Immune-mediated inflammatory diseases (IMIDs) of the gastrointestinal (GI) tract, with features that often mimic each other, commonly present clinical challenges. But key characteristics can help distinguish the most common – inflammatory bowel disease (IBD) – from other IMIDs, allowing for proper diagnosis and treatment, according to a new review.
“Although these disorders share a common pathophysiology, the defects can occur anywhere in the complex network of cytokines, inflammatory mediators, and innate and adaptive systems, leading to unregulated inflammation,” the authors of the review reported in JGH Open.
“Precise knowledge about them will help determine the possible targeted therapy. Thus, it is essential to distinguish these disorders from IBD,” underscored the authors, who were affiliated with the department of gastroenterology at All India Institute of Medical Sciences, New Delhi, India.
IBD, with its two major phenotypes of Crohn’s disease and ulcerative colitis, represents the most common IMIDs of the GI tract.
However, alternative diagnoses with overlapping features that can often be confused with IBD are plentiful, including celiac disease, GI vasculitis, eosinophilic gastroenteritis, some monogenic disorders, sarcoidosis, immune checkpoint inhibitor-induced colitis (ICI colitis), and microscopic colitis, explained the authors.
They recommended that, when evaluating patients with the common features that the disorders share, “one should think with an open mind and look for other possibilities, especially in patients not responding to conventional therapies.”
Monogenic disorders that mimic IBD
To determine monogenic disorders that mimic IBD, a key starting point can be the utilization of next-generation sequencing methods, which have become more available and less costly, the authors explained.
Most monogenic IBD variants present in the first decade of life and can be classified into different groups based on the pathways involved, they noted. These include disorders of epithelial barrier integrity, immune dysregulation, immunodeficiency, autoinflammatory disorders, and innate immune defects, including phagocyte killing.
Though monogenic IBD phenotypes are rare, measures to identify them are important, and can include taking peripheral blood counts, immunoglobulin profiles, and lymphocyte assays to identify common immunodeficiency disorders such as CVID and lymphocyte disorders.
While treatment can be difficult, “targeting the underlying defective immune pathway might be beneficial,” the authors noted, adding that some monogenic disorders, such as mutations of IL-10, can be effectively cured by hematopoietic stem cell transplantation (HSCT), while IL-1b receptor antagonists may be helpful in those with excesses in IL-1b.
Celiac disease, previously believed to be a childhood disease, can occur at any age and, unlike IBD, has known environmental and genetic causes, with genetically predisposed individuals experiencing symptoms triggered by the ingestion of gluten proteins.
The disease can be diagnosed by the presence of serological markers including IgA tTG, anti-endomysial antibody, and anti-deamidated gliadin peptide antibodies, the authors noted.
In addition, they may have evidence of villous atrophy of the duodenal epithelium “with the exception in children, where more than 10 times elevation of IgA tTG is sufficient to make a diagnosis.”
Management includes avoidance of gluten-containing food products and nutritional supplementation of deficient nutrients and vitamins, and fewer than 5% of patients do not respond if they adhere to a gluten-free diet.