Metallothionein protects against the cytotoxic and DNA-damaging effects of nitric oxide

In inflammatory states, nitric oxide (.NO) may be synthesized from precursor L-arginine via inducible .NO synthase (iNOS) in large amounts for prolonged periods of time. When .NO acts as an effector molecule under these conditions, it may be toxic to cells by inhibition of iron-containing enzymes or initiation of DNA single-strand breaks. In contrast to molecular targets of .NO, considerably less is known regarding mechanisms by which cells become resistant to .NO. Metallothionein (MT), the major protein thiol induced in cells exposed to cytokines and bacterial products, is capable of forming iron-dinitrosyl thiolates in vitro. Therefore, we tested the hypothesis that overexpression of MT reduces the sensitivity of NIH 3T3 cells to the .NO donor, S-nitrosoacetylpenicillamine (SNAP), and to .NO released from cells (NIH 3T3-DFG-iNOS) after infection with a retroviral vector expressing human iNOS gene. There was a 4-fold increase in MT in cells transfected with the mouse MT-1 gene (NIH 3T3/MT) compared to cells transfected with the promoter-free inverted gene (NIH 3T3/TM). NIH 3T3/MT cells were more resistant than NIH 3T3/TM cells to the cytotoxic effects of SNAP (0.1-1.0 mM) or .NO released from NIH 3T3-DFG-iNOS cells. A brief (1 h) exposure to 10 mM SNAP caused DNA single-strand breaks that were 9-fold greater in NIH 3T3/TM compared to NIH 3T3/MT cells. Electron paramagnetic resonance spectroscopy of NIH 3T3 cells revealed a greater peak at g = 2.04 (e.g., iron-dinitrosyl complex) in NIH 3T3/MT than NIH 3T3/TM cells. These data are consistent with a role for cytoplasmic MT in interacting with .NO and reducing .NO-induced cyto- and nuclear toxicity.

LPD lipopolyplex initiates a potent cytokine response and inhibits tumor growth

Our laboratory has recently developed a lipopolyplex consisting of DOTAP:cholesterol liposomes, protamine sulfate, and plasmid DNA (LPD) that provides improved systemic gene delivery compared with lipoplex following tail vein injection in mice. Because endothelial cells are the primary cells transfected in the lung, it was hypothesized that LPD might be an effective vector for gene therapy of pulmonary metastases. This hypothesis was examined by testing the efficacy of cytokine (IL-12) and tumor suppressor (p53) strategies for treatment of an experimental model of pulmonary metastasis in C57Bl/6 mice. Surprisingly, all LPD complexes including those containing an 'empty' plasmid provided a potent (>50% inhibition) and dose-dependent antitumor effect, compared with dextrose-treated controls. In addition, i.v. injections of LPD containing 'empty' plasmid also inhibited tumor growth in a subcutaneous model of C3 fibrosarcomma. The antitumor effect correlated well with a strong and rapid proinflammatory cytokine (TNF-alpha, IL-12 and IFN-gamma) response. Naked plasmid DNA did not elicit a cytokine response and the response required assembly of DNA into a lipoplex or the LPD lipopolyplex. Except for the heart, elevated levels of cytokine were observed in all organs (lung, liver, kidney and spleen) where LPD is known to have gene transfer activity. Methylation of immune-stimulatory CpG motifs in the plasmid component of LPD inhibited the proinflammatory cytokine response as well as the antitumor effect of LPD in both tumor systems. This suggests that i. v. administration of LPD elicits a systemic proinflammatory cytokine response that mediates the antitumor activity of the lipopolyplex. In addition, the antitumor activity was not observed in SCID mice suggesting a possible role for B or T lymphocytes in the antitumor response initiated by LPD. This represents the first demonstration that an intravenously administered cationic liposome-based nonviral vector can promote a systemic, Th1-like innate immune response. The immune adjuvant properties of LPD might prove to be suitable for delivering tumor-specific antigens in the context of DNA vaccination.

Effect of immune response on gene transfer to the lung via systemic administration of cationic lipidic vectors

Cationic lipid-mediated intravenous gene delivery shows promise in treating pulmonary diseases including lung tumor metastases, pulmonary hypertension, and acute respiratory distress syndrome. Nevertheless, clinical applications of cationic lipidic vectors via intravenous administration are limited by their transient gene expression. In addition, repeated dosing is not effective at frequent intervals. In an effort to elucidate the mechanism of gene inactivation, we report in this study that cationic lipid-protamine-DNA (LPD) complexes, but not each component alone, can induce a high level of cytokine production, including interferon-gamma and tumor necrosis factor-alpha. Furthermore, we demonstrate that LPD administration triggers apoptosis in the lung, a phenomenon that may be mediated in part by the two cytokines. Treatment of mice with antibodies against the two cytokines prolongs the duration of gene expression and also improves lung transfection on a second administration of LPD. Although the mechanism underlying LPD-induced cytokine production is unclear, methylation of the DNA significantly decreased the level of both interferon-gamma and tumor necrosis factor-alpha, suggesting that unmethylated CpG sequences in plasmid DNA play an important role. These data suggest that decreasing the CpG-mediated immune response while not affecting gene expression may be a useful therapeutic strategy to improve cationic lipid-mediated intravenous gene delivery to the lung.

High-level production and purification of P30P2MSP1(19), an important vaccine antigen for malaria, expressed in the methylotropic yeast Pichia pastoris

P30P2MSP1(19) is a recombinant subunit vaccine derived from merozoite surface protein 1 (MSP1) of Plasmodium falciparum, the causative agent of malaria. P30P2MSP1(19) consists of two universal T-cell epitopes fused to the most C-terminal 19-kDa portion of MSP1, and this protein has previously shown promising potential as a vaccine for malaria. However, previous attempts at producing this molecule in Saccharomyces cerevisiae resulted in the production of a truncated form of the molecule missing most of the universal T-cell epitopes. Here, we report the production of full-length P30P2MSP1(19) in Pichia pastoris. As salt precipitation is a common problem during P. pastoris high-density fermentation, we utilized an alternative low-salt, fully defined medium that did not reduce growth rates or biomass yields to avoid precipitation. A total of 500 mg/L of secreted purified protein was produced in high cell density fermentation and the protein was purified in one step utilizing nickel-chelate chromatography. P30P2MSP1(19) produced in Pichia was reactive with monoclonal antibodies that recognize only conformational epitopes on correctly folded MSP1. Rabbits immunized with this molecule generated higher and more uniform antibody titers than rabbits immunized with the protein produced in Saccharomyces. P30P2MSP1(19) produced in Pichia may prove to be a more efficacious vaccine than that produced in Saccharomyces and Pichia would provide a system for the cost-effective production of such a vaccine.

Cyclicity, estrus expression and pregnancy rates in beef heifers with different reproductive tract scores following progesterone supplementation

Two experiments were conducted to determine effects of progesterone (P4) on cyclicity, estrus expression rate (EER) and artificial insemination pregnancy rate (AIPR) in beef heifers with various reproductive tract scores (RTS; 1 to 5; 1, immature, acyclic; 5, mature, cyclic). In Experiment 1, Angus-cross heifers (n = 100, 20 per RTS category; mean (±SEM) age, 15 ± 0.8 mo) were randomly assigned to receive a CIDR (Days -17 to -10) or no CIDR (untreated control), with weekly blood samples and ultrasonography (Days 0-85). Among heifers with RTS 2 to 4, median interval to cyclicity were shorter (P < 0.05) for heifers in CIDR versus control. In Experiment 2, Angus-cross heifers (n = 11,098) were assigned RTS, body condition score (BCS; 1 to 9; 1, emaciated; 9, obese) and temperament score (calm versus excitable). Heifers with RTS 2-5 (n = 10,569) were allocated to CO-Synch (n = 5099) or CO-Synch + CIDR (n = 5470). Estrus was detected until AI (72 h after PGF2α), with pregnancy diagnosis ∼70 d later. Controlling for RTS (P < 0.0001), BCS (P < 0.0001), temperament (P < 0.0001), age (P < 0.0001), treatment by RTS (P < 0.01), treatment by BCS (P < 0.01), and treatment by age, EER differed between CO-Synch and CO-Synch + CIDR (71.0 vs 75.9%, respectively, P < 0.0001). Accounting for RTS (P < 0.0001), BCS (P < 0.0001), temperament (P < 0.0001), age (P < 0.0001), heifers detected in estrus (P < 0.0001), RTS by treatment (P < 0.01), BCS by treatment (P < 0.01), and age by treatment, AIPR differed between CO-Synch versus CO-Synch + CIDR (55.3 vs 61.0%, P < 0.0001). In conclusion, exogenous P4 hastened cyclicity in pre- and peri-pubertal beef heifers. Further, it increased EER and AIPR. However, RTS, BCS and age influenced EER and AIPR. Among RTS 4 and 5, EER was greater for CO-Synch + CIDR vs CO-Synch. Among RTS 3 to 5, AIPR was greater for CO-Synch + CIDR versus CO-Synch. Progesterone status or supplementation at onset of synchronization protocols was critical to pregnancy outcomes, emphasizing heifer development for early puberty or progesterone supplementation.

Nutritional Modulation of Host Defense Peptide Synthesis: A Novel Host-Directed Antimicrobial Therapeutic Strategy?

The escalating threat of antimicrobial resistance underscores the imperative for innovative therapeutic strategies. Host defense peptides (HDPs), integral components of innate immunity, exhibit profound antimicrobial and immunomodulatory properties. Various dietary compounds, such as short-chain fatty acids, vitamins, minerals, sugars, amino acids, phytochemicals, bile acids, probiotics, and prebiotics have been identified to enhance the synthesis of endogenous HDPs without provoking inflammatory response or compromising barrier integrity. Additionally, different classes of these compounds synergize in augmenting HDP synthesis and disease resistance. Moreover, dietary supplementation of several HDP-inducing compounds or their combinations have demonstrated robust protection in rodents, rabbits, pigs, cattle, and chickens from experimental infections. However, the efficacy of these compounds in inducing HDP synthesis varies considerably among distinct compounds. Additionally, the regulation of HDP genes occurs in a gene-specific, cell type-specific, and species-specific manner. In this comprehensive review, we systematically summarized the modulation of HDP synthesis and the mechanism of action attributed to each major class of dietary compounds, including their synergistic combinations, across a spectrum of animal species including humans. We argue that the ability to enhance innate immunity and barrier function without triggering inflammation or microbial resistance positions the nutritional modulation of endogenous HDP synthesis as a promising host-directed approach for mitigating infectious diseases and antimicrobial resistance. These HDP-inducing compounds, particularly in combinations, harbor substantial clinical potential for further exploration in antimicrobial therapies for both human and other animals.

484. Identification of Early Features to Differentiate Hospitalized Children Admitted for Suspected MIS-C from Alternative Diagnoses

Background

Multi-system inflammatory syndrome in children (MIS-C) is a rare consequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). MIS-C shares features with common infectious and inflammatory syndromes and differentiation early in the course is difficult. Identification of early features specific to MIS-C may lead to faster diagnosis and treatment. We aimed to determine clinical, laboratory, and cardiac features distinguishing MIS-C patients within the first 24 hours of admission to the hospital from those who present with similar features but ultimately diagnosed with an alternative etiology.

Methods

We performed retrospective chart reviews of children (0-20 years) who were admitted to Vanderbilt Children’s Hospital and evaluated under our institutional MIS-C algorithm between June 10, 2020-April 8, 2021. Subjects were identified by review of infectious disease (ID) consults during the study period as all children with possible MIS-C require an ID consult per our institutional algorithm. Clinical, lab, and cardiac characteristics were compared between children with and without MIS-C. The diagnosis of MIS-C was determined by the treating team and available consultants. P-values were calculated using two-sample t-tests allowing unequal variances for continuous and Pearson’s chi-squared test for categorical variables, alpha set at < 0.05.

Results

There were 128 children admitted with concern for MIS-C. Of these, 45 (35.2%) were diagnosed with MIS-C and 83 (64.8%) were not. Patients with MIS-C had significantly higher rates of SARS-CoV-2 exposure, hypotension, conjunctival injection, abdominal pain, and abnormal cardiac exam (Table 1). Laboratory evaluation showed that patients with MIS-C had lower platelet count, lymphocyte count and sodium level, with higher c-reactive protein, fibrinogen, B-type natriuretic peptide, and neutrophil percentage (Table 2). Patients with MIS-C also had lower ejection fraction and were more likely to have abnormal electrocardiogram.

Conclusion

We identified early features that differed between patients with MIS-C from those without. Development of a diagnostic prediction model based on these early distinguishing features is currently in progress.

Disclosures

Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Quidel (Grant/Research Support, Other Financial or Material Support, Donation of supplies/kits)Sanofi (Grant/Research Support, Other Financial or Material Support, HAI/NAI testing) Natasha B. Halasa, MD, MPH, Genentech (Individual(s) Involved: Self): I receive an honorarium for lectures - it’s a education grant, supported by genetech, Other Financial or Material Support, Other Financial or Material Support; Sanofi (Individual(s) Involved: Self): Grant/Research Support, Research Grant or Support James A. Connelly, MD, Horizon Therapeutics (Advisor or Review Panel member)X4 Pharmaceuticals (Advisor or Review Panel member)

Habitability and performance issues for long duration space flights

Advancing technology, coupled with the desire to explore space has resulted in increasingly longer manned space missions. Although the Long Duration Space Flights (LDSF) have provided a considerable amount of scientific research on human ability to function in extreme environments, findings indicate long duration missions take a toll on the individual, both physiologically and psychologically. These physiological and psychological issues manifest themselves in performance decrements; and could lead to serious errors endangering the mission, spacecraft and crew. The purpose of this paper is threefold: 1) to document existing knowledge of the effects of LDSF on performance, habitability, and workload, 2) to identify and assess potential tools designed to address these decrements, and 3) to propose an implementation plan to address these habitability, performance and workload issues.

Habitability research priorities for the International Space Station and beyond

Advanced technology and the desire to explore space have resulted in increasingly longer manned space missions. Long Duration Space Flights (LDSF) have provided a considerable amount of scientific research on the ability of humans to adapt and function in microgravity environments. In addition, studies conducted in analogous environments, such as winter-over expeditions in Antarctica, have complemented the scientific understanding of human performance in LDSF. These findings indicate long duration missions may take a toll on the individual, both physiologically and psychologically, with potential impacts on performance. Significant factors in any manned LDSF are habitability, workload and performance. They are interrelated and influence one another, and therefore necessitate an integrated research approach. An integral part of this approach will be identifying and developing tools not only for assessment of habitability, workload, and performance, but also for prediction of these factors as well. In addition, these tools will be used to identify and provide countermeasures to minimize decrements and maximize mission success. The purpose of this paper is to identify research goals and methods for the International Space Station (ISS) in order to identify critical factors and level of impact on habitability, workload, and performance, and to develop and validate countermeasures. Overall, this approach will provide the groundwork for creating an optimal environment in which to live and work onboard ISS as well as preparing for longer planetary missions.

Is Intestinal Microbiota Fully Restored After Chickens Have Recovered from Coccidiosis?

The intestinal microbiota is known to be altered by Eimeria-induced coccidiosis, but it remains unclear whether the microbiota is fully restored after recovery. To address this, 110 newly hatched Cobb male broiler chickens were challenged with 2 × 104 sporulated oocysts of Eimeria maxima (EM) strain M6 or mock-infected with saline on day 10. Body weight and feed intake were recorded. Additionally, 10 mock- and 12 EM-infected birds were randomly selected to assess the small intestinal lesion, fecal oocyst shedding, and ileal and cecal microbiota compositions using 16S rRNA gene sequencing at 3, 5, 7, 14, and 21 days post-infection (dpi). EM infection significantly decreased (p < 0.001) body weight by 5 dpi, persisting through 21 dpi. The infection also reduced (p < 0.05) weight gain, feed intake, and feed efficiency in the first week; however, these parameters became comparable in the second and third weeks. At 7 dpi, during the peak of infection, major lactic acid bacteria were enriched, while short-chain fatty acid-producing bacteria were mostly suppressed in both the ileum and cecum. Opportunistic pathogens such as Escherichia and Clostridium perfringens transiently bloomed at 7 dpi. By 14 dpi, differential bacterial enrichment subsided, and nearly all commensal bacteria returned to healthy levels by 21 dpi. Coupled with comparable growth performance between healthy and EM-recovered chickens, we conclude that the intestinal microbiota is largely restored to its healthy state after recovery. Understanding the microbiota's responses to coccidiosis may inform probiotic-based mitigation strategies.

Modeling Agrilus planipennis (Coleoptera: Buprestidae) within-tree colonization patterns and development of a subsampling technique

Emerald ash borer, Agrilus planipennis Fairmaire, an insect native to central Asia, was first detected in southeast Michigan in 2002, and has since killed millions of ash trees (Fraxinus spp.) in North America. The objectives of this study were to 1) determine an optimal sampling location on girdled ash trap trees for detection of A. planipennis larvae based on measurements of tree characteristics, and 2) develop a whole-tree estimation method for extrapolating larval densities from subsampled heights. We conducted sampling at 1-m increments, recording larval presence, height on tree bole, bolt diameter, and bark roughness for 58 infested ash trees. Analyzing height and diameter separately, generalized linear mixed models indicated the probability of A. planipennis detection was maximized at 17.2 cm for diameter and increased linearly as vertical height increased. There was also a positive relationship between intermediate bark roughness and A. planipennis presence. Stepwise regression indicated the optimal bolts for extrapolating whole tree larval densities were, in order of importance, at heights of 1-2 m, 4-5 m, 7-8 m, and 0-1 m. Subsampling with just one or two bolts explained 70% and 86%, respectively, of the variance in A. planipennis densities. Our results can be used by resource managers to improve efficiency of detection efforts and estimate infestations of A. planipennis.