Association between the Polymorphisms of TLR4 and CD14 Genes and Alzheimer's Disease

Alzheimer's disease (AD) is a heterogeneous and progressive neurodegenerative disease which in Western society mainly accounts for clinical dementia. Inflammation plays a key role in AD and dissecting the genetics of inflammation may provide an answer to the possible treatment. Hence, the better understanding of different molecular and cellular inflammatory mechanisms is crucial for complete knowledge of AD pathophysiology, and for its prevention and drug therapy. Accordingly, in the present study we evaluated whether the pro-inflammatory polymorphisms of lipopolysaccaride- receptors, +896A/G Toll-Like Receptor (TLR4) and -260C/T CD14, are risk factors for AD. The study included both 626 AD patients (427 women and 199 men; age range: 53-98 years; mean age: 74.88 ± 8.44) from Northern Italy and age and gender matched controls. Our results demonstrate that the +896A/G TLR4 single nucleotide polymorphism (SNP) is associated with AD, whereas no association has been observed with -260C/T CD14 SNP. Furthermore, no differences have been observed evaluating the combined presence of +896A+TLR4/-260T+CD14 “high responder”(proinflammatory- profile). However, our results showing the involvement of TLR4 in AD pathophysiology, strengthen the suggestion that systemic inflammation plays a key role in AD. Carriers of high responder SNP, affected by mild cognitive impairment might, be the ideal target for a preventive treatment with biologics as monoclonal antibodies directed against the pro-inflammatory cytokines to decrease the level of systemic inflammation involved in AD pathophysiology.