Host Antigens Research Articles

HLA class II profile in patients with different stages of cystic echinococcosis according to the WHO ultrasound imaging classification.

The factors involving in the natural history and determinants of different features of human cystic echinococcosis (CE) are not adequately understood. Several host-related factors including the genetic structure of the host and human leukocyte antigens (HLAs) are believed to be involved in the natural history of CE in humans. The present study was conducted to investigate the association between HLA class II genes and active and inactive stages of hepatic cystic echinococcosis. Echinococcus granulosus cyst samples and patient information were collected from the biobank of the Iranian Hydatid Disease Registry from 2019 to 2022. HLA-DRB and HLA-DQB were characterized by PCR method. CE patients were categorized into three active (CE1 and CE2), inactive (CE4 and CE5), and transitional (CE3) stages according to the WHO ultrasound classification of CE. In total, 77 participants including 38 patients (36.8% men and 63.2% women) with different stages of CE as well as 39 healthy individuals (38.5% men and 61.5% women) were included in the study. Findings of the study showed that the frequency of HLA-DRB1*03 was significantly lower in the patients compared to the healthy individuals. The frequencies of HLA-DQB and HLA-DRB alleles were not differed significantly between active, inactive, and transitional stages of E. granulosus cysts. Findings of this study indicate the potential role of this allele in the susceptibility of human to cystic echinococcosis. Further large-scale studies in different endemic countries are required to document the significance of HLA-DQB and HLA-DRB as a host-related factor in the natural history of CE in human.

Exploring computational approaches to design mRNA Vaccine against vaccinia and Mpox viruses.

Messenger RNA (mRNA) vaccines emerged as a powerful tool in the fight against infections. Unlike traditional vaccines, this unique type of vaccine elicits robust and persistent innate and humoral immune response with a unique host cell-mediated pathogen gene expression and antigen presentation. This offers a novel approach to combat poxviridae infections. From the genome of vaccinia and Mpox viruses, three key genes (E8L, E7R, and H3L) responsible for virus attachment and virulence were selected and employed for designing the candidate mRNA vaccine against vaccinia and Mpox viral infection. Various bioinformatics tools were employed to generate (B cell, CTL, and HTL) epitopes, of which 28 antigenic and immunogenic epitopes were selected and are linked to form the mRNA vaccine construct.Additional components, including a 5' cap, 5' UTR, adjuvant, 3' UTR, and poly(A) tail, were incorporated to enhance stability and effectiveness.Safety measures such as testing for human homology and in silico immune simulations were implemented to avoid autoimmunity and to mimics the immune response of human host to the designed mRNA vaccine, respectively. The mRNA vaccine's binding affinity was evaluated by docking it with TLR-2, TLR-3, TLR-4, and TLR-9 receptors which are subsequently followed by molecular dynamics simulations for the highest binding one to predict the stability of the binding complex. With a 73% population coverage, the mRNA vaccine looks promising, boasting a molecular weight of 198 kDa and a molecular formula of C8901H13609N2431O2611S48 and it is said to be antigenic, nontoxic and nonallergic, making it safe and effective in preventing infections with Mpox and vaccinia viruses, in comparison with other insilico-designed vaccine for vaccinia and Mpox viruses. However, further validation through in vivo and in vitro techniques is underway to fully assess its potential.

Immunopathological mechanisms and clinical manifestations of ocular graft-versus-host disease following hematopoietic stem cell transplantation.

Graft-versus-host disease is among themost common clinical complications following allogeneic hematopoietic stem cell transplantation. It causes inflammation-mediated destruction and dysfunction of various organ systems including ocular tissues in 60-90% of the patients and is termed ocular GVHD (oGVHD). In oGVHD, donor-derived T-cells recognize host antigens as foreign, resulting in immune dysregulation, inflammation and fibrosis of lacrimal glands, meibomian glands, cornea, and conjunctiva. The clinical presentation in oGVHD patients range from mild dry eye symptoms to catastrophic inflammation mediated pathological changes which can cause corneal perforation and blindness. In this review article, we provide detailed insights into the impact of mucosal barrier disruption, the afferent and efferent phases of immunological response involving activation of antigen presenting cells and T cells, respectively. We evaluate the evidence outlining the effector phase of the disease leading to cellular destruction and eventually fibrosis in patients with oGVHD. Finally, we discuss the well-established criteria for the diagnosis of oGVHD.

UNIQUE MONOCYTE EXPRESSION SIGNATURE IN A STXBP2 MUTATION CAUSING INFANTILE ONSET VEO-IBD AND HLH

Abstract Mutations in syntaxin-binding-protein-2 (STXBP2) can result in NK cell dysfunction leading to a hyperinflammatory state including familial HLH and infantile onset inflammatory bowel disease (IBD). While the function of STXBP2 in NK cells and cytotoxic T cells has been well described, it is highly expressed in monocytes with unclear relevance. We report the case of an infant who presented with severe infantile onset diarrhea with an identified pathogenic mutation in STXBP2. We sought to utilize scRNA-Seq to study the impact of STXBP2 deficiency on monocyte transcription, with the goal of generating insight into the pathogenesis of disease. METHODS: Trio whole exome sequencing was performed. PBMCs were collected from the described patient (case), and two control groups: 3 patients with VEO-IBD, and 3 age matched healthy controls. Single cell RNA-Seq was performed using the 10x platform and data analysis was done using Seurat in R. RESULTS: A male infant presented at 1 week of age with diarrhea and metabolic acidosis. Endoscopic evaluation at 4 weeks of age showed histologic findings of colitis and marked epithelial cell changes, including cell rounding. WES identified a homozygous pathogenic mutation in STXBP2. Due to significant risk of HLH, he underwent evaluation for stem cell transplant. However, in the interim he developed severe HLH requiring ICU level care. He recovered following aggressive treatment and underwent HSCT at 4 months of age and retransplant for graft failure at 11 months of age. He is currently in endoscopic remission off therapy. We analyzed PBMCs from the case patient using single cell RNA-Seq, as compared to patients with VEO-IBD and age-matched controls. STXBP2 expression was most enriched in monocyte populations and reduced in the case patient compared to controls. 231 and 187 genes were differentially expressed in the case monocytes as compared to both controls. The case patient had a paucity of non-classical monocytes. Within the classical monocytes, differentially expressed genes showed enrichment of host defense, cytokine processes, and apoptotic processes. Within the intermediate monocytes, differentially expressed genes showed enrichment of chemotaxis pathways, antigen presentation and T cell activation processes. CONCLUSIONS: Mutations in STXBP2 are a life-threatening cause of fHLH and infantile onset IBD. We report a case of infantile onset IBD due to a homozygous mutation in STXBP2 with resolution of disease post HSCT. Transcriptional analysis of PBMCs from this patient reveals a paucity of non-classical monocytes in the peripheral blood, and differential regulation of genes implicated in host defenses, antigen presentation, chemotaxis and apoptosis. These results may suggest the role of monocyte function in pathogenesis of STXBP2 and in other forms of IBD.

Intracellular Pathogens: Infection, Immunity, and Intervention.

Intracellular pathogens comprise a diverse group of pathogens that all share a required location in a host cell to infect, survive, and replicate. Intracellular location allows pathogens to hide from host immune responses, avoid competition with other pathogens, mediate host cellular functions, replicate safely, and cause infection that is difficult to target with therapeutics. All intracellular pathogens have varying routes of infiltration into host cells and different host cell preferences. For example, bacteria Mycobacterium tuberculosis chooses to invade antigen-presenting cells, which allows them to moderate host antigen presentation to memory cells, whereas rabies virus prefers to invade neurons because they have pre-existing innate immunity protection systems. Regardless of the pathway that each intracellular pathogen follows, all share the capacity to cause disease if they succeed in entering host cells. Here, we give an overview of selected intracellular pathogens and infections they cause, immune responses they induce, and intervention strategies used to treat and control them.

Targeting Proteasomes and the MHC Class I Antigen Presentation Machinery to Treat Cancer, Infections and Age-Related Diseases

The majority of T-cell responses involve proteasome-dependent protein degradation and the downstream presentation of oligopeptide products complexed with major histocompatibility complex (MHC) class I (MHC-I) molecules to peptide-restricted CD8+ T-cells. However, evasion of host immunity is a cancer hallmark that is achieved by disruption of host antigen processing and presentation machinery (APM). Consequently, mechanisms of immune evasion promote cancer growth and survival as well as de novo and acquired resistance to immunotherapy. A multitude of cell signaling pathways modulate the APM and MHC-I-dependent antigen presentation. Pharmacologics that specifically target and modulate proteasome structure and activity represent a novel emerging strategy to improve the treatment of cancers and other diseases characterized by aberrant protein accumulation. FDA-approved pharmacologics that selectively activate proteasomes and/or immunoproteasomes can be repositioned to overcome the current bottlenecks that hinder drug development to enhance antigen presentation, modulate the immunopeptidome, and enhance the cytotoxic activity of endogenous or engineered T-cells. Strategies to enhance antigen presentation may also improve the antitumor activity of T-cell immunotherapies, checkpoint inhibitors, and cancer vaccines. Proteasomes represent actionable therapeutic targets to treat difficult-to-treat infectious processes and neurodegenerative diseases that are characterized by the unwanted accrual of insoluble, deleterious, and potentially toxic proteins. Taken together, we highlight the breadth and magnitude of the proteasome and the immense potential to amplify and unmask the immunopeptidomic landscape to improve the treatment of a spectrum of human diseases.

Listeria monocytogenes: a promising vector for tumor immunotherapy.

Cancer receives enduring international attention due to its extremely high morbidity and mortality. Immunotherapy, which is generally expected to overcome the limits of traditional treatments, serves as a promising direction for patients with recurrent or metastatic malignancies. Bacteria-based vectors such as Listeria monocytogenes take advantage of their unique characteristics, including preferential infection of host antigen presenting cells, intracellular growth within immune cells, and intercellular dissemination, to further improve the efficacy and minimize off-target effects of tailed immune treatments. Listeria monocytogenes can reshape the tumor microenvironment to bolster the anti-tumor effects both through the enhancement of T cells activity and a decrease in the frequency and population of immunosuppressive cells. Modified Listeria monocytogenes has been employed as a tool to elicit immune responses against different tumor cells. Currently, Listeria monocytogenes vaccine alone is insufficient to treat all patients effectively, which can be addressed if combined with other treatments, such as immune checkpoint inhibitors, reactivated adoptive cell therapy, and radiotherapy. This review summarizes the recent advances in the molecular mechanisms underlying the involvement of Listeria monocytogenes vaccine in anti-tumor immunity, and discusses the most concerned issues for future research.

Host range, transmissibility and antigenicity of a pangolin coronavirus.

The pathogenic and cross-species transmission potential of SARS-CoV-2-related coronaviruses (CoVs) remain poorly characterized. Here we recovered a wild-type pangolin (Pg) CoV GD strain including derivatives encoding reporter genes using reverse genetics. In primary human cells, PgCoV replicated efficiently but with reduced fitness and showed less efficient transmission via airborne route compared with SARS-CoV-2 in hamsters. PgCoV was potently inhibited by US Food and Drug Administration approved drugs, and neutralized by COVID-19 patient sera and SARS-CoV-2 therapeutic antibodies in vitro. A pan-Sarbecovirus antibody and SARS-CoV-2 S2P recombinant protein vaccine protected BALB/c mice from PgCoV infection. In K18-hACE2 mice, PgCoV infection caused severe clinical disease, but mice were protected by a SARS-CoV-2 human antibody. Efficient PgCoV replication in primary human cells and hACE2 mice, coupled with a capacity for airborne spread, highlights an emergence potential. However, low competitive fitness, pre-immune humans and the benefit of COVID-19 countermeasures should impede its ability to spread globally in human populations.

Mining Autoimmune-Disorder-Linked Molecular-Mimicry Candidates in Clostridioides difficile and Prospects of Mimic-Based Vaccine Design: An In Silico Approach.

Molecular mimicry, a phenomenon in which microbial or environmental antigens resemble host antigens, has been proposed as a potential trigger for autoimmune responses. In this study, we employed a bioinformatics approach to investigate the role of molecular mimicry in Clostridioides difficile-caused infections and the induction of autoimmune disorders due to this phenomenon. Comparing proteomes of host and pathogen, we identified 23 proteins that exhibited significant sequence homology and were linked to autoimmune disorders. The disorders included rheumatoid arthritis, psoriasis, Alzheimer's disease, etc., while infections included viral and bacterial infections like HIV, HCV, and tuberculosis. The structure of the homologous proteins was superposed, and RMSD was calculated to find the maximum deviation, while accounting for rigid and flexible regions. Two sequence mimics (antigenic, non-allergenic, and immunogenic) of ≥10 amino acids from these proteins were used to design a vaccine construct to explore the possibility of eliciting an immune response. Docking analysis of the top vaccine construct C2 showed favorable interactions with HLA and TLR-4 receptor, indicating potential efficacy. The B-cell and T-helper cell activity was also simulated, showing promising results for effective immunization against C. difficile infections. This study highlights the potential of C. difficile to trigger autoimmunity through molecular mimicry and vaccine design based on sequence mimics that trigger a defensive response.

Transient Co-Expression of Bioactive Murine Interferon-Gamma and HBsAg in Tobacco and Lettuce Leaves

Background: The synchronous expression of antigen and adjuvant proteins in plant hosts presents an intriguing potential for vaccine production and the enhancement of appropriate immune responses. In this study, we examined the expression of bioactive murine interferon-gamma (mIFN-γ) along with HBsAg in tobacco and lettuce leaves aimed to further perform the analysis of immune responses in the mouse model.
 Methods: Monocistronic and bicistronic cassettes, carrying genes encoding mIFN-γ and HBsAg in various orders, were constructed. These cassettes were placed under the control of the 35S CaMV promoter and included the 5ʹ leader sequence of Tobacco Ech Virus (TEV). Through Agrobacterium infiltration, the cassettes were transferred into plant leaves. The concentration of mIFN-γ in different constructs and HBsAg was tested by ELISA. Murine IFN-γ was characterized through Western blotting, and its bioactivity was evaluated by assessing the up-regulation of MHC class II in macrophages derived from mouse bone marrow.
 Results: Extracts of agroinfiltrated leaves contained recombinant mIFN-γ and HBsAg proteins at about 14 unit/mg and 50 ng/mg of soluble protein, respectively. Subsequently, mIFN-γ was purified from the plant extract and its ability to up-regulate MHC class II in mouse bone marrow-derived macrophages was confirmed by immunofluorescence.
 Conclusion: The co-expression of recombinant HBsAg and mIFN-γ using TEV 5ʹ leader-based cassettes in tobacco and lettuce leaves produced both proteins with active mIFN-γ in different concentrations. The attractive utility and feasibility of using plant transient co-expression systems aimed to co-delivery of vaccine antigen and appropriate cytokine to elicit immune response for different applications.

Integrating core subtractive proteomics and reverse vaccinology for multi-epitope vaccine design against Rickettsia prowazekii endemic typhus.

Rickettsia prowazekii is an intracellular, obligate, gram-negative coccobacillus responsible for epidemic typhus. Usually, the infected body louse or its excrement when rubbed into the skin abrasions transmits the disease. The infection withR. prowazekiicauses the highest death rate (> 20% without antibiotic treatment and now 1-7%), followed by epidemic typhus, which often manifests in unsanitary conditions (up to 15-30%). Conventionally, vaccine design has required pathogen growth and both assays (in vivo and in vitro), which are costly and time-consuming. However, advancements in bioinformatics and computational biology have accelerated the development of effective vaccine designs, reducing the need for traditional, time-consuming laboratory experiments. Subtractive genomics and reverse vaccinology have become prominent computational methods for vaccine model construction. Therefore, the RefSeq sequence of Rickettsia prowazekii (strain Madrid E) (Proteome ID: UP000002480) was subjected to subtractive genomic analysis, including factors such as non-similarity to host proteome, essentiality, subcellular localization, antigenicity, non-allergenicity, and stability. Based on these parameters, the vaccine design process selected specific proteins such as outer membrane protein R (O05971_RICPR PETR; OmpR). Eventually, the OmpR was subjected to a reverse vaccinology approach that included molecular docking, immunological simulation, and the discovery of B-cell epitopes and MHC-I and MHC-II epitopes. Consequently, a chimeric or multi-epitope-based vaccine was proposed by selecting the V11 vaccine and its 3D structure modeling along with molecular docking against TLR and HLA protein, in silico simulation, and vector designing. The obtained results from this investigation resulted in a new perception of inhibitory ways against Rickettsia prowazekii by instigating novel immunogenic targets. To further assess the efficacy and protective ability of the newly designed V11 vaccine against Rickettsia prowazekii infections, additional evaluation such as in vitro or in vivo immunoassays is recommended.

Hepatic graft-versus-host disease: what we know, when to biopsy, and how to diagnose

Graft-versus-host disease (GVHD) is one of the serious complications that may develop after hematopoietic cell transplantation (HCT), for hematologic malignancies, solid organ transplantation, and other hematologic disorders. GVHD develops due to T lymphocytes present in the graft attacking the host antigens, which results in tissue damage. A significant number of HCT patients develop acute or chronic GVHD, which may affect multiple organs including the liver. The diagnosis of hepatic GVHD (hGVHD) is challenging as many other conditions in HCT patients may lead to liver dysfunction. Particularly challenging among the various conditions that give rise to liver dysfunction is differentiating sinusoidal obstruction syndromeand drug-induced liver injury (DILI) from hGVHD on clinical grounds and laboratory tests. Despite the minimal risks involved in performing a liver biopsy, the information gleaned from the histopathologic changes may help in the management of these very complex patients. There is a spectrum of histologic features found in hGVHD, and most involve histopathologic changes affecting the interlobular bile ducts. These include nuclear and cytoplasmic abnormalities including dysmorphic bile ducts, apoptosis, and cholangiocyte necrosis, among others. The hepatitic form of hGVHD typically shows severe acute hepatitis. With chronic hGVHD, there is progressive bile duct loss and eventually fibrosis. Accurate diagnosis of hGVHD is paramount so that timely treatment and management can be initiated. Techniques to prevent and lower the risk of GVHD from developing have recently evolved. If a diagnosis of acute GVHD is made, the first-line of treatment is steroids. Recurrence is common and steroid resistance or dependency is not unusual in this setting. Second-line therapies differ amonginstitutions and have not been uniformly established. The development of GVHD, particularly hGVHD, is associated with increased morbidity and mortality.

Microbiota-Gut-Brain Axis: Modulator of Host Metabolism and Appetite

The gut harbors an enormous diversity of microbes that are essential for the maintenance of homeostasis in health and disease. A growing body of evidence supports the role of this microbiota in influencing host appetite and food intake. Individual species within the gut microbiota are under selective pressure arising from nutrients available and other bacterial species present. Each bacterial species within the gut aims to increase its own fitness, habitat, and survival via specific fermentation of dietary nutrients and secretion of metabolites, many of which can influence host appetite and eating behavior by directly affecting nutrient sensing and appetite and satiety-regulating systems. These include microbiota-produced neuroactives and short-chain fatty acids. In addition, the gut microbiota is able to manipulate intestinal barrier function, interact with bile acid metabolism, modulate the immune system, and influence host antigen production, thus indirectly affecting eating behavior. A growing body of evidence indicates that there is a crucial role for the microbiota in regulating different aspects of eating-related behavior, as well as behavioral comorbidities of eating and metabolic disorders. The importance of intestinal microbiota composition has now been shown in obesity, anorexia nervosa, and forms of severe acute malnutrition. Understanding the mechanisms in which the gut microbiota can influence host appetite and metabolism will provide a better understanding of conditions wherein appetite is dysregulated, such as obesity and other metabolic or eating disorders, leading to novel biotherapeutic strategies.

IFN-γR/STAT1 signaling in recipient hematopoietic antigen-presenting cells suppresses graft-versus-host disease.

The absence of IFN-γ receptor (IFN-γR) or STAT1 signaling in donor cells has been shown to result in reduced induction of acute graft-versus-host disease (GVHD). In this study, we unexpectedly observed increased activation and expansion of donor lymphocytes in both lymphohematopoietic organs and GVHD target tissues of IFN-γR/STAT1-deficient recipient mice, leading to rapid mortality following the induction of GVHD. LPS-matured, BM-derived Ifngr1-/- Stat1-/- DCs (BMDCs) were more potent allogeneic stimulators and expressed increased levels of MHC II and costimulatory molecules. Similar effects were observed in human antigen-presenting cells (APCs) with knockdown of Stat1 by CRISPR/Cas9 and treatment with a JAK1/2 inhibitor. Furthermore, we demonstrated that the absence of IFN-γR/STAT1 signaling in hematopoietic APCs impaired the presentation of exogenous antigens, while promoting the presentation of endogenous antigens. Thus, the indirect presentation of host antigens to donor lymphocytes was defective in IFN-γR/STAT1-deficient, donor-derived APCs in fully donor chimeric mice. The differential effects of IFN-γR/STAT1 signaling on endogenous and exogenous antigen presentation could provide further insight into the roles of the IFN-γ/STAT1 signaling pathway in the pathogenesis of GVHD, organ rejection, and autoimmune diseases.

A Quantum Vaccinomics Approach for the Design and Production of MSP4 Chimeric Antigen for the Control of Anaplasma phagocytophilum Infections.

Anaplasma phagocytophilum Major surface protein 4 (MSP4) plays a role during infection and multiplication in host neutrophils and tick vector cells. Recently, vaccination trials with the A. phagocytophilum antigen MSP4 in sheep showed only partial protection against pathogen infection. However, in rabbits immunized with MSP4, this recombinant antigen was protective. Differences between rabbit and sheep antibody responses are probably associated with the recognition of non-protective epitopes by IgG of immunized lambs. To address this question, we applied quantum vaccinomics to identify and characterize MSP4 protective epitopes by a microarray epitope mapping using sera from vaccinated rabbits and sheep. The identified candidate protective epitopes or immunological quantum were used for the design and production of a chimeric protective antigen. Inhibition assays of A. phagocytophilum infection in human HL60 and Ixodes scapularis tick ISE6 cells evidenced protection by IgG from sheep and rabbits immunized with the chimeric antigen. These results supported that the design of new chimeric candidate protective antigens using quantum vaccinomics to improve the protective capacity of antigens in multiple hosts.

Role of endothelial cells in graft-versus-host disease.

To date, the only curative treatment for high-risk or refractory hematologic malignancies non-responsive to standard chemotherapy is allogeneic hematopoietic transplantation (allo-HCT). Acute graft-versus-host disease (GVHD) is a donor T cell-mediated immunological disorder that is frequently fatal and the leading cause of non-relapse mortality (NRM) in patients post allo-HCT. The pathogenesis of acute GVHD involves recognition of minor and/or major HLA mismatched host antigens by donor T cells followed by expansion, migration and finally end-organ damage due to combination of inflammatory cytokine secretion and direct cytotoxic effects. The endothelium is a thin layer of endothelial cells (EC) that line the innermost portion of the blood vessels and a key regulator in vascular homeostasis and inflammatory responses. Endothelial cells are activated by a wide range of inflammatory mediators including bacterial products, contents released from dying/apoptotic cells and cytokines and respond by secreting cytokines/chemokines that facilitate the recruitment of innate and adaptive immune cells to the site of inflammation. Endothelial cells can also be damaged prior to transplant as well as by alloreactive donor T cells. Prolonged EC activation results in dysfunction that plays a role in multiple post-transplant complications including but not limited to veno-occlusive disease (VOD), transplant associated thrombotic microangiopathy (TA-TMA), and idiopathic pneumonia syndrome. In this mini review, we summarize the biology of endothelial cells, factors regulating EC activation and the role of ECs in inflammation and GVHD pathogenesis.

Indole-3-Carbinol Supplement Reduces GvHD Related Mortality in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Introduction: Following allogeneic hematopoietic stem cell transplant (allo-HCT), donor T cells react against host antigens and cause severe graft versus host disease (GvHD) (Majhail N.S. et al., 2015. Biol Blood Marrow Transplant). Disruption of gut integrity is one of the major contributors to GvHD morbidity and mortality. Dysbiosis due to GvHD decreases host immunity and increases transplant-related mortality (Taur Y. et al., 2014. Blood). Indole, a bacterial metabolite, and indole derivatives are known to ameliorate host immunity and gut epithelial barrier function through modulating goblet cells, innate lymphoid cells (ILCs), dendritic cells (DCs) and T cell subsets (Gutiérrez-Vázquez C. & Quintana F.J., 2018. Immunity; Hubbard T.D. et al., 2015.Sci Rep). Indoles act via the aryl hydrocarbon receptor (AHR) expressed in innate lymphoid cells to generate regulatory T cells (Tregs) while inhibiting Th1 polarization (Gutiérrez-Vázquez C. & Quintana F.J., 2018. Immunity; Hubbard T.D. et al., 2015. Sci Rep). Previously, we showed that enteral administration of indole 3-carboxaldehyde (ICA) to murine allo-transplant recipients reduces GvHD severity and mortality (Swimm A. et al., 2018. Blood). However, since ICA is not available as a GMP-compliant FDA- approved pharmaceutical, our goal is to identify indoles for clinical research that have protective effects against GvHD. Here, we report that indole-3-carbinol (I3C), an indole currently marketed as a nutritional supplement, induces Treg generation and higher survival in allo-HCT. Methods: To study modulation of T cell subsets by indoles, mice were gavaged daily for 14 days with corn-oil suspensions of 50, 100, 200 or 400mg/kg of I3C, 150mg/kg of ICA, or corn oil alone. On day 15, mice were euthanized and splenocytes were isolated to study T cell subsets. To investigate the effect of I3C on GvHD, lethally irradiated (9Gy) B10.BR (H-2Kk) mice received 5 x 106 T cell-depleted bone marrow (TCDBM) cells with or without 2 x 106 T cells from MHC mismatched C57BL/6 (H-2Kb) donors. Allo-transplanted mice received either vehicle or 200mg/kg of I3C daily from day -2 to day 40. Mice were weighed and assessed twice a week for first 30 days and once a week afterwards. Lethally irradiated (9Gy) C57BL/6 mice were received 5 x 106 TCDBM cells with or without 5 x 105 T cells from FVB (H2Kq) donors and 14 days of daily gavage with vehicle or 200 mg/kg of I3C or 150mg/kg of ICA to study gut bacterial translocation into mesenteric lymph nodes (MLN). On the following day, MLNs were collected, immediately homogenized in 0.25ml sterile PBS and cultured (100ul) on Blood Agar plate to determine CFU/g tissue. Results: Percentages of regulatory T cells (Tregs) in the spleen were significantly increased at 14 days in non-transplanted mice treated with 200mg/kg of I3C (11.38%, n=5), 400mg/kg of I3C (11.48%%, n=5) and ICA (11%%, n=5) compared to mice treated with vehicle (6.74%%, n=5) (Figure 1), whereas frequencies of CD8+ T cells were unchanged. Allo-transplanted mice treated with I3C had higher survival (57.14%, n=7) compared to the vehicle-treated control group (33.33%, n=9) (Figure 2). However, weight gain was slower in the I3C-treated mice compared to surviving vehicle-treated mice. Allo-transplanted recipient mice showed trend of reduced bacterial translocation into MLNs of mice that received 200mg/kg of I3C and ICA. Our results indicate I3C supplement enhances rate of survival and decreases gut bacterial translocation into MLNs in allo-HCT recipients. Continuing experiments will study bacterial composition, histological changes, and determine mechanisms for I3C restoration of gut integrity in all-HCT recipients. Conclusion: The results above suggest indoles increase regulatory T cells. Allo-bone marrow transplant recipients treated with indoles had improved survival. We propose I3C as a prospective supplement to treat GvHD in all-HCT patients. Keywords: Allo-HCT, GvHD, Indoles, I3C, Tregs, Survival Acknowledgement: Research reported in this publication was supported in part by the Morningside Center for Innovative and Affordable Medicine through the generous support of donors and Emory University. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

HLA, gut microbiome and hepatic autoimmunity.

Genetic susceptibility to autoimmune liver diseases is conferred mainly by polymorphisms of genes encoding for the human leukocyte antigens (HLA). The strongest predisposition to autoimmune hepatitis type 1 (AIH-1) is linked to the allele DRB1*03:01, possession of which is associated with earlier disease onset and more severe course. In populations where this allele is very rare, such as in Asia, and in DRB1*03-negative patients, risk of AIH-1 is conferred by DRB1*04, which is associated with later disease onset and milder phenotype. AIH type 2 (AIH-2) is associated with DRB1*07. The pediatric condition referred to as autoimmune sclerosing cholangitis (ASC), is associated with the DRB1*13 in populations of Northern European ancestry. DRB1*1501 is protective from AIH-1, AIH-2 and ASC in Northern European populations. Possession of the DRB1*08 allele is associated with an increased risk of primary biliary cholangitis (PBC) across different populations. DRB1*03:01 and B*08:01 confer susceptibility to primary sclerosing cholangitis (PSC), as well as DRB1*13 and DRB1*15 in Europe. The hepatic blood supply is largely derived from the splanchnic circulation, suggesting a pathophysiological role of the gut microbiome. AIH appears to be associated with dysbiosis, increased gut permeability, and translocation of intestinal microbial products into the circulation; molecular mimicry between microbial and host antigens may trigger an autoaggressive response in genetically-predisposed individuals. In PBC an altered enteric microbiome may affect intestinal motility, immunological function and bile secretion. Patients with PSC have a gut microbial profile different from health as well as from patients with inflammatory bowel disease without PSC.

Abnormal antibodies to self-carbohydrates in SARS-CoV-2-infected patients.

Our immune system is critical for preventing and treating SARS-CoV-2 infections, but aberrant immune responses can have deleterious effects. While antibodies to glycans could recognize the virus and influence the clinical outcome, little is known about their roles. Using a carbohydrate antigen microarray, we profiled serum antibodies in healthy control subjects and COVID-19 patients from two separate cohorts. COVID-19 patients had numerous autoantibodies to self-glycans, including antiganglioside antibodies that can cause neurological disorders. Additionally, nearly all antiglycan IgM signals were lower in COVID-19 patients, indicating a global dysregulation of this class of antibodies. Autoantibodies to certain N-linked glycans correlated with more severe disease, as did low levels of antibodies to the Forssman antigen and ovalbumin. Collectively, this study indicates that expanded testing for antiglycan antibodies could be beneficial for clinical analysis of COVID-19 patients and illustrates the importance of including host and viral carbohydrate antigens when studying immune responses to viruses.

Is IDO1 an adequate target for treatment in glioblastoma?

e14039 Background: Glioblastoma (GB) is the most prevalent primary brain tumor in adults. The first-line treatment is based on standard brain surgery and adjuvant radio-chemotherapy. Indoleamine 2,3-dioxygenase 1 (IDO1) is a catabolic enzyme that plays a role in the metabolism of tryptophan (Trp), thereby promoting a state of immunosuppression. New treatments inhibiting this pathway are being tested in GB. This study aims to assess the expression of IDO in GB patients to determine whether this enzyme may be an actionable target for the treatment of GB. Methods: This is a retrospective transversal study whose database comes from the GLIOCAT project. Expression of IDO protein and mRNA was evaluated in tumor specimens of newly diagnosed GB patients by immunohistochemistry (IHC) (percentage of positive tumor cells) with an antibody anti-IDO1 (Sigma-Aldrich Cat#HPA027772) and by RNA sequencing (RNA-seq). RNA-seq (IIlumina HiSeq2000) in paired-end mode with a read length of 2x76bp using TruSeq SBS Kit v4). Reads were mapped to the human reference genome version hg38 with STAR. Genes were quantified with RSEM using gencode annotation version 24. Normalization of gene expression was performed with the trimmed-mean of M values (TMM) method. IDO gene expression values of -6 logCPM were considered as not expressed. Results: From the 255 samples assessed by IHC, 199 patients (78%) did not express IDO1 protein (mean 0.8±2.73, range 0-21%). From the 139 samples assessed by RNA-seq, TMM values, were negative for 49.6%, while low expression was detected for the other samples (mean -3.36 +/- 3.15 logCPM, range -6.12-4.32). Conclusions: Although IDO1 is barely expressed in normal brain tissue, certain studies show that its expression is upregulated in GB, either by tumor cells or indirectly induced in host antigen presenting cells, leading to immune evasion. Therefore, the metabolism of Trp is an attractive pathway to be targeted for the treatment of GB; however, our results show that IDO may not be the main target to be inhibited due to its undetectable or very low levels of expression.