Background Respiratory syncytial virus (RSV) infection in infants is a major cause of viral bronchiolitis and hospitalisation. We have previously shown in a murine model that ongoing infection with the gut helminth Heligmosomoides polygyrus ( H. polygyrus) protects against RSV infection through type I interferon (IFN-I) dependent reduction of viral load. Yet, the cellular basis for this protection has remained elusive. Given that recruitment of mononuclear phagocytes to the lung is critical for early RSV infection control, we assessed their role in this coinfection model. Methods Mice were infected by oral gavage with H. polygyrus. Myeloid immune cell populations were assessed by flow cytometry in lung, blood and bone marrow throughout infection and after secondary infection with RSV. Monocyte numbers were depleted by anti-CCR2 antibody or increased by intravenous transfer of enriched monocytes. Results H. polygyrus infection induces bone marrow monopoiesis, increasing circulatory monocytes and lung mononuclear phagocytes in a IFN-I signalling dependent manner. This expansion causes enhanced lung mononuclear phagocyte counts early in RSV infection that may contribute to the reduction of RSV load. Depletion or supplementation of circulatory monocytes prior to RSV infection confirms that these are both necessary and sufficient for helminth induced antiviral protection. Conclusions H. polygyrus infection induces systemic monocytosis contributing to elevated mononuclear phagocyte numbers in the lung. These cells are central to an anti-viral effect that reduces the peak viral load in RSV infection. Treatments to promote or modulate these cells may provide novel paths to control RSV infection in high risk individuals.

Paper mulberry pollens are known to trigger severe allergies that can also cause asthma exacerbations. In Islamabad, the paper mulberry pollen concentrations are thought to peak between the 10th and 31st of March each year, depending on the weather in the preceding months. However, more accurate prediction of high pollen days would allow patients to take more timely precautionary measures. We developed and validated two prediction algorithms that took historical pollen data and historical weather data in Islamabad as its input. One is based on linear regression and the other is based on phenological modelling. These algorithms gave encouraging results where the mean absolute error for start day was between 2.33 and 3.67 days. On the other hand, for peak day, the mean absolute error was recorded between 3.33 and 4 days. These results could be used in a website or app to notify patients and healthcare providers to start preparing for the paper mulberry pollen season and its adverse effects.

Background: Group 2 innate lymphoid cells (ILC2s) play a critical role in asthma pathogenesis. Non-steroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is associated with reduced signaling via EP2, a receptor for prostaglandin E 2 (PGE 2). However, the respective roles for the PGE 2 receptors EP2 and EP4 (both share same downstream signaling) in the regulation of lung ILC2 responses has yet been deciphered. Methods: The roles of PGE 2 receptors EP2 and EP4 on ILC2-mediated lung inflammation were investigated using genetically modified mouse lines and pharmacological approaches in IL-33- and Alternaria alternata (A.A.)-induced lung allergy models. The effects of PGE 2 receptors and downstream signals on ILC2 metabolic activation and effector function were examined using in vitro cell cultures. Results: Deficiency of EP2 rather than EP4 augments IL-33-induced lung ILC2 responses and eosinophilic inflammation in vivo. In contrast, exogenous agonism of EP4 but not EP2 markedly restricts IL-33- and Alternaria alternata-induced lung ILC2 responses and eosinophilic inflammation. Mechanistically, PGE 2 directly suppresses IL-33-dependent ILC2 activation through the EP2/EP4-cAMP pathway, which downregulates STAT5 and MYC pathway gene expression and ILC2 energy metabolism. Blocking glycolysis diminishes IL-33-dependent ILC2 responses in mice lacking endogenous PG synthesis but not in PG-competent mice. Conclusion: We have defined a mechanism for optimal suppression of lung ILC2 responses by endogenous PGE 2-EP2 signaling which underpins the clinical findings of defective EP2 signaling in patients with NERD. Our findings also indicate that exogenously targeting the PGE 2-EP4-cAMP and energy metabolic pathways may provide novel opportunities for treating ILC2-initiated lung inflammation in asthma and NERD.

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.

This systematic review evaluates the efficacy and safety of biologicals for chronic rhinosinusitis with nasal polyps (CRSwNP) compared to the standard of care. Pubmed, EMBASE and Cochrane Library were searched for RCTs. Critical and important CRSwNP-related outcomes were considered. The risk of bias and the certainty of the evidence were assessed using GRADE. RCTs evaluated (dupilumab-2, omalizumab-4, mepolizumab-2, reslizumab-1) included 1236 adults, with follow-up 20-64 weeks. Dupilumab reduces the need for surgery (NFS) and oral corticosteroid (OCS) use (RR 0.28; 95%CI 0.20-0.39, moderate certainty) and improves with high certainty smell (mean difference (MD) +10.54; 95%CI +9.24 to +11.84) and quality of life (QoL) (MD -19.14; 95%CI 95%CI -22.80 to -15.47), with fewer treatment-related adverse events (TAEs) (RR 0.95; 95%CI 0.89-1.02, moderate certainty). Omalizumab reduces NFS (RR 0.85; 95%CI 0.78 to 0.92, high certainty), decreases OCS use (RR 0.38; 95%CI 0.10-1.38, moderate certainty), improves with high certainty smell (MD +3.84; 95%CI +3.64 to +4.04) and QoL (MD -15.65; 95%CI -16.16 to -15.13), with increased TAE (RR 1.73; 95%CI 0.60-5.03, moderate certainty). There is low certainty for mepolizumab reducing NFS (RR 0.78; 95%CI 0.64 to 0.94) and improving QoL (MD -13.3; 95% CI -23.93 to -2.67) and smell (MD +0.7; 95%CI -0.48 to +1.88), with increased TAEs (RR 1.64; 95%CI 0.41-6.50). The evidence for reslizumab is very uncertain.

In past ten years, microRNAs (miRNAs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases and their potential as biomarkers in liquid biopsies. They act as master post-transcriptional regulators that control most cellular processes. As one miRNA can target several mRNAs, often within the same pathway, dysregulated expression of miRNAs may alter particular cellular responses and contribute or lead to the development of various diseases. In this review, we give an overview of the current research on miRNAs in allergic diseases, including atopic dermatitis, allergic rhinitis and asthma. Specifically, we discuss how individual miRNAs function in the regulation of immune responses in epithelial cells and specialized immune cells in response to different environmental factors and respiratory viruses. In addition, we review insights obtained from experiments with murine models of allergic airway and skin inflammation and offer an overview of studies focusing on miRNA discovery using profiling techniques and bioinformatic modelling of the network effect of multiple miRNAs. In conclusion, we highlight the importance of research into miRNA function in allergy and asthma to improve our knowledge of the molecular mechanisms involved in the pathogenesis of this heterogeneous group of diseases.

This systematic review evaluates the efficacy, safety and economic impact of dupilumabcompared to standard of care for uncontrolled moderate-to-severe atopic dermatitis (AD). Pubmed, EMBASE and Cochrane Library were searched for RCTs and health economic evaluations. Critical and important AD-related outcomes were considered. The risk of bias and the certainty of the evidence were assessed using GRADE. Seven RCTs including 1845 subjects > 12 years treated with dupilumab16 to 52 weeks were evaluated. For adultsthere is high certainty that dupilumabdecreasesSCORAD (MD -30,72; 95%CI -34,65% to -26,79%) and EASI-75 (RR 3.09; 95%CI 2.45 to 3.89), pruritus (RR 2.96; 95%CI 2.37 to 3.70), rescue medication (RR 3.46; 95%CI 2.79 to 4.30), sleep disturbance (MD -7.29; 95%CI -8.23 to -6.35), anxiety/depression (MD -3.08; 95% CI -4.41 to -1.75) and improves quality of life (MD -4.80; 95% CI -5.55 to -4.06). The efficacy for adolescents is similar. Dupilumab-related adverse events (AEs) slightly increase (low certainty). The evidence for dupilumab-related serious AE is uncertain. The incremental cost-effectiveness ratio ranged from 28,500 £ (low certainty) to 124,541 US$ (moderate certainty).More data on long term safety are needed both for children and adults, together with more efficacy data in the paediatric population.

This systematic review evaluates the efficacyand safety of omalizumab for chronic spontaneous urticaria (CSU). Pubmed, EMBASE and Cochrane Library were searched for RCTs. Critical and important CSU-related outcomes were considered. The risk of bias and the certainty of the evidence were assessed using GRADE. Ten RCTs including 1620 subjects aged 12 to 75 years old treated with omalizumab for 16 to 40 weeks were evaluated. Omalizumab 150 mg: does not result in clinically meaningful improvement(high certainty) of the urticaria activity score (UAS)7 (mean difference (MD) -5; 95%CI -7.75 to -2.25) and the itch severity score(ISS)7 (MD -2.15; 95% CI -3.2 to -1.1); does not increase (moderate certainty) quality of life (QoL) (Dermatology Life Quality Index (DLQI); MD -2.01; 95%CI -3.22 to -0.81); decreases (moderate certainty) rescue medication use (MD -1.68; 95%CI -2.95 to -0.4). Omalizumab 300 mg:results in clinically meaningful improvements(moderate certainty)of the UAS7 (MD -11.05; 95%CI -12.87 to -9.24), theISS7 (MD -4.45; 95%CI -5.39 to -3.51), and QoL (high certainty)(DLQI; MD -4.03; 95% CI -5.56 to -2.5); decreases (moderate certainty) rescue medication use (MD -2.04; 95%CI -3.19 to -0.88) and drug-related serious AEs (RR 0.77; 95%CI 0.20 to 2.91).

In December 2019, China reported the first cases of the coronavirus disease 2019 (COVID-19). This disease, caused by the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), has developed into a pandemic. To date it has resulted in ~5.6 million confirmed cases and caused 353,334 related deaths worldwide. Unequivocally, the COVID-19 pandemic is the gravest health and socio-economic crisis of our time. In this context, numerous questions have emerged in demand of basic scientific information and evidence-based medical advice on SARS-CoV-2 and COVID-19. Although the majority of the patients show a very mild, self-limiting viral respiratory disease, many clinical manifestations in severe patients are unique to COVID-19, such as severe lymphopenia and eosinopenia, extensive pneumonia, a “cytokine storm” leading to acute respiratory distress syndrome, endothelitis, thrombo-embolic complications and multiorgan failure. The epidemiologic features of COVID-19 are distinctive and have changed throughout the pandemic. Vaccine and drug development studies and clinical trials are rapidly growing at an unprecedented speed. However, basic and clinical research on COVID-19-related topics should be based on more coordinated high-quality studies. This paper answers pressing questions, formulated by young clinicians and scientists, on SARS-CoV-2, COVID-19 and allergy, focusing on the following topics: virology, immunology, diagnosis, management of patients with allergic disease and asthma, treatment, clinical trials, drug discovery, vaccine development and epidemiology. Over 140 questions were answered by experts in the field providing a comprehensive and practical overview of COVID-19 and allergic disease.