Tag: inflammatory bowel disease

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Growing up with Dogs (But not Cats) Protects Against Crohn’s Disease

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Young children who grow up with a dog or in a large family appears to confer some protection later on in life from Crohn’s disease, according to a study presented at Digestive Disease Week® (DDW) 2022.

Crohn’s disease is a common type of inflammatory bowel disease that often develops in young adults, smokers, and those with a close family member who has IBD. Symptoms include diarrhoea, abdominal pain and weight loss. Treatments currently aim to prevent symptom flare-ups through diet modification, medication, and surgery.

“Our study seems to add to others that have explored the ‘hygiene hypothesis’ which suggests that the lack of exposure to microbes early in life may lead to lack of immune regulation toward environmental microbes,” said Williams Turpin, PhD, the study’s senior author and a research associate with Mount Sinai Hospital and the University of Toronto.

Researchers used an environmental questionnaire to collect information from nearly 4300 first-degree relatives of people with Crohn’s disease enrolled in the Crohn’s and Colitis Canada Genetic, Environmental, and Microbial (CCC-GEM) project. Using responses to the questionnaire and historical data collected at the time of recruitment, Dr Turpin and his team analysed several environmental factors, including family size, the presence of dogs or cats as household pets, the number of bathrooms in the house, living on a farm, drinking unpasteurised milk and drinking well water. The analysis also included age at the time of exposure.

The study found that exposure to dogs, especially from ages 5 to 15, was associated with healthy gut permeability and balance between the microbes in the gut and the body’s immune response, which may all help protect against Crohn’s disease. Similar effects were observed with exposure to dogs across all age groups.

“We did not see the same results with cats, though we are still trying to determine why,” Dr Turpin said. “It could potentially be because dog owners get outside more often with their pets or live in areas with more green space, which has been shown previously to protect against Crohn’s.”

Another protective factor seemed to be living with three or more family members in the first year of life, which was associated with microbiome composition later in life. The gut microbiome is believed to play a role in a number of health conditions, such as inflammatory bowel disease, colorectal cancer, diabetes, and high blood pressure.

Dr Turpin and his colleagues hope their findings may assist physicians in asking detailed questions of patients to determine who is at highest risk. However, he noted that the early life environmental factors were assessed by questionnaires, so caution is warranted in interpreting these results due to possible recall bias at recruitment. The reasons dog ownership and larger families appear to provide protection from Crohn’s remain unclear.

Source: Digestive Disease Week

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Damaging Candida Strains in Inflammatory Bowel Disease

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Anatomy of the gut
Source: Pixabay CC0

In the human gut, individual strains of Candida albicans are incredibly varied, and some C. albicans strains may damage the gut of patients with inflammatory bowel disease (IBD), according to a new study published in Nature. The findings suggest a possible way to tailor treatments to individual patients in the future.

The researchers used an array of techniques to study Candida strains from the colons of people with or without ulcerative colitis, a chronic, relapsing and remitting inflammatory disorder of the colon and rectum and one of the main forms of IBD. They found that certain strains, which they call “high-damaging,” produce candidalysin, a potent toxin that damages immune cells.

“Such strains retained their “high-damaging” properties when they were removed from the patient’s gut and triggered pro-inflammatory immunity when colonised in mice, replicating certain disease hallmarks,” said senior author Dr Iliyan Iliev, an associate professor of immunology in medicine at Weill Cornell Medicine.

IBD is estimated to affect between one in 11 and one in 26 people worldwide. The condition can significantly impact patients’ quality of life. There are a handful of available therapies, but treatments may not always be effective. The study showed that steroids, one of the common treatments, may not work. Treating mice with steroids to suppress intestinal inflammation failed in the presence of “high-damaging” C. albicans strains.

“Our findings suggest that C. albicans strains do not cause spontaneous intestinal inflammation in a host with intact immunity,” Dr Iliev said. “But they do expand in the intestines when inflammation is present and can be a factor that influences response to therapy in our models and perhaps in patients.”

Most studies of the human microbiome in healthy individuals and those with IBD have focused on bacteria and viruses, but recent studies  by Dr Iliev and others has highlighted the role of fungi. Intestinal fungi play an important role in regulating immunity at surfaces exposed to the outside, such as the intestines and lungs, due to their potent immune-stimulating characteristics. While the mycobiota – the body’s fungi community – has been linked to IBD, the pro-inflammatory of gut the mycobiota was not understood.

In the new study, the investigators initially found that Candida strains, while highly diverse in the intestines of both patients with and without colitis, were on average more abundant in the patients with IBD. But that did not explain disease outcomes in individual patients. So, the investigators set out to identify the characteristics of these strains that cause damage and how they relate to individual patients.

The researchers observed that in the patients with ulcerative colitis, severe disease was associated with the presence of “high-damaging” Candida strains, all of which produce the candidalysin toxin. The scientists showed that the toxin damages immune cells called macrophages, prompting a storm of the pro-inflammatory cytokine IL-1β.

The researchers then grew macrophages in the presence of Candida strains and found that the ability of the strains to induce IL-1β corresponded closely to the severity of colitis in the patients.

“Our finding shows that a cell-damaging toxin candidalysin released by “high damaging” C. albicans strains during the yeast-hyphae morphogenesis triggers pathogenic immunological responses in the gut,” said first author Dr Xin Li.

Experiments in mice delineated that candidalysin-producing “high-damaging” strains induced the expansion of a population of T cells called Th17 cells and other inflammation-associated immune cells, such as neutrophils.

“Neutrophils contribute to tissue damage and their accumulation is a hallmark of active IBD,” said Dr Ellen Scherl, a professor of inflammatory bowel disease. “The indication that these processes might in part be driven by a fungal toxin released by yeast strains in specific patients could potentially inform personalized treatment approaches.”

Consistent with this finding, blocking IL-1β signalling had a dramatic effect in reducing colitis signs in mice that harboured these highly pro-inflammatory strains. The researchers noted that other recent studies have linked IBD to IL-1β in a general way, prompting ongoing investigations of drugs targeting related pathways as potential IBD therapies.

“We do not know whether specific strains are acquired by specific patients during the course of disease or whether they have been always there and become a problem during episodes of active disease” Dr Iliev said. “Nevertheless, our findings highlight a mechanism by which commensal fungal strains can turn against their host and overdrive inflammation.”

The team’s next steps are to investigate the persistence candidalysin-producing strains in the inflamed colon of specific IBD patients, as well as ways to choose patients for mycobiome therapy.

Source: Weill Cornell Medicine

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For Older IBD Patients, Vedolizumab is a Safer Option

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Vedolizumab appeared to be safer than tumour necrosis factor (TNF) inhibitors in older adults with inflammatory bowel disease (IBD), according to the results of a large retrospective study.

Vedolizumab is a fully humanised monoclonal antibody which targets α4β7 integrin, and prevents leukocyte movement from the blood into inflamed gut tissue.

At the virtual Crohn’s and Colitis Congress, Bharati Kochar, MD, of Massachusetts General Hospital in Boston, presented data showing that all-cause hospitalisation during the 12 months after initiating biologic treatment was lower in new users of vedolizumab than in those starting TNF inhibitors, with a hazard ratio of 0.81 (95% CI 0.68-0.96)

“The American population is rapidly aging, and the number of Americans 65 and older in 2060 will be more than double what it was in 2014,” Dr Kochar said. “The combination of increasing IBD incidence, improvements in disease treatment-related knowledge, and decreasing IBD mortality is resulting in a high prevalence of older adults with IBD,” she added.

It is estimated that a quarter of Americans over 65 have IBD, yet are less likely to receive adequate immunosuppression. Over 65s are underrepresented in IBD clinical trials, creating a lack of understanding over what medications work or not in this age group.

To answer this question, Dr Kochar and her team analysed a 20% sample of Medicare claims database. Patients were included if they were diagnosed with Crohn’s disease or ulcerative colitis and if they initiated treatment with vedolizumab, infliximab, adalimumab, golimumab, or certolizumab from 2014 to 2018 after being on Medicare for 12 months while not receiving any of those medications.

There were 488 new users of vedolizumab and 2213 initiators of TNF inhibitors in the analysis group, with an average age of 71. More than half were women and most were white, 44% had ulcerative colitis and over half of patients had Carlson Comorbidity Index scores of 2 or higher.

There was otherwise no significant difference between vedolizumab and TNF for IBD-related hospitalisation (HR 0.77, 95% Ci 0.53-1.12), IBD-related surgery: (HR 0.78, 95% CI 0.49-1.22), or new steroid prescription within 60 days of starting the biologic (HR 1.01, 95% CI 0.86-1.18).

In the 6-month period prior to biologic initiation, nearly one-third had a prescription for budesonide, 58% had a prescription for a systemic corticosteroid, and nearly one-third were being prescribed immunomodulators.

“In conclusion, I think it’s important to use your clinical judgment to treat the patient in front of you, and these data should simply help contextualise risk for older IBD patients newly initiating vedolizumab or TNF inhibitors,” said Dr Kochar.

“There is a vast need for additional large and robust comparative effectiveness and safety studies for older adults with IBD, with the rapid proliferation of new IBD medications,” she concluded.

Source: MedPage Today

Presentation information: Kochar B, et al “Comparative effectiveness and safety of vedolizumab and anti-tumor necrosis factor agents in older adults with inflammatory bowel diseases in Medicare administrative claims database” CCC 2021