Innate Immune Function Research Articles

Transcriptional reprogramming from innate immune functions to a pro-thrombotic signature by monocytes in COVID-19

Although alterations in myeloid cells have been observed in COVID-19, the specific underlying mechanisms are not completely understood. Here, we examine the function of classical CD14+ monocytes in patients with mild and moderate COVID-19 during the acute phase of infection and in healthy individuals. Monocytes from COVID-19 patients display altered expression of cell surface receptors and a dysfunctional metabolic profile that distinguish them from healthy monocytes. Secondary pathogen sensing ex vivo leads to defects in pro-inflammatory cytokine and type-I IFN production in moderate COVID-19 cases, together with defects in glycolysis. COVID-19 monocytes switch their gene expression profile from canonical innate immune to pro-thrombotic signatures and are functionally pro-thrombotic, both at baseline and following ex vivo stimulation with SARS-CoV-2. Transcriptionally, COVID-19 monocytes are characterized by enrichment of pathways involved in hemostasis, immunothrombosis, platelet aggregation and other accessory pathways to platelet activation and clot formation. These results identify a potential mechanism by which monocyte dysfunction may contribute to COVID-19 pathology.

Role of Adenylyl Cyclase Type 7 in Functions of BV-2 Microglia.

To assess the role of adenylyl cyclase type 7 (AC7) in microglia's immune function, we generated AC7 gene knockout (AC7 KO) clones from a mouse microglial cell line, BV-2, using the CRISPR-Cas9 gene editing system. The ability of BV-2 cells to generate cAMP and their innate immune functions were examined in the presence or absence of ethanol. The parental BV-2 cells showed robust cAMP production when stimulated with prostaglandin-E1 (PGE1) and ethanol increased cAMP production in a dose-dependent manner. AC7 KO clones of BV-2 cells showed diminished and ethanol-insensitive cAMP production. The phagocytic activity of the parental BV-2 cells was inhibited in the presence of PGE1; AC7 KO BV-2 cells showed lower and PGE1-insensitive phagocytic activity. Innate immune activities of the parental BV-2 cells, including bacterial killing, nitric oxide synthesis, and expression of arginase 1 and interleukin 10 were activated as expected with small effects of ethanol. However, the innate immune activities of AC7 KO cells were either drastically diminished or not detected. The data presented suggest that AC7 has an important role in the innate immune functions of microglial cells. AC7's involvement in ethanol's effects on immune functions remains unclear. Further studies are needed.

CfIRF8-like interacts with the TBK1/IKKε family protein and regulates host antiviral innate immunity

The interferon regulatory factor (IRF) family, a class of transcription factors with key functions, are important in host innate immune defense and stress response. However, further research is required to determine the functions of IRFs in invertebrates. In this study, the coding sequence of an IRF gene was obtained from the Zhikong scallop (Chlamys farreri) and named CfIRF8-like. The open reading frame of CfIRF8-like was 1371 bp long and encoded 456 amino acids. Protein domain prediction revealed a typical IRF domain in the N-terminus of the CfIRF8-like protein and a typical IRF3 domain in the C-terminus. Multiple sequence alignment confirmed the conservation of the amino acid sequences of these two functional protein domains. Phylogenetic analysis showed that CfIRF8-like clustered with mollusk IRF8 proteins and then clustered with vertebrate IRF3, IRF4, and IRF5 subfamily proteins. Quantitative real-time PCR detected CfIRF8-like mRNA in all tested scallop tissues, with the highest expression in the gills. Simultaneously, the expression of CfIRF8-like transcripts in gills was significantly induced by polyinosinic–polycytidylic acid challenge. The results of protein interaction experiments showed that CfIRF8-like could directly bind the TBK1/IKKε family protein of scallop (CfIKK2) via its N-terminal IRF domain, revealing the presence of an ancient functional TBK1/IKKε-IRF signaling axis in scallops. Finally, dual-luciferase reporter assay results showed that the overexpression of CfIRF8-like in human embryonic kidney 293T cells could specifically activate the interferon β promoter of mammals and the interferon-stimulated response element promoter in dose-dependent manners. The findings of this preliminary analysis of the signal transduction and immune functions of scallop CfIRF8-like protein lay a foundation for an in-depth understanding of the innate immune function of invertebrate IRFs and the development of comparative immunology. The experimental results also provide theoretical support for the breeding of scallop disease-resistant strains.

A somatic hypermutation-based machine learning model stratifies individuals with Crohn's disease and controls.

Crohn's disease (CD) is a chronic relapsing-remitting inflammatory disorder of the gastrointestinal tract that is characterized by altered innate and adaptive immune function. Although massively parallel sequencing studies of the T cell receptor repertoire identified oligoclonal expansion of unique clones, much less is known about the B cell receptor (BCR) repertoire in CD. Here, we present a novel BCR repertoire sequencing data set from ileal biopsies from pediatric patients with CD and controls, and identify CD-specific somatic hypermutation (SHM) patterns, revealed by a machine learning (ML) algorithm trained on BCR repertoire sequences. Moreover, ML classification of a different data set from blood samples of adults with CD versus controls identified that V gene usage, clusters, or mutation frequencies yielded excellent results in classifying the disease (F1 > 90%). In summary, we show that an ML algorithm enables the classification of CD based on unique BCR repertoire features with high accuracy.

611: HOST IMMUNE ENDOTYPING IN PEDIATRIC ACUTE RESPIRATORY FAILURE

Introduction: Acute respiratory failure (ARF) is a common reason for admission to the pediatric intensive care unit (PICU). The ability to immune endotype critically ill children with ARF to understand if adaptive or innate defects belie severity of illness, and then modulate these defects by evaluating therapies in an ex vivo fashion may be paradigm shifting. We have previously shown that T-cell IFN-γ (adaptive) and monocyte TNF-α (innate) production, as quantitated by the Enzyme-Linked Immune Absorbent Spot (ELISpot) assay, reflect immune competence in COVID-19 pneumonia, and illness severity is associated with decreased circulating lymphocytes with innate and adaptive immune suppression, evidenced by decreased IFN-ɣ and TNF-α production. This promising approach may have significant benefits in critically ill children, as it is unknown if specific measures of innate and adaptive immune function correlate with illness severity. We hypothesize that serial quantitative analysis of IFN-γ and TNF-α production by ELISpot will accurately reflect host immune status in critically ill children with ARF. Methods: In this IRB approved prospective cohort study, children admitted to the PICU with ARF had serial blood analysis using ELISpot for IFN-γ and TNF-α production after positive stimulus with CD3/28 and LPS respectively. ELISpot reporting for cytokine production is done as number of cells secreting the relevant cytokine; data was compared to relevant patient metadata and clinical outcomes. Results: We are currently enrolling patients, and have analyzed two patients with ARF secondary to pneumonia. Patient 1 had 19 cells secreting IFN-ɣ on day 1 and 69 cells on day 5; and 582 cells secreting TNF-α on day 1 and 1217 cells on day 5. Patient 2 had 18 cells secreting IFN-ɣ on day 1 and 144 cells on day 5; and 189 cells secreting TNF-α on day 1 and 466 cells on day 5. Conclusions: Preliminary analysis of IFN-γ and TNF-α production by ELISpot shows surprisingly more IFN-γ reduction early in disease course, which may be a driver of viral replication and severity of illness. Over 5 days, both patients had appropriately hyper inflammatory innate responses. With improved power and additional time points, there is potential to introduce adaptive stimulants early in disease trajectory that may alter clinical outcomes.

27: PRE-CARDIOPULMONARY BYPASS BIOMARKERS PREDICT POOR OUTCOMES IN NEONATAL CONGENITAL HEART DISEASE

Introduction: Neonates requiring cardiopulmonary bypass (CPB) for congenital heart disease have higher rates of postoperative mortality and morbidity than older children. However, identified risk factors for poor outcome to date have been limited to non-modifiable demographic or surgical factors. We aimed to identify novel biomarkers measured preoperatively that correlate with poor outcomes. Methods: Plasma samples were collected immediately prior to CPB in 65 consented subjects. Twenty-eight soluble analytes were measured via individual or multiplexed ELISA and tested for association with the validated “ICU-30” composite poor outcome, defined as (1) mortality within 30 days of CPB, (2) ICU stay >30 days, or (3) ICU readmission within 30 days. Differences in biomarker concentrations between subjects with and without ICU-30 were assessed using a Wilcoxon rank sum test. Associations of standardized biomarkers and ICU-30 was tested with logistic regression, adjusting for surgical complexity. Results: Samples for 63 patients were included for analysis (2 subjects did not undergo CPB after blood collection); 18 subjects (28%) had the ICU-30 outcome. Patients with ICU-30 were more likely to have a chromosomal abnormality, with no difference in gestational age or birth weight. There was no difference between age at CPB surgery and CPB time during operation. Seven biomarkers differed between those with and without ICU-30: angiopoietin 2, interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, growth differentiation factor-15, C-C motif ligand 2 (CCL2), and neutrophil gelatinase-associated lipocalin (NGAL) were higher in patients with ICU-30, and ADAMTS13 (A disintegrin and metalloproteinase with thrombospondin motifs 13) was lower in those with ICU-30. When controlling for STAT category, TNF-alpha (aOR 5.4, 95% CI 1.6-19.0), IL-6 (aOR 3.0, 95% CI 1.3-6.8), CCL2 (aOR 2.6, 95% CI 1.3-5.2), and NGAL (aOR 2.6, 95% CI 1.3-5.1) were associated with ICU-30. Conclusions: Four novel preoperative plasma biomarkers implicating innate immunity and renal function were associated with worse outcomes in neonates requiring CPB independent of STAT operation. Biomarkers have the potential to identify preoperative risk factors and mechanistic pathways for prognostication and targeted therapeutic interventions.

Essential immune functions of fibroblasts in innate host defense.

The term fibroblast has been used generally to describe spindle-shaped stromal cells of mesenchymal origin that produce extracellular matrix, establish tissue structure, and form scar. Current evidence has found that cells with this morphology are highly heterogeneous with some fibroblastic cells actively participating in both innate and adaptive immune defense. Detailed analysis of barrier tissues such as skin, gut, and lung now show that some fibroblasts directly sense pathogens and other danger signals to elicit host defense functions including antimicrobial activity, leukocyte recruitment, and production of cytokines and lipid mediators relevant to inflammation and immunosuppression. This review will synthesize current literature focused on the innate immune functions performed by fibroblasts at barrier tissues to highlight the previously unappreciated importance of these cells in immunity.

Innate immune function during antineoplastic treatment is associated with 12-months survival in non-small cell lung cancer.

The immune system has proven to be a key player in the progression as well as containment of cancer with new treatment strategies based on immunotherapy targeting this interaction. Assessing immune function could reveal critical information about the immune response to therapeutic interventions, revealing predictive biomarkers for tailored care and precision medicine. We investigated immune function in 37 patients with inoperable non-small cell lung cancer (NSCLC) undergoing treatment with PD-L1 immune checkpoint inhibitor (ICI), chemotherapy (CT) or chemo-radiotherapy (CT/RT). Blood samples before (day 0) and during therapy (day 7, 21 and 80) were investigated by a standardized immunoassay, TruCulture®. Outcomes revealed a developing innate immune response induced by both immunotherapy and chemotherapy. NSCLC-patients displayed evidence of chronic innate immune activation and exhaustion prior to treatment. This pattern was particularly pronounced during treatment in patients dying within 12-months follow-up. Compared to treatment with CT, ICI demonstrated a higher ex vivo-stimulated release of proinflammatory cytokines. These preliminary findings may pave the way for tailored treatment and immune-monitoring.

TRNA-like Transcripts from the NEAT1-MALAT1 Genomic Region Critically Influence Human Innate Immunity and Macrophage Functions.

The evolutionary conserved NEAT1-MALAT1 gene cluster generates large noncoding transcripts remaining nuclear, while tRNA-like transcripts (mascRNA, menRNA) enzymatically generated from these precursors translocate to the cytosol. Whereas functions have been assigned to the nuclear transcripts, data on biological functions of the small cytosolic transcripts are sparse. We previously found NEAT1-/- and MALAT1-/- mice to display massive atherosclerosis and vascular inflammation. Here, employing selective targeted disruption of menRNA or mascRNA, we investigate the tRNA-like molecules as critical components of innate immunity. CRISPR-generated human ΔmascRNA and ΔmenRNA monocytes/macrophages display defective innate immune sensing, loss of cytokine control, imbalance of growth/angiogenic factor expression impacting upon angiogenesis, and altered cell-cell interaction systems. Antiviral response, foam cell formation/oxLDL uptake, and M1/M2 polarization are defective in ΔmascRNA/ΔmenRNA macrophages, defining first biological functions of menRNA and describing new functions of mascRNA. menRNA and mascRNA represent novel components of innate immunity arising from the noncoding genome. They appear as prototypes of a new class of noncoding RNAs distinct from others (miRNAs, siRNAs) by biosynthetic pathway and intracellular kinetics. Their NEAT1-MALAT1 region of origin appears as archetype of a functionally highly integrated RNA processing system.

Immunomodulatory drug fingolimod (FTY720) restricts the growth of opportunistic yeast Candida albicans in vitro and in a mouse candidiasis model.

Fingolimod (FTY720) is a drug derived from the fungicidal compound myriocin. As it was unclear whether FTY720 has antifungal effects as well, we aimed to characterize its effect on Candida albicans in vitro and in a mouse candidiasis model. First, antifungal susceptibility testing was performed in vitro. Then, a randomized, six-arm, parallel, open-label trial was conducted on 48 mice receiving oral FTY720 (0.3 mg/kg/day), intraperitoneal C. albicans inoculation, or placebo with different combinations and chorological patterns. The outcome measures of the trial included serum concentrations of interleukin-10 and interferon-gamma, absolute lymphocyte counts, and fungal burden values in the mice's livers, kidneys, and vaginas. Broth microdilution assay revealed FTY720's minimum inhibitory concentration (MIC99) to be 0.25 mg/mL for C. albicans. The infected mice treated with FTY720 showed lower fungal burden values than the ones not treated with FTY720 (p<0.05). As expected, the mice treated with FTY720 showed a less-inflammatory immune profile compared to the ones not treated with FTY720. We hypothesize that FTY720 synergizes the host's innate immune functions by inducing the production of reactive oxygen species. Further studies are warranted to unveil the mechanistic explanations of our observations and clarify further aspects of repurposing FTY720 for clinical antifungal usage.

Innate immune function and antioxidant capacity of nestlings of an African raptor covary with the level of urbanisation around breeding territories.

Urban areas provide breeding habitats for many species. However, animals raised in urban environments face challenges such as altered food availability and quality, pollution and pathogen assemblages. These challenges can affect physiological processes such as immune function and antioxidant defences which are important for fitness. Here, we explore how levels of urbanisation influence innate immune function, immune response to a mimicked bacterial infection and antioxidant capacity of nestling Black Sparrowhawks Accipiter melanoleucus in South Africa. We also explore the effect of timing of breeding and rainfall on physiology since both can influence the environmental condition under which nestlings are raised. Finally, because urbanisation can influence immune function indirectly, we use path analyses to explore direct and indirect associations between urbanisation, immune function and oxidative stress. We obtained measures of innate immunity (haptoglobin, lysis, agglutination, bactericidal capacity), indices of antioxidant capacity (total non-enzymatic antioxidant capacity (tAOX) and total glutathione from nestlings from 2015 to 2019. In addition, in 2018 and 2019, we mimicked a bacterial infection by injecting nestlings with lipopolysaccharide and quantified their immune response. Increased urban cover was associated with an increase in lysis and a decrease in tAOX, but not with any of the other physiological parameters. Furthermore, except for agglutination, no physiological parameters were associated with the timing of breeding. Lysis and bactericidal capacity, however, varied consistently with the annual rainfall pattern. Immune response to a mimicked a bacterial infection decreased with urban cover but not with the timing of breeding nor rainfall. Our path analyses suggested indirect associations between urban cover and some immune indices via tAOX but not via the timing of breeding. Our results show that early-life development in an urban environment is associated with variation in immune and antioxidant functions. The direct association between urbanisation and antioxidant capacity and their impact on immune function is likely an important factor mediating the impact of urbanisation on urban-dwelling animals. Future studies should explore how these results are linked to fitness and whether the responses are adaptive for urban-dwelling species.

Mucocutaneous manifestations of Behçet's disease: Pathogenesis and management from perspectives of vasculitis.

Behçet's disease (BD) is a systemic inflammatory disorder characterized by vasculitis affecting blood vessels of any caliber or type. It can present with a wide spectrum of vasculitic lesions, including erythema nodosum-like lesions and retinal vasculitis, and may also lead to larger vessel diseases, such as aortic aneurysm and deep vein thrombosis. The full etiology of BD remains unclear, but it is considered a polygenetic disease with multiple genetic risk factors that promote immune dysregulation and thrombophilia. Inflammation can be triggered by environmental factors, such as bacteria or viruses, and the dysregulation of innate and adaptive immune cell subsets. Neutrophils and lymphocytes are the primary players involved in BD pathogenesis, with specific innate (i.e., neutrophil-derived reactive oxygen species and neutrophil extracellular traps) and adaptive (i.e., anti-endothelial cell antibodies) processes inducing endothelial cell activation and chemotaxis of inflammatory cells, leading to coagulation and vasculitis. These inflammation-induced vasculitic or vasculopathic features are observed in most mucocutaneous BD lesions, although vasculitis per se is often pathologically evident only during a brief period of the disease process. Due to the multifactorial nature of BD-associated inflammation, broad-spectrum anti-inflammatory medications, including glucocorticoids and immunosuppressive drugs, have been the mainstay for managing BD. In addition, inhibitors of interleukin (IL)-1, tumor necrosis factor (TNF)-α, and IL-17, which target innate and adaptive immune functions dysregulated in BD, have emerged as promising new therapeutics. In this review, we discuss the muco-cutaneous manifestations of BD by focusing on the underlying vasculitic components in their pathologies, as well as the current array of treatment options.

Innate immunity dysregulation in aging eye and therapeutic interventions.

The prevalence of eye diseases increases considerably with age, resulting in significant vision impairment. Although the pathobiology of age-related eye diseases has been studied extensively, the contribution of immune-related changes due to aging remains elusive. In the eye, tissue-resident cells and infiltrating immune cells regulate innate responses during injury or infection. But due to aging, these cells lose their protective functions and acquire pathological phenotypes. Thus, dysregulated ocular innate immunity in the elderly increases the susceptibility and severity of eye diseases. Herein, we emphasize the impact of aging on the ocular innate immune system in the pathogenesis of infectious and non-infectious eye diseases. We discuss the role of age-related alterations in cellular metabolism, epigenetics, and cellular senescence as mechanisms underlying altered innate immune functions. Finally, we describe approaches to restore protective innate immune functions in the aging eye. Overall, the review summarizes our current understanding of innate immune functions in eye diseases and their dysregulation during aging.

Child Health, Agriculture and Integrated Nutrition (CHAIN): protocol for a randomised controlled trial of improved infant and young child feeding in rural Zimbabwe

IntroductionOver one-quarter of children in sub-Saharan Africa are stunted; however, commercial supplements only partially meet child nutrient requirements, cannot be sustainably produced, and do not resolve physiological barriers to adequate...

Immune and stress physiology of two captively-housed tortoise species.

Ecoimmunology affords us the ability to better understand immunological processes through consideration of external factors, such as the thermal microenvironment. This consideration is imperative when examining the immunological processes of ectothermic organisms like reptiles. Reptiles uniquely rely heavily on their innate immune function but remain poorly understood in immunological studies. In this study, we examined innate immunity in two zoo-housed tortoise species, the Indian star tortoise (Geochelone elegans, Schoepff, 1795) and northern spider tortoise (Pyxis arachnoides brygooi, Vuillemin & Domergue, 1972). Bacterial killing assays (BKAs) were optimized and used to assess the monthly immunocompetence of these tortoises to three different bacteria: Escherichia coli, Salmonella enterica, and Staphylococcus aureus. We evaluated differences in blood biochemistry values (lactate and glucose) among months and species as well as fecal corticosterone (CORT) between species. Lastly, we examined the potential influences of individual thermal microenvironments on bactericidal ability. Both G. elegans and P. a. brygooi demonstrated immunocompetence against all bacterial challenges, but only bactericidal ability against E. coli varied over months. Optimal BKA serum dilutions, blood glucose levels, and fecal CORT concentrations differed between the two species. Finally, there was evidence that the thermal microenvironment influenced the tortoises' bactericidal ability against E. coli. Through use of nonmodel organisms, such as tortoises, we are given insight into the inner workings of innate immunity and a better understanding of the complexities of the vertebrate immune system.

Genome-Wide DNA Methylation Profile Indicates Potential Epigenetic Regulation of Aging in the Rhesus Macaque Thymus.

We analyzed whole-genome bisulfite sequencing (WGBS) and RNA sequencing data of two young (1 year old) and two adult (9 years old) rhesus macaques (Macaca mulatta) to characterize the genomic DNA methylation profile of the thymus and explore the molecular mechanism of age-related changes in the thymus. Combining the two-omics data, we identified correlations between DNA methylation and gene expression and found that DNA methylation played an essential role in the functional changes of the aging thymus, especially in immunity and coagulation. The hypomethylation levels of C3 and C5AR2 and the hypermethylation level of C7 may lead to the high expressions of these genes in adult rhesus macaque thymuses, thus activating the classical complement pathway and the alternative pathway and enhancing their innate immune function. Adult thymuses had an enhanced coagulation pathway, which may have resulted from the hypomethylation and upregulated expressions of seven coagulation-promoting factor genes (F13A1, CLEC4D, CLEC4E, FCN3, PDGFRA, FGF2 and FGF7) and the hypomethylation and low expression of CPB2 to inhibit the degradation of blood clots. Furthermore, the functional decline in differentiation, activation and maturation of T cells in adult thymuses was also closely related to the changes in methylation levels and gene expression levels of T cell development genes (CD3G, GAD2, ADAMDEC1 and LCK) and the thymogenic hormone gene TMPO. A comparison of the age-related methylated genes among four mammal species revealed that most of the epigenetic clocks were species-specific. Furthermore, based on the genomic landscape of allele-specific DNA methylation, we identified several age-related clustered sequence-dependent allele-specific DNA methylated (cS-ASM) genes. Overall, these DNA methylation patterns may also help to assist with understanding the mechanisms of the aging thymus with the epigenome.

Macrophage acetyl-CoA carboxylase regulates acute inflammation through control of glucose and lipid metabolism.

Acetyl-CoA carboxylase (ACC) regulates lipid synthesis; however, its role in inflammatory regulation in macrophages remains unclear. We generated mice that are deficient in both ACC isoforms in myeloid cells. ACC deficiency altered the lipidomic, transcriptomic, and bioenergetic profile of bone marrow-derived macrophages, resulting in a blunted response to proinflammatory stimulation. In response to lipopolysaccharide (LPS), ACC is required for the early metabolic switch to glycolysis and remodeling of the macrophage lipidome. ACC deficiency also resulted in impaired macrophage innate immune functions, including bacterial clearance. Myeloid-specific deletion or pharmacological inhibition of ACC in mice attenuated LPS-induced expression of proinflammatory cytokines interleukin-6 (IL-6) and IL-1β, while pharmacological inhibition of ACC increased susceptibility to bacterial peritonitis in wild-type mice. Together, we identify a critical role for ACC in metabolic regulation of the innate immune response in macrophages, and thus a clinically relevant, unexpected consequence of pharmacological ACC inhibition.

Evaluating the impact of three progestin-based hormonal contraceptive methods on immunologic changes in the female genital tract and systemically (CHIME Study): a prospective cohort study protocol

BackgroundGonadal hormones can modify immune function, which may impact susceptibility to infectious diseases, including Human Immunodeficiency Virus (HIV). There is limited knowledge about how hormonal contraceptives (HC) influence the immune response during the course of use. The CHIME study aims to evaluate the effect of long-acting progestin-based hormonal contraceptives (depot medroxyprogesterone acetate, etonogestrel implant, and levonorgestrel intrauterine device) on immunologic changes in the female genital tract (FGT) and systemic compartment.MethodsCHIME is an observational cohort study where participants attend 2 visits prior to initiating the HC method of their choice, and then attend 6 visits over 12 months with biological sampling (vaginal swabs, cervicovaginal lavage, cytobrush and blood) for immunological, bacteriological, and virological analyses at each visit. Immune profiling will be evaluated by multi-color flow cytometry to determine how different T-cell subsets, in particular the CD4 T-cell subsets, change during the course of contraceptive use and whether they have different profiles in the FGT compared to the systemic compartment. The study aims are (1) to characterize the alterations in FGT and systemic immune profiles associated with three long-acting progestin-only HC and (2) to evaluate the vaginal microenvironment, determined by 16 s rRNA sequencing, as an individual-level risk factor and moderator of genital and systemic immune profile changes following exposure to three commonly used HC. Data collection started in March 2019 and is scheduled to be completed in October 2024.DiscussionThe CHIME study aims to contribute to the body of research designed to evaluate the comparative impact of three long-acting progestin-only HC on innate and adaptive immune functions to understand how immunologic effects alter STI and HIV susceptibility.

Immune response to arbovirus infection in obesity.

Obesity is a global health problem that affects 650 million people worldwide and leads to diverse changes in host immunity. Individuals with obesity experience an increase in the size and the number of adipocytes, which function as an endocrine organ and release various adipocytokines such as leptin and adiponectin that exert wide ranging effects on other cells. In individuals with obesity, macrophages account for up to 40% of adipose tissue (AT) cells, three times more than in adipose tissue (10%) of healthy weight individuals and secrete several cytokines and chemokines such as interleukin (IL)-1β, chemokine C-C ligand (CCL)-2, IL-6, CCL5, and tumor necrosis factor (TNF)-α, leading to the development of inflammation. Overall, obesity-derived cytokines strongly affect immune responses and make patients with obesity more prone to severe symptoms than patients with a healthy weight. Several epidemiological studies reported a strong association between obesity and severe arthropod-borne virus (arbovirus) infections such as dengue virus (DENV), chikungunya virus (CHIKV), West Nile virus (WNV), and Sindbis virus (SINV). Recently, experimental investigations found that DENV, WNV, CHIKV and Mayaro virus (MAYV) infections cause worsened disease outcomes in infected diet induced obese (DIO) mice groups compared to infected healthy-weight animals. The mechanisms leading to higher susceptibility to severe infections in individuals with obesity remain unknown, though a better understanding of the causes will help scientists and clinicians develop host directed therapies to treat severe disease. In this review article, we summarize the effects of obesity on the host immune response in the context of arboviral infections. We have outlined that obesity makes the host more susceptible to infectious agents, likely by disrupting the functions of innate and adaptive immune cells. We have also discussed the immune response of DIO mouse models against some important arboviruses such as CHIKV, MAYV, DENV, and WNV. We can speculate that obesity-induced disruption of innate and adaptive immune cell function in arboviral infections ultimately affects the course of arboviral disease. Therefore, further studies are needed to explore the cellular and molecular aspects of immunity that are compromised in obesity during arboviral infections or vaccination, which will be helpful in developing specific therapeutic/prophylactic interventions to prevent immunopathology and disease progression in individuals with obesity.

Hosu-53, a Novel Potent Dihydroorotate Dehydrogenase Inhibitor Accentuates CD47 Blockade Therapy Resulting in Long Term Survival in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a complex disease characterized by leukemia stem cells in a state of differentiation arrest leading to suboptimal innate immune function and immunosuppression. The effectiveness of allogeneic hematopoietic stem cell transplantation, NK cell directed therapies, and recently CD47 blockade highlights the importance of immune surveillance as potentially curative therapies for AML. Dihydroorotate dehydrogenase inhibitors (DHODHi) have been reported to have both cytotoxic and differentiation properties which propelled their clinical development for AML. We developed HOSU-53, a novel DHODHi which is described in detail in another abstract at this meeting. HOSU-53 has (i) nanomolar potency against human DHODH biochemical activity, (ii) in vitro anti-proliferative activity toward AML with a potent tumor DNA damage response, (iii) favorable oral bioavailability, (iv) a monitorable on-target pharmacodynamic biomarker predictive of efficacy and toxicity, and (v) superior in vivo survival outcome in disseminated AML cell line derived xenograft models. Prior anti-viral studies using DHODHi have shown that deprivation of pyrimidine synthesis and associated DNA damage response can enhance innate immune activation. Therefore, we hypothesized that HOSU-53 could enhance phagocytosis and antibody dependent cellular phagocytosis (ADCP) and thereby synergize with myeloid immune checkpoint blockade therapies. Herein, we report compelling preclinical data demonstrating curative potential in AML xenograft models. Treating AML cells with HOSU-53 resulted in restored ability to phagocytose E.coli suggesting enhanced innate immunity. Given our previous reports that DHODHi could induce cell surface markers such as CD38, we next validated that HOSU-53 can increase expression of calreticulin (CALR) and CD47. In vitro treatment with HOSU-53 demonstrated increased tumor surface expression of the pro-phagocytic signal, CALR and a dose dependent increase in CD47 expression. We performed ADCP assays using murine bone marrow derived macrophages and observed enhanced phagocytosis when AML cells were pretreated with HOSU-53, prompting us to conduct in vivo validation using the MOLM-13 disseminated model. Mice were enrolled four days post-engraftment to receive single agent anti-CD47 monoclonal antibody at 0.5mg daily for 21 days and either daily 4 or 10 mg/kg HOSU-53, based on our prior dose optimization studies. We also investigated the combination of CD47 antibody with each dose level of HOSU-53. All monotherapy cohorts resulted in significant prolonged survival, but still eventually succumb to AML disease. In contrast, the combination cohorts resulted in disease-free survival as determined by the absence of measurable human CD45+ cells in spleen or bone marrow cells harvested from mice at the end of treatment on day 80, or on day 106 after remaining on study for 25 days without continued treatment. The curative potential in this model prompted us to repeat our study in a model with higher tumor burden. In this follow-up study, mice were enrolled ten days post engraftment to receive daily HOSU-53 (4 or 10 mg/kg) or B6H12 anti-CD47 (0.5mg daily or every three days for 21 days) or combinations of these treatments. We observed that anti-CD47 monotherapy was ineffective with this more established tumor model, but HOSU-53 monotherapy was comparable to our previous study and both 10 mg/kg combination cohorts significantly prolonged survival (Fig. 1, ongoing study). Further mechanistic studies of HOSU-53-mediated synergy of CD47 therapy are ongoing. Herein, using our DHODHi HOSU-53, we describe that pyrimidine depletion can enhance innate immunity to potentiate CD47 blockade therapy, representing a novel treatment approach. We show HOSU-53 increased tumor innate immune function, CALR expression and subsequently increased in vitro phagocytosis with CD47 blockade. Furthermore, in vivo combination of HOSU-53 with anti-CD47 antibody promoted dramatic synergy exhibiting a potentially curative approach in an otherwise very aggressive tumor model. HOSU-53 is currently in the IND-enabling studies phase with plans for filing an IND application in 2023 for phase 1 clinical trials in AML and MM. This data and our previously reported combination of HOSU-53 with anti-CD38 antibodies warrants the clinical translation of DHODHi in combination with immunotherapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal