Histopathologic Evaluation and Scoring of Viral Lung Infection

Exploration and structure-activity relationship research of benzenesulfonamide derivatives as potent TRPV4 inhibitors for treating acute lung injury

RN-9893, a TRPV4 antagonist identified by Renovis Inc., showcased notable inhibition of TRPV4 channels. This research involved synthesizing and evaluating three series of RN-9893 analogues for their TRPV4 inhibitory efficacy. Notably, compounds 1b and 1f displayed a 2.9 to 4.5-fold increase in inhibitory potency against TRPV4 (IC50 = 0.71 ± 0.21 μM and 0.46 ± 0.08 μM, respectively) in vitro, in comparison to RN-9893 (IC50 = 2.07 ± 0.90 μM). Both compounds also significantly outperformed RN-9893 in TRPV4 current inhibition rates (87.6 % and 83.2 % at 10 μM, against RN-9893's 49.4 %). For the first time, these RN-9893 analogues were profiled in an in vivo mouse model, where intraperitoneal injections of 1b or 1f at 10 mg/kg notably mitigated symptoms of acute lung injury induced by lipopolysaccharide (LPS). These outcomes indicate that compounds 1b and 1f are promising candidates for acute lung injury treatment.

Faecalibacterium duncaniae as a novel next generation probiotic against influenza

The gut-lung axis is critical during viral respiratory infections such as influenza. Gut dysbiosis during infection translates into a massive drop of microbially produced short-chain fatty acids (SCFAs). Among them, butyrate is important during influenza suggesting that microbiome-based therapeutics targeting butyrate might hold promises. The butyrate-producing bacterium Faecalibacterium duncaniae (formerly referred to as F. prausnitzii) is an emerging probiotic with several health-promoting characteristics. To investigate the potential effects of F. duncaniae on influenza outcomes, mice were gavaged with live F. duncaniae (A2-165 or I-4574 strains) five days before infection. Supplementation of F. duncaniae was associated with less severe disease, a lower pulmonary viral load, and lower levels of lung inflammation. F. duncaniae supplementation impacted on gut dysbiosis induced by infection, as assessed by 16S rRNA sequencing. Interestingly, F. duncaniae administration was associated with a recovery in levels of SCFAs (including butyrate) in infected animals. The live form of F. duncaniae was more potent that the pasteurized form in improving influenza outcomes. Lastly, F. duncaniae partially protected against secondary (systemic) bacterial infection. We conclude that F. duncaniae might serve as a novel next generation probiotic against acute viral respiratory diseases.

Mucosal vaccine-induced cross-reactive CD8+ T cells protect against SARS-CoV-2 XBB.1.5 respiratory tract infection

A nasally delivered chimpanzee adenoviral-vectored severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine (ChAd-SARS-CoV-2-S) is currently used in India (iNCOVACC). Here, we update this vaccine by creating ChAd-SARS-CoV-2-BA.5-S, which encodes a prefusion-stabilized BA.5 spike protein. Whereas serum neutralizing antibody responses induced by monovalent or bivalent adenoviral vaccines were poor against the antigenically distant XBB.1.5 strain and insufficient to protect in passive transfer experiments, mucosal antibody and cross-reactive memory T cell responses were robust, and protection was evident against WA1/2020 D614G and Omicron variants BQ.1.1 and XBB.1.5 in mice and hamsters. However, depletion of memory CD8+ T cells before XBB.1.5 challenge resulted in loss of protection against upper and lower respiratory tract infection. Thus, nasally delivered vaccines stimulate mucosal immunity against emerging SARS-CoV-2 strains, and cross-reactive memory CD8+ T cells mediate protection against lung infection by antigenically distant strains in the setting of low serum levels of cross-reactive neutralizing antibodies.

A bivalent form of a RBD-specific synthetic antibody effectively neutralizes SARS-CoV-2 variants

Coronavirus Disease 2019 (COVID-19) pandemic is severely impacting the world, and tremendous efforts have been made to deal with it. Despite many advances in vaccines and therapeutics, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants remains an intractable challenge. We present a bivalent Receptor Binding Domain (RBD)-specific synthetic antibody, specific for the RBD of wild-type (lineage A), developed from a non-antibody protein scaffold composed of LRR (Leucine-rich repeat) modules through phage display. We further reinforced the unique feature of the synthetic antibody by constructing a tandem dimeric form. The resulting bivalent form showed a broader neutralizing activity against the variants. The in vivo neutralizing efficacy of the bivalent synthetic antibody was confirmed using a human ACE2-expressing mouse model that significantly alleviated viral titer and lung infection. The present approach can be used to develop a synthetic antibody showing a broader neutralizing activity against a multitude of SARS-CoV-2 variants.

Antiviral and antibacterial potential of electrosprayed PVA/PLGA nanoparticles loaded with chlorogenic acid for the management of coronavirus and Pseudomonas aeruginosa lung infection

Respiratory tract infections are a common cause of morbidity and mortality globally. The current paper aims to treat this respiratory disorder. Therefore, we elucidated the phytochemical profile of Euphorbia milii flowers and isolated chlorogenic acid (CGA) for the first time. The electrospraying technique was utilized to prepare CGA nanoparticles in polyvinyl alcohol (PVA)/PLGA polymeric matrix. Complete in vitro characterizations were performed to determine particle size, polydispersity index (PDI), zeta potential, loading efficiency (LE), scanning electron microscopy and in vitro release study. The optimum formula (F2) with a particle size (454.36 ± 36.74 nm), a surface charge (-4.56 ± 0.84 mV), % of LE (80.23 ± 5.74), an initial burst (29.46 ± 4.79) and % cumulative release (97.42 ± 4.72) were chosen for further activities. In the murine lung infection model, PVA/PLGA NPs loaded with CGA (F2) demonstrated in vivo antibacterial activity against Pseudomonas aeruginosa. Using a plaque assay, the in vitro antiviral activity was investigated. The F2 exhibited antiviral activity against coronavirus (HCoV-229E) and (Middle East respiratory syndrome coronavirus (MERS-CoV), NRCEHKU270). The IC₅₀ of F2 against HCoV-229E and MERS-CoV was 170 ± 1.1 and 223 ± 0.88 µg/mL, respectively. The values of IC₅₀ of F2 were significantly lower (p < .05) than that of free CGA. Therefore, the encapsulation of CGA into electrospray PVA/PLGA NPs would be a promising tool as an antimicrobial agent.

Adverse outcomes in SARS-CoV-2-infected pregnant mice are gestational age-dependent and resolve with antiviral treatment

SARS-CoV-2 infection during pregnancy is associated with severe COVID-19 and adverse fetal outcomes, but the underlying mechanisms remain poorly understood. Moreover, clinical studies assessing therapeutics against SARS-CoV-2 in pregnancy are limited. To address these gaps, we developed a mouse model of SARS-CoV-2 infection during pregnancy. Outbred CD1 mice were infected at E6, E10, or E16 with a mouse-adapted SARS-CoV-2 (maSCV2) virus. Outcomes were gestational age-dependent, with greater morbidity, reduced antiviral immunity, greater viral titers, and impaired fetal growth and neurodevelopment occurring with infection at E16 (third trimester equivalent) than with infection at either E6 (first trimester equivalent) or E10 (second trimester equivalent). To assess the efficacy of ritonavir-boosted nirmatrelvir, which is recommended for individuals who are pregnant with COVID-19, we treated E16-infected dams with mouse-equivalent doses of nirmatrelvir and ritonavir. Treatment reduced pulmonary viral titers, decreased maternal morbidity, and prevented offspring growth restriction and neurodevelopmental impairments. Our results highlight that severe COVID-19 during pregnancy and fetal growth restriction is associated with heightened virus replication in maternal lungs. Ritonavir-boosted nirmatrelvir mitigated maternal morbidity along with fetal growth and neurodevelopment restriction after SARS-CoV-2 infection. These findings prompt the need for further consideration of pregnancy in preclinical and clinical studies of therapeutics against viral infections.

Synergistic Power of Piceatannol and/or Vitamin D in Bleomycin-Induced Pulmonary Fibrosis In Vivo: A Preliminary Study

Oxidative stress and epigenetic alterations, including the overexpression of all class I and II histone deacetylases (HDACs), particularly HDAC2 and HDAC4, have been identified as key molecular mechanisms driving pulmonary fibrosis. Treatment with piceatannol (PIC) or vitamin D (Vit D) has previously exhibited mitigating impacts in pulmonary fibrosis models. The present study investigated the effects of PIC, Vit D, or a combination (PIC-Vit D) on the expression of HDAC2, HDAC4, and transforming growth factor-beta (TGF-β) in the lungs; the phosphatidylinositide-3-kinase (PI3K)/AKT signaling pathway; and the antioxidant status of the lungs. The objective was to determine if the treatments had protective mechanisms against pulmonary fibrosis caused by bleomycin (BLM) in rats. Adult male albino rats were given a single intratracheal dosage of BLM (10 mg/kg) to induce pulmonary fibrosis. PIC (15 mg/kg/day, oral (p.o.)), Vit D (0.5 μg/kg/day, intraperitoneal (i.p.)), or PIC-Vit D (15 mg/kg/day, p.o. plus 0.5 μg/kg/day, i.p.) were given the day following BLM instillation and maintained for 14 days. The results showed that PIC, Vit D, and PIC-Vit D significantly improved the histopathological sections; downregulated the expression of HDAC2, HDAC4, and TGF-β in the lungs; inhibited the PI3K/AKT signaling pathway; decreased extracellular matrix (ECM) deposition including collagen type I and alpha smooth muscle actin (α-SMA); and increased the antioxidant capacity of the lungs by increasing the levels of glutathione (GSH) that had been reduced and decreasing the levels of malondialdehyde (MDA) compared with the BLM group at a p-value less than 0.05. The concomitant administration of PIC and Vit D had a synergistic impact that was greater than the impact of monotherapy with either PIC or Vit D. PIC, Vit D, and PIC-Vit D exhibited a notable protective effect through their antioxidant effects, modulation of the expression of HDAC2, HDAC4, and TGF-β in the lungs, and suppression of the PI3K/AKT signaling pathway.

Age-dependent acquisition of pathogenicity by SARS-CoV-2 Omicron BA.5

Pathology studies of SARS-CoV-2 Omicron variants of concern (VOC) are challenged by the lack of pathogenic animal models. While Omicron BA.1 and BA.2 replicate in K18-hACE2 transgenic mice, they cause minimal to negligible morbidity and mortality, and less is known about more recent Omicron VOC. Here, we show that in contrast to Omicron BA.1, BA.5-infected mice exhibited high levels of morbidity and mortality, correlating with higher early viral loads. Neither Omicron BA.1 nor BA.5 replicated in brains, unlike most prior VOC. Only Omicron BA.5-infected mice exhibited substantial weight loss, high pathology scores in lungs, and high levels of inflammatory cells and cytokines in bronchoalveolar lavage fluid, and 5- to 8-month-old mice exhibited 100% fatality. These results identify a rodent model for pathogenesis or antiviral countermeasure studies for circulating SARS-CoV-2 Omicron BA.5. Further, differences in morbidity and mortality between Omicron BA.1 and BA.5 provide a model for understanding viral determinants of pathogenicity.

Topical Adenosine Inhibits Inflammation and Mucus Production in Viral Acute Rhinosinusitis

OBJECTIVE

Viral acute rhinosinusitis (ARS) is the leading cause of work and school absence and antibiotic over-prescription. There are limited treatment options available to ameliorate the symptoms caused by viral ARS. We have previously demonstrated that topical adenosine treatment enhances mucociliary clearance in the sino-nasal tract. Here, we assessed the therapeutic potential of topical adenosine in a mouse model of viral ARS.

METHODS

The effect of topical adenosine on inflammatory response and mucin gene expression was examined in a mouse model of viral ARS induced by respiratory syncytial virus (RSV) nasal-only infection. We also investigated the inflammatory effect of both endogenous and exogenous adenosine in the sino-nasal tract.

RESULTS

Topical adenosine significantly inhibited the expression of pro-inflammatory cytokines, goblet hyperplasia, mucin expression, and cell damage in the nose of mice with viral ARS. This treatment did not prolong virus clearance. This inhibitory effect was primarily mediated by the A2A adenosine receptor (AR). Although previous studies have shown that adenosine induces a robust inflammatory response in the lungs, neither endogenous nor exogenous adenosine produced inflammation in the sino-nasal tract. Instead, exogenous adenosine inhibited the baseline expression of TNF and IL-1β in the nose. Additionally, baseline expression of ARs was lower in the nose than that in the trachea and lungs.

CONCLUSION

We demonstrated that intranasal adenosine administration effectively decreased inflammation and mucus production in a mouse model of viral ARS.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:2095-2103, 2023.

Removal of senescent cells reduces the viral load and attenuates pulmonary and systemic inflammation in SARS-CoV-2-infected, aged hamsters

Older age is one of the strongest risk factors for severe COVID-19. In this study, we determined whether age-associated cellular senescence contributes to the severity of experimental COVID-19. Aged golden hamsters accumulate senescent cells in the lungs, and the senolytic drug ABT-263, a BCL-2 inhibitor, depletes these cells at baseline and during SARS-CoV-2 infection. Relative to young hamsters, aged hamsters had a greater viral load during the acute phase of infection and displayed higher levels of sequelae during the post-acute phase. Early treatment with ABT-263 lowered pulmonary viral load in aged (but not young) animals, an effect associated with lower expression of ACE2, the receptor for SARS-CoV-2. ABT-263 treatment also led to lower pulmonary and systemic levels of senescence-associated secretory phenotype factors and to amelioration of early and late lung disease. These data demonstrate the causative role of age-associated pre-existing senescent cells on COVID-19 severity and have clear clinical relevance.

Adverse outcomes in SARS-CoV-2 infected pregnant mice are gestational age-dependent and resolve with antiviral treatment

SARS-CoV-2 infection during pregnancy is associated with severe COVID-19 and adverse fetal outcomes, but the underlying mechanisms remain poorly understood. Moreover, clinical studies assessing therapeutics against SARS-CoV-2 in pregnancy are limited. To address these gaps, we developed a mouse model of SARS-CoV-2 infection during pregnancy. Outbred CD1 mice were infected at embryonic day (E) 6, E10, or E16 with a mouse adapted SARS-CoV-2 (maSCV2) virus. Outcomes were gestational age-dependent, with greater morbidity, reduced anti-viral immunity, greater viral titers, and more adverse fetal outcomes occurring with infection at E16 (3rd trimester-equivalent) than with infection at either E6 (1st trimester-equivalent) or E10 (2nd trimester-equivalent). To assess the efficacy of ritonavir-boosted nirmatrelvir (recommended for pregnant individuals with COVID-19), we treated E16-infected dams with mouse equivalent doses of nirmatrelvir and ritonavir. Treatment reduced pulmonary viral titers, decreased maternal morbidity, and prevented adverse offspring outcomes. Our results highlight that severe COVID-19 during pregnancy and adverse fetal outcomes are associated with heightened virus replication in maternal lungs. Ritonavir-boosted nirmatrelvir mitigated adverse maternal and fetal outcomes of SARS-CoV-2 infection. These findings prompt the need for further consideration of pregnancy in preclinical and clinical studies of therapeutics against viral infections.

Establishment and Validation of the Risk Nomogram of Poor Prognosis in Patients with Severe Pulmonary Infection Complicated with Respiratory Failure

Objective

To investigate the prognosis of patients with severe pulmonary infection combined with respiratory failure and analyze the influencing factors of prognosis.

Methods

The clinical data of 218 patients with severe pneumonia complicated with respiratory failure were retrospectively analyzed. The risk factors were analyzed by univariate and multivariate logistic regression analyses. The risk nomogram and Bootstrap self-sampling method were used for internal inspection. Calibration curves and receiver operating characteristic (ROC) curve were drawn to assess the predictive ability of the model.

Results

Among 218 patients, 118 (54.13%) cases had a good prognosis and 100 (45.87%) cases had a poor prognosis. Multivariate logistic regression analysis showed that the number of complicated basic diseases ≥5, APACHE II score >20, MODS score >10, PSI score >90, and multi-drug resistant bacterial infection were independent risk factors affecting the prognosis (P<0.05), and the level of Alb was an independent protective factor (P<0.05). The consistency index (C-index) was 0.775, and the Hosmer Lemeshow goodness-of-fit test showed that the model was not significant (P>0.05). The area under the curve (AUC) was 0.813 (95% CI: 0.778~0.895), with the sensitivity of 83.20%, and the specificity of 77.00%.

Conclusion

The risk nomograph model had good discrimination and accuracy in predicting the prognosis of patients with severe pulmonary infection combined with respiratory failure, which may provide a basis for early identification and intervention of patients at clinical risk and improve the prognosis.

Ferrets as Models for Viral Respiratory Disease

Domestic ferrets (Mustela putorius furo) have been used in biomedical research to study influenza viruses since the early 20th century. Ferrets have continued to gain importance for the study of viral respiratory disease due to their disease susceptibility and anatomic similarities to humans. Here we review features of ferret biology and management that should be considered when planning to work with this species, particularly in models of respiratory disease. We specifically discuss biosafety and husbandry, clinical and pathologic assessments, and anesthetic considerations for ferrets with respiratory disease and systemic illness. These considerations are important for animal welfare, fidelity of the model to human disease, and ensuring accuracy and reproducibility of acquired data. Finally, we briefly review the use of ferrets to study respiratory diseases by discussing their respiratory anatomy and 2 frequently studied viral respiratory diseases, influenza and coronavirus disease 2019 (COVID-19).

Impact of adjuvant: Trivalent vaccine with quadrivalent-like protection against heterologous Yamagata-lineage influenza B virus

As new vaccine technologies and platforms, such as nanoparticles and novel adjuvants, are developed to aid in the establishment of a universal influenza vaccine, studying traditional influenza split/subunit vaccines should not be overlooked. Commercially available vaccines are typically studied in terms of influenza A H1 and H3 viruses but influenza B viruses need to be examined as well. Thus, there is a need to both understand the limitations of split/subunit vaccines and develop strategies to overcome those limitations, particularly their ability to elicit cross-reactive antibodies to the co-circulating Victoria (B-V) and Yamagata (B-Y) lineages of human influenza B viruses. In this study, we compared three commercial influenza hemagglutinin (HA) split/subunit vaccines, one quadrivalent (H1, H3, B-V, B-Y HAs) and two trivalent (H1, H3, B-V HAs), to characterize potential differences in their antibody responses and protection against a B-Y challenge. We found that the trivalent adjuvanted vaccine Fluad, formulated without B-Y HA, was able to produce antibodies to B-Y (cross-lineage) on a similar level to those elicited from a quadrivalent vaccine (Flucelvax) containing both B-V and B-Y HAs. Interestingly, Fluad protected mice from a lethal cross-lineage B-Y viral challenge, while another trivalent vaccine, Fluzone HD, failed to elicit antibodies or full protection following challenge. Fluad immunization also diminished viral burden in the lungs compared to Fluzone and saline groups. The success of a trivalent vaccine to provide protection from a cross-lineage influenza B challenge, similar to a quadrivalent vaccine, suggests that further analysis of different split/subunit vaccine formulations could identify mechanisms for vaccines to target antigenically different viruses. Understanding how to increase the breadth of the immune response following immunization will be needed for universal influenza vaccine development.

The Significance of Implementing Bilevel Positive Airway Pressure under Cluster Nursing in Improving the Survival Possibility of Patients with Severe Pulmonary Infection Complicated by Respiratory Failure

Objective. To explore the significance of bilevel positive airway pressure (BIPAP) under cluster nursing in improving the survival probability of patients with severe pulmonary infection (SPI) complicated by respiratory failure (RF). Methods. This research included 153 SPI patients complicated by RF ( $\text{SPI}+\text{RF}$ ) admitted between January 2020 and March 2022, including 55 cases in group A who were treated with BIPAP under cluster care during hospitalization, 47 cases in group B receiving invasive continuous mechanical ventilation during hospitalization, and 51 cases in group C treated with BIPAP under routine care during hospitalization. The three cohorts were compared regarding pre- and posttreatment serum inflammatory factors (IFs), blood gas (BG) parameters, heart rate (HR), and respiratory rate (RR). Besides, the cumulative time of ventilator use, successful ventilator weaning rate, mortality, and incidence of adverse events were counted. Finally, patients were scored for their psychological state using the Hamilton Anxiety/Depression Scale (HAMA/HAMD). Results. The posttreatment TNF-α, IL-6, PCT, WBC, and PaCO2 reduced statistically in all the three groups, with the lowest levels found in group A and the highest in group B ( $P<0.05$ ); while PaO2 and SpO2 increased, with the highest values found in group A and the lowest in group B ( $P<0.05$ ). Among the three groups, group A had the shortest duration of ventilator use, the highest successful weaning rate, and the lowest incidence of adverse events ( $P<0.05$ ). Besides, HAMA and HAMD scores were the lowest in group A among the three groups, while those in group B were higher compared with group C ( $P<0.05$ ). Conclusion. The implementation of BIPAP under cluster nursing can effectively reduce inflammatory responses of $\text{SPI}+\text{RF}$ patients, improve their vital signs, and enhance their psychological state, which has extremely high clinical application value.

Diet-Induced Obesity and NASH Impair Disease Recovery in SARS-CoV-2-Infected Golden Hamsters

Obese patients with non-alcoholic steatohepatitis (NASH) are prone to severe forms of COVID-19. There is an urgent need for new treatments that lower the severity of COVID-19 in this vulnerable population. To better replicate the human context, we set up a diet-induced model of obesity associated with dyslipidemia and NASH in the golden hamster (known to be a relevant preclinical model of COVID-19). A 20-week, free-choice diet induces obesity, dyslipidemia, and NASH (liver inflammation and fibrosis) in golden hamsters. Obese NASH hamsters have higher blood and pulmonary levels of inflammatory cytokines. In the early stages of a SARS-CoV-2 infection, the lung viral load and inflammation levels were similar in lean hamsters and obese NASH hamsters. However, obese NASH hamsters showed worse recovery (i.e., less resolution of lung inflammation 10 days post-infection (dpi) and lower body weight recovery on dpi 25). Obese NASH hamsters also exhibited higher levels of pulmonary fibrosis on dpi 25. Unlike lean animals, obese NASH hamsters infected with SARS-CoV-2 presented long-lasting dyslipidemia and systemic inflammation. Relative to lean controls, obese NASH hamsters had lower serum levels of angiotensin-converting enzyme 2 activity and higher serum levels of angiotensin II—a component known to favor inflammation and fibrosis. Even though the SARS-CoV-2 infection resulted in early weight loss and incomplete body weight recovery, obese NASH hamsters showed sustained liver steatosis, inflammation, hepatocyte ballooning, and marked liver fibrosis on dpi 25. We conclude that diet-induced obesity and NASH impair disease recovery in SARS-CoV-2-infected hamsters. This model might be of value for characterizing the pathophysiologic mechanisms of COVID-19 and evaluating the efficacy of treatments for the severe forms of COVID-19 observed in obese patients with NASH.

Metagenomic next-generation sequencing for the detection of pathogenic microorganisms in patients with pulmonary infection

OBJECTIVE

To explore the clinical value of metagenomic next-generation sequencing (mNGS) in diagnosing pulmonary infectious diseases.

METHODS

A retrospective analysis was performed on 82 patients with pulmonary infection who were admitted to the Eighth Affiliated Hospital of Guangxi Medical University & Guigang City People's Hospital from January 2020 to December 2021. The pathogens were detected by mNGS and conventional methods (culture and PCR). Then, the type and number of detected pathogens, as well as the specificity and sensitivity, were compared between the two methods. In addition, the positive rates of bacteria, fungi, tubercle bacillus, and mixed infection in bronchoalveolar lavage fluid, sputum, pleural effusion, and blood detected by mNGS, and the advantage in required test time were evaluated.

RESULTS

More types and numbers of pathogens were detected by mNGS with a higher sensitivity but a lower specificity, as compared to the conventional detection methods (all P<0.05). The positive rates and integrity rates of bacteria, fungi, and tubercle bacillus detected by mNGS were higher than those by conventional methods (all P<0.05). Moreover, there was no difference in the overall sensitivity of mNGS among different sample types, but the sensitivities of mNGS in bronchoalveolar lavage fluid and sputum samples were significantly higher than those of conventional methods (both P<0.05). The average test time for mNGS was shorter than that of conventional methods.

CONCLUSION

mNGS can detect more types and numbers of pathogenic microorganisms, improve the detection sensitivity, and reduce the detection time in patients with pulmonary infection.

Vitamin D and the Ability to Produce 1,25(OH)2D Are Critical for Protection from Viral Infection of the Lungs

Vitamin D supplementation is linked to improved outcomes from respiratory virus infection, and the COVID-19 pandemic renewed interest in understanding the potential role of vitamin D in protecting the lung from viral infections. Therefore, we evaluated the role of vitamin D using animal models of pandemic H1N1 influenza and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. In mice, dietary-induced vitamin D deficiency resulted in lung inflammation that was present prior to infection. Vitamin D sufficient (D+) and deficient (D-) wildtype (WT) and D+ and D- Cyp27B1 (Cyp) knockout (KO, cannot produce 1,25(OH)2D) mice were infected with pandemic H1N1. D- WT, D+ Cyp KO, and D- Cyp KO mice all exhibited significantly reduced survival compared to D+ WT mice. Importantly, survival was not the result of reduced viral replication, as influenza M gene expression in the lungs was similar for all animals. Based on these findings, additional experiments were performed using the mouse and hamster models of SARS-CoV-2 infection. In these studies, high dose vitamin D supplementation reduced lung inflammation in mice but not hamsters. A trend to faster weight recovery was observed in 1,25(OH)2D treated mice that survived SARS-CoV-2 infection. There was no effect of vitamin D on SARS-CoV-2 N gene expression in the lung of either mice or hamsters. Therefore, vitamin D deficiency enhanced disease severity, while vitamin D sufficiency/supplementation reduced inflammation following infections with H1N1 influenza and SARS-CoV-2.

Alteration of the gut microbiota's composition and metabolic output correlates with COVID-19-like severity in obese NASH hamsters

Obese patientss with nonalcoholic steatohepatitis (NASH) are particularly prone to developing severe forms of coronavirus disease 19 (COVID-19). The gut-to-lung axis is critical during viral infections of the respiratory tract, and a change in the gut microbiota's composition might have a critical role in disease severity. Here, we investigated the consequences of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the gut microbiota in the context of obesity and NASH. To this end, we set up a nutritional model of obesity with dyslipidemia and NASH in the golden hamster, a relevant preclinical model of COVID-19. Relative to lean non-NASH controls, obese NASH hamsters develop severe inflammation of the lungs and liver. 16S rRNA gene profiling showed that depending on the diet, SARS-CoV-2 infection induced various changes in the gut microbiota's composition. Changes were more prominent and transient at day 4 post-infection in lean animals, alterations still persisted at day 10 in obese NASH animals. A targeted, quantitative metabolomic analysis revealed changes in the gut microbiota's metabolic output, some of which were diet-specific and regulated over time. Our results showed that specifically diet-associated taxa are correlated with disease parameters. Correlations between infection variables and diet-associated taxa highlighted a number of potentially protective or harmful bacteria in SARS-CoV-2-infected hamsters. In particular, some taxa in obese NASH hamsters (e.g. Blautia and Peptococcus) were associated with pro-inflammatory parameters in both the lungs and the liver. These taxon profiles and their association with specific disease markers suggest that microbial patterns might influence COVID-19 outcomes.

A TMPRSS2 inhibitor acts as a pan-SARS-CoV-2 prophylactic and therapeutic

The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced owing to emerging variants of concern1,2. Development of host-directed therapeutics and prophylactics could limit such resistance and offer urgently needed protection against variants of concern3,4. Attractive pharmacological targets to impede viral entry include type-II transmembrane serine proteases (TTSPs) such as TMPRSS2; these proteases cleave the viral spike protein to expose the fusion peptide for cell entry, and thus have an essential role in the virus lifecycle5,6. Here we identify and characterize a small-molecule compound, N-0385, which exhibits low nanomolar potency and a selectivity index of higher than 106 in inhibiting SARS-CoV-2 infection in human lung cells and in donor-derived colonoids7. In Calu-3 cells it inhibits the entry of the SARS-CoV-2 variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta). Notably, in the K18-human ACE2 transgenic mouse model of severe COVID-19, we found that N-0385 affords a high level of prophylactic and therapeutic benefit after multiple administrations or even after a single administration. Together, our findings show that TTSP-mediated proteolytic maturation of the spike protein is critical for SARS-CoV-2 infection in vivo, and suggest that N-0385 provides an effective early treatment option against COVID-19 and emerging SARS-CoV-2 variants of concern.

Clofoctol inhibits SARS-CoV-2 replication and reduces lung pathology in mice

Drug repurposing has the advantage of shortening regulatory preclinical development steps. Here, we screened a library of drug compounds, already registered in one or several geographical areas, to identify those exhibiting antiviral activity against SARS-CoV-2 with relevant potency. Of the 1,942 compounds tested, 21 exhibited a substantial antiviral activity in Vero-81 cells. Among them, clofoctol, an antibacterial drug used for the treatment of bacterial respiratory tract infections, was further investigated due to its favorable safety profile and pharmacokinetic properties. Notably, the peak concentration of clofoctol that can be achieved in human lungs is more than 20 times higher than its IC₅₀ measured against SARS-CoV-2 in human pulmonary cells. This compound inhibits SARS-CoV-2 at a post-entry step. Lastly, therapeutic treatment of human ACE2 receptor transgenic mice decreased viral load, reduced inflammatory gene expression and lowered pulmonary pathology. Altogether, these data strongly support clofoctol as a therapeutic candidate for the treatment of COVID-19 patients.

Antivirals targeting SARS-CoV-2 are sorely needed. In this study, we screened a library of approximately 2000 drug compounds that have been used or are still used in the clinics. Among them, we identified clofoctol as an antiviral against SARS-CoV-2. This molecule is an antibacterial drug used for the treatment of bacterial respiratory tract infections and it was further investigated due to its safety profile and its properties to accumulate in the lungs. We further demonstrated that, in vivo, this compound reduces inflammatory gene expression and lowers pulmonary pathology. The antiviral and anti-inflammatory properties of clofoctol, associated with its safety profile and unique pharmacokinetic properties make a strong case for proposing clofoctol as an affordable therapeutic candidate for the treatment of COVID-19 patients.

Alteration of the gut microbiota following SARS-CoV-2 infection correlates with disease severity in hamsters

Mounting evidence suggests that the gut-to-lung axis is critical during respiratory viral infections. We herein hypothesized that disruption of gut homeostasis during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may associate with early disease outcomes. To address this question, we took advantage of the Syrian hamster model. Our data confirmed that this model recapitulates some hallmark features of the human disease in the lungs. We further showed that SARS-CoV-2 infection associated with mild intestinal inflammation, relative alteration in intestinal barrier property and liver inflammation and altered lipid metabolism. These changes occurred concomitantly with an alteration of the gut microbiota composition over the course of infection, notably characterized by a higher relative abundance of deleterious bacterial taxa such as Enterobacteriaceae and Desulfovibrionaceae. Conversely, several members of the Ruminococcaceae and Lachnospiraceae families, including bacteria known to produce the fermentative products short-chain fatty acids (SCFAs), had a reduced relative proportion compared to non-infected controls. Accordingly, infection led to a transient decrease in systemic SCFA amounts. SCFA supplementation during infection had no effect on clinical and inflammatory parameters. Lastly, a strong correlation between some gut microbiota taxa and clinical and inflammation indices of SARS-CoV-2 infection severity was evidenced. Collectively, alteration of the gut microbiota correlates with disease severity in hamsters making this experimental model valuable for the design of interventional, gut microbiota-targeted, approaches for the control of COVID-19.Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; COVID-19, coronavirus disease 2019; SCFAs, short-chain fatty acids; dpi, day post-infection; RT-PCR, reverse transcription polymerase chain reaction; IL, interleukin. ACE2, angiotensin converting enzyme 2; TMPRSS2, transmembrane serine protease 2.

A defective viral genome strategy elicits broad protective immunity against respiratory viruses

RNA viruses generate defective viral genomes (DVGs) that can interfere with replication of the parental wild-type virus. To examine their therapeutic potential, we created a DVG by deleting the capsid-coding region of poliovirus. Strikingly, intraperitoneal or intranasal administration of this genome, which we termed eTIP1, elicits an antiviral response, inhibits replication, and protects mice from several RNA viruses, including enteroviruses, influenza, and SARS-CoV-2. While eTIP1 replication following intranasal administration is limited to the nasal cavity, its antiviral action extends non-cell-autonomously to the lungs. eTIP1 broad-spectrum antiviral effects are mediated by both local and distal type I interferon responses. Importantly, while a single eTIP1 dose protects animals from SARS-CoV-2 infection, it also stimulates production of SARS-CoV-2 neutralizing antibodies that afford long-lasting protection from SARS-CoV-2 reinfection. Thus, eTIP1 is a safe and effective broad-spectrum antiviral generating short- and long-term protection against SARS-CoV-2 and other respiratory infections in animal models.

Intranasal vaccination with a Newcastle disease virus-vectored vaccine protects hamsters from SARS-CoV-2 infection and disease

The pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19). Worldwide efforts are being made to develop vaccines to mitigate this pandemic. We engineered two recombinant Newcastle disease virus (NDV) vectors expressing either the full-length SARS-CoV-2 spike protein (NDV-FLS) or a version with a 19 amino acid deletion at the carboxy terminus (NDV-Δ19S). Hamsters receiving two doses (prime-boost) of NDV-FLS developed a robust SARS-CoV-2-neutralizing antibody response, with elimination of infectious virus in the lungs and minimal lung pathology at five days post-challenge. Single-dose vaccination with NDV-FLS significantly reduced SARS-CoV-2 replication in the lungs but only mildly decreased lung inflammation. NDV-Δ19S-treated hamsters had a moderate decrease in SARS-CoV-2 titers in lungs and presented with severe microscopic lesions, suggesting that truncation of the spike protein was a less effective strategy. In summary, NDV-vectored vaccines represent a viable option for protection against COVID-19.