A recent study was conducted to find out the association between the gut microbiota in humans and overall longevity. The study was conducted by researchers at the Xi’an Jiaotong University, China.
Microbiome: an enigma
The microbiome has been a subject of paramount importance in health sciences of recent. Our idea of a human as a single physical being of trillions of cells of varied shapes and functions working in coordination is considered outdated. We have known for a long time that there are various microorganisms living in symbiosis within our body, but their quantity and function was unknown.
It has been discovered that the number microbes in our body is higher than our own cells - we could say that we are more microbe than humans. As more research is done, it is being realised that these organisms play a vital role in our survival.
Microbiota and ageing
The largest number of microbiota is found in our intestines. They have been found to be responsible for numerous things, from our digestive capabilities to our body composition and even our mental health and intelligence. With the realisation of the gravity of their impact in our lives, there was a question of whether the microbes can impact our lifespan as well.
Ageing is one of the primary challenges of modern healthcare due to the increased burden of diseases and morbidity with advancing age. Occurrence of cardiovascular, musculoskeletal and neurodegenerative diseases increases along with other pathologies in old age. Physical and mental capacity also shows significant deterioration with age.
Studies have shown that our genetic and environmental factors influence lifespan and healthy living. It has been calculated that our age of death in adulthood is 25% inherited. Yet, our approach to disease treatment is mostly to assist our organ systems to cope with respective disease pathologies with medicinal or surgical interventions.
However, the fact that our body is significantly composed of these various bugs like bacteria, fungi, and viruses living in harmony within our bodies should direct us to interventions augmenting their roles. Gut microbiome has been associated with gut health and diseases like obesity, diabetes, cardiovascular diseases and cancer.
The study
The new study explored here tried to determine if there was any correlation between microbiota and their impact on human lifespan.
The study selected four key longevity related traits for analysis:
- healthspan
- parental longevity
- parental lifespan
- longevity
These longevity and lifespan health traits were collected from a genome-wide association study (GWAS). GWAS has been widely used for exploring candidate genetic variants for multiple complex traits and diseases. The data was collected from a large population of European descent and English descent ancestry. Correlation of genetics in population is a vital parameter to find out genetic correlation in different phenotypes.
The data on the microbiota was collected from a previous GWAS meta-analysis and four candidate microbiota were selected:
- Sporobacter
- Roseburia
- Collinsella
- Veillonella
Following this, the study tried to establish both correlation and causation between lifespan traits and microbiome candidates.
LSDC regression to estimate correlation of longevity trait and gut microbiota
Linkage disequilibrium score (LDSC) regression was used to estimate genetic correlations across the longevity related traits and the candidate microbiota based on GWAS summary data. LSDC regression is a powerful tool to estimate genetic correlations across human complex traits from GWAS information. It used statistical summary as data instead of individual genotype data.
MR analysis to verify causal association
Mendelian randomization analysis (MR) helps in assessing potential causation between exposures and outcomes based on observed data. It has the advantage of eliminating errors of confounding factors and reverse causality in epidemiological study results.
Conclusion
The study confirmed several old observations and provided new insight into the strong genetic correlation between healthy diverse gut microbiome and healthy ageing.
Some of the significant observations were:
- positive causation between Collinsella and parental longevity
- strong association between Sporobacter and longevity with their shared influence on immune function and immune-mediated inflammatory diseases
- positive causal relation between Veillonella and longevity, with a higher correlation for longevity
- correlation Roseburia and longevity established from LSDC regression
With these observations along with our old knowledge of role played by gut microbes in our overall health and longevity, microbiome and their targeted influence can emerge as an important avenue for exploration of extended healthy lifespans.
Author: Joydev Bhattacharjee
Reference
Association between gut microbiota and longevity: a genetic correlation and mendelian randomization study - He, D., Liu, L., Zhang, Z. et al. - BMC Microbiology, December 2022
