Cytokine--intestinal epithelial cell interactions: implications for immune mediated bowel disorders.
Ruemmele FM. Seidman EG.
Ste. Justine Hospital, Department of Pediatrics, University of Montreal, Canada.
The intestinal epithelial cell population is comprised of a dynamic continuum, ranging from undifferentiated, actively proliferating crypt cells, to mature absorptive villus enterocytes, lacking mitotic capacity. Under normal conditions, the constant loss of differentiated villus tip cells via apoptosis leads to a complete renewal of the epithelial cell population every few days. The physiological factors regulating enterocyte proliferation, maturation and apoptosis in health, as well as those that modulate these events in disease states remain largely unknown. It has been demonstrated in vitro that immature crypt cell proliferation is stimulated by factors such as TGF alpha and TNF alpha, whereas TFG beta and IFN gamma inhibit mitotic activity. Further studies showed that intestinal epithelial cells are able to produce and secrete several cytokines such as IL6, IL8, TNF alpha, TGF alpha and TGF beta, indicating the potential for autocrine and paracrine responses. A variety of immune mediated bowel disorders, including celiac disease, Crohn's disease and ulcerative colitis, are characterized by accelerated epithelial cell turnover and apoptosis, leading to altered crypt/villus morphology. There is increasing evidence that these changes, and the accompanying functional alterations of the bowel epithelium, are mediated by the cytokines released from infiltrating inflammatory cells, as well as from enterocytes themselves in an autocrine fashion.
Department of Gastroenterology and Clinical Nutrition, Royal Children's Hospital, Parkville, Victoria, Melbourne, Australia.
Encouraging results have been reported from several large trials of tetravalent rhesus rotavirus vaccine, with efficacy of 70-80% against severe disease. A recent Venezuelan study showed similar results to trials in USA and Europe. The vaccine may soon be licensed in USA. It provides the exciting prospect of a strategy to prevent one of the world's major child killers. Other candidate vaccines are under development including human-bovine reassortants, neonatal strains, non-replicating rotaviruses, vector vaccines and other genetically engineered products. Second and third generation rotavirus vaccines are on the horizon. The need for a rotavirus vaccine is well accepted by paediatricians, but public health authorities need to be lobbied. Other issues which need to be addressed include relative importance of non-group A rotaviruses, possible administration with OPV, the influence of breast feeding, and most importantly, cost. It is essential that rotavirus vaccine is somehow made available to all of the world's children, not just those in developed countries.
Human intestinal capillariasis (Capillaria philippinensis) in Taiwan.
Department of Pediatrics, Kaohsiung Medical College, Taiwan, R.O.C.
A human case of intestinal capillariasis was first recognized in the Philippines in the mid-1960s. The parasitosis is a life threatening disease and has been reported from Thailand, Japan, Taiwan. Korea, Iran, and Egypt. Clinical symptoms include diarrhea, abdominal pain, borborygmi, marked weight loss, protein and electrolyte loss, and cachexia. Capillariasis may be fatal if treatment is not given early. We observed 7 cases living in the more rural areas of Taiwan. Two cases had histories of travelling to Thailand. These two cases might have been infected in Thailand while stayed there. The other 5 cases didn't have histories of going abroad. According to the route of transmission, freshwater and brackish-water fish may act as the intermediate host of the parasite. People who like to eat raw fish, and have had long term diarrhea with abdominal pain and borborygmi, capillariasis philippinensis should be highly suspected. The most simple and convenient method of diagnosing capillariasis is stool examination. Treatment with mebendazole or albendazole for 20-30 days is known to be effective. All 7 cases we observed were cured through adequate treatment with anthelmintics and general management. A case, found in Kaohsiung Medical College Hospital in 1983, may be the first case in Taiwan.