The small intestine is essential for digestion, nutrient absorption, immune regulation, and microbial balance. Its epithelial lining, containing specialized cells like Paneth cells and tuft cells, is crucial for maintaining intestinal homeostasis. Paneth cells produce antimicrobial peptides and growth factors that support microbial regulation and intestinal stem cells, while tuft cells act as chemosensors, detecting environmental changes and modulating immune responses. Along with immune cells such as intraepithelial lymphocytes, innate lymphoid cells, T cells, and macrophages, they form a strong defense system that protects the epithelial barrier. Disruptions in this balance contribute to chronic inflammation, microbial dysbiosis, and compromised barrier function-key features of inflammatory bowel disease, celiac disease, and metabolic syndromes. Furthermore, dysfunctions in the small intestine and immune cells are linked to systemic diseases like obesity, diabetes, and autoimmune disorders. Recent research highlights promising therapeutic strategies, including modulation of epithelial and immune cell functions, probiotics, and gene editing to restore gut health and address systemic effects. This review emphasizes the pivotal roles of small intestinal epithelia and immune cells in maintaining intestinal homeostasis, their involvement in disease development, and emerging treatments for intestinal and systemic disorders.
Humans ; Intestinal Mucosa/cytology* ; Intestine, Small/cytology* ; Animals ; Inflammatory Bowel Diseases/immunology* ; Celiac Disease/immunology* ; Paneth Cells/immunology*

BACKGROUNDIntestinal T-cell lymphoma (ITCL) is a heterogeneous lymphoid neoplastic group with variable clinical and pathological features. ITCL in oriental countries is different from enteropathy-type intestinal T-cell lymphoma (ETCL) in relation to celiac disease and Epstein-Barr virus (EBV). The objective of this study was to investigate the clinicopathological features, immunophenotype, expression of cytotoxic molecule (TIA-1), T-cell receptor (TCR)-gamma gene rearrangement, and Epstein-Barr virus (EBV) latent infection in primary ITCL without celiac disease in Chinese.

METHODSThe clinical data of 42 patients were analyzed, and the patients were followed up. Compared with human reactive lymphoid tissues, in situ hybridization for EBER1/2, polymerase chain reaction for TCR-gamma gene rearrangement, and immunohistochemical staining for immunophenotypes, TIA-1 and EBV latent membrane proteins (LMP-1) were investigated. Survival curves of different clinicopathological features, immuno-phenotypes, expression of LMP1, TCR-gamma gene rearrangement and therapy were analyzed.

RESULTSThree fourths of the patients suffered from ITCL in China were men with a peak age incidence in the 4th decade. Common presenting features included fever and hemotochezia. The prognosis was poor with a median survival of 3.0 months. The lesions were mostly localized in the ileocecum and colon. About 38/42 (90.5%) patients demonstrated pleomorphic medium-sized on large cells. Histological features of celiac disease were rarely seen. All 42 patients with ITCL revealed CD45RO positive. Neoplastic cells partially expressed T-cell differentiated antigens (CD3epsilon, CD4, CD8) and NK cell associated antigen (CD56). The positive frequency of CD3epsilon, CD4, CD8 and CD56 was 28/42 (66.7%), 7/42 (16.7%), 10/42 (23.8%) and 12/42 (28.6%) respectively. Thirty-nine cells (92.9%) expressed TIA-1, but none expressed CD20 and CD68. More than half of the patients (64.3%, 64.3% and 59.5%) revealed TCR-gamma gene rearrangement by three different TCR-gamma primers respectively. EBER1/2 was detected in 41 (97.6%) of the 42 patients. The expression frequency of LMP-1 was 38.1% (16/42).

CONCLUSIONSPrimary ITCL without celiac disease in Chinese is a special highly EBV-associated clinicopathological entity. There are few similarities in patients with celiac disease in western countries. A small proportion of primary ITCLs in Chinese and extranodal NK/T-cell lymphoma of nasal type belong to the same spectrum.

Adolescent ; Adult ; Celiac Disease ; complications ; Child ; Epstein-Barr Virus Infections ; complications ; Female ; Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor ; Humans ; Immunophenotyping ; In Situ Hybridization ; Intestinal Neoplasms ; immunology ; pathology ; virology ; Lymphoma, T-Cell ; immunology ; pathology ; virology ; Male ; Middle Aged ; RNA, Viral ; genetics ; Viral Matrix Proteins ; genetics