Nat Genet's new discovery of the brain-gut axis, Dr. Qin Youwen and other large cohort multi-omics reveal the potential pathogenic bacteria of depression

Could changes in gut microbiota trigger mental disorders? Which bacteria can affect people's mood through the brain-gut axis? On February 3, 2022, Guillaume Méric of Baker Heart and Diabetes Institute, Australia, in collaboration with Michael Inouye (first author is Qin Youwen) published the article Combined effects of host genetics and diet on human gut microbiota and incident disease in a Nature Genetics single population cohort, revealing that specific gut bacteria are potential causative factors of depression [1]
.

Based on thousands of Finns, researchers found that Morganella (Morganella spp.
) in a variety of gut bacteria increases the risk of major depression
.

As early as 2008, an article exploring the relationship between depression and inflammation reported that a chemical secreted by Morganella can cause a strong immune response in the blood of patients with depression, and other Gram-negative bacteria have similar phenomena [2]
.

University of California microbiologist Jack Gilbert commented that the latest study is "further evidence" that inflammation caused by gut microbes can affect people's mood, with important clinical implications
.

It is not uncommon for the gut microbiota to influence psychosis
.

Not long ago, Frontiers in Psychiatry reported that two patients with depression were relieved by fecal transplantation (fpsyt.
2022.
815422)
.

A multi-center collaborative study in China, based on 311 patients and healthy controls, found gut bacterial species, metabolic pathways and metabolites associated with depression [3]
.

The main goal of the Melbourne research team was not to find the microbes that influence depression
.

They analyzed genomic variation, gut microbiota composition, diet, and disease occurrence in ~6,000 Finns, revealing the influence of host genetic background and diet on gut microbiota, as well as the relationship between microbiota and complex diseases
.

Currently, few studies can simultaneously provide so many types of biological big data in one research population
.

This cohort is part of the FINRISK 2002 project to study the characteristics and risk factors of chronic diseases in Finns, a series of studies that have been carried out for about 50 years
.

The research team selected the gut bacteria that can affect the incidence of complex diseases by combining genetic variation sites that affect the composition of gut microbiota and combining genetic data of 46 common complex diseases
.

Of the many combinations, Morganella has the clearest link to depression
.

Those with a genetic background that increased Morganella abundance had a higher risk of depression than others
.

Since the genetic background is inborn and difficult to change, this finding based on genetic information is a reliable evidence
.

Subsequently, using 16-year follow-up data, the researchers found an increased incidence of depression in the population with higher Morganella abundance at baseline (181 incidences)
.

Taken together, both genetics and follow-up data consistently support an increased risk of depression in intestinal Morganella
.

(Both genetics and follow-up data support Morganella's influence on the onset of depression
.

MDD: Major depressive disorder) In addition to Morganella, Klebsiella (also known as Raoultella[4,5]) has also been found to increase the risk of depression
.

Both genera belong to the Enerobacteriaceae (Enterobacteriaceae) family, which contains bacteria that are higher in depressed patients than normal [6]
.

However, the study of gut microbiota and the brain-gut axis is still in its infancy, depression has multiple phenotypes, and bacteria can also affect mental disorders in many ways
.

It is not known whether depression can be relieved by reducing or killing Morganella in the gut
.

This will be a bigger challenge! Original link: https://doi.
org/10.
1038/s41588-021-00991-z Plate maker: Eleven References 1.
Qin, Y.
, et al.
, Combined effects of host genetics and diet on human gut microbiota and incident disease in a single population cohort.
Nature Genetics, 2022.
2.
Maes, M.
, M.
Kubera, and J.
-C.
Leunis, The gut-brain barrier in major depression: intestinal mucosal dysfunction with an increased translocation of LPS from gram negative enterobacteria (leaky gut) plays a role in the inflammatory pathophysiology of depression.
Neuro endocrinology letters, 2008.
29 1: p.
117-24.
3.
Yang, J.
, et al.
, Landscapes of bacterial and metabolic signatures and their interaction in major depressive disorders.
Science Advances, 2020.
6(49): p.
eaba8555.
4.
Wyres, KL, MMC Lam, and KE Holt, Population genomics of Klebsiella pneumoniae.
Nat Rev Microbiol, 2020.
18(6): p.
344-359.
5.
Ma, Y.
, et al.
,
.