Regulation of immunity by Taeniids: lessons from animal models and in vitro studies.

Taeniidae is the largest family of the Cyclophyllidea order of parasites despite being composed of just two genera: Taenia spp and Echinococcus spp. These parasites are flatworms with a terrestrial life cycle, having an immature or larval stage called metacestode, which develops into the mature form within the intestine of the primary host after being consumed in raw or poorly cooked meat. Consumed eggs hatch into oncospheres, penetrate the intestinal walls and are transported via the bloodstream to later develop into metacestodes within the muscles and internal organs of secondary and sometimes primary hosts, thereby initiating the cycle again. Larval stages of both Taenia spp and Echinococcus spp are well known to produce tissue-dwelling, long-lasting infections; in this stage, these parasites can reach centimetres (macroparasites) and both genera may cause life-threatening diseases in humans. Establishing such long-term infections requires an exceptional ability to modulate host immunity for long periods of time. In this review, we analyse the immunoregulatory mechanisms induced by these tapeworms and their products, mainly discussing the importance of taeniid strategies to successfully colonize their hosts, such as antigen-presenting cell phenotype manipulation and the consequent induction of T-cell anergy, among others.

Probiotics and autoimmunity: an evolutionary perspective.

Probiotics are microorganisms that have demonstrated beneficial effects on human health. Probiotics are usually isolated from the commensal microflora that inhabits the skin and mucosas. We propose that probiotics represent the species of microorganisms that have established a symbiotic relationship with humans for the longest time. Cultural practices of ancient human societies used to favor that symbiosis and the transmission of probiotics from generation to generation. New practices, introduced as a result of industrialization, such as childbirth by surgical delivery, ingestion of pasteurized and synthetic compounds-supplemented food, cleaner homes, indiscriminate use of antibiotics and so on, have led in recent years to the replacement of probiotics by other microorganisms that are not as well adapted to the microenvironments of the human body. These newly settled microorganisms lack many of the beneficial effects of probiotics. Our hypothesis is that the sudden change (from an evolutive perspective) in human intestinal microflora may importantly contribute to the rise in the incidence of autoimmune diseases, observed in the last half a century.