ABSTRACT
In human adults, mucosal membranes represent an enormous surface area (up to 400 m 2 of surface), composed of single layers of epithelium covered by mucus, that line the respiratory, gastrointestinal, and urogenital tracts, as well as the eye conjunctiva, the inner ear, and the ducts of all exocrine glands [1, 2]. These surfaces constitute the most common portal of entry for pathogens; indeed, it is estimated that 70% of the potentially infectious agents invade and infect the host by mucosal routes [3]. Globally, mucosaassociated infections, such as acquired immunodeficiency syndrome
(AIDS), tuberculosis, influenza, pneumonia, and sexually transmitted diseases are major causes of illness and serve big socioeconomic burdens in both developed and low-and middle-income countries [4].
