Galectins in Intestinal Inflammation: Galectin-1 Expression Delineates Response to Treatment in Celiac Disease Patients.

Galectins, a family of animal lectins characterized by their affinity for N-acetyllactosamine-enriched glycoconjugates, modulate several immune cell processes shaping the course of innate and adaptive immune responses. Through interaction with a wide range of glycosylated receptors bearing complex branched N-glycans and core 2-O-glycans, these endogenous lectins trigger distinct signaling programs thereby controling immune cell activation, differentiation, recruitment and survival. Given the unique features of mucosal inflammation and the differential expression of galectins throughout the gastrointestinal tract, we discuss here key findings on the role of galectins in intestinal inflammation, particularly Crohn's disease, ulcerative colitis, and celiac disease (CeD) patients, as well as in murine models resembling these inflammatory conditions. In addition, we present new data highlighting the regulated expression of galectin-1 (Gal-1), a proto-type member of the galectin family, during intestinal inflammation in untreated and treated CeD patients. Our results unveil a substantial upregulation of Gal-1 accompanying the anti-inflammatory and tolerogenic response associated with gluten-free diet in CeD patients, suggesting a major role of this lectin in favoring resolution of inflammation and restoration of mucosal homeostasis. Thus, a coordinated network of galectins and their glycosylated ligands, exerting either anti-inflammatory or proinflammatory responses, may influence the interplay between intestinal epithelial cells and the highly specialized gut immune system in physiologic and pathologic settings.

Whipple's disease.

Whipple's disease is a rare multisystemic infectious disorder affecting predominantly middle-aged men. Clinical manifestations are very variable with a very long, insidious, prediagnostic course. Weight loss, chronic diarrhea, arthralgias, and low-grade fever are characteristic features in most patients. Although gastrointestinal compromise is very common, atypical clinical forms are being increasingly recognized. Although a bacterial cause was strongly suggested for many years, the infectious agent was elusive until recently. The bacillus that was classified as an actinomycete was named Tropheryma whipplei and has singular characteristics. It presents affinity for the periodic acid-Schiff stain, but it is negative for Ziehl-Neelsen staining and has a characteristic trilamellar cell wall. Its genetic material has been recently sequenced, and culture was finally performed on a human fibroblast cell line. Pathological specimens show macrophage infiltration with mostly intracellular invasion of live bacteria. Immunologic factors, such as a subtle defect of cellular immunity possibly specific for the Whipple's bacterium, are believed to play a role in pathogenesis. The diagnosis requires the histologic assessment of diseased tissue, showing the characteristic infiltration, as a first approach, and confirmatory tests such as electron microscopy and/or polymerase chain reaction. Antibiotic treatment is mandatory and leads to a rapid clinical improvement and remission in most patients. Although the rationale for treatment is largely empiric, current recommendations include a 2-week parenteral therapy (third generation cephalosporin) followed by a long-term therapy with trimethoprim-sulphamethoxazole. This approach has been shown to reduce the number of relapses and was effective for prevention and/or treatment of the neurologic compromise.