Nodular lymphoid hyperplasia in the gastrointestinal tract in adult patients: A review

Epithelial Control of Gut-Associated Lymphoid Tissue Formation through p38α-Dependent Restraint of NF-κB Signaling

The protein kinase p38α mediates cellular responses to environmental and endogenous cues that direct tissue homeostasis and immune responses. Studies of mice lacking p38α in several different cell types have demonstrated that p38α signaling is essential to maintaining the proliferation-differentiation balance in developing and steady-state tissues. The mechanisms underlying these roles involve cell-autonomous control of signaling and gene expression by p38α. In this study, we show that p38α regulates gut-associated lymphoid tissue (GALT) formation in a noncell-autonomous manner. From an investigation of mice with intestinal epithelial cell-specific deletion of the p38α gene, we find that p38α serves to limit NF-κB signaling and thereby attenuate GALT-promoting chemokine expression in the intestinal epithelium. Loss of this regulation results in GALT hyperplasia and, in some animals, mucosa-associated B cell lymphoma. These anomalies occur independently of luminal microbial stimuli and are most likely driven by direct epithelial-lymphoid interactions. Our study illustrates a novel p38α-dependent mechanism preventing excessive generation of epithelial-derived signals that drive lymphoid tissue overgrowth and malignancy.

Capsule Endoscopy for Ileitis with Potential Involvement of Other Sections of the Small Bowel

Ileitis is defined as inflammation of the ileum. This condition includes ulcers, aphthous ulcers, erosions, and nodular or erythematous mucosa. Various etiologies are associated with ileitis. Crohn's disease, ulcerative colitis, medications such as nonsteroidal anti-inflammatory drugs, infectious conditions, neoplasms, infiltrative disorders, vasculitides, spondyloarthritis, endometriosis, and radiation therapy-related conditions involve the ileum. However, the differential diagnosis of terminal ileitis can be difficult in many cases. Video capsule endoscopy (VCE) has become a useful tool for the diagnosis of a variety of small bowel lesions. This review describes each of the various conditions associated with ileitis and the diagnostic value of VCE for ileitis, which may help identify and evaluate these conditions in clinical practice. Based on the information provided by VCE, a definitive diagnosis could be made using the patients' medical history, clinical course, laboratory and ileocolonoscopic findings, radiologic imaging findings, and histologic findings.

Nodular hyperplasia of the gastrointestinal tract after liver transplantation: role of immunosuppressive therapy? A case report

Nodular lymphoid hyperplasia (NLH) of the gastrointestinal tract is a rare disease usually reported in patients with congenital or acquired immunodeficiency and chronic gastrointestinal infections. However, no case of NLH in a patient receiving immunosuppressive therapy has been reported to date. We describe the case of a woman who developed chronic diarrhea related to NLH 9 years after liver transplantation. Other causes of diarrhea and NLH were excluded. Her immunosuppressive regimen consisted on mycophenolate mofetil (MMF) and tacrolimus. Reduction of MMF dose improved symptoms but led to a rising aminotransferase level. Given the risk of graft rejection, MMF at full dose was resumed and she was started on symptomatic treatment for diarrhea. The role of immunosuppressive drugs in the pathogenesis of NLH may be related to the reduction of T- and B-lymphocyte proliferation and decreasing antibody production. NLH will further develop to compensate functionally inadequate lymphoid tissue, as reported in congenital immunodeficiency states.