Marta Sochocka

Inflammatory Response in the CNS: Friend or Foe?

Inflammatory reactions could be both beneficial and detrimental to the brain, depending on strengths of their activation in various stages of neurodegeneration. Mild activation of microglia and astrocytes usually reveals neuroprotective effects and ameliorates early symptoms of neurodegeneration; for instance, released cytokines help maintain synaptic plasticity and modulate neuronal excitability, and stimulated toll-like receptors (TLRs) promote neurogenesis and neurite outgrowth. However, strong activation of glial cells gives rise to cytokine overexpression/dysregulation, which accelerates neurodegeneration. Altered mutual regulation of p53 protein, a major tumor suppressor, and NF-κB, the major regulator of inflammation, seems to be crucial for the shift from beneficial to detrimental effects of neuroinflammatory reactions in neurodegeneration. Therapeutic intervention in the p53-NF-κB axis and modulation of TLR activity are future challenges to cope with neurodegeneration.

Vascular oxidative stress and mitochondrial failure in the pathobiology of Alzheimer's disease: a new approach to therapy.

Vascular and metabolic dysfunctions and mitochondrial failure are now believed to be contributors to Alzheimer’s disease (AD) pathogenesis. Vascular dysfunction includes reduced cerebral blood flow (CBF), blood-brain barrier (BBB) disturbances and cerebral amyloid angiopathy (CAA). Mitochondrial failure results in deregulation of Ca 2+ homeostasis and elevated reactive oxygen species (ROS) generation, both of which are linked to neurotoxicity. Increased levels of ROS stimulate proinflammatory gene transcription and release of cytokines, such as IL-1, IL-6, and TNF-α, and chemokines, thereby inducing neuroinflammation. Conversely, inflammatory reactions activate microglia and astrocytes to generate large amounts of ROS, so neuroinflammation could be perceived as a cause and a consequence of chronic oxidative stress. The interaction between oxidative stress and neuroinflammation leads to amyloid-β (Aβ) generation. The deposition of Aβ peptide in the brain generates a cascade of pathological events, including the formation of neurofibrillary tangles (NFTs), inflammatory reactions, increased oxidative stress and mitochondrial dysfunction, which are causative factors of cell death and dementia. The purpose of this paper is to provide current evidence on vascular dysfunction and mitochondrial failure, both in neurons and glia and in brain vascular wall cells in the context of potential application for treatment of AD and other neurodegenerations.

Vascular factors and epigenetic modifications in the pathogenesis of Alzheimer's disease

Alzheimers disease (AD) is a debilitating illness with no known cure. Nowadays accumulating evidence suggested that the vascular endothelium and chronic hypoperfusion may play important role in pathobiology of AD. The vascular endothelium which regulates the passage of macromolecules and circulating cells from blood to tissue, is a major target of oxidative stress, playing a critical role in the pathophysiology of vascular diseases. Since the vascular endothelium, neurons and glia are all able to synthesize, store and release reactive oxygen species (ROS) and vascular active substances in response to certain stimuli, their contribution to the pathophysiology of AD can be very important. New evidence indicates that continuous formation of free ROS induces cellular damage and decreases antioxidant defenses. Specifically, oxidative stress increases vascular endothelial permeability and promotes leukocyte adhesion. We summarize the reports that sporadic, late-onset of AD results from vascular etiology. Recently an involvement of epigenetic alterations in the etiology of AD is also intensively investigated. Gaining a more complete understanding of the essential components and underlying mechanisms involved in epigenetic regulation could lead to novel treatments for a number of neurological and psychiatric conditions.

The influence of donepezil and EGb 761 on the innate immunity of human leukocytes: effect on the NF-κB system.

Ginkgo biloba special extract EGb 761 and donepezil are drugs used in Alzheimer therapy. The influence of donepezil and EGb 761 on two mechanisms of innate immunity, natural antiviral resistance of human leukocytes ex vivo and NF-κB activation, was studied. Correlation between the innate immunity of leukocytes and NF-κB activation was investigated. The effect of the two drugs on resistance of human leukocytes to vesicular stomatitis virus (VSV) infection was also assessed. Two groups of healthy blood donors (n=30) were distinguished: one with resistant leukocytes (n=15) and one (n=15) with leukocytes sensitive to VSV. The degree of natural resistance of human peripheral blood leukocytes (PBLs) was determined by studying the kinetics of VSV replication. NF-κB activation was assayed by immunocytochemical staining. Efficiency of donepezil and EGb 761 was determined by a special regression model. The toxicity of the preparations to PBLs and the cell lines L(929) and A(549) and their effect on the different viruses was established. Results showed that donepezil used in concentrations of 10-50 μg/ml and EGb761 of 25-100 μg/ml stimulated resistance of human leukocytes. At the same concentrations both preparations decreased activation of transcriptional factor NF-κB. Correlation between innate immunity of PBLs and NF-κB activation was observed. Comparison of the effects of these two drugs showed that EGb 761 is more effective in stimulating leukocyte resistance. Donepezil and EGb 761 regulated innate immunity of human leukocytes by stimulating resistance and modulating NF-κB activation. The natural drug was more efficient in stimulating innate antiviral immunity of human leukocytes.

The Infectious Etiology of Alzheimer’s Disease

Background: Inflammation is a part of the first line of defense of the body against invasive pathogens, and plays a crucial role in tissue regeneration and repair. A proper inflammatory response ensures the suitable resolution of inflammation and elimination of harmful stimuli, but when the inflammatory reactions are inappropriate it can lead to damage of the surrounding normal cells. The relationship between infections and Alzheimer’s Disease (AD) etiology, especially late-onset AD (LOAD) has been continuously debated over the past three decades. Methods: This review discusses whether infections could be a causative factor that promotes the progression of AD and summarizes recent investigations associating infectious agents and chronic inflammation with AD. Preventive and therapeutic approaches to AD in the context of an infectious etiology of the disease are also discussed. Results: Emerging evidence supports the hypothesis of the role of neurotropic viruses from the Herpesviridae family, especially Human herpesvirus 1 (HHV-1), Cytomegalovirus (CMV), and Human herpesvirus 2 (HHV-2), in AD neuropathology. Recent investigations also indicate the association between Hepatitis C virus (HCV) infection and dementia. Among bacteria special attention is focused on spirochetes family and on periodontal pathogens such as Porphyromonas gingivalis or Treponema denticola that could cause chronic periodontitis and possibly contribute to the clinical onset of AD. Conclusion: Chronic viral, bacterial and fungal infections might be causative factors for the inflammatory pathway in AD.

Effect of donepezil on innate antiviral immunity of human leukocytes

BACKGROUND The effect of donepezil on two mechanisms of innate immunity: leukocyte resistance to viral infection and cytokine production was studied. METHODS The degree of natural resistance of human peripheral blood leukocytes (PBLs) was determined by studying the kinetics of vesicular stomatitis virus (VSV) replication. A titer of 0-1 log TCID(50) indicated complete resistance, 2-3 log partial resistance, and >4 lack of resistance. Cytokine levels were determined with use of ELISA test. NFkappaB activation was assayed by immunocytochemical staining. RESULTS Preliminary study of VSV replication in the PBLs of Alzheimers disease patients showed a high sensitivity to infection, except of PBL those under donepezil therapy. The PBL resistance stimulated us to study the effect of donepezil on innate immunity. Donepezil inhibited VSV replication in the leukocytes of healthy blood donors but influence on infection in L929 and A549 cells was not shown. The effect was dose dependent and individually differentiated. The production of TNFalpha and IFNs was reduced in infected leukocytes in a dose-dependent manner in the PBLs of the healthy blood donors and of AD patients. NFkappaB activation was also reduced by donepezil. CONCLUSIONS Donepezil regulate two mechanisms of innate immunity of leukocytes: resistance to viruses and cytokine production.

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.

Comparison of microbiological and physicochemical methods for enumeration of microorganisms.

Determination of the number of cultured bacteria is essential for scientific and industrial practice. A spread plate technique is the most common and accurate method for counting of microorganisms. However, time consuming incubation does not allow for a quick estimation of the number of bacteria in a growing culture. In the present study, the results of photometric measurements: direct optical density method (OD at 585 nm), UV absorbance at 260 and/or 280 nm of separated and lysed bacteria by sodium hydroxide and surfactant with the spread plate technique were compared. The linear regression model for bacterial strains Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was used to compare these three methods. The UV measurement method enabled determination of the number of bacteria with similar precision. The procedure for solubilized bacteria UV measurement is robust, and is not influenced by dispersions in the original culture medium.

Age- and disease-related innate immunity of human leukocytes ex vivo

Two mechanisms of innate immunity, i.e. resistance to viral infection and the production of cytokines by leukocytes, were compared in blood isolated from four groups of donors: healthy young (19-35 years old), healthy elderly (over 60), elderly Alzheimers disease (AD) patients, and elderly patients with alimentary tract cancer (CA). Peripheral blood leukocytes (PBLs) were isolated by gradient centrifugation in Gradisol G. The degree of resistance was calculated from the kinetics of vesicular stomatitis virus (VSV) replication in the PBLs. Cytokine (TNFα, IFNα, IFNγ, IL-12, and IL-10) levels were determined by ELISA. The antiviral resistance of the PBLs varied, but a difference was observed only between the young and elderly groups and not between the healthy elderly controls and those with AD or cancer. Differences observed in all the groups concerned the ability and intensity of cytokine production. The most impressive results were obtained for spontaneous TNF and IFNα release. While TNF was released spontaneously by the PBLs of the elderly CA patients and the young healthy group, it was usually undetected in the AD and only sometimes in the healthy elderly group. Leukocytes isolated from the elderly groups responded to VSV infection with more intense IFNα and IFNγ production than the younger group.

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 pro-inflammatory 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.