Cytokine response and damages in the lungs of aging Syrian hamsters on a high-fat diet infected with the SARS-CoV-2 virus.

Hypertriglyceridemia, obesity, and aging are among the key risk factors for severe COVID-19 with acute respiratory distress syndrome (ARDS). One of the main prognostic biomarkers of ARDS is the level of cytokines IL-6 and TNF-α in the blood. In our study, we modeled hyperglyceridemia and hypercholesterolemia on 18-month-old Syrian hamsters (Mesocricetus auratus). By 18 months, the animals showed such markers of aging as weight stabilization with a tendency to reduce it, polycystic liver disease, decreased motor activity, and foci of alopecia. The high-fat diet caused an increase in triglycerides and cholesterol, as well as fatty changes in the liver. On the third day after infection with the SARS-CoV-2 virus, animals showed a decrease in weight in the groups with a high-fat diet. In the lungs of males on both diets, there was an increase in the concentration of IFN-α, as well as IL-6 in both males and females, regardless of the type of diet. At the same time, the levels of TNF-α and IFN-γ did not change in infected animals. Morphological studies of the lungs of hamsters with SARS-CoV-2 showed the presence of a pathological process characteristic of ARDS. These included bronchointerstitial pneumonia and diffuse alveolar damages. These observations suggest that in aging hamsters, the immune response to pro-inflammatory cytokines may be delayed to a later period. Hypertriglyceridemia, age, and gender affect the severity of COVID-19. These results will help to understand the pathogenesis of COVID-19 associated with age, gender, and disorders of fat metabolism in humans.

Subchronic Toxicity of the New Iodine Complex in Dogs and Rats.

Background: Complexes of iodine (povidone-iodine and cadexomers) are among the most important antiseptics used in clinical and veterinary medicines. However, high local irritation activity and systemic toxicity limits their oral administration. The purpose of the study was to compare the effect of a new complex of iodine (PA, potentiator of anticancer antibiotics), in which iodine is coordinated by carbohydrates and polypeptides) on the organisms of rats and dogs treated orally with the drug for 30 days. Methods: Wistar rats and Beagle dogs served as experimental animal models. Effect of PA on the animal organism was examined through the measurements of hormones level changes, hematological and clinical chemistry parameters alterations, necropsy and histological examination. Results: The established maximum tolerated dose (MTD) of 2,000 mg/kg PA led to a decrease in the rate of body weight gain in male and female rats. Changes in hematological and certain biochemical parameters in rats at doses of 1,000 and 2,000 mg/kg were observed. Histological study of the thyroid gland revealed changes in the shape and size of the follicles along with colloid resorption. Administration of a half of MTD (180 mg/kg) and lower doses did not result in any change in dogs (thyroid-stimulating hormone, triiodothyronine, and thyroxine). Conclusions: The results of our study show that the pathogenetic action of PA takes place along the path of induction of an inflammatory response with the development of thyrotoxicosis, rather than hypothyroidism. The mechanism of induction of an inflammatory response is also confirmed by histological studies of lesions of the thyroid gland and testes in rats (Figure S1). The no-observed-adverse-effect level (NOAEL) of PA is estimated to be 180 mg/kg (or iodine 22.8 mg/kg) in dogs, which is equivalent to 100 mg/kg (or iodine 12.3 mg/kg) in humans.

Genomic Insight into Mechanisms of Reversion of Antibiotic Resistance in Multidrug Resistant Mycobacterium tuberculosis Induced by a Nanomolecular Iodine-Containing Complex FS-1.

Drug induced reversion of antibiotic resistance is a promising way to combat multidrug resistant infections. However, lacking knowledge of mechanisms of drug resistance reversion impedes employing this approach in medicinal therapies. Induction of antibiotic resistance reversion by a new anti-tuberculosis drug FS-1 has been reported. FS-1 was used in this work in combination with standard anti-tuberculosis antibiotics in an experiment on laboratory guinea pigs infected with an extensively drug resistant (XDR) strain Mycobacterium tuberculosis SCAID 187.0. During the experimental trial, genetic changes in the population were analyzed by sequencing of M. tuberculosis isolates followed by variant calling. In total 11 isolates obtained from different groups of infected animals at different stages of disease development and treatment were sequenced. It was found that despite the selective pressure of antibiotics, FS-1 caused a counter-selection of drug resistant variants that speeded up the recovery of the infected animals from XDR tuberculosis. Drug resistance mutations reported in the genome of the initial strain remained intact in more sensitive isolates obtained in this experiment. Variant calling in the sequenced genomes revealed that the drug resistance reversion could be associated with a general increase in genetic heterogeneity of the population of M. tuberculosis. Accumulation of mutations in PpsA and PpsE subunits of phenolpthiocerol polyketide synthase was observed in the isolates treated with FS-1 that may indicate an increase of persisting variants in the population. It was hypothesized that FS-1 caused an active counter-selection of drug resistant variants from the population by aggravating the cumulated fitness cost of the drug resistance mutations. Action of FS-1 on drug resistant bacteria exemplified the theoretically predicted induced synergy mechanism of drug resistance reversion. An experimental model to study the drug resistance reversion phenomenon is hereby introduced.