Portal to the Interior: Viral Pathogenesis

James Williams, OMD, LAc – Director of Integrative Medicine, East-West College of Natural Medicine and consultant on integrative medicine to Scripps Clinic. Correspondence address: 665 Orpheus Ave., Encinitas, CA 92024 E-mail: [email protected]. Abstract Most antigens, particularly viruses, enter the body through the mucosal epithelia where they are carried by afferent lymphatics to regional lymph nodes for presentation to the immune system. Although they share immunological similarities, immune processes that protect the mucosa are distinct from innate and acquired immunity. The barrier formed by the intestinal mucosa is the most studied, with its microenvironment having a marked influence on both local and systemic immune responses. A healthy microenvironment and resilient neighboring tissue provide protection against inflammation known to dampen mucosal immunity, promote carcinogenesis, contribute to systemic inflammatory processes, and result in autoimmune diseases. Numerous natural substances improve this microenvironment and thereby enhance immunity against microbial infections. Since mucosal immunity forms the first line of defense against many commonly transmitted pathogens, restoring and maintaining mucosal immunity is critical for disease prevention and intervention. This article discusses the nature of mucosal immunity and its relationship to viral infections and other conditions, and reviews natural compounds that help restore mucosal immunity. (Altern Med Rev 2003;8(4):395-409) Introduction The human gastrointestinal and respiratory tracts harbor the largest number and greatest diversity of microorganisms in the body. Proximity to the external environment makes these tissues especially vulnerable to pathogens and allergens, so it is not surprising mucosal tissue contains the greatest immunological activity and number of immune cells, cytokines, and secondary lymphoid tissues. Causes of mucosal immune dysfunction include microbial infections, dietary indiscretions such as excess refined sugars and lack of fiber, allergies and food intolerances, indiscriminant and overuse of oral antibiotics, disruption of lipid and fatty acid metabolism, and aging. All of these etiologies, most a product of modern lifestyle, can result in dysfunctional mucosal immunity and may even be responsible for a wide range of chronic diseases. The author intends to demonstrate the increasing importance of mucosal immunity in the clinical setting to stimulate further research in this age of emerging viruses.