Obesity exacerbates influenza-induced respiratory disease via the arachidonic acid-p38 MAPK pathway

Obesity paradox in patients with community-acquired pneumonia: Have you fully considered the confounding factors?

There exists a notion that there is an obesity paradox in the prognosis of community-acquired pneumonia. In other words, obese individuals with community-acquired pneumonia have a better prognosis. The study by Wang et al supports this claim, but we believe that the obesity paradox should not be proposed hastily as it is influenced by numerous subjective and objective confounding factors.

The protein disulfide isomerase A3 and osteopontin axis promotes influenza-induced lung remodelling

BACKGROUND AND PURPOSE

Fibrotic lung remodelling after a respiratory viral infection represents a debilitating clinical sequela. Studying or managing viral-fibrotic sequela remains challenging, due to limited therapeutic options and lack of understanding of mechanisms. This study determined whether protein disulfide isomerase A3 (PDIA3) and secreted phosphoprotein 1 (SPP1), which are associated with pulmonary fibrosis, can promote influenza-induced lung fibrotic remodelling and whether inhibition of PDIA3 or SPP1 can resolve viral-mediated fibrotic remodelling.

EXPERIMENTAL APPROACH

A retrospective analysis of TriNetX data sets was conducted. Serum from healthy controls and influenza A virus (IAV)-infected patients was analysed. An inhibitor of PDIA3, punicalagin, and a neutralizing antibody for SPP1 were administered in mice. Macrophage cells treated with macrophage colony-stimulating factor (M-CSF) were used as a cell culture model.

KEY RESULTS

The TriNetX data set showed an increase in lung fibrosis and decline in lung function in flu-infected acute respiratory distress syndrome (ARDS) patients compared with non-ARDS patients. Serum samples revealed a significant increase in SPP1 and PDIA3 in influenza-infected patients. Lung PDIA3 and SPP1 expression increased following viral infection in mouse models. Punicalagin administration 2 weeks after IAV infection in mice caused a significant decrease in lung fibrosis and improved oxygen saturation. Administration of neutralizing SPP1 antibody decreased lung fibrosis. Inhibition of PDIA3 decreased SPP1secretion from macrophages, in association with diminished disulfide bonds in SPP1.

CONCLUSION AND IMPLICATIONS

The PDIA3-SPP1 axis promotes post-influenza lung fibrosis in mice and that pharmacological inhibition of PDIA3 or SPP1 can treat virus-induced lung fibrotic sequela.

Elevated body mass index is not significantly associated with reduced influenza vaccine effectiveness

Elevated body mass index (BMI) has been linked to severe influenza illness and impaired vaccine immunogenicity, but the relationship between BMI and clinical vaccine effectiveness (VE) is less well described. This secondary analysis of data from a test-negative study of outpatients with acute respiratory illness assessed BMI and VE against medically attended, PCR-confirmed influenza over seven seasons (2011-12 through 2017-18). Vaccination status was determined from electronic medical records (EMR) and self-report; BMI was estimated from EMR-documented height and weight categorized for adults as obesity (≥ 30 kg/m2), overweight (25-29 kg/m2), or normal and for children based on standardized z-scales. Current season VE by virus type/subtype was estimated separately for adults and children. Pooled VE for all seasons was calculated as 1-adjusted odds ratios from logistic regression with an interaction term for BMI and vaccination. Among 28,089 adults and 12,380 children, BMI category was not significantly associated with VE against outpatient influenza for any type/subtype. Adjusted VE against A/H3N2, A/H1N1pdm09, and B in adults ranged from 16-31, 46-54, and 44-57%, and in children from 29-34, 57-65, and 50-55%, respectively, across the BMI categories. Elevated BMI was not associated with reduced VE against laboratory confirmed, outpatient influenza illness.

The Impact of Obesity on the Host-Pathogen Interaction with Influenza Viruses - Novel Insights: Narrative Review

After exposure to a viral pathogen, the host-pathogen interaction is essential to determine whether or not infection will ensue, and what the clinical outline of the infection will be. Recent research has shown that the patient with obesity presents a set of particular pathophysiological changes that lead to higher severity of viral infections, and this is particularly true for infection with influenza viruses. Herein, we describe the main metabolic, endocrine, and immune dysregulations that occur in the presence of obesity and their impact on driving intra-host viral diversity, leading to heightened severity and virulence of influenza. We show that obesity is linked to modified responses of both the innate and adaptive immune systems during viral infections, including influenza. Due to chronic inflammation and metabolic, endocrine, and signaling pathway disruptions, individuals with obesity have a suboptimal immune response. This results in longer illness duration, increased virus shedding, higher risk of hospitalization and complications, and greater mortality rates. Additionally, they may have a blunted response to vaccination and a higher likelihood of genetic mutation selection. Understanding the intricate interplay between obesity and viral pathogenesis is crucial for developing efficacious therapeutic approaches and public health policies, particularly in light of the escalating worldwide incidence of obesity.