Association between Periodontal Health Status and Cognitive Abilities. The Role of Cytokine Profile and Systemic Inflammation.

BACKGROUND: Contemporary neurobiology, periodontal medicine, and immunology are now focusing on the relationship between chronic periodontitis and systemic diseases, which also include Alzheimer's disease (AD). However a causative relationship between dementia and periodontitis has yet to be confirmed. OBJECTIVE: The aim of the study was to determine whether periodontal health status and cognitive abilities are correlated with the relative changes in systemic measures of pro- and anti-inflammatory cytokines as a reflection of systemic inflammation. We hypothesized that poor periodontal health status may be associated with cognitive impairment and dementia via the exacerbation of systemic inflammation. METHODS: Based on the periodontal and psychiatric examinations and the cytokine levels produced by unstimulated and LPS-stimulated PBL isolated from 128 participants, we have examined if the coexisting of these two clinically described conditions may have influence on the systemic inflammation. Mini- Mental State Examination (MMSE) and Bleeding on Probing (BoP) test results were combined into the one mathematical function U, which determines the severity of specific condition, called Cognitive and periodontal impairment state. Similarly, the levels of cytokines were combined into the one mathematical function V, whose value determines the level of Inflammatory state. The correlation between U and V was determined. RESULTS: These results confirm that the presence of cognitive decline and the additional source of proinflammatory mediators, like periodontal health problems, aggravate the systemic inflammation. CONCLUSION: It is most likely that the comorbidity of these two disorders may deepen the cognitive impairment, and neurodegenerative lesions and advance to dementia and AD.

The effects of killer cell immunoglobulin-like receptor (KIR) genes on susceptibility to HIV-1 infection in the Polish population.

Killer cell immunoglobulin-like receptors (KIR) are the most polymorphic receptors of natural killer (NK) cells. Their activity diversifies the functions of NK cells in the antiviral immune response, so the presence of certain KIR may affect transmission of HIV-1. The aim of the study was to evaluate the influence of KIR genes on the susceptibility to HIV-1 infection in the Polish population depending on the route of exposure. We determined the frequencies of activating (2DS1, 2DS2, 2DS3, 2DS4f, 2DS4del, 2DS5, 3DS1) and inhibitory (2DL1, 2DL2, 2DL3, 2DL5, 3DL1) KIRs in HIV-1-positive patients (n = 459), individuals exposed to HIV-1 but uninfected (EU, n = 118) and in uninfected, healthy blood donors (BD, n = 98). Analysis was performed using stepwise logistic regression. Apart from KIRs, CCR5-∆32, and CCR2-64I, alleles were also analyzed, as we knew or suspected that these features could affect susceptibility to HIV infection. The regression confirmed the protective effect of CCR5-∆32 (OR = 0.25, p = 0.006) and CCR2-64I (OR = 0.59, p = 0.032) against HIV infection. Among KIR genes, 2DL3 was found to be a protective factor (OR = 0.30, p = 0.015). A similar effect was seen for 3DS1 but only in intravenous drug users (IDUs) (OR = 0.30, p = 0.019), not in sexually exposed people. 2DL5 was found to be a factor facilitating HIV infection (OR = 2.13, p = 0.013). A similar effect was observed for 2DL2 but only in females (OR = 2.15, p = 0.040), and 2DS1 in IDUs (OR = 3.03, p = 0.022). Our results suggest a beneficial role of KIR3DS1 and 2DL3 supporting resistance to HIV infection and a harmful effect of 2DS1, 2DL5, and 2DL2 genes promoting HIV acquisition.

The role genes encoding of killer cell immunoglobulin-like receptors (KIRs) and their ligands in susceptibility to and progression of HIV infection.

NK cells are a part of the innate antiviral response. Their activity is regulated by signals from the surface receptors. Some of them, known as killer cell immunoglobulin-like receptors (KIRs), determine the quality and intensity of the immunological response, together with their ligands (HLA class I). KIR genes are very polymorphic, and this is reflected in the NK activity modulation. The stimulation of NK cells, especially in the early stages of the infection, can reduce the transmission of HIV or slow down the progression of infection. The varied KIR/HLA repertoire is a limiting factor for the risk of HIV infection and disease progression. Such diversity enables optimal regulation of NK cells and maintenance of the balance between activation to eliminate infected cells and inhibition. The control of NK cell activity via KIR3DL1/3DS1 and HLA-Bw4 (especially Bw4-80I) seems to be very important in the HIV context. With a few exceptions, it leads to a reduction of susceptibility to HIV infection and better viremia control, and slows down depletion of CD4+ T cells. Incompatibility of sexual partners for KIRs and HLA may oblige NK cells from the exposed partner to reject incoming cells from the HIV-positive partner. The presence of the inhibitory KIR, in the absence of its ligand, results in a lower threshold of NK cell activation, which reduces the chance of infection. The presence of an inhibitory receptor with a low affinity to the ligand (KIR2DL3+HLA-C1) is associated with lower susceptibility, and the effective NK cell inhibition (KIR2DL2+HLA-C1) results in increased susceptibility to HIV infection. The advantage of activating KIRs, especially in the presence of their ligands, is associated with higher cytolytic abilities, and thus reduced risk of HIV infection. If the virus is not eliminated in an early stage of infection, massive activation of NK is unfavorable due to the excessive stimulation of the immune system.