Airway Microbiome and Serum Metabolomics Analysis Identify Differential Candidate Biomarkers in Allergic Rhinitis

Allergic rhinitis (AR) is a common heterogeneous chronic disease with a high prevalence and a complex pathogenesis influenced by numerous factors, involving a combination of genetic and environmental factors. To gain insight into the pathogenesis of AR and to identity diagnostic biomarkers, we combined systems biology approach to analyze microbiome and serum composition. We collected inferior turbinate swabs and serum samples to study the microbiome and serum metabolome of 28 patients with allergic rhinitis and 15 healthy individuals. We sequenced the V3 and V4 regions of the 16S rDNA gene from the upper respiratory samples. Metabolomics was used to examine serum samples. Finally, we combined differential microbiota and differential metabolites to find potential biomarkers. We found no significant differences in diversity between the disease and control groups, but changes in the structure of the microbiota. Compared to the HC group, the AR group showed a significantly higher abundance of 1 phylum (Actinobacteria) and 7 genera (Klebsiella, Prevotella and Staphylococcus, etc.) and a significantly lower abundance of 1 genus (Pelomonas). Serum metabolomics revealed 26 different metabolites (Prostaglandin D2, 20-Hydroxy-leukotriene B4 and Linoleic acid, etc.) and 16 disrupted metabolic pathways (Linoleic acid metabolism, Arachidonic acid metabolism and Tryptophan metabolism, etc.). The combined respiratory microbiome and serum metabolomics datasets showed a degree of correlation reflecting the influence of the microbiome on metabolic activity. Our results show that microbiome and metabolomics analyses provide important candidate biomarkers, and in particular, differential genera in the microbiome have also been validated by random forest prediction models. Differential microbes and differential metabolites have the potential to be used as biomarkers for the diagnosis of allergic rhinitis.

Treatment of COVID-19 pneumonia and acute respiratory distress with ramatroban, a thromboxane A2 and prostaglandin D2 receptor antagonist: A 4-Patient Case Series Report

Importance Hypoxemia in COVID-19 pneumonia is dispositive for hospitalization and mechanical ventilation and contributes to mortality. Other than oxygen supplementation, there is no treatment that resolves hypoxemia in COVID-19 pneumonia. Objective COVID-19 pneumonia sustains a massive increase in lipid mediators, especially thromboxane A2 >> PGE2 > PGD2. Thromboxane A2 induces pulmonary venoconstriction, increases pulmonary capillary pressure and contributes to pulmonary edema. High thromboxane A2 metabolite levels are strongly associated with respiratory failure and mortality in hospitalized COVID-19 patients. Ramatroban (Baynas®, Bayer Yakuhin Ltd., Japan) is an inexpensive, orally bioavailable, thromboxane A2 receptor antagonist. Ramatroban was administered to patients with COVID-19 pneumonia and hypoxemia to explore the effect of thromboxane A2 antagonism on clinical symptoms and outcomes. Design, Setting, and Participants A retrospective case series comprising 4 consecutive outpatients, 22 to 87 years of age, with COVID-19 pneumonia and hypoxemia treated with ramatroban between April and July 2021 in India. Main Outcomes and Measures The primary outcome measure was blood oxygen saturation using pulse oximetry (SpO2). Secondary outcome measures were respiratory distress and need for hospitalization. Results Four COVID-19 outpatients had developed progressive respiratory distress and hypoxemia. Within 12-36 hours of the first dose of ramatroban, all four patients experienced increase in SpO2 and decrease in respiratory distress, which obviated hospitalization. Continued treatment for 5 days was associated with complete resolution of respiratory distress and hypoxemia. Conclusions and Relevance There is an unmet medical need for drugs that target the hemodynamic, prothrombotic, and maladaptive immune responses that lead to pneumonia and respiratory failure following SARS-CoV-2 infection. As an anti-vasospastic, broncho-relaxant, anti-thrombotic and immunomodulatory agent, ramatroban addresses the fundamental host response mechanisms underlying respiratory and critical organ failure in COVID-19. Ramatroban merits study in randomized clinical trials that might offer hope for a cost-effective pandemic treatment.

Treatment of COVID-19 pneumonia and acute respiratory distress with ramatroban, a thromboxane A2 and prostaglandin D2 receptor antagonist: A 4-Patient Case Series Report

Importance Hypoxemia in COVID-19 pneumonia is dispositive for hospitalization and mechanical ventilation and contributes to mortality. Other than oxygen supplementation, there is no treatment that resolves hypoxemia in COVID-19 pneumonia. Objective COVID-19 pneumonia sustains a massive increase in lipid mediators, especially thromboxane A2 >> PGE2 > PGD2. Thromboxane A2 induces pulmonary venoconstriction, increases pulmonary capillary pressure and contributes to pulmonary edema. High thromboxane A2 metabolite levels are strongly associated with respiratory failure and mortality in hospitalized COVID-19 patients. Ramatroban (Baynas®, Bayer Yakuhin Ltd., Japan) is an inexpensive, orally bioavailable, thromboxane A2 receptor antagonist. Ramatroban was administered to patients with COVID-19 pneumonia and hypoxemia to explore the effect of thromboxane A2 antagonism on clinical symptoms and outcomes. Design, Setting, and Participants A retrospective case series comprising 4 consecutive outpatients, 22 to 87 years of age, with COVID-19 pneumonia and hypoxemia treated with ramatroban between April and July 2021 in India. Main Outcomes and Measures The primary outcome measure was blood oxygen saturation using pulse oximetry (SpO2). Secondary outcome measures were respiratory distress and need for hospitalization. Results Four COVID-19 outpatients had developed progressive respiratory distress and hypoxemia. Within 12-36 hours of the first dose of ramatroban, all four patients experienced increase in SpO2 and decrease in respiratory distress, which obviated hospitalization. Continued treatment for 5 days was associated with complete resolution of respiratory distress and hypoxemia. Conclusions and Relevance There is an unmet medical need for drugs that target the hemodynamic, prothrombotic, and maladaptive immune responses that lead to pneumonia and respiratory failure following SARS-CoV-2 infection. As an anti-vasospastic, broncho-relaxant, anti-thrombotic and immunomodulatory agent, ramatroban addresses the fundamental host response mechanisms underlying respiratory and critical organ failure in COVID-19. Ramatroban merits study in randomized clinical trials that might offer hope for a cost-effective pandemic treatment.

Treatment of COVID-19 pneumonia and acute respiratory distress with ramatroban, a thromboxane A2 and prostaglandin D2 receptor antagonist: A 4-Patient Case Series Report

COVID-19 associated pneumonia and acute respiratory distress syndrome are accompanied by a massive and sustained increase in lung and systemic thromboxane (Tx) A2. TxA2 is a short-lived, potent vasoconstrictor of pulmonary veins > arteries, and thereby selectively increases pulmonary venous resistance, promoting an increase in pulmonary capillary pressure. TxA2 also increases vascular permeability which, in the lungs, exaggerates pressure-mediated transudation into the alveolar space, causing pulmonary edema and ARDS. Also relevant to COVID-19 pathophysiology, TxA2 contracts bronchial smooth muscle, triggers and amplifies platelet activation, mediates apoptosis of immature thymocytes, and promotes a procoagulant state, all of which are mediated by TxA2 receptor (TPr) activation. The stable TxA2 metabolite, 11-dehydro-TxB2, is elevated in direct proportion to COVID-19 severity. Though inactive at TPr, 11-dehydro-TxB2 activates PGD2 / DP2 receptors (DPr2) which promote a Th2 immune response that is atypical for viral infections and inhibits antiviral defense by suppressing interferon λ expression. Ramatroban is an orally bioavailable, potent, dual antagonist of TPr and DPr2 receptors. We report use of ramatroban (Baynas®, Bayer Yakuhin Ltd., Japan) in 4 COVID-19 outpatients, 22 to 87 years of age, with acute onset / worsening of respiratory distress and hypoxemia. All four patients experienced a decrease in respiratory distress and increase in SpO2, within hours of the first dose of ramatroban and, thereby, avoided hospitalization. By the 5th day all 4 patients had complete resolution of respiratory distress and hypoxemia. Ramatroban has an established safety profile, having been indicated in Japan for the treatment of allergic rhinitis for over 20 years. As an anti-vasospastic, broncho-relaxant, anti-thrombotic and immunomodulator, ramatroban addresses the fundamental host response mechanisms underlying respiratory and critical organ failure in COVID-19, and merits urgent clinical trials that might impact the ongoing pandemic.

Protective Effect of Low-Dose Alcohol Consumption against Post-Ischemic Neuronal Apoptosis: Role of L-PGDS

Ischemic stroke is one of the leading causes of permanent disability and death in adults worldwide. Apoptosis is a major element contributing to post-ischemic neuronal death. We previously found that low-dose alcohol consumption (LAC) protects against neuronal apoptosis in the peri-infarct cortex following transient focal cerebral ischemia. Lipocalin-type prostaglandin D2 synthase (L-PGDS), which is mainly localized in the central nervous system (CNS), was previously shown to inhibit neuronal apoptosis. Therefore, we determined whether L-PGDS is involved in the protective effect of LAC against post-ischemic neuronal apoptosis. Wild-type (WT), CaMKIIαCreERT2/+/L-PGDS+/+, and CaMKIIαCreERT2/+/L-PGDSflox/flox mice on a C57BL/6J background were gavage fed with ethanol or volume-matched water once a day for 8 weeks. Tamoxifen (2 mg/day) was given intraperitoneally to CaMKIIαCreERT2/+/L-PGDS+/+ and CaMKIIαCreERT2/+/L-PGDSflox/flox mice for 5 days during the fourth week. AT-56 (30 mg/kg/day), a selective inhibitor of L-PGDS, was given orally to AT-56-treated WT mice from the fifth week for four weeks. Cerebral ischemia/reperfusion (I/R) injury, TUNEL-positive neurons, and cleaved caspase-3-positive neurons were measured at 24 h of reperfusion after a 90 min unilateral middle cerebral artery occlusion (MCAO). We found that 0.7 g/kg/day but not 2.8 g/kg/day ethanol significantly upregulated L-PGDS in the cerebral cortex. In addition, 0.7 g/kg/day ethanol diminished cerebral ischemia/reperfusion (I/R) injury and TUNEL-positive and cleaved caspase-3-positive neurons in the peri-infarct cortex in WT and CaMKIIαCreERT2/+/L-PGDS+/+ mice. Furthermore, the neuroprotective effect of 0.7 g/kg/day ethanol was alleviated in AT-56-treated WT and CaMKIIαCreERT2/+/L-PGDSflox/flox mice. Our findings suggest that LAC may protect against cerebral I/R injury by suppressing post-ischemic neuronal apoptosis via an upregulated L-PGDS.

Plant Sterol-Poor Diet Is Associated with Pro-Inflammatory Lipid Mediators in the Murine Brain

Plant sterols (PSs) cannot be synthesized in mammals and are exclusively diet-derived. PSs cross the blood-brain barrier and may have anti-neuroinflammatory effects. Obesity is linked to lower intestinal uptake and blood levels of PSs, but its effects in terms of neuroinflammation—if any—remain unknown. We investigated the effect of high-fat diet-induced obesity on PSs in the brain and the effects of the PSs campesterol and β-sitosterol on in vitro microglia activation. Sterols (cholesterol, precursors, PSs) and polyunsaturated fatty acid-derived lipid mediators were measured in the food, blood, liver and brain of C57BL/6J mice. Under a PSs-poor high-fat diet, PSs levels decreased in the blood, liver and brain (>50%). This effect was reversible after 2 weeks upon changing back to a chow diet. Inflammatory thromboxane B2 and prostaglandin D2 were inversely correlated to campesterol and β-sitosterol levels in all brain regions. PSs content was determined post mortem in human cortex samples as well. In vitro, PSs accumulate in lipid rafts isolated from SIM-A9 microglia cell membranes. In summary, PSs levels in the blood, liver and brain were associated directly with PSs food content and inversely with BMI. PSs dampen pro-inflammatory lipid mediators in the brain. The identification of PSs in the human cortex in comparable concentration ranges implies the relevance of our findings for humans.

Effects of non-steroidal anti-inflammatory drugs and other eicosanoid pathway modifiers on antiviral and allergic responses. EAACI task force on eicosanoids consensus report in times of COVID-19

Non-steroidal anti-inflammatory drugs (NSAIDs) and other eicosanoid pathway modifiers are among the most ubiquitously used medications in the general population. Their broad anti-inflammatory, antipyretic and analgesic effects are applied against symptoms of respiratory infections, including SARS-CoV-2, as well as in other acute and chronic inflammatory diseases that often coexist with allergy and asthma. However, the current pandemic of COVID-19 also revealed the gaps in our understanding of their mechanism of action, selectivity and interactions not only during viral infections and inflammation, but also in asthma exacerbations, uncontrolled allergic inflammation, and NSAIDs-exacerbated respiratory disease (NERD). In this context, the consensus report summarises currently available knowledge, novel discoveries and controversies regarding the use of NSAIDs in COVID-19, and the role of NSAIDs in asthma and viral asthma exacerbations. We also describe here novel mechanisms of action of leukotriene receptor antagonists (LTRAs), outline how to predict responses to LTRA therapy and discuss a potential role of LTRA therapy in COVID-19 treatment. Moreover, we discuss interactions of novel T2 biologicals and other eicosanoid pathway modifiers on the horizon, such as prostaglandin D2 antagonists and cannabinoids, with eicosanoid pathways, in context of viral infections and exacerbations of asthma and allergic diseases. Finally, we identify and summarise the major knowledge gaps and unmet needs in current eicosanoid research.

Treatment of COVID-19 pneumonia and acute respiratory distress with ramatroban, a thromboxane A2 and prostaglandin D2 receptor antagonist: A 4-Patient Case Series Report

COVID-19 associated pneumonia and acute respiratory distress syndrome are characterized by a lipid mediator storm with massive increases in lung and systemic thromboxane A2 >> prostaglandin D2. Thromboxane A2 is a potent vasoconstrictor of pulmonary veins >> arteries, and thereby promotes an increase in pulmonary capillary pressures, transudation of fluid into the alveolar space, pulmonary edema and ARDS. Thromboxane A2 also increases vascular permeability, contracts bronchial smooth muscle, triggers and amplifies platelet activation, and promotes a prothrombotic state. PGD2 promotes a Th2 immune response that is atypical for viral infections and inhibits antiviral defense by suppressing interferon λ expression. D-dimers, urinary 11-dehydro-TxB2, and IL-13, a Th2 cytokine, have emerged as key biomarkers of severity and organ failure in COVID-19. Ramatroban is an orally bioavailable, potent, dual antagonist of the thromboxane A2 (TPr) and PGD2 (DPr2) receptors. We report use of ramatroban in 4 COVID-19 outpatients, 22 to 87 years of age, with acute onset / worsening of respiratory distress and hypoxemia. All four patients experienced decrease in respiratory distress and increase in SpO2, within hours of the first dose and thereby avoided hospitalization. By the 5th day all 4 patients had complete resolution of respiratory distress and hypoxemia. Ramatroban (Baynas®, Bayer Yakuhin Ltd., Japan) has an established safety profile, having been indicated in Japan for the treatment of allergic rhinitis for over 20 years. As a broncho-relaxant, anti-vasospastic, anti-thrombotic and immunomodulator, ramatroban addresses the fundamental pathophysiologic mechanisms underlying respiratory and critical organ failure in COVID-19, and therefore merits urgent clinical trials that might impact the ongoing pandemic.