HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Aoshiba, K. Articles by Nagai, A. PubMed PubMed Citation Articles by Aoshiba, K. Articles by Nagai, A.

Senescence Hypothesis for the Pathogenetic Mechanism of Chronic Obstructive Pulmonary Disease

¹ Pulmonary Division, Graduate School of Medical Science, and ² First Department of Medicine, Tokyo Women's Medical University, Tokyo, Japan

Correspondence and requests for reprints should be addressed to Kazutetsu Aoshiba, M.D., First Department of Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan. E-mail: kaoshiba{at}chi.twmu.ac.jp

ABSTRACT

We report herein that pulmonary emphysematous lesions appear to be a dynamic phenomenon that involves not only the gradual loss of alveolar structure but also apoptosis, cellular proliferation, and cellular senescence. Cellular proliferation compensates for increased alveolar cell apoptosis in patients with chronic obstructive pulmonary disease (COPD). However, smoking, age, and the increased cell cycle turnover that compensates for apoptosis accelerate alveolar cell senescence, thereby halting cellular proliferation and tipping the balance toward apoptosis, which, in turn, promotes the formation of emphysematous lesions. As a result, alveolar cells disappear and the emphysematous lesions progress. At the same time, cellular senescence is believed to induce inflammation. More specifically, senescent alveolar cells induce inflammation by producing various inflammatory cytokines in tissue. Lymphocytes and Clara cells may also age more rapidly in the lungs of patients with COPD. Lymphocyte senescence may induce an autoimmune reaction and increase susceptibility to infection, and Clara cell senescence may impair airway regeneration as well as sustain airway inflammation. Thus, cellular senescence may be involved in arrested tissue repair, chronic inflammation, and increased susceptibility to infection, which are the typical features of COPD.

Key Words: chronic obstructive pulmonary disease • apoptosis • cellular proliferation • cellular senescence • telomere