WASHINGTON, DC – October 20, 2014 -- Lactobacillus species, commonly seen in yogurt cultures, correlate, in the guts of mouse models, with mitigation of lupus symptoms, while Lachnospiraceae, a type of Clostridia, correlate with worsening, according to research published ahead of print in Applied and Environmental Microbiology. "Our results suggest that the same investigation shold be performed in human subjects with lupus," says principal investigator Xin Luo of Virginia Tech, Blacksburg, VA.
In the study, the investigators first showed that mouse models of lupus had higher levels of Lachnospiraceae (a type of Clostridia), and lower Lactobacillusthan control mice. They also compared male and female mice, and found that the differences were present only in females. These results suggest that the gut bacteria may contribute to lupus, a disease which is nine times as prevalent in women as in men, says first author Husen Zhang.
They also monitored the gut microbiota over time in both lupus and control mice, and found that in the former, Clostridia increased in both early and late stages of the disease.
In further experiments, the investigators treated the symptoms in the lupus mice with either retinoic acid alone or vitamin A plus retinoic acid. The latter worsened the symptoms—surprisingly, Luo says, because it had been expected to reduce them—and in those mice, Clostridia increased, while Lactobacillusdeclined. Retinoic acid alone improved the symptoms, with opposite population changes in the gut bacteria.
The research suggests, but does not prove that altering the gut microbiota could mitigate lupus. Nonetheless, Luo suggests that people with lupus should eatLactobacillus-containing probiotics, such as live culture yogurts, to reduce lupus flares. More generally, "The use of probiotics, prebiotics, and antibiotics has the potential to alter microbiota dysbiosis, which in turn could improve lupus symptoms," says co-principal investigator Husen Zhang. Ultimately, says Luo, fecal transplant might prove valuable as a treatment for lupus.
"We were inspired in part to perform this research by a study on type 1 diabetes, which found that that disease is dependent on gut microbiota," says Zhang. "Like type 1 diabetes, lupus is an autoimmune disease that is even more prevalent [than type 1 diabetes] in women."
Applied and Environmental Microbiology is a publication of the American Society for Microbiology (ASM). The ASM is the largest single life science society, composed of over 39,000 scientists and health professionals. Its mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.
WASHINGTON, DC – September 30, 2014 – A species of gut bacteria called Clostridium ramosum, coupled with a high-fat diet, may cause animals to gain weight. The work is published this week in mBio®, the online open-access journal of the American Society for Microbiology.
A research team from the German Institute of Human Nutrition Potsdam-Rehbruecke in Nuthetal observed that mice harboring human gut bacteria including C. ramosum gained weight when fed a high-fat diet. Mice that did not have C. ramosum were less obese even when consuming a high-fat diet, and mice that had C. ramosum but consumed a low-fat diet also stayed lean.
Previous studies have found C. ramosum and other representatives of the Erysipelotrichi class in obese humans, said senior study author Michael Blaut, PhD, head of the institute’s Department of Gastrointestinal Microbiology. This suggests that growth of this organism in the digestive tract is stimulated by high-fat diets, which in turn improves nutrient uptake and enhances the effect of such diets on body weight and body fat.
“We were surprised that presence or absence of one species in a defined bacterial community affected body weight and body fat development in mice,” says Blaut.
Blaut and colleagues investigated the role of C. ramosum in three groups of mice: some harbored a simplified human intestinal microbiota (bacteria) of eight bacterial species including C. ramosum; some had simplified human intestinal microbiota except for C. ramosum, and some had C. ramosum only. The researchers called the first group SIHUMI, the second group SIHUMIw/oCra and the third group Cra. Mice were fed either a high-fat diet or low-fat diet for four weeks.
After four weeks eating a high-fat diet, the mouse groups did not differ in energy intake, diet digestibility, and selected markers of low-grade inflammation. However, SIHUMI mice and Cra mice fed a high-fat diet gained significantly more body weight and body fat, which implies that they converted food more efficiently to energy than did the SIHUMIw/oCra mice. By contrast, all groups of mice fed a low-fat diet stayed lean, indicating that the obesity effect of C. ramosum only occurred on high-fat diets.
The obese SIHUMI and Cra mice also had higher gene expression of glucose transporter 2 (Glut2), a protein that enables absorption of glucose and fructose, and fat transport proteins including fatty acid translocase (Cd36).
“Our results indicate that Clostridium ramosum improves nutrient uptake in the small intestine and thereby promotes obesity,” Blaut said. Associations between obesity and increased levels of lipopolysaccharides (components of the cell wall of gram-negative bacteria) causing inflammation, or increased formation of molecules called short chain fatty acids, reported by other researchers, were not found in this study, he said: “This possibly means that there is more than one mechanism underlying the promotion of obesity by intestinal bacteria.”
Through additional studies Blaut said he hopes to learn more about how C. ramosum affects its host’s energy metabolism and whether similar results occur in conventional mice given the bacteria. “Unraveling the underlying mechanism may help to develop new strategies in the prevention or treatment of obesity,” he said.
The current study was supported by the German Institute of Human Nutrition Potsdam-Rehbruecke.
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mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.
The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.
WASHINGTON, DC – September 29, 2014 – Bacteria that metabolize ammonia, a major component of sweat, may improve skin health and some day could be used for the treatment of skin disorders, such as acne or chronic wounds. In a study conducted by AOBiome LLC, human volunteers using the bacteria reported better skin condition and appearance compared with a placebo control group. The researchers presented the study results at the 5th ASM Conference on Beneficial Microbes in Washington, DC.
WASHINGTON, DC – September 29, 2014 -- Plants have a symbiotic relationship with certain bacteria. These ‘commensal’ bacteria help the pants extract nutrients and defend against invaders – an important step in preventing pathogens from contaminating fruits and vegetables. Now, scientists have discovered that plants may package their commensal bacteria inside of seeds; thus ensuring that sprouting plants are colonized from the beginning. The researchers, from the University of Notre Dame, presented their findings today at the 5th ASM Conference on Beneficial Microbes.
Critically Ill ICU Patients Lose Almost All of Their Gut Microbes—And The Ones Left Aren’t The Good Guys
WASHINGTON, DC—September 23, 2014—Researchers at the University of Chicago have shown that after a long stay in the Intensive Care Unit (ICU) only a handful of pathogenic microbe species remain behind in patients’ intestines. The team tested these remaining pathogens and discovered that some can become deadly when provoked by conditions that mimic the body’s stress response to illness.