Leptin-producing monocytes in the airway submucosa may contribute to asthma pathogenesis

Kaoru Watanabe; Maho Suzukawa; Shizuka Kawauchi-Watanabe; Sayaka Igarashi; Isao Asari; Sahoko Imoto; Hiroyuki Tashimo; Takeshi Fukami; Akira Hebisawa; Shigeto Tohma; Takahide Nagase; Ken Ohta

doi:10.1016/j.resinv.2022.09.005

Leptin-producing monocytes in the airway submucosa may contribute to asthma pathogenesis

Respir Investig. 2023 Jan;61(1):5-15. doi: 10.1016/j.resinv.2022.09.005. Epub 2022 Nov 9.

Authors

Affiliations

¹ National Hospital Organization Tokyo National Hospital, 3-1-1 Takeoka, Kiyose-City, Tokyo 204-8585, Japan; Department of Respiratory Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
² National Hospital Organization Tokyo National Hospital, 3-1-1 Takeoka, Kiyose-City, Tokyo 204-8585, Japan. Electronic address: fueta-tky@umin.ac.jp.
³ National Hospital Organization Tokyo National Hospital, 3-1-1 Takeoka, Kiyose-City, Tokyo 204-8585, Japan.
⁴ National Hospital Organization Tokyo National Hospital, 3-1-1 Takeoka, Kiyose-City, Tokyo 204-8585, Japan; Department of Histopathology, Asahi General Hospital, I-1326, Asahi City, Chiba 289-2511, Japan.
⁵ Department of Respiratory Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
⁶ National Hospital Organization Tokyo National Hospital, 3-1-1 Takeoka, Kiyose-City, Tokyo 204-8585, Japan; Japan Anti-Tuberculosis Association, Fukujuji Hospital, 3-1-24 Matsuyama, Kiyose-City, Tokyo 204-8522, Japan.

PMID: 36369154
DOI: 10.1016/j.resinv.2022.09.005

Abstract

Background: Obesity leads to an increase in the incidence and severity of asthma. Adipokines, such as leptin, secreted by adipocytes induce systemic inflammation, causing airway inflammation. We previously reported that leptin activates both inflammatory and structural cells, including lung fibroblasts. However, little is known about the differential leptin expression and responsiveness to leptin in asthmatic individuals and healthy controls (HC). In this study, we investigated the expression and origin of leptin in asthmatic airways. We also compared the effect of leptin on asthmatic and HC fibroblasts.

Methods: Lung specimens from asthmatic and non-asthmatic patients were analyzed by immunohistochemical staining using anti-leptin and anti-CD163 antibodies. Leptin mRNA and protein levels in human monocytes were detected by real-time PCR and western blotting and ELISA, respectively. We used flow cytometry to analyze asthmatic and HC lung fibroblasts for leptin receptor (Ob-R) expression. Further, we determined cytokine levels using cytometric bead array and ELISA and intracellular phosphorylation of specific signaling molecules using western blotting.

Results: Asthma specimens displayed accumulation of leptin-positive inflammatory cells, which were also positive for CD163, a high-affinity scavenger receptor expressed by monocytes and macrophages. Leptin expression was observed at both transcript and protein levels in human blood-derived monocytes. No significant differences were observed between asthmatic and HC lung fibroblasts in Ob-R expression, cytokine production, and intracellular phosphorylation of p38 mitogen-activated protein kinase.

Conclusions: Our findings reveal similar responsiveness of control and asthmatic fibroblasts to leptin. However, the accumulation of inflammatory leptin-producing monocytes in the airway may contribute to the pathogenesis of asthma.

Keywords: Fibroblast; Immunohistochemistry; Inflammation; Obesity; p38-MAPK.

MeSH terms

Asthma* / metabolism
Cytokines / metabolism
Humans
Inflammation
Lung / pathology
Monocytes* / metabolism
Monocytes* / pathology

Substances

Cytokines