this group. We characterized immune correlates of survival in peripheral blood of acute melioidosis patients with and without DM and highlight different immune response patterns. We demonstrate the importance of circulating NK cells and show that CX3CR1 expression on lymphocytes is a novel correlate of survival from acute melioidosis. Furthermore, excessive serum levels of IL‐15 and IL‐18BP contribute to poor outcome independent of DM comorbidity. CD8⁺ T cells and granzyme B expression in NK cells are important for survival of non‐DM patients, whereas high antibody titers against B. pseudomallei and double‐negative T cells are linked to survival of DM patients. Recall responses support a role of γδ T‐cell‐derived IFN‐γ in the establishment of protective immunity in the DM group. Defining the hallmarks of protection in people with DM is crucial for the design of new therapies and vaccines targeting this rapidly expanding risk group.

T cell subsets: an integral component in pathogenesis of rheumatic heart disease

Acute rheumatic fever (ARF) is a consequence of pharyngeal infection of group A streptococcal (GAS) infection. Carditis is the most common manifestation of ARF which occurs in 30-45% of the susceptible individuals. Overlooked ARF cases might further progress towards rheumatic heart disease (RHD) in susceptible individuals, which ultimately leads to permanent heart valve damage. Molecular mimicry between streptococcal antigens and human proteins is the most widely accepted theory to describe the pathogenesis of RHD. In the recent past, various subsets of T cells have been reported to play an imperative role in the pathogenesis of RHD. Alterations in various T cell subsets, viz. Th1, Th2, Th17, and Treg cells, and their signature cytokines influence the immune responses and are associated with pathogenesis of RHD. Association of other T cell subsets (Th3, Th9, Th22, and T_FH) is not defined in context of RHD. Several investigations have confirmed the up-regulation of adhesion molecules and thus infiltration of T cells into the heart tissues. T cells secrete both Th type 1 and type 2 cytokines and these auto-reactive T cells play a key role in progression of heart valve damage. In this review, we are going to discuss about the role of T cell subsets and their corresponding cytokines in the pathogenesis of RHD.

Pathophysiology of Acute Illness and Injury

The pathophysiology of acute illness and injury recognizes three main effectors: infection, trauma, and ischemia-reperfusion injury. Each of them can act by itself or in combination with the other two in developing a systemic inflammatory reaction syndrome (SIRS) that is a generalized reaction to the morbid event. The time course of SIRS is variable and influenced by the number and severity of subsequent insults (e.g., reparative surgery, acquired hospital infections). It occurs simultaneously with a complex of counter-regulatory mechanisms (compensatory anti-inflammatory response syndrome, CARS) that limit the aggressive effects of SIRS. In adjunct, a progressive dysfunction of the acquired (lymphocytes) immune system develops with increased risk for immunoparalysis and associated infectious complications. Both humoral and cellular effectors participate to the development of SIRS and CARS. The most important humoral mediators are pro-inflammatory (IL-1β, IL-6, IL-8, IL-12) and anti-inflammatory (IL-4, IL-10) cytokines and chemokines, complement, leukotrienes, and PAF. Effector cells include neutrophils, monocytes, macrophages, lymphocytes, and endothelial cells. The endothelium is a key factor for production of remote organ damage as it exerts potent chemo-attracting effects on inflammatory cells, allows for leukocyte trafficking into tissues and organs, and promotes further inflammation by cytokines release. Moreover, the loss of vasoregulatory properties and the increased permeability contribute to the development of hypotension and tissue edema. Finally, the disseminated activation of the coagulation cascade causes the widespread deposition of microthrombi with resulting maldistribution of capillary blood flow and ultimately hypoxic cellular damage. This mechanism together with increased vascular permeability and vasodilation is responsible for the development of the multiple organ dysfunction syndrome (MODS).

PEGylated IL-10 (Pegilodecakin) Induces Systemic Immune Activation, CD8+ T Cell Invigoration and Polyclonal T Cell Expansion in Cancer Patients

Tumor-reactive T cell exhaustion prevents the success of immune therapies. Pegilodecakin activates intratumoral CD8⁺ T cells in mice and induces objective tumor responses in patients. Here we report that pegilodecakin induces hallmarks of CD8⁺ T cell immunity in cancer patients, including elevation of interferon-γ and GranzymeB, expansion and activation of intratumoral CD8⁺ T cells, and proliferation and expansion of LAG-3⁺ PD-1⁺ CD8⁺ T cells. On pegilodecakin, newly expanded T cell clones, undetectable at baseline, become 1%-10% of the total T cell repertoire in the blood. Elevation of interleukin-18, expansion of LAG-3⁺ PD-1⁺ T cells and novel T cell clones each correlated with objective tumor responses. Combined pegilodecakin with anti-PD-1 increased the expansion of LAG-3⁺ PD-1⁺ CD8⁺ T cells.

Cell death at the cross roads of host-pathogen interaction in Mycobacterium tuberculosis infection

Tuberculosis (TB) continues to be the leading cause of death by any single infectious agent, accounting for around 1.7 million annual deaths globally, despite several interventions and support programs by national and international agencies. With the development of drug resistance in Mycobacterium tuberculosis (M. tb), there has been a paradigm shift in TB research towards host-directed therapy. The potential targets include the interactions between host and bacterial proteins that are crucial for pathogenesis. Hence, collective efforts are being made to understand the molecular details of host-pathogen interaction for possible translation into host-directed therapy. The present review focuses on 'host cell death modalities' of host-pathogen interaction, which play a crucial role in determining the outcome of TB disease progression. Several cell death modalities that occur in response to mycobacterial infection have been identified in human macrophages either as host defences for bacterial clearance or as pathogen strategies for multiplication and dissemination. These cell death modalities include apoptosis, necrosis, pyroptosis, necroptosis, pyronecrosis, NETosis, and autophagy. These processes are highly overlapping with several mycobacterial proteins participating in more than one cell death pathway. Until now, reviews in M. tb and host cell death have discussed either focusing on host evasion strategies, apoptosis, autophagy, and necrosis or describing all these forms with limited discussions of their role in host-pathogen interactions. Here, we present a comprehensive review of various mycobacterial factors modulating host cell death pathways and the cross-talk between them. Besides this, we have discussed the networking of host cell death pathways including the interference of host miRNA during M. tb infection with their respective targets. Through this review, we present the host targets that overlap across several cell death modalities and the technical limitations of methodology in cell death research. Given the compelling need to discover alternative drug target(s), this review identifies these overlapping cell death factors as potential targets for host-directed therapy.

March1-dependent modulation of donor MHC II on CD103+ dendritic cells mitigates alloimmunity

In transplantation, donor dendritic cells (do-DCs) initiate the alloimmune response either by direct interaction with host T cells or by transferring intact donor MHC to host DCs. However, how do-DCs can be targeted for improving allograft survival is still unclear. Here we show CD103⁺ DCs are the major do-DC subset involved in the acute rejection of murine skin transplants. In the absence of CD103⁺ do-DCs, less donor MHC-II is carried to host lymph nodes, fewer allogenic T cells are primed and allograft survival is prolonged. Incubation of skin grafts with the anti-inflammatory mycobacterial protein DnaK reduces donor MHC-II on CD103⁺DCs and prolongs graft survival. This effect is mediated through IL-10-induced March1, which ubiquitinates and decreases MHC-II levels. Importantly, in vitro pre-treatment of human DCs with DnaK reduces their ability to prime alloreactive T cells. Our findings demonstrate a novel therapeutic approach to dampen alloimmunity by targeting donor MHC-II on CD103⁺DCs.

Donor-derived dendritic cells (do-DC) in the graft can contribute to the induction of alloimmunity and tissue rejection, but how do-DC can be targeted for improving graft survival is unclear. Here the authors show that reducing MHC-II expression on do-DCs by DnaK pre-treatment can decrease the priming of alloimmunity and prolong graft survival in mouse models.

Association between HLA-DR Expression and Multidrug-resistant Infection in Patients with Severe Acute Pancreatitis

Multidrug-resistant (MDR) bacterial infection is a common complication of severe acute pancreatitis (SAP). This study aimed to explore the association between human leukocyte antigen-antigen D-related (HLA-DR) expression and multidrug-resistant infection in patients with SAP. A total of 24 SAP patients who were admitted to Nanjing Drum Tower Hospital between May 2015 and December 2016 were enrolled in the study. The percentages of CD4+, CD8+, natural killer (NK), and HLA-DR (CD14+) cells and the CD4+/CD8+ cell ratio on days 1,7,14, and 28 after admission were determined by flow cytometry. Eighteen patients presented with the symptoms of infection. Among them, 55.6% patients (10/18) developed MDR infection. The most common causative MDR organisms were Enterobacter cloacae and Acinetobacter baumannii. The CD4+/CD8+ cell ratio and the percentage of NK cells were similar between patients with non-MDR and patients with MDR infections. In patients without infection, the HLA-DR percentage was maintained at a high level throughout the 28 days. Compared to the patients without any infection, the HLA-DR percentage in patients with non-MDR infection was reduced on day 1 but increased and reached similar levels on day 28. In patients with MDR infection, the HLA-DR percentage remained below normal levels at all-time points. It was concluded that persistent down-regulation of HLA-DR expression is associated with MDR bacterial infection in patients with SAP.

Interleukin-10-Producing DC-10 Is a Unique Tool to Promote Tolerance Via Antigen-Specific T Regulatory Type 1 Cells

The prominent role of tolerogenic dendritic cells (tolDCs) in promoting immune tolerance and the development of efficient methods to generate clinical grade products allow the application of tolDCs as cell-based approach to dampen antigen (Ag)-specific T cell responses in autoimmunity and transplantation. Interleukin (IL)-10 potently modulates the differentiation and functions of myeloid cells. Our group contributed to the identification of IL-10 as key factor in inducing a subset of human tolDCs, named dendritic cell (DC)-10, endowed with the ability to spontaneously release IL-10 and induce Ag-specific T regulatory type 1 (Tr1) cells. We will provide an overview on the role of IL-10 in modulating myeloid cells and in promoting DC-10. Moreover, we will discuss the clinical application of DC-10 as inducers of Ag-specific Tr1 cells for tailoring Tr1-based cell therapy, and as cell product for promoting and restoring tolerance in T-cell-mediated diseases.

Sepsis-Induced Immunosuppression in Neonates

Neonates, especially those born preterm, are at increased risk of sepsis and adverse long-term effects associated with infection-related inflammation. Distinct neonatal immune responses and dysregulated inflammation are central to this unique susceptibility. The traditional separation of sepsis into an initial hyper-inflammatory response followed by hypo-inflammation is continually under review with new developments in this area of research. There is evidence to support the association of mortality in the early acute phase of sepsis with an overwhelming hyper-inflammatory immune response. Emerging evidence from adults suggests that hypo- and hyper-inflammation can occur during any phase of sepsis and that sepsis-immunosuppression is associated with increased mortality, morbidity, and risk to subsequent infection. In adults, sepsis-induced immunosuppression (SII) is characterised by alterations of innate and adaptive immune responses, including, but not limited to, a prominent bias toward anti-inflammatory cytokine secretion, diminished antigen presentation to T cells, and reduced activation and proliferation of T cells. It is unclear if sepsis-immunosuppression also plays a role in the adverse outcomes associated with neonatal sepsis. This review will focus on exploring if key characteristics associated with SII in adults are observed in neonates with sepsis.

Immune Function in Critically Ill Dogs

Background

People with critical illness (CI) commonly develop various forms of immune dysfunction, however, there is limited information concerning immune dysfunction in dogs with CI.

Hypothesis

The immune response in CI dogs differs from that of healthy dogs.

Animals

Immunologic variables were compared between 14 dogs with CI, defined as APPLE_fast score of >20 points, admitted to the University of Missouri Veterinary Health Center Small Animal Clinic Intensive Care Unit and healthy controls (n = 15).

Methods

Cohort study evaluating constitutive and lipopolysaccharide (LPS)‐stimulated TNF‐α, IL‐6, and IL‐10 production, phagocytosis of opsonized E. coli and respiratory burst capacity after opsonized E. coli or phorbol 12‐myristate 13‐acetate (PMA) stimulation, peripheral blood lymphocyte phenotype, and monocyte expressions of HLA‐DR and TLR‐4.

Results

Lipopolysaccharide‐stimulated leukocyte TNF‐α (median, Q1, Q3; CI, 49, 49, 120; control, 655, 446, 1174 pg/mL; P = < 0.001), IL‐6 (median, Q1, Q3; CI, 49, 49, 64; control, 100, 49, 166 pg/mL; P = 0.029), and IL‐10 (CI, 49, 49, 56; control, 96, 49, 203 pg/mL; P = 0.014) production and both E. coli (median, Q1, Q3; CI, 60.5, 43, 88.5; control, 86.6, 81, 89.2%; P = 0.047) and PMA (CI, 40, 11.7, 70; control, 93, 83, 97.6%; P = < 0.001)‐stimulated respiratory burst capacity significantly decreased in CI dogs. Percentage of monocytes expressing TLR‐4 greater in the CI dogs (median, Q1, Q3; CI, 46.9, 24.3, 64.2; control, 16.4, 9.4, 26.2%; P = 0.005).

Conclusion

These findings suggest dogs with CI develop immune system alterations that result in reduced respiratory burst function and cytokine production despite upregulation of TLR‐4.

Therapeutic Effect of Exogenous Truncated IK Protein in Inflammatory Arthritis

Inhibitor K562 (IK) protein was first isolated from the culture medium of K562, a leukemia cell line. It is known to be an inhibitory regulator of interferon-γ-induced major histocompatibility complex class (MHC) II expression. Previously, we found that transgenic (Tg) mice constitutively expressing truncated IK (tIK) showed reduced numbers of pathogenic Th1 and Th17 cells, which are known to be involved in the development of rheumatoid arthritis (RA). Here, we investigated whether exogenous tIK protein has a therapeutic effect in arthritis in disease models and analyzed its mechanism. Exogenous tIK protein was produced in an insect expression system and applied to the collagen antibody-induced arthritis (CAIA) mouse disease model. Injection of tIK protein alleviated the symptoms of arthritis in the CAIA model and reduced Th1 and Th17 cell populations. In addition, treatment of cultured T cells with tIK protein induced expression of A20, a negative regulator of nuclear factor-κB (NFκB)-induced inflammation, and reduced expression of several transcription factors related to T cell activation. We conclude that exogenous tIK protein has the potential to act as a new therapeutic agent for RA patients, because it has a different mode of action to biopharmaceutical agents, such as tumor necrosis factor antagonists, that are currently used to treat RA.

Zoonotic intestinal helminths interact with the canine immune system by modulating T cell responses and preventing dendritic cell maturation

Parasite co-evolution alongside the mammalian immune system gave rise to several modulatory strategies by which they prevent exaggerated pathology and facilitate a longer worm survival. As little is known about the immunoregulatory potential of the zoonotic canine parasites Ancylostoma caninum and Toxocara canis in the natural host, the present study aimed to investigate whether their larval excretory-secretory (ES) products can modulate the canine immune system. We demonstrated TcES to increase the frequency of CD4+ Foxp3^high T cells, while both AcES and TcES were associated with elevated Helios expression in Foxp3^high lymphocytes. ES products were further capable of inducing IL-10 production by lymphocytes, which was mainly attributed to CD8+ T cells. ES treatment of PBMCs prior to mitogen stimulation inhibited polyclonal proliferation of CD4+ and CD8+ T cells. Moreover, monocyte-derived ES-pulsed dendritic cells reduced upregulation of MHC-II and CD80 in response to lipopolysaccharide. The data showed that regulation of the canine immune system by A. caninum and T. canis larvae comprises the modification of antigen-specific and polyclonal T cell responses and dendritic cell maturation.

The MHC class II antigen presentation pathway in human monocytes differs by subset and is regulated by cytokines

Monocytes play a critical role in the innate and adaptive immune systems, performing phagocytosis, presenting antigen, and producing cytokines. They are a heterogeneous population that has been divided in humans into classical, intermediate, and non-classical subsets, but the roles of these subsets are incompletely understood. In this study, we investigated the expression patterns of MHC class II (MHCII) and associated molecules and find that the intermediate monocytes express the highest levels of the MHC molecules, HLA-DR (tested in n = 30 samples), HLA-DP (n = 30), and HLA-DQ (n = 10). HLA-DM (n = 30), which catalyzes the peptide exchange on the MHC molecules, is also expressed at the highest levels in intermediate monocytes. To measure HLA-DM function, we measured levels of MHCII-bound CLIP (class II invariant chain peptide, n = 23), which is exchanged for other peptides by HLA-DM. We calculated CLIP:MHCII ratios to normalize CLIP levels to MHCII levels, and found that intermediate monocytes have the lowest CLIP:MHCII ratio. We isolated the different monocyte subsets (in a total of 7 samples) and analyzed their responses to selected cytokines as model of monocyte activation: two M1-polarizing cytokines (IFNγ, GM-CSF), an M2-polarizing cytokine (IL-4) and IL-10. Classical monocytes exhibit the largest increases in class II pathway expression in response to stimulatory cytokines (IFNγ, GM-CSF, IL-4). All three subsets decrease HLA-DR levels after IL-10 exposure. Our findings argue that intermediate monocytes are the most efficient constitutive antigen presenting subset, that classical monocytes are recruited into an antigen presentation role during inflammatory responses and that IL-10 negatively regulates this function across all subsets.

Reduction of T-Helper Cell Responses to Recall Antigen Mediated by Codelivery with Peptidoglycan via the Intestinal Nanomineral-Antigen Pathway

Naturally occurring intestinal nanomineral particles constituently form in the mammalian gut and trap luminal protein and microbial components. These cargo loaded nanominerals are actively scavenged by M cells of intestinal immune follicles, such as Peyer’s patches and are passed to antigen-presenting cells. Using peripheral blood mononuclear cell populations as an in vitro model of nanomineral uptake and antigen presentation, we show that monocytes avidly phagocytose nanomineral particles bearing antigen and peptidoglycan (PGN), and that the presence of PGN within particles downregulates their cell surface MHC class II and upregulates programmed death receptor ligand 1. Nanomineral delivery of antigen suppresses antigen-specific CD4⁺ T cell responses, an effect that is enhanced in the presence of PGN. Blocking the interleukin-10 receptor restores CD4⁺ T cell responses to antigen codelivered with PGN in nanomineral form. Using human intestinal specimens, we have shown that the in vivo nanomineral pathway operates in an interleukin-10 rich environment. Consequently, the delivery of a dual antigen–PGN cargo by endogenous nanomineral in vivo is likely to be important in the establishment of intestinal tolerance, while their synthetic mimetics present a potential delivery system for therapeutic applications targeting the modulation of Peyer’s patch T cell responses.

Structural and Functional Characterization of Recombinant Interleukin-10 from Indian Major Carp Labeo rohita

Interleukin-10, an important regulator of both the innate and adaptive immune systems, is a multifunctional major cytokine. Though it is one of the major cytokines, IL-10 from the Indian major carp, Labeo rohita, has not yet been characterized. In the present study, we report large scale production and purification of biologically active recombinant IL-10 of L. rohita (rLrIL-10) using a heterologous expression system and its biophysical and functional characterization. High yield (~70 mg/L) of soluble rLrIL-10 was obtained at shake flask level. The rLrIL-10 was found to exist as a dimer. Far-UV CD spectroscopy showed presence of predominantly alpha helices. The tertiary structure of the purified rLrIL-10 was verified by fluorescence spectroscopy. Two-dimensional gel analysis revealed the presence of six isoforms of the rLrIL-10. The rLrIL-10 was biologically active and its administration significantly reduced serum proinflammatory cytokines, namely, interleukin 1β, TNFα, and IL-8, and augmented the NKEF transcript levels in spleen of L. rohita. Anti-inflammatory role of the rLrIL-10 was further established by inhibition of phagocytosis using NBT reduction assay in vitro. The data indicate that the dimeric alpha helical structure and function of IL-10 of L. rohita as a key regulator of anti-inflammatory response have remained conserved during evolution.

Pediatric Respiratory and Systemic Effects of Chronic Air Pollution Exposure: Nose, Lung, Heart, and Brain Pathology

Exposures to particulate matter and gaseous air pollutants have been associated with respiratory tract inflammation, disruption of the nasal respiratory and olfactory barriers, systemic inflammation, production of mediators of inflammation capable of reaching the brain and systemic circulation of particulate matter. Mexico City (MC) residents are exposed to significant amounts of ozone, particulate matter and associated lipopolysaccharides. MC dogs exhibit brain inflammation and an acceleration of Alzheimer’s-like pathology, suggesting that the brain is adversely affected by air pollutants. MC children, adolescents and adults have a significant upregulation of cyclooxygenase-2 (COX2) and interleukin-1β (IL-1β) in olfactory bulb and frontal cortex, as well as neuronal and astrocytic accumulation of the 42 amino acid form of β-amyloid peptide (Aβ42), including diffuse amyloid plaques in frontal cortex. The pathogenesis of Alzheimer’s disease (AD) is characterized by brain inflammation and the accumulation of Aβ42, which precede the appearance of neuritic plaques and neurofibrillary tangles, the pathological hallmarks of AD. Our findings of nasal barrier disruption, systemic inflammation, and the upregulation of COX2 and IL-1β expression and Aβ42 accumulation in brain suggests that sustained exposures to significant concentrations of air pollutants such as particulate matter could be a risk factor for AD and other neurodegenerative diseases.