Increased blood neutrophiles in patients with obesity and asthma

Understanding the underlying mechanisms of adult-onset asthma and identifying risk factors may extend the knowledge of pathophysiology and medication response, leading to a better treatment approach. The presented study showed that blood neutrophils were increased in patients with severe obesity and asthma.

It is known that obesity is an important risk factor for adult-onset asthma. “However, the association between obesity and markers of inflammation in this patient group has not been intensively studied,” Dr Helena Backman (Umea University, Sweden) explained during her presentation [1].

The aim of the current study was to investigate the association between obesity and inflammatory markers in adult-onset asthma. Since 1985, blood samples have been collected within different population-based studies in Northern Sweden. In 2019–2020, previous participants were invited to follow-ups including structured interviews, spirometry, measurements of exhaled nitric oxide (FeNO), skin prick testing, blood samples, and BMI. BMI was categorised as underweight (<18.5), normal weight (18.5–24.9), overweight (25–29.9), obesity (30–34.9), and severe obesity (≥35). Inclusion criteria included asthma-onset after 15 years of age.

In total, 251 patients participated in the study with a mean age of 63 years and mean BMI of 29.1. Of these, 0% had underweight, 22% had normal weight, 41% had overweight, 26% had obesity, and 11% severe obesity. Increased mean blood neutrophils (5.3x10⁹/L) were observed in participants with severe obesity (P<0.001). Of participants with obesity, 83% had blood neutrophils ≥4x10⁹/L compared with 32% of patients with normal weight. Between BMI categories, atopy, FeNO, and blood eosinophils did not differ significantly. Lower lung function for both FEV₁ and FVC (83% and 82%, respectively) was seen in severe obesity as well.

In conclusion, severe obesity was strongly associated with blood neutrophils in adult-onset asthma. The identification of increased neutrophils in severely obese adults suggested that neutrophils play an essential role in the pathogenesis of obesity-related disease.

1. Backman H, et al. Obesity and inflammatory markers in adult-onset asthma. Abstract 4215. ERS 2021, 5–8 September.

 

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Posted on 9 November, 2021