The relationship between premature ageing and immune responses in the oral cavity of Down syndrome

Down syndrome (DS) is the most common chromosomal disorder resulting in various abnormalities such as mental retardation, immunodeficiency and physical abnormities. Especially, abnormality of the immune function is important pathological features in this syndrome, and leads to increased susceptibility to viral or bacterial infections. Interestingly, several studies have showed that they have high susceptibility of severe periodontal disease, even though they have lower or equal prevalence of dental caries. Many studies have attempted to clarify this phenomenon but it remains unsolved. It is also well known that DS is a premature ageing syndrome. DS has been considered as a model of precocious, abnormal ageing of immune function in human. Age-related declines in immune function cause more susceptibility to infections in the elderly. In addition, it is well known that ageing is related with telomere shortening. Furthermore, DS has an accelerated telomere shortening. However, there are only a few reports that focus on the relations among ageing, telomere length and high susceptibility of oral infectious disease in individuals with DS. Therefore, we summarize our current knowledge on the relations between the oral disease and immunodeficiency in individuals with DS taking account of telomere shortening and ageing.