Innate Response Research Articles

Abortive infection of bat fibroblasts with SARS-CoV-2

Bats are tolerant to highly pathogenic viruses such as Marburg, Ebola, and Nipah, suggesting the presence of a unique immune tolerance toward viral infection. Here, we compared severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection of human and bat (Rhinolophus ferrumequinum) pluripotent cells and fibroblasts. Since bat cells do not express an angiotensin-converting enzyme 2 (ACE2) receptor that allows virus infection, we transduced the human ACE2 (hA) receptor into the cells and found that transduced cells can be infected with SARS-CoV-2. Compared to human embryonic stem cells-hA, infected bat induced Pluripotent Stem Cells (iPSCs)-hA produced about a 100-fold lower level of infectious virus and displayed lower toxicity. In contrast, bat embryonic fibroblast-hA produced no infectious virus while being infectable and synthesizing viral RNA and proteins, suggesting abortive infection. Indeed, electron microscopy failed to detect virus-like particles in infected bat fibroblasts in contrast to bat iPSCs or human cells, consistent with the latter producing infectious viruses. This suggests that bat somatic but not pluripotent cells have an effective mechanism to control virus replication. Consistent with previous results by others, we find that bat cells have a constitutively activated innate immune system, which might limit SARS-CoV-2 infection compared to human cells.

Targeting the IL-5 pathway in eosinophilic asthma: A comparison of anti-IL-5 versus anti-IL-5 receptor agents.

Eosinophilic asthma is characterized by frequent exacerbations, poor symptom control and accelerated lung function decline. It is now recognized that the immune response underlying eosinophilic asthma involves a complex network of interconnected pathways from both the adaptive and innate immune systems. Within this response, interleukin-5 (IL-5) plays a central role in eosinophil differentiation, activation and survival and has emerged as a key target for therapies treating severe asthma. The monoclonal antibodies mepolizumab and reslizumab target the ligand IL-5, preventing its interaction with eosinophils; in contrast, benralizumab binds to the IL-5 receptor (IL-5R), preventing IL-5 from binding and leading to substantially greater eosinophil reduction by enhanced antibody-dependent cell-mediated cytotoxicity. Although no direct head-to-head clinical trials of asthma have been published to formally evaluate the clinical significance of these different therapeutic approaches, the potential benefits of partial versus complete eosinophil depletion continue to remain an important area of study and debate. Here, we review the existing real-world and clinical study data of anti-IL-5/anti-IL-5R therapies in severe eosinophilic asthma.

Immunosenescence: How Aging Increases Susceptibility to Bacterial Infections and Virulence Factors.

The process of aging leads to a progressive decline in the immune system function, known as immunosenescence, which compromises both innate and adaptive responses. This includes impairments in phagocytosis and decreased production, activation, and function of T- and B-lymphocytes, among other effects. Bacteria exploit immunosenescence by using various virulence factors to evade the host's defenses, leading to severe and often life-threatening infections. This manuscript explores the complex relationship between immunosenescence and bacterial virulence, focusing on the underlying mechanisms that increase vulnerability to bacterial infections in the elderly. Additionally, it discusses how machine learning methods can provide accurate modeling of interactions between the weakened immune system and bacterial virulence mechanisms, guiding the development of personalized interventions. The development of vaccines, novel antibiotics, and antivirulence therapies for multidrug-resistant bacteria, as well as the investigation of potential immune-boosting therapies, are promising strategies in this field. Future research should focus on how machine learning approaches can be integrated with immunological, microbiological, and clinical data to develop personalized interventions that improve outcomes for bacterial infections in the growing elderly population.

Exploring the Role of Secondary Metabolites from Plants and Microbes as Modulators of Macrophage Differentiation.

Recent research has uncovered that secondary metabolites-biologically active compounds produced by plants, microbes, and other organisms-play a significant role in regulating the differentiation and function of macrophages. Macrophages, key components of the innate immune system, are crucial for a wide range of physiological processes, including immune response modulation, tissue homeostasis, and host defense against pathogens. This research delves into the mechanisms by which secondary metabolites influence macrophage differentiation signaling pathways, with a focus on how specific compounds affect macrophage polarization and functional phenotypes. Understanding these effects can open new avenues for developing therapeutic strategies that target macrophage-mediated immune responses. Secondary metabolites, such as nitrogen (N) and sulfur (S) containing compounds, terpenoids, and phenolic compounds from plants and microbes, can modulate macrophage differentiation by influencing cytokine production and activity. The activation of signaling pathways in macrophages involves multiple receptors and transcription factors, including IFN-γ receptor activation leading to STAT1 activation, TLR4 triggering IRF5, NFκB, and AP1, IL-4 receptor activation leading to STAT6 and IRF4 activation, PPARγ activation via the fatty acid receptor, TLR4 increasing CREB and C/EBP levels. The complex interplay between transcription factors and cytokines is crucial for maintaining the balance between the M1 and M2 states of macrophages. Despite these insights, further research is needed to unravel the specific molecular mechanisms involved and to identify promising secondary metabolites that could be translated into clinical applications.

Clinical associations of complement-activating collectins, collectin-10, collectin-11 and mannose-binding lectin in preterm neonates.

Premature and low-birthweight infants are at especially high risk of perinatal complications, including impaired thermoregulation, infections and respiratory distress. Such adverse effects and the need for invasive procedures are associated with high mortality among preterms. This study focused on the influence of the innate immune system and tested the levels of collectins, collectin-10 (CL-10), collectin-11 (CL-11) and mannose-binding lectin (MBL) in preterm neonates. Cord blood was collected from 535 preterms (born at gestational age ≤37 weeks). COLEC10 and COLEC11 polymorphisms were analyzed by real-time PCR and those of MBL2 by PCR/PCR-RFLP. The concentrations of collectins in sera from cord blood were determined with ELISA. Low concentrations of CL-10 in cord sera (<462 ng/ml corresponding to the 10th percentile) were significantly associated with births at GA ≤32 weeks. Median levels of both CL-10 and CL-11 were significantly lower in preterms with very low birthweight (<1500 g), low Apgar 1' score and those who needed prolonged hospitalisation. Lower median CL-10 was also observed in fetal growth restriction cases. An important finding was the decreased concentrations of CL-10, CL-11 and MBL in respiratory distress syndrome (RDS). For CL-10 and CL-11, that relationship was confined to infants born at GA ≥33 weeks and/or with body mass at birth ≥1500 g. Only CL-10 was found to influence susceptibility to early-onset infections. COLEC11 heterozygosity for the activity-decreasing polymorphism (rs7567833, +39618 A>G, His219Arg) was more common in preterm premature rupture of membranes (pPROM) cases, compared with corresponding reference groups. Furthermore, C/T or T/T genotypes at COLEC11 at rs3820897 (-9570 C>T) as well as MBL deficiency-associated MBL2 gene variants were more common in preterms diagnosed with RDS than among unaffected newborns. The complement-activating collectins investigated here could be important for maintaining homeostasis in preterm neonates. Despite similar structure and specificity, MBL, CL-10 and CL-11 manifest a different spectrum of clinical associations.

Microbiome-derived metabolite effects on intestinal barrier integrity and immune cell response to infection.

The gut microbiota exerts a significant influence on human health and disease. While compositional changes in the gut microbiota in specific diseases can easily be determined, we lack a detailed mechanistic understanding of how these changes exert effects at the cellular level. However, the putative local and systemic effects on human physiology that are attributed to the gut microbiota are clearly being mediated through molecular communication. Here, we determined the effects of gut microbiome-derived metabolites l-tryptophan, butyrate, trimethylamine (TMA), 3-methyl-4-(trimethylammonio)butanoate (3,4-TMAB), 4-(trimethylammonio)pentanoate (4-TMAP), ursodeoxycholic acid (UDCA), glycocholic acid (GCA) and benzoate on the first line of defence in the gut. Using in vitro models of intestinal barrier integrity and studying the interaction of macrophages with pathogenic and non-pathogenic bacteria, we could ascertain the influence of these metabolites at the cellular level at physiologically relevant concentrations. Nearly all metabolites exerted positive effects on barrier function, but butyrate prevented a reduction in transepithelial resistance in the presence of the pathogen Escherichia coli, despite inducing increased apoptosis and exerting increased cytotoxicity. Induction of IL-8 was unaffected by all metabolites, but GCA stimulated increased intra-macrophage growth of E. coli and tumour necrosis-alpha (TNF-α) release. Butyrate, 3,4-TMAB and benzoate all increased TNF-α release independent of bacterial replication. These findings reiterate the complexity of understanding microbiome effects on host physiology and underline that microbiome metabolites are crucial mediators of barrier function and the innate response to infection. Understanding these metabolites at the cellular level will allow us to move towards a better mechanistic understanding of microbiome influence over host physiology, a crucial step in advancing microbiome research.

The Miniaturized Isolation of Neutrophil Granules (MING) method allowed a deep proteome mapping of human neutrophil granules.

Neutrophils are the innate immune system's first line of defense, and their storage organelles are essential to their function. The storage organelles are divided into three different granule types named azurophilic, specific, and gelatinase granules, besides a fourth component called secretory vesicles. The isolation of neutrophil's granules is challenging, and the existing procedures rely on large sample volumes, about 400 mL of peripheral blood, precluding the use of multiple biological and technical replicates. Therefore, the aim of this study was to develop a miniaturized isolation of neutrophil granules (MING) method, using biochemical assays, mass spectrometry-based proteomics and a machine learning approach to investigate the protein content of these organelles. Neutrophils were isolated from 40 mL of blood collected from three apparently healthy volunteers and disrupted using nitrogen cavitation; the organelles were fractionated with a discontinuous 3-layer Percoll density gradient. The isolation was proven successful and allowed for a reasonable separation of neutrophil's storage organelles using a gradient approximately 37 times smaller than the methods described in the literature. Moreover, mass spectrometry-based proteomics identified 368 proteins in at least 3 of the 5 analyzed samples, and using a machine learning strategy aligned with markers from the literature, the localization of 50 proteins was predicted with confidence. When using markers determined within our dataset by a clusterization tool, the localization of 348 proteins was confidently determined. Importantly, this study was the first to investigate the proteome of neutrophil granules using technical and biological replicates, creating a reliable database for further studies.

Altered Microbiome Promotes Pro-Inflammatory Pathways in Oesophago-Gastric Tumourigenesis.

The upper gastrointestinal microbiome is a dynamic entity that is involved in numerous processes including digestion, production of vitamins and protection against pathogens. Many external and intrinsic factors may cause changes in the proportions of bacteria within the microbial community, termed 'dysbiosis'. A number of these have been identified as risk factors for a range of diseases, including oesophago-gastric carcinoma. A narrative review was conducted to elucidate the current evidence on the role of the microbiome in promoting oesophago-gastric tumourigenesis. Significant causes of dysbiosis including age, medications and GORD were examined and key pro-inflammatory pathways implicated in tumourigenesis and their interaction with the microbiome were described. An association between microbial dysbiosis and development of oesophago-gastric cancer may be mediated via activation of pro-inflammatory pathways, the inflammasome and the innate immune system. Advances in sequencing technology allow microbial communities to be fingerprinted by sequencing the 16S rRNA gene, enabling a deeper understanding of the genera that may be implicated in driving tumourigenesis. Developing a greater understanding of the influence of the microbiota on oesophago-gastric tumourigenesis may enable advances to be made in the early detection of malignancy and in the development of novel systemic therapies, leading to improved rates of survival.

Temperature, dietary lipids, and Aeromonas hydrophila modulate self-protection mechanisms in pacu Piaractus mesopotamicus Holmberg 1887.

Water temperature has a direct influence on several physiological processes in fish. This study investigated the effects of the exposure of pacu (Piaractus mesopotamicus) to 10 days of reduced temperature in stress and innate immune and antioxidant systems, all of which are involved in energy mobilization. Two groups of fish, fed a control diet or a diet with a higher lipid level, were exposed for 10 days to 16°C and then inoculated with Aeromonas hydrophila bacterin. Samples were taken before and after 5 and 10 days of exposure. The results showed that the low temperature (16°C) was a stressor, increasing cortisol levels. Higher levels of cortisol were seen in fish with more body fat, especially at 16°C, compared to those fed control diet. The immune system was enhanced by low temperature that activated the hemolytic activity of the complement system (HAC50) and lysozyme after 10 days of exposure in fish with more body fat. Bacterin inoculation, regardless of temperature and body fat, impaired the respiratory activity of leukocytes, but the complement system activity remained at the levels seen before cold activation. Similarly, lysozyme remained at the levels seen before cold activation, showing later activation. Furthermore, soon after inoculation (at 3 and 6 h), bacterin induced oxidative stress that decreased at 24 h when the concentration of reduced glutathione (GSH) showed lower levels, suggesting that GSH was consumed to attenuate the oxidative stress. Pacu was resilient to the reduced temperature, displaying protective responses to the stressful condition using lipids to modulate these responses.

Antioxidant and immunomodulatory activities of ethanol extracts from Syzygium cumini L. Skeels and Pogostemon cablin Benth

Syzygium cumini and Pogostemon cablin are mostly cultivated in tropical climates for culinary and perfumery purposes, yet their potential medicinal properties remain underreported. The aim of this study was to examine the antioxidant and immunomodulatory activities of ethanol extracts from S. cumini (EESC) and P. cablin (EEPC). Reflux extraction was carried out using 96% ethanol on the collected plant specimens to produce EESC and EEPC. Secondary metabolites of each extract were identified using gas chromatography-mass spectrometry (GC-MS). The extracts were measured for total phenol and flavonoid levels and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The immunomodulatory activity test was carried out in vivo by assessing several parameters, including the phagocytic index via the carbon clearance method, organ indices, antibody titers, and delayed-type hypersensitivity (DTH) response, using sheep red blood cells (SRBC) as antigens. The extracts were also examined for their anti-inflammatory activity in acute and chronic inflammation models. In the DPPH antioxidant test, EESC and EEPC had IC50 values of 12.33 µg/mL and 182.17 µg/mL, respectively. Both extracts showed immunosuppressant activity, marked by a phagocytic index of &lt;1. EESC yielded lower organ indices for the liver (p=0.025 at 200 mg/kg BW), spleen (p=0.028 at 100 mg/kg BW), and thymus (p=0.032 at 200 mg/kg BW) compared to the control group. For EEPC, lower organ indices were observed in the liver at 100 mg/kg BW (p=0.005) and 200 mg/kg BW (p=0.031). In the primary antibody titer and DTH tests, both EESC and EEPC showed immunosuppressant activity at 200 and 400 mg/kg BW (p&lt;0.05). The extracts suppressed both the innate and adaptive immune systems. Both EEPC (p=0.004) and EESC at 100 mg/kg BW (p=0.03) significantly reduced serum TNF-α levels. In conclusion, EESC and EEPC have the potential as immunosuppressive and anti-inflammatory agents.

Antibacterial activity of recombinant liver-expressed antimicrobial peptide-2 derived from olive flounder, Paralichthys olivaceus

Liver-expressed antimicrobial peptide-2 (LEAP-2) is a cysteine-rich peptide that plays a crucial role in the innate immune system of fish. To investigate the molecular function of LEAP-2 from olive flounder, Paralichthys olivaceus, we cloned the gene encoding LEAP-2 using PCR and expressed it in Escherichia coli. Analysis of LEAP-2 expression revealed predominant transcripts in the liver and lower levels in the intestine of olive flounder, whereas their expression levels in the liver and head kidney increased, during the initial stage of infection with the aquapathogenic bacterium Edwardsiella piscicida. Recombinant LEAP-2 (rOfLEAP-2) purified from E. coli exhibited antimicrobial activity, as demonstrated by the ultrasensitive radial diffusion assay, against both Gram-positive (Bacillus subtilis, Streptococcus parauberis, and Lactococcus garvieae) and Gram-negative (Vibrio harveyi and E. coli) bacteria, with minimum inhibitory concentrations ranging from 25 to 100 μg/mL depending on the species tested. The antibacterial activity of rOfLEAP-2 was attributed to its ability to disrupt bacterial membranes, validated by the N-phenylnaphthalen-1-amine uptake assays and scanning electron microscope analysis against E. coli, V. harveyi, B. subtilis, and L. garvieae treated with rOfLEAP-2. Furthermore, a synergistic enhancement of antibacterial activity was observed when rOfLEAP-2 was combined with ampicillin or synthetic LEAP-1 peptide, suggesting a distinct mechanism of action from those of other antimicrobial agents. These findings provide evidence for the antibacterial efficacy of LEAP-2 from olive flounder, highlighting its potential therapeutic application against pathogenic bacteria.

JAK/STAT signaling pathway is involved in antibacterial immunity in the green peach aphid Myzus persicae (Sulzer)

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway within the innate immune system plays a crucial role in defending insects against bacterial, fungal, and viral pathogens. In this study, we identified and cloned five key genes of this signaling pathway in Myzus persicae: MpDome-1, MpDome-2, MpJak, MpStat92E-1, and MpStat92E-2. Our results illustrated that these genes were highly expressed in first, second and third-instar nymphs. Tissue-specific expression analysis revealed that the five genes were predominantly expressed in the gut. Upon bacterial challenge, particularly with Staphylococcus aureus, the expression levels of all five genes were significantly upregulated. Additionally, Escherichia coli infection significantly upregulated the expression levels of MpDome-1 and MpDome-2, while MpJak, MpStat92E-1 and MpStat92E-2 were weakly upregulated. Functional analysis through RNA interference-mediated knockdown of these target genes revealed a significant increase in mortality following infection with E. coli and S. aureus compared with the control group. These findings suggest that the JAK/STAT signaling pathway is crucial for immune defense against bacterial infections in M. persicae.

Inflammation in Chemotherapy-Induced Cardiotoxicity.

In this review we describe the role of inflammation in chemotherapy-induced cardiotoxicity with a particular focus on anthracycline-induced cardiomyopathy (AIC). First, we discuss inflammation associated with anthracyclines at a cellular level. Next, we discuss the clinical implications of these inflammatory mechanisms for early detection and cardioprotective strategies in patients undergoing anthracycline treatment. Key inflammatory pathways identified in AIC include cytokine release, upregulation of the innate immune system via toll-like receptors, and activation of the inflammasome. Emerging evidence suggests a role for inflammatory biomarkers in detecting subclinical AIC. Advanced imaging techniques, such as cardiac PET with novel tracers targeting inflammation, may enhance early detection. Both traditional cardioprotective strategies and novel anti-inflammatory therapies show potential in preventing and treating AIC. Understanding the inflammatory mechanisms involved in AIC provides new opportunities for early detection and targeted cardioprotective strategies in patients undergoing anthracycline treatment and informs our understanding of other forms of chemotherapy-induced cardiotoxicity.

Key role for inflammation-related signaling in the pathogenesis of myopia based on evidence from proteomics analysis

The mechanisms underlying myopia pathogenesis are not well understood. Using publicly-available human and animal datasets, we expound on the roles of known, implicated proteins, and new myopia-related signaling pathways were hypothesized. Proteins identified from human serum or ocular fluids, and from ocular tissues in myopic animal models, were uploaded and analyzed with the QIAGEN Ingenuity Pathway Analysis (IPA) software (March 2023). With each IPA database update, more potentially-relevant proteins and signaling pathways previously unavailable during data acquisition are added, allowing extraction of novel conclusions from existing data. Canonical pathway analysis was used to analyze these data and calculate an IPA activation z-score—which indicates not only whether an association is significant, but also whether the pathway is likely activated or inhibited. Cellular immune response and cytokine signaling were frequently found to be affected in both human and animal myopia studies. Analysis of two publicly-available proteomic datasets highlighted a potential role of the innate immune system and inflammation in myopia development, detailing specific signaling pathways involved such as Granzyme A (GzmA) and S100 family signaling in the retina, and activation of myofibroblast trans-differentiation in the sclera. This perspective in myopia research may facilitate development of more effective and targeted therapeutic agents.

Causal relationship between beta-2 microglobulin and B-cell malignancies: genome-wide meta-analysis and a bidirectional two-sample Mendelian randomization study.

Beta-2 microglobulin (β2M) is acknowledged as a prognostic biomarker for B-cell malignancies. However, insights into the impact of β2M on B-cell malignancy risk, and vice versa, are limited. We conducted a genome-wide meta-analysis (GWMA), bidirectional two-sample Mendelian randomization (TSMR) analysis, and pathway enrichment analysis to explore the causal relationship between β2M and B-cell malignancies and the underlying biological processes. The GWMA identified 55 lead SNPs across five genomic regions (three novel: WDR72, UMOD, and NLRC5) associated with β2M. In the UKB, genetically predicted β2M showed a positive association with diffuse large B-cell lymphoma (DLBCL; odds ratio [OR]: 1.742 per standard deviation increase in β2M; 95% confidence interval [CI]: 1.215-2.498; P = 3.00 × 10-3; FDR = 7.50× 10-3) and Hodgkin lymphoma (HL; OR: 2.270; 95% CI: 1.525-3.380; P = 5.15 × 10-5; FDR =2.58 × 10-4). However, no associations were found with follicular lymphoma (FL), chronic lymphoid leukemia (CLL), or multiple myeloma (MM). Reverse TSMR analysis revealed no association between genetically predicted B-cell malignancies and β2M. In FinnGen, β2M was found to be associated with an increased risk of DLBCL (OR: 2.098; 95% CI: 1.358-3.242; P = 8.28 × 10-4; FDR = 4.14 × 10-3), HL (OR: 1.581; 95% CI: 1.167-2.142; P = 3.13 × 10-3; FDR = 5.22 × 10-3), and FL (OR: 2.113; 95% CI: 1.292-3.455; P = 2.90 × 10-3; FDR = 5.22 × 10-3). However, no association was found with CLL or MM. Reverse TSMR analysis indicated that genetically predicted DLBCL, FL, and MM may perturb β2M levels. Pathway enrichment analysis suggested that the innate immune system represents a convergent biological process underlying β2M, DLBCL, and HL. Our findings suggested that elevated levels of β2M were associated with an increased risk of DLBCL and HL, which is potentially linked to dysfunction of the innate immune system.

Current progress on trained immunity-based vaccines

Trained immunity-based vaccines (TIbV) is an emerging vaccine strategy in the field of vaccine research, referring to vaccines designed based on the principles of trained immunity (TI). TI involves the enhanced immune response of innate immune cells upon re-stimulation after being trained. TIbV, built on the concept of TI, aims to enhance resistance to various infectious pathogens by training the host's innate immune system to acquire natural immune memory. This approach is designed to bolster immunity against a wide range of infectious agents, including those not covered by conventional vaccines. This article reviews the concepts, mechanisms, application areas, and future prospects of TIbV, intending to offer a new perspective for vaccine development and design.

Detection and Localization of IL-8 and CXCR1 in Rainbow Trout Larvae in Response to Pseudomonas aeruginosa Lipopolysaccharide

The salmonid industry faces challenges due to the susceptibility of fish to opportunistic pathogens, particularly in early developmental stages. Understanding the immunological capacity during these stages is crucial for developing effective disease control strategies. IL-8R, a member of the G-protein-coupled receptor family, acts as a receptor for Interleukin 8 (IL-8). The binding of IL-8 to IL-8R plays a major role in the pathophysiology of a wide spectrum of inflammatory conditions. This study focused on the immune response capacity of rainbow trout (Oncorhynchus mykiss) larvae by analyzing IL-8/CXCR1 response to lipopolysaccharide (LPS) from Pseudomonas aeruginosa. Previous research demonstrated that LPS from P. aeruginosa acts as a potent immunostimulant in teleost, enhancing pro-inflammatory cytokines. The methodology included in silico analysis and the synthesis and characterization of an omCXCR1-derived epitope peptide, which was used to produce omCXCR1-specific anti98 serum in mice. The research revealed that rainbow trout larvae 19 days post-hatching (dph) exhibited pronounced immune responses post-stimulation with 1 µg/mL of LPS. This was evidenced by the upregulated protein expression of IL-8 and omCXCR1 in trout larvae 2 and 8 h after LPS challenge, as analyzed by ELISA and immunohistochemistry. Furthermore, fluorescence microscopy successfully revealed the colocalization of IL-8 and its receptor in cells from mucosal tissues after LPS challenge in larvae 19 dph. These findings underscore the efficacy of LPS immersion as a method to activate the innate immune system in trout larvae. Furthermore, we propose IL-8 and its receptor as molecular markers for evaluating immunostimulation in the early developmental stages of salmonids.

8278 Myxedema Coma With COVID-19 Infection

Abstract Disclosure: R. Kalas: None. V. Manohar: None. N.S. Bapat: None. Y. Kim: None. Myxedema coma is a rare medical emergency that occurs in severe hypothyroidism with a mortality rate reaching 60%. The hallmarks include depressed mental status and hypothermia, but hypotension, hyponatremia, bradycardia, and hypoventilation can also occur. This complication can occur in patients with a longstanding history of severe hypothyroidism especially when precipitated by an acute event such as infection, myocardial infarction, or surgery. Prompt recognition and treatment of the condition is important to prevent fatal outcomes. We present a case of myxedema coma in the setting of COVID-19 infection and nonadherence to medication. A 91-year-old woman with history of hypothyroidism, hypertension, coronary artery disease, cardiomyopathy, and chronic obstructive pulmonary disease presented with dyspnea. Her home medications included levothyroxine 75 mcg daily, which she reported not taking for at least 3 weeks. Vital signs revealed a normal heart rate and blood pressure of 84 beats/min and 137/78 mmHg, but the patient was hypothermic to 35.7 °C. On exam, she was somnolent. Labs were notable for markedly elevated TSH level of 111 (0.380 - 4.700 uIU/mL), low free T4 level of 0.57 (0.93 - 1.70 ng/dL), random cortisol level of 25.5 (6.2-18.4 ug/dL), and positive SARS-COV-2 PCR test. Chest x-ray revealed bilateral lower lung parenchymal consolidations and arterial blood gas revealed a pH of 7.29 and pCO2 of 52.5 (35-45 mm Hg), indicating hypercapnia. She was treated for COVID pneumonia and given concern for COVID induced myxedema coma she was given IV levothyroxine 100 mcg for 2 days, after which the patient’s hypothermia and somnolence improved, with an improved repeat free T4 level 0.87 ng/dL. She was subsequently transitioned to oral levothyroxine 112 mcg daily and discharged after improvement of her COVID symptoms. Myxedema coma is a rare complication of decompensated hypothyroidism, frequently triggered by an infection. Thyroid hormone plays an important role in regulating both the innate and adaptive immune systems. As a result, individuals with hypothyroidism are at increased risk of acquiring infections, which can further lead to myxedema coma. COVID-19 infection has been associated with thyrotoxicosis, thyroiditis and hypothyroidism. Given the associated high mortality rate, regardless of the underlying precipitant, prompt diagnosis and early administration of thyroid hormone replacement therapy is crucial to improve outcomes. Presentation: 6/3/2024

7970 C3 and C4 Levels Decrease Post-prandial in Adolescents with type 1 Diabetes

Abstract Disclosure: C.P. Damilano: None. C. Yu: None. D. Zhou: None. R.P. Hoffman: None. Introduction: Cardiovascular disease will be the primary cause of future death for adolescents with type 1 diabetes (T1D) and its origins are likely to occur in this age group. Adolescents with T1D have increased systemic inflammation which is likely to play a significant role in the pathogenesis of cardiovascular disease. The complement system, in particular, components C3 and C4 are part of the innate immune system that regulates inflammation. Increased C3 and C4 levels are associated with increased cardiometabolic risk. Objective: Most studies of inflammation are done while fasting but TNFα and IL6 increase postprandially in adolescent T1D following both high and low glycemic index (GI) meals. The goal of this study was to determine whether there are similar post-prandial changes in C3 and C4 levels. Methodology: Twelve, non-obese children and adolescents, 10-18 years old, with T1D were recruited from the Diabetes Clinic of Nationwide Children's Hospital. A randomized cross-over design for their two subsequent visits was used. After an overnight fast baseline blood samples were taken to measure plasma glucose, C3, total C4 protein, and total C4. Rapid acting insulin was given to cover meal carbohydrate without glucose correction, and blood samples were repeated (30, 60, 90, and 120 minutes) to measure glucose and C3 and C4 levels. Visits 1 and 2 were identical except for GI of the given meal. Visits were rescheduled if the fasting glucose was greater than 200 mg/dl. Repeated measures ANOVA and Spearman’s correlation were used. Results: Glucose response was significantly greater following high GI meal (Δglucose: high 52±12 vs low 6±5 mg/dl, mean±SE, p&amp;lt;0.001). For C3 levels, there was a significant post-prandial decrease (time effect p=0.049), but no meal effect or meal x time interaction. No specific time differences were found. C4 levels were also suppressed postprandially (p&amp;lt;0.001) and there was again no meal effect or meal by time interaction. Post hoc analysis found that C4 levels were lower at 60 min than at 0 min (p=0.007), 90 min (p=0.002) or 120 min (p&amp;lt;0.001). Conclusions: C3 and C4 levels decrease post-prandially in adolescents with T1D in contrast to increases in TNFα and IL6. Future research is clearly needed to clarify the postprandial interactions between the complement and inflammatory systems and potential pathogenic role in cardiovascular disease. Presentation: 6/3/2024

CD151 identifies an NK cell subset that is enriched in COVID-19 patients and correlates with disease severity

Severe coronavirus disease 2019 (COVID-19) often leads to acute respiratory distress syndrome and multi-organ dysfunction, driven by a dysregulated immune response, including a cytokine storm with elevated proinflammatory cytokine levels. Natural killer (NK) cells are part of the innate immune system with a fundamental role in the defense against viral infections. However, during COVID-19 acute infection, they exhibit an altered phenotype and impaired functionality contributing to the immunopathogenesis of the disease. In this work, we have studied a cohort of patients with COVID-19 (ranging from mild to severe) by analyzing IL-15, TGF-β, PlGF and GDF-15 plasma levels and performing multiparametric flow cytometry studies. Our results revealed that severe COVID-19 patients exhibited high levels of IL-15, PlGF and GDF-15, along with an enrichment of anNK cell subset expressing the CD151 tetraspanin, which correlated with IL-15 plasma levels and disease severity. In patients, these CD151+ NK cells displayed a more activated phenotype characterized by an increased expression of HLA-DR, CD38 and granzyme B, a distinct receptor repertoire, with lower levels of CD160 and CD31 and higher levels of CD55 and, remarkably, a higher expression of tissue-resident markers CD103 and the NK cell decidual marker CD9. Last of all, in individuals with severe disease, we identified an expansion of a CD151brightCD9+ NK cell subset, suggesting that these cells play a specific role in COVID-19. Altogether, our findings suggest that CD151+ NK cells may have a relevant role in COVID-19 immunopathogenesis.