IJAR.2026.128
Type of Article: Original Research
Volume 14; Issue 2 (June 2026)
Page No.: 9511-9523
DOI: https://dx.doi.org/10.16965/ijar.2026.128
Age-Related Deterioration of Elastic Fibres in the Human Trachea and Main Bronchi: A Quantitative Histomorphometric Study
Doni R Praveen Kumar *1, Arasada Archana 2, T. Neeraja 3, K. Lakshmi Kumari 4, Parvathavarthine 5.
*1 Assistant professor, Department of Anatomy, Government Medical College, Paderu, ASR Dist, 531024. ORCiD: 0000-0002-2567-2204
2 Assistant professor, Department of Anatomy, Government Medical College, Paderu, ASR Dist, 531024. ORCiD: 0009-0004-9765-8542
3 Associate professor, Department of Anatomy, Government Medical College, Paderu, ASR Dist, 531024 ORCiD: 0009-0007-6565-7387
4 Professor and Head, Department of Anatomy, Government Medical College, Paderu, ASR Dist, 531024 ORCiD: 0009-0001-7064-4931
5 Professor and Head,Department of Anatomy, PSP Medical College Hospital and Research Institute, Tambaram – Kanchipuram Main Road, Oragadam, Panruti, Sriperumbudur Taluk, Kancheepurum Dist, Tamilnadu , 631604. ORCiD: 0009-0002-5065-3566
Corresponding Author: Dr. Doni R Praveen Kumar, Assistant professor, Department of Anatomy, Government Medical College, Paderu, ASR Dist, 531024, Andhra Pradesh, India. E-Mail: donipraveen66@gmail.com
Abstract
Background: Elastic fibres confer recoil and patency to the trachea and main bronchi, but systematic quantitative evidence for normal airway ageing is limited.
Objective: To quantify age-related changes in elastic fibre architecture of the human trachea and main bronchi.
Methods: In a cross-sectional cadaveric study (September 2025–January 2026), full-thickness tracheal and main bronchial segments were sampled from 41 adults (21–93 years) and stratified into four age groups (18–39, 40–59, 60–79, ≥80 years). Verhoeff–Van Gieson staining was used for elastin visualization. From four regions (tracheal anterior and posterior walls; right and left main bronchi), 775 quality-controlled fields (20×) underwent morphometry for elastic area fraction, fibre density, fragmentation index, and fibre thickness; observers were blinded to age. Non-parametric group comparisons and Spearman correlations assessed age effects.
Results: Elastic area fraction declined progressively with age in all regions (all p<0.001), with reductions of ~29–41% from the youngest to oldest groups. Fibre density decreased by ~29–32% (all p<0.001). Fragmentation increased more than three-fold across regions (all p<0.001) and showed very strong positive correlations with age (r=0.893–0.947). Elastic area fraction correlated strongly and negatively with age (r=−0.785 to −0.850). Multivariable regression confirmed age as the dominant predictor, while sex effects were not significant. The posterior tracheal wall consistently retained higher elastic area fraction than the anterior wall (overall p<0.001).
Conclusion: Normal ageing is associated with substantial loss and fragmentation of airway elastic fibres, supporting observed declines in expiratory flow and cough effectiveness in healthy elders.
Keywords: Elastic fibres, Trachea, Main bronchi, Ageing, Verhoeff–Van Gieson, Morphometry.
REFERENCES
[1]. Karakioulaki M, Tzanakis N. Extracellular matrix remodelling in COPD. Eur Respir Rev. 2020;29:190124.
https://doi.org/10.1183/16000617.0124-2019
PMid:33208482 PMCid:PMC9488912
[2]. Burgess JK, Weiss DJ, Westergren-Thorsson G, Wigen J, Dean CH, Mumby S, et al. Extracellular matrix as a driver of chronic lung diseases. Am J Respir Cell Mol Biol. 2024;70:239-246.
https://doi.org/10.1165/rcmb.2023-0176PS
PMid:38190723
[3]. Christopoulou ME, Papakonstantinou E, Stolz D. Matrix metalloproteinases in chronic obstructive pulmonary disease. Int J Mol Sci. 2023;24:3786.
https://doi.org/10.3390/ijms24043786
PMid:36835197 PMCid:PMC9966421
[4]. Saputra PB, Purwati DD, Ulhaq AUD, Yolanda S, Djatioetomo YCED, Rosyid AN, et al. Neutrophil elastase in the pathogenesis of chronic obstructive pulmonary disease: a review. Curr Respir Med Rev. 2023;19:29-35.
https://doi.org/10.2174/1573398X18666220929170117
[5]. Bhatt SP, Bodduluri S, Reinhardt JM, Nakhmani A, Crapo JD, Silverman EK, et al. Mechanically affected lung and progression of emphysema. Am J Respir Crit Care Med. 2025;211:1409-1417.
https://doi.org/10.1164/rccm.202409-1820OC
PMid:40009041 PMCid:PMC12369868
[6]. Bhana RH, Magan AB. Lung mechanics: a review of solid mechanical elasticity in lung parenchyma. J Elast. 2023;153:53-117.
https://doi.org/10.1007/s10659-022-09973-6
PMid:36619653 PMCid:PMC9808719
[7]. Heinz A. Elastases and elastokines: elastin degradation and its significance in health and disease. Crit Rev Biochem Mol Biol. 2020;55:252-273.
https://doi.org/10.1080/10409238.2020.1768208
PMid:32530323
[8]. de Ryk J, Thiesse J, Namati E, McLennan G. Stress distribution in a three dimensional, geometric alveolar sac under normal and emphysematous conditions. Int J Chron Obstruct Pulmon Dis. 2007;2:81-91.
https://doi.org/10.2147/copd.2007.2.1.81
PMid:18044070 PMCid:PMC2692121
[9]. Wang K, Liao Y, Li X, Wang R, Zeng Z, Cheng M, et al. Inhibition of neutrophil elastase prevents cigarette smoke exposure-induced formation of neutrophil extracellular traps and improves lung function in a mouse model of chronic obstructive pulmonary disease. Int Immunopharmacol. 2023;114:109537.
https://doi.org/10.1016/j.intimp.2022.109537
PMid:36495695
[10]. Fagiola M, Reznik S, Riaz M, Qyang Y, Lee S, Avella J, et al. The relationship between elastin cross-linking and alveolar wall rupture in human pulmonary emphysema. Am J Physiol Lung Cell Mol Physiol. 2023;324:L1-L10.
https://doi.org/10.1152/ajplung.00284.2022
PMid:37014816
[11]. Suki B, Bates JH. Lung tissue mechanics as an emergent phenomenon. J Appl Physiol. 2011;110:1111-1118.
https://doi.org/10.1152/japplphysiol.01244.2010
PMid:21212247 PMCid:PMC3075131
[12]. Fessler HE, Macklem PT. Percolation and phase transitions. Am J Respir Crit Care Med. 2007;176:1065-1066.
https://doi.org/10.1164/rccm.200704-557ED
PMid:17823359
[13]. Fagiola M, Gu G, Avella J, Cantor J. Free lung desmosine: a potential biomarker for elastic fiber injury in pulmonary emphysema. Biomarkers. 2022;27:319-324.
https://doi.org/10.1080/1354750X.2022.2043443
PMid:35170389
[14]. Reichheld SE, Muiznieks LD, Stahl R, Simonetti K, Sharpe S, Keeley FW. Conformational transitions of the cross-linking domains of elastin during self-assembly. J Biol Chem. 2014;289:10057-10068.
https://doi.org/10.1074/jbc.M113.533893
PMid:24550393 PMCid:PMC3974977
[15]. Chen YJ, Jeng JH, Chang HH, Huang MY, Tsai FF, Yao CCJ. Differential regulation of collagen, lysyl oxidase and MMP-2 in human periodontal ligament cells by low- and high-level mechanical stretching. J Periodontal Res. 2013;48:466-474.
https://doi.org/10.1111/jre.12028
PMid:23190051 PMCid:PMC10298483
[16]. Mecham RP. Elastin in lung development and disease pathogenesis. Matrix Biol. 2018;73:6-20.
https://doi.org/10.1016/j.matbio.2018.01.005
PMid:29331337 PMCid:PMC6041195
[17]. Schräder CU, Heinz A, Majovsky P, Karaman Mayack B, Brinckmann J, Sippl W, et al. Elastin is heterogeneously cross-linked. J Biol Chem. 2018;293:15107-15119.
https://doi.org/10.1074/jbc.RA118.004322
PMid:30108173 PMCid:PMC6166741
[18]. Stone PJ, Morris SM, Thomas KM, Schuhwerk K, Mitchelson A. Repair of elastase-digested elastic fibers in acellular matrices by replating with neonatal rat-lung lipid interstitial fibroblasts or other elastogenic cell types. Am J Respir Cell Mol Biol. 1997;17:289-301.
https://doi.org/10.1165/ajrcmb.17.3.2597
PMid:9308916
[19]. Shifren A, Mecham RP. The stumbling block in lung repair of emphysema: elastic fiber assembly. Proc Am Thorac Soc. 2006;3:428-433.
https://doi.org/10.1513/pats.200601-009AW
PMid:16799087 PMCid:PMC2658707
[20]. Shen J, Lin X, Liu J, Li X. Effects of cross-link density and distribution on static and dynamic properties of chemically cross-linked polymers. Macromolecules. 2018;52:121-134.
https://doi.org/10.1021/acs.macromol.8b01389
[21]. Liu Y, Xian W, He J, Li Y. Interplay between entanglement and crosslinking in determining mechanical behaviors of polymer networks. Int J Smart Nano Mater. 2023;14:474-495.
https://doi.org/10.1080/19475411.2023.2261777
[22]. Mariano CA, Sattari S, Ramirez GO, Eskandari M. Effects of tissue degradation by collagenase and elastase on the biaxial mechanics of porcine airways. Respir Res. 2023;24:105.
https://doi.org/10.1186/s12931-023-02376-8
PMid:37031200 PMCid:PMC10082978
[23]. Trębacz H, Barzycka A. Mechanical properties and functions of elastin: an overview. Biomolecules. 2023;13:574.
https://doi.org/10.3390/biom13030574
PMid:36979509 PMCid:PMC10046833
[24]. Burla F, Mulla Y, Vos B, Aufderhorst-Roberts A, Koenderink G. From mechanical resilience to active material properties in biopolymer networks. Nat Rev Phys. 2019;1:249-263.
https://doi.org/10.1038/s42254-019-0036-4
[25]. Jamhawi NM, Koder RL, Wittebort RJ. Elastin recoil is driven by the hydrophobic effect. Proc Natl Acad Sci U S A. 2024;121:e2304009121.
https://doi.org/10.1073/pnas.2304009121
PMid:38442161 PMCid:PMC10945822
