August 2014 – GOLLYGEE!

Intestinal tracts of germ free mice and mice given clostridia bacteria. The higher levels of mucus in the clostria tracts is thought to prevent allergens from leaking into the bloodstream.

Science News brings word of a recent PNAS report on gut bacteria and allergies. In the study, researchers gave a group of mice antibiotics to wipe out their gut microbiome. Feeding the mice peanuts after this treatment seemed to induce allergy-like responses, that weren’t observed in mice who didn’t receive the treatment. The researchers gave the mice Clostridia bacteria to replenish the microbiome, and the response diminished.

Cathryn Nagler of the University of Chicago and colleagues treated some mice with antibiotics to wipe out the animals’ gut bacteria, and then triggered an allergy-like response to peanut particles. Peanuts revved up the germ-free animals’ immune systems — but mice with normal gut bacteria didn’t have the bad reaction.

Giving germ-free mice a dose of Clostridia bacteria made the animals more like their counterparts with normal gut flora. The microbes encourage mouse cells to make mucus that helps seal up the intestines, keeping food particles from slipping into the bloodstream and riling up the immune system, the researchers found.

The researchers suggest that this might also hold true for humans.

Carbohydrate rich diets, especially refined carbohydrates, have been linked to higher rates of colon cancer in the developed world, when compared to developing nations. A new report in the journal Cell, provides insight into how this might come to be. Science News explains:

To probe the link between colon tumors and gut microbes, the researchers treated mice engineered to be prone to colon cancer with antibiotics. By eradicating intestinal bacteria, the drugs hindered malignant lumps of cells called polyps from growing in the lining of the colon and small intestines. The team then noticed that feeding the rodents a diet low in sugar and starch also reduced the growth of polyps.

The mice had two gene mutations often linked to colon cancer in people,one of which derails a cell’s ability to fix errors that arise during DNA replication, known as the mismatch DNA repair system.

A mismatch repair deficiency causes cells in the lining of the colon to divide quickly, explains study leader Alberto Martin, an immunologist at the University of Toronto. Bacteria and carbs speed the process, he says, damaging the genome and leading to tumor growth.

The researchers surmised that when microbes feast on carbohydrates, the germs must produce a chemical that pushes colon cells lacking the ability to repair DNA mismatches toward uncontrollably multiplying into tumors.

The researchers discovered that gut bacteria process carbohydrates into butyrate, which can induce cancer in APC^Min/+MSH2^−/− mice by allowing cancerous MSH2^−/−cells to proliferate uncontrollably in the colon.

GOLLYGEE!

Month: August 2014

do gut bacteria prevent allergies?

carbs fuel colon cancer in mice