Examples of non-infectious granulomatous diseases are sarcoidosis, Crohns disease, berylliosis, giant-cell arteritis, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, pulmonary rheumatoid nodules, and aspiration of food and other particulate material into the lung. The infectious pathophysiology of granulomas is discussed primarily here. The key association between IFN-γ and granulomas is that IFN-γ activates macrophages so that they become more powerful in killing intracellular organisms. Activation of macrophages by IFN-γ from Th1 helper cells in mycobacterial infections allows the macrophages to overcome the inhibition of phagolysosome maturation caused by mycobacteria (to stay alive inside macrophages). The first steps in IFN-γ-induced granuloma formation are activation of Th1 helper cells by macrophages releasing IL-1 and IL-12 in the presence of intracellular pathogens, and presentation of antigens from those pathogens. Next the Th1 helper cells aggregate around the macrophages and release IFN-γ, which activates the macrophages. Further activation of macrophages causes a cycle of further killing of intracellular bacteria, and further presentation of antigens to Th1 helper cells with further release of IFN-γ. Finally, macrophages surround the Th1 helper cells and become fibroblast-like cells walling off the infection. Activity during pregnancy
Uterine Natural Killer cells (NK) secrete high levels of chemoattractants, such as IFN-γ in mice. IFN-γ dilates and thins the walls of maternal spiral arteries to enhance blood flow to the implantation site. This remodeling aids in the development of the placenta as it invades the uterus in its quest for nutrients. IFN-γ knockout mice fail to initiate normal pregnancy-induced modification of decidual arteries.
Especially in Latin America, a granulomatous mass (known as an amoeboma) may form in the wall of the ascending colon or rectum due to long-lasting immunological cellular response, and is sometimes confused with cancer.The ingestion of one viable cyst may cause an infection.Steroid therapy can occasionally provoke severe amoebic colitis in people with any E. histolytica infection. This bears high mortality: on average more than 50% with severe colitis die. Cause
Amoebiasis is an infection caused by the amoeba Entamoeba histolytica. Transmission
Amoebiasis is usually transmitted by the fecal-oral route, but it can also be transmitted indirectly through contact with dirty hands or objects as well as by anal-oral contact. Infection is spread through ingestion of the cyst form of the parasite, a semi-dormant and hardy structure found in feces. Any non-encysted amoebae, or trophozoites, die quickly after leaving the body but may also be present in stool: these are rarely the source of new infections. Since amoebiasis is transmitted through contaminated food and water, it is often endemic in regions of the world with limited modern sanitation systems, including México, Central America, western South America, South Asia, and western and southern Africa.Amoebic dysentery is one form of travelers diarrhea, although most travelers diarrhea is bacterial or viral in origin. Pathogenesis
Amoebiasis results from tissue destruction induced by the E. histolytica parasite. E. histolytica causes tissue damage by three main events: direct host cell killing, inflammation, and parasite invasion.