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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. [ABSTRACT FROM AUTHOR]

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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

HIV infection causes progressive immune system deficiency, the development of AIDS and eventual death. Genetic factors play a very important role in the susceptibility to HIV infection and disease progression. Estimation of their effects is realized by comparing different patients groups. Four group of HIV-infected patients are taken into account: RP - rapid progressors, SP - slow progressors, LTNP - long term non-progressors and EU - exposed but uninfected. Genetic factors influencing the course of disease can be divided in groups, for example genes coding proteins connected with viral entry into cells (chemokine receptors, chemokines, lectins receptors), proteins engaged in the innate response to viral infections (cytokines, MBL, cyclophilin A, TRIM-5 alpha, APOBEC3G), human leukocyte antigens (HLAs) and killer cell immunoglobulin-like receptors (KIRs). It is suggested that some sequences of human endogenous retroviruses (HERV) and microRNA (miRNA) can also interact with the course of HIV infection. Knowledge of the roles of genetic determinants in HIV infection is very important and useful for their cognitive significance as well as in the prognosis of AIDS progression and the selection of specific therapies for individual patients. It is also a basis for the development of new antiviral drugs and vaccines.

Retroviruses-derived elements in the human genome constitute 90% of non-coding mobile sequences. Reverse transcriptase (RT) plays an essential role in their transposition as do long terminal repeats (LTRs), which contain promotors, enhancers, and regulatory sequences. Some retroelements (pseudogens and retrogenes, e.g. SINE) are non-autonomic and do not possess their own RT. These elements are dependent on autonomic elements (retroposons, e.g. LINE, retrotransposons, exo- and endogenous retroviruses). The genome of retroviruses is composed of gag, pol, and env genes flanked by long terminal repeats. Endogenous retroviruses are probably the remnants of ancient germ cell infection by exogenous retroviruses and are transmissible to the next generation in a Mendelian way. Most of them are defective (because of mutation accumulation), but some are still active and their expression is regulated by different factors (UV radiation, inflammatory cytokines, steroid hormones, and exogenous virus products). Retroelements as well as their gene products exert influence on the organism's functions. They influence the plasticity and evolution of genomes, are a source of promotors and regulatory sequences, but they also supply additional signals of transcription initiation, mRNA splicing, and STOP codons. One of the positive aspects of human endogenous retroviruses (HERVs) is the participation of their products in normal syncytiotrophoblast formation. They also block exogenous retrovirus replication by receptor interference or antisense mRNA. Their presence is considered to be connected with a number of autoimmunological diseases (multiple sclerosis, insulin-dependent diabetes mellitus, systemic lupus erythematosus), cancer, or even psychiatric disorders (schizophrenia). There are also other problems connected with the potential role of ERVs in genomic therapy (with retroviruses vectors) and transplantology (xenotransplantation).