Tropical Journal of Medical Research | Vol 17  Issue 2  Jul-Dec 2014 69 Cathelicidin expression and role in oral health and diseases: A short review Mythri Potturu, Prem Anand Prabhakaran 1 , Neetu Oommen 2 , Deepa Muraleedharan Sarojini 3 , Sukumaran Nair Sunil 2 Department of Oral and Maxillofacial Pathology, Vipula Care Hospital, Vijayawada, Andhra Pradesh, 1 Department of Oral and Maxillofacial Pathology, Amrita School of Dentistry, Kerala, 2 Departments of Oral and Maxillofacial Pathology and 3 Oral Medicine and Radiology, Azeezia Dental College and Research, Kollam, Kerala, India Abstract The oral cavity is a unique environment in which antimicrobial peptides play a key role in maintaining health. Cathelicidins are small cationic antimicrobial host defense peptides that possess broad-spectrum antimicrobial activity. Humans possess a single cathelicidin, which was first cloned from human bone marrow cDNA. Its mature form is known as LL-37. Various immune and epithelial cells secrete LL-37, and its level varies in response to caries, periodontal, congenital, inflammatory, and malignant diseases in the oral region. Human cathelicidin peptide LL-37 exhibits antimicrobial activity against bacteria that cause oral pathological conditions, including cariogenic disease and periodontitis. Further research on LL-37 is needed as its usefulness as a new class of antimicrobial drugs still remains to be proven and may have future therapeutic applications. Keywords: Antimicrobial peptides, cathelicidins, defense peptides, innate immunity, LL-37 INTRODUCTION The human oral cavity is a harbor to a variety of microorganisms that can colonize and cause disease. Oral mucous membrane acts as the first barrier of resistance to oral infections. In order to provide an efficient defense the oral mucosa is equipped with various innate mechanisms against invading microbial pathogens. Most do not require the specific recognition of the invading pathogen and within oral innate immunity three distinct barriers can be identified: A chemical, a physical, and a mechanical barrier. The flow of saliva has a mechanical effect, flushing microorganisms from mucosal and tooth surfaces. [1] While a neutral pH and antimicrobial peptides in saliva contribute to the chemical shield on the surface of the oral mucosa, the intact stratified squamous epithelium supported by the lamina propria presents a physical barrier to oral microorganisms. The continuous shedding by exfoliation of epithelial squames Access this article online Quick Response Code: Website: www.tjmrjournal.org DOI: 10.4103/1119-0388.140414 limits microbial colonization of the surface and forms a mechanical cellular barrier. These cells, together with professional antigen presenting cells such as dendritic cells and oral epithelial macrophages, form the first line of cellular innate immunity in the oral cavity. All these cells are equipped with sensors and communicate with each other upon microbial challenge or a danger signal. Subsequently, further immune or pro-inflammatory cascades are triggered providing an adequate and coordinated immune response. One of the most important contributors in maintaining the balance between health and disease in this complex oral environment is antimicrobial peptides. These include several salivary antimicrobial peptides, the β-defensins expressed in the epithelium, the α-defensins expressed in neutrophils, and the cathelicidin, LL-37, expressed in both epithelium and neutrophils. [2] These peptides are part of the host innate immune response. In addition to antimicrobial, antifungal, and antiviral activities, some of these peptides also possess antitumor or immune modulatory properties. Address for correspondence: Dr. Prem Anand Prabhakaran, Department of Oral and Maxillofacial Pathology, Amrita School of Dentistry, Kerala, India. E-mail: premanandp@aims.amrita.edu R EVIEW A RTICLE [Downloaded free from http://www.tjmrjournal.org on Friday, September 19, 2014, IP: 117.228.149.135] || Click here to download free Android application for thi