MUCOSAL IMMUNITY AND PATHOMECHANISM OF THE SPELEOTHERAPEUTIC EFFICACY
Prof. dr Svetozar Dluholucky, Dr. V. Rajcanova
Despite the fact that speleotherapy has been used approximately for thirty years in the treatment of chronic and allergic respiratory disorders, it is still not fully accepted as an effective method. Even the latest reviews of unconventional therapies of asthma did not mention about speleotherapy (Lewith G T, Watkins AD, 1996). There are at least two reasons for this: 1) Even though a lot of oral presentations were done on UIS meetings, only few were published in official medical journals; 2) only recent knowledge about the pathomechanism of inflammatory and allergic respiratory diseases allows to put forth valid explanation of speleotherapeutic effectiveness. Authors present the pathomechanism of inflammatory mucosal changes and possible modes of speleotherapeutic efficacy.
In the past, the researchers were not able to explain the beneficial effect of speleotherapy in such different pathologic conditions such as chronic bronchitis and allergic-asthmatic state.
Recent regards to asthma characterize it as an inflammatory disease of multifactorial origin, whose expression is dependent on genetic, infectious, and environmental factors.
Bronchial hyperreactivity and hypersecretion are not primary causes of asthma but rather the consequences of inflammation. Asthma affects all age groups in increased number, but requires special consideration in the pediatric age group. Besides genetic influences (parental history of asthma and atopy), the environmental factors seem to play an important role.
Maternal smoking during pregnancy, lack of breast feeding, early allergen and air pollutant exposure together with repeated viral respiratory infections attack the respiratory mucosal layer. Asthma, as well as repeated viral infections, affects the epithelial surface of airways. Histologic alterations include metaplastic changes- initially as goblet cell metaplasia to be followed later by squamous metaplasia. Inflammatory cells accumulation of both subepithelial and intraepithelial spaces and thickened basement membrane are typical for microbial and allergic state. Airway epithelium is involved not only as a target of the inflammatory lesions, but also can be an active participant in the pathogenetic processes that lead to the development and maintenance of asthma or chronic bronchitis. Asthma can be characterized as a “chronic desquamative eosinophilic bronchitis” derived from a lot of mediators and cytokines. IL-3 and IL-4 are overproduced under the T-Helper 2 lymphocytes, activating a self-perpetuating vicious circle of leukotrienes, GM-CSF, prostaglandins, and oxygen free radicals damage. Eosinophilic chemokines (RANTES, MCP-3) and adhesive molecules of endothelial layer potentiate transudation and epithelial damage. Another but quite similar process is involved in chronic nonallergic bronchitis, due to viral infection and environmental pollution. Initially, the process is mediated by IL-1, IL-6, and TNFa, activating T-Helper 1 lymphocytes, producing IL-2. This next step is followed by PMN activation with the production of inflammatory mediators and epithelial damage that is rougly the same as in the allergic state. Persistent inflammatory process is progressive and self-perpetuating. Its origin is in the early childhood when it is potentially reversible. Noncharacteristic febrile viral wheezy bronchitis develops in spells of the asthma state or repeated bronchitic attacks. Late consequence in adulthood is COPD or severe bronchial asthma.
Authors, experienced with speleotherapy, uniformly refer the subjective and objective improvement of chronic and allergic respiratory disorders after even one course of speleotherapy in both adults and particularly children. Predominantly, the karst caves have been used but silver and salt mines are effective too. The karst aerosol has been the most extensively studied- it is generally cold with high humidity, calcium and magnesium content, absolutely free of germs, yeasts, and aggressive allergens. Low concentration of radon (minute from the viewpoint of potential risk) ionizes the environmental molecule which in turn produce the highly electronegative aerosol. This negative charge of aerosol is rougly similar in all kinds of caves and mines.
What is the effect of speleotherapy? Cave environment with its high humidity and low temperature hydrates the damaged epithelium and improves mucous viscosity. The absence of bacteria, yeasts, and allergens avoids inflammatory irritation while high calcium potentiates this anti-inflammatory effect. High magnesium content has a relaxing effect to bronchial muscle and it has been proven to block the cell membrane calcium channel and phospholipase A2 activation. The electronegative charge of aerosol improves the cilial regeneration and its activity, thus affecting the bronchial clearance. Many authors refer decreasing of the inflammatory parameters in their patients after speleotherapy and confirming the improvement of permeability and function of the mucosal epithelium.
Stephen I. Rennard et al. presented in CHEST (107,3/March 1995, Suppl. 127S-131S) the article “Is asthma an epithelial disease?” The long-term results of speleotherapy support the positive answer to this question. Beneficial effect of the cave aerosol improves the course of chronic and allergic respiratory diseases through healing of the mucosal barrier.