Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Christopher B Forsyth; Maliha Shaikh; Phillip A Engen; Fabian Preuss; Ankur Naqib; Breanna A Palmen; Stefan J Green; Lijuan Zhang; Zlata R Bogin; Kristi Lawrence; Deepak Sharma; Garth R Swanson; Faraz Bishehsari; Robin M Voigt; Ali Keshavarzian

doi:10.3389/fragi.2024.1352299

Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Front Aging. 2024 Mar 4:5:1352299. doi: 10.3389/fragi.2024.1352299. eCollection 2024.

Authors

Christopher B Forsyth^{1

2

3}, Maliha Shaikh², Phillip A Engen², Fabian Preuss⁴, Ankur Naqib^{2

5}, Breanna A Palmen⁴, Stefan J Green^{2

5}, Lijuan Zhang², Zlata R Bogin², Kristi Lawrence², Deepak Sharma², Garth R Swanson^{1

2

3}, Faraz Bishehsari^{1

2

3}, Robin M Voigt^#^{1

2

3}, Ali Keshavarzian^#^{1

2

3

6}

Affiliations

¹ Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States.
² Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States.
³ Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States.
⁴ Department of Biological Sciences, University of Wisconsin Parkside, Kenosha, WI, United States.
⁵ Genomics and Microbiome Core Facility, Rush University Medical Center, Chicago, IL, United States.
⁶ Department of Physiology, Rush University Medical Center, Chicago, IL, United States.

^# Contributed equally.

Abstract

Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.

Keywords: aging; anti-microbial peptides; dysbiosis; gene expression; inflammaging; microbiota; tight junction.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This research was supported in part by the National Institute on Alcohol Abuse and Alcoholism (R24AA026801, AK), National Institute on Aging (R01AG056653, RV-Zuwala), National Institute of Diabetes and Digestive and Kidney Diseases (R01DK124280, GS), and National Cancer Institute (R01CA279487, FB). In addition, this research was supported in part by philanthropic funding from Mr. and Mrs. Larry Field, Mr. and Mrs. Glass, Mrs. Marcia, Mr. Silas Keehn, the Sklar Family, the Johnson Family, and Mr. Harlan Berk. The funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication.