Cardiometabolic disease (CMD) has emerged as the leading cause of death among western lowland gorillas in zoo environments¹. Despite ongoing efforts to improve gorilla health and well-being in zoo settings, the exact etiology of this condition remains poorly understood. In humans, microbial imbalances and microbial metabolites have been linked to cardiovascular diseases^2-3. By analyzing faecal samples from zoo-housed and wild gorillas, we identified key microbial markers associated with CMD, providing valuable insights into potential preventive and therapeutic strategies. We collected faecal samples from zoo-housed gorillas across the United States and Europe and from wild gorillas from the Central African Republic. 

Key findings

Wild and zoo-housed gorillas presented distinct microbiome compositions. One of the most remarkable characteristics of zoo-housed gorillas, regardless of health status, was the high gut microbiome diversity and a gut metabolic environment more associated with increased fermentation of simple carbohydrates and in particular, dietary protein, mainly in U.S. individuals. Wild gorillas exhibited lower microbiome diversity but maintained metabolomic profile associated with processing high-fiber diets. European zoo-housed gorillas presented a microbiome composition that was more like wild individuals than to their U.S. counterparts. This distinction likely reflects differences in exposure to fibrous foods between U.S. and European zoos and may suggest a greater emphasis on highly lignified or pectin-rich diets in European settings.

Microbial traits distinguishing CMD-affected gorillas from healthy individuals in U.S. zoo-housed settings were identified. CMD was associated with reduced metabolism of sulfur-containing amino acids and hexoses, as well as decreased fecal levels of butyrate and propionate. This observation may denote altered or reduced capacity for the microbial metabolism of dietary carbohydrates and proteins in affected gorillas, contrary to what we observed in unaffected individuals. Additionally, affected gorillas showed an increased abundance of potential enteric pathogens, such as Campylobacter coli, which has been linked to intestinal inflammation and systemic health complications, including myocarditis⁴.

Another key observation was the depletion of microbial pathways involved in sulfate assimilation and cysteine biosynthesis in CMD-affected gorillas. Sulfur-containing amino acids like methionine and cysteine play an essential role in cardiovascular health^5-6. These metabolic alterations mirror patterns observed in human cardiovascular diseases, highlighting the relevance of studying nonhuman primates to better understand CMD pathophysiology.

References:

1. McManamon & Lowenstine. Cardiovascular disease in great apes. Fowler’s zoo and wild animal.
2. Nemet, I. et al. A cardiovascular disease-linked gut microbial metabolite acts via adrenergic receptors. Cell 180, 862–877.e22 (2020).
3. Tang, W. H. W. & Hazen, S. L. The contributory role of gut microbiota in cardiovascular disease. J. Clin. Invest. 124, 4204–4211 (2014).
4. Gomes, S.A. et al.Campylobacter coli Myocarditis: a case report. Cardiol Young 32, 1172-1174 (2022).
5. Shi, Y. et al. Homocysteine promotes cardiac fibrosis by regulating the Akt/FoxO3 pathway. Ann Transl Med 9, 1732 (2021).
6. Wilcken, D. E. & Wilcken, B. The pathogenesis of coronary artery disease. A possible role for methionine metabolism. J. Clin. Invest. 57, 1079–1082 (1976).

The cover image of this blog presents Malui, a western lowland gorilla (Gorilla gorilla gorilla) from Dzanga Sangha Protected Areas, Central African Republic. Photo by Anna Stryková.