Coronavirus disease 2019 and asthma, allergic rhinitis: molecular mechanisms and host-environmental interactions.

PURPOSE OF REVIEW: Coronavirus disease 2019 (COVID-19), a respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus), is a pandemic in over 120 countries worldwide. Risk factors for severe COVID-19 include older age, ethnicity, sex, comorbidities, and living conditions. Although asthmatics and those with allergies are susceptible to more severe outcomes to viral infections, interestingly, asthma has not been reported to be a major comorbidity of COVID-19. However, there are some conflicting reports on the impact of asthma on COVID-19. The underlying immunological and molecular mechanisms may explain at least in part these observations. Furthermore, environmental factors like air pollution that have detrimental effects on asthma and respiratory illnesses also have an impact on COVID-19. RECENT FINDINGS: Angiotensin-converting enzyme 2 (ACE2) is the receptor for the attachment and entry of SARS-CoV-2 into the host cells that is upregulated by Th1-mediated responses. In asthmatics, ACE2 gene expression is generally reduced and recent studies have shown a negative correlation between the levels of Th2 cytokines including IL-4, IL-5, and IL-13 in airway epithelial cells and other type 2 biomarkers with ACE2 expression. This may explain in part the potential protective role of asthma on COVID-19. Here, we review the relation of respiratory viral illnesses and asthma, the immune-molecular mechanisms of SARS-CoV-2 infection, the impact of asthma on COVID-19 and that of SARS-CoV-2 on asthma and allergic rhinitis, and the impact of environmental factors like air pollution on COVID-19. SUMMARY: Expression of ACE2 in airway epithelial cells in SARS-COV-2 is influenced by inflammatory profile. Respiratory allergic diseases like asthma appear to have a protective effect against SARS-COV-2 infection. However, the clinical association between asthma and SARS-COV-2 is not fully established and the underlying immune-molecular mechanisms may explain these observations.

Value of leukocytosis and elevated C-reactive protein in predicting severe coronavirus 2019 (COVID-19): A systematic review and meta-analysis.

BACKGROUND: Since December 2019, coronavirus 2019 (COVID-19) has spread worldwide. Identifying poor prognostic factors is helpful for risk stratification. In this meta-analysis, we investigated the association between severe COVID-19 and a change in white blood cell (WBC) count, an elevation of C-reactive protein (CRP), and fever. Moreover, we aimed to evaluate the diagnostic accuracy of leukocytosis and an elevation of CRP. METHODS: We performed a systematic search of PubMed, EMBASE, Scopus, and the Cochrane Library through April 20th, 2020. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. A sensitivity analysis was conducted according to the study size (>200 or <200) and median age (>55 or <55). Meta-regression analyses were conducted to examine possible sources of heterogeneity. We calculated the diagnostic accuracy of leukocytosis and CRP. RESULTS: Eighteen studies with 3278 patients were selected. Fever, leukocytosis, and elevated CRP were associated with poor outcomes (OR (95% CI) 1.63 (1.06-2.51), 4.51 (2.53-8.04), and 11.97 (4.97-28.8), respectively). Leukopenia was associated with a better prognosis (OR 0.56, 95% CI 0.40-0.78). Sensitivity analyses showed similar tendencies. Meta-regression analysis for leukocytosis indicated that age, dyspnea, and hypertension contributed to heterogeneity. The pooled area under the leukocytosis and CRP curves were 0.70 (0.64-0.76) and 0.89 (0.80-0.99), respectively. CONCLUSION: In patients with COVID-19, fever, leukocytosis, and an elevated CRP were associated with severe outcomes. Leukocytosis and CRP on arrival may predict poor outcomes.