炎症の慢性化機構―その因子分解の試み 慢性関節リウマチと慢性しん出性中耳炎を中心に

Abstract

Inflammation is a general defense mechanism conducted by various kinds of chemical mediators, most of which are enzymatically decomposited substance of injured cells. As a rule, the inflammation ceases due to a kind of homeostasis and feedback reaction in a few days, but sometimes such mechanism is deranged and the inflammation enters into the chronic state and occasionally remains through life. A number of factors are working to make the inflammation chronic. In the present paper, several analytical studies were confined to two types of typical chronic inflammation, rheumatoid arthritis (RA) and otitis media with effusion (OME), either clinicopathologically or experimentally.RA is a chronic inflammation which starts in the joint with systemic background. The articular cavity has a quite limited space among bone-cartilage and is lined by soft interlocking synovial cells. This anatomically confined space makes the inflammatory process slower and complicated because of its less efficient clearing of reactants or by-products of both stimulatory and inhibitory natures. The inflammatory process starts as a result of “type III antigen-antibody reaction” and the destruction of the connective tissue is carried out by the aid of “lysosomal enzyme” released from inflammatory cells such as neutrophils, macrophages and synovial cells. Establishment of a local producing system of rheumatoid immune complexes, which have initially been supplied from circulation, and the “one-way” (post-capillary venule→lymph follicle→IgG production→IC→phagocytosis by M∅ and granulocyte→enzyme [collagenase] release→destruction of hard tissue) process of inflammation in such a limited space are considered to make the inflammation intractable and a vicious closed-circuit of inflammation will occur.The middle ear is also a very limited closed space in the bone connected to the airway by the auditory tube with isthmus, which is covered by respiratory ciliated epithelia. There are some similarities between RA and OME in their anatomical structure and histopathological patterns; such as lympho-plasmacyte infiltration with follicle, vascular proliferation, inflammatory edema, M∅ infiltration and lining cell reaction. IgG, IgA and occasionally IgE producing plasma cells, goblet cell transformation of ciliated cells and obstruction of the auditory tube by mucin, exudated cells, plasma and desquamated cell debris are characteristic of OME.Active or passive Arthus' reaction in the middle ear of chinchilla is quite similar to human OME in tympanographic and clinicopathological points of view. Vascular reaction, severe cellular and humoral exudation, desquamation of epithelia, edema, goblet cell transformation of epithelia, obstruction of the auditory tube with mucinous secreta, lymphoplasmacytic cell proliferation and existence of memory and typical tympanographic change; all those changes similar to human OME were experimentally obtainable.Upon these observations it could be concluded that a similar immuno-inflammatory process takes place in both RA and OME in an anatomically confined, soft tissue lined interosseous space.