Cytokines and cognition--the case for a head-to-toe inflammatory paradigm

IL-6 induces regionally selective spinal cord injury in patients with the neuroinflammatory disorder transverse myelitis

Transverse myelitis (TM) is an immune-mediated spinal cord disorder associated with inflammation, demyelination, and axonal damage. We investigated the soluble immune derangements present in TM patients and found that IL-6 levels were selectively and dramatically elevated in the cerebrospinal fluid and directly correlated with markers of tissue injury and sustained clinical disability. IL-6 was necessary and sufficient to mediate cellular injury in spinal cord organotypic tissue culture sections through activation of the JAK/STAT pathway, resulting in increased activity of iNOS and poly(ADP-ribose) polymerase (PARP). Rats intrathecally infused with IL-6 developed progressive weakness and spinal cord inflammation, demyelination, and axonal damage, which were blocked by PARP inhibition. Addition of IL-6 to brain organotypic cultures or into the cerebral ventricles of adult rats did not activate the JAK/STAT pathway, which is potentially due to increased expression of soluble IL-6 receptor in the brain relative to the spinal cord that may antagonize IL-6 signaling in this context. The spatially distinct responses to IL-6 may underlie regional vulnerability of different parts of the CNS to inflammatory injury. The elucidation of this pathway identifies specific therapeutic targets in the management of CNS autoimmune conditions.

Low-dose endotoxemia and human neuropsychological functions

Epidemiological data demonstrate an association between systemic low-grade inflammation defined as 2- to 3-fold increases in circulating inflammatory mediators and age-related decline in cognitive function. However, it is not known whether small elevations of circulating cytokine levels cause direct effects on human neuropsychological functions. We investigated changes in emotional, cognitive, and inflammatory parameters in an experimental in vivo model of low-grade inflammation. In a double-blind crossover study, 12 healthy young males completed neuropsychological tests before as well as 1.5, 6, and 24 h after an intravenous injection of Escherichia coli endotoxin (0.2 ng/kg) or saline in two experimental sessions. Endotoxin administration had no effect on body temperature, cortisol levels, blood pressure or heart rate, but circulating levels of tumor necrosis factor (TNF) and interleukin (IL)-6 increased 2- and 7-fold, respectively, reaching peak values at 3 h, whereas soluble TNF-receptors and IL-1 receptor antagonist peaked at 4.5 h. The neutrophil count increased and the lymphocyte count declined. In this model, low-dose endotoxemia did not affect cognitive performance significantly but declarative memory performance was inversely correlated with cytokine increases. In conclusion, our findings demonstrate a negative association between circulating IL-6 and memory functions during very low-dose endotoxemia independently of physical stress symptoms, and the hypothalamo-pituitary-adrenal axis.

Cognitive Status, Muscle Strength, and Subsequent Disability in Older Mexican Americans

OBJECTIVES

To examine the association between Mini-Mental State Examination (MMSE) score and subsequent muscle strength (measured using handgrip strength) and to test the hypothesis that muscle strength will mediate any association between impaired cognition and incident activity of daily living (ADL) disability over a 7-year period in elderly Mexican Americans who were initially not disabled.

DESIGN

A 7-year prospective cohort study (1993-2001).

SETTING

Five southwestern states (Texas, New Mexico, Colorado, Arizona, and California).

PARTICIPANTS

Two thousand three hundred eighty-one noninstitutionalized Mexican-American men and women aged 65 and older with no ADL disability at baseline.

MEASUREMENTS

In-home interviews in 1993/1994, 1995/1996, 1998/1999, and 2000/2001 assessed social and demographic factors, medical conditions (diabetes mellitus, stroke, heart attack, and arthritis), body mass index (BMI), depressive symptomatology, handgrip muscle strength, and ADLs. MMSE score was dichotomized as less than 21 for poor cognition and 21 or greater for good cognition. Main outcomes measures were mean and slope of handgrip muscle strength over the 7-year period and incident disability, defined as new onset of any ADL limitation at the 2-, 5-, or 7-year follow-up interview periods.

RESULTS

In mixed model analyses, there was a significant cross-sectional association between having poor cognition (MMSE<21) and lower handgrip strength, independent of age, sex, and time of interview (estimate=-1.41, standard error (SE)=0.18; P<.001). With the introduction of a cognition-by-time interaction term into the model, there was also a longitudinal association between poor cognition and change in handgrip strength over time (estimate=-0.25, SE=0.06; P<.001), indicating that subjects with poor cognition had a significantly greater decline in handgrip strength over 7 years than those with good cognition, independent of age, sex, and time. This longitudinal association between poor cognition and greater muscle decline remained significant (P<.001) after controlling for age, sex, education, and time-dependent variables of depression, BMI, and medical conditions. In general estimation equation models, having poor cognition was associated with greater risk of 7-year incident ADL disability (odds ratio=2.01, 95% confidence interval (CI)=1.60-2.52); the magnitude of the association decreased to 1.66 (95% CI=1.31-2.10) when adjustment was made for handgrip strength.

CONCLUSION

Older Mexican Americans with poor cognition had steeper decline in handgrip muscle strength over 7 years than those with good cognition, independent of other demographic and health factors. A possible mediating effect of muscle strength on the association between poor cognition and subsequent ADL disability was also indicated.

An immune risk phenotype, cognitive impairment, and survival in very late life: impact of allostatic load in Swedish octogenarian and nonagenarian humans

In the previous OCTO longitudinal study, we identified an immune risk phenotype (IRP) of high CD8 and low CD4 numbers and poor proliferative response. We also demonstrated that cognitive impairment constitutes a major predictor of nonsurvival. In the present NONA longitudinal study, we simultaneously examine in a model of allostatic load IRP and compromised cognition in 4-year survival in a population-based sample (n = 138, 86-94 years). Immune system measurements consisted of determinations of T-cell subsets, plasma interleukin 6 and cytomegalovirus and Epstein-Barr virus serology. Interleukin 2 responsiveness to concanavalin A, using data from the previous OCTO (octogenarians) immune study, hereafter OCTO immune, was also examined. Cognitive status was rated using a battery of neuropsychological tests. Logistic regression indicated that the IRP and cognitive impairment together predicted 58% of observed deaths. IRP was associated with late differentiated CD8+CD28-CD27- cells (p < .001), decreased interleukin 2 responsiveness (p < .05) and persistent viral infection (p < .01). Cognitive impairment was associated with increased plasma interleukin 6 (p < .001). IRP individuals with cognitive impairment were all deceased at the follow-up, indicating an allostatic overload.

Serum C-Reactive Protein and Cognitive Function in Healthy Elderly Italian Community Dwellers

BACKGROUND

Chronic low-grade inflammation, as measured with the peripheral serum marker C-reactive protein (sCRP), may be a risk factor for dementia in elderly persons.

METHODS

The relationship between sCRP and score on the Mini-Mental State Examination (MMSE), a commonly used screening cognitive measure, was investigated in 540 well functioning, healthy, and cognitively normal elders (age 73 +/- 6 years). Sociodemographic status, lifestyle, health status, traditional and nontraditional cardiovascular risk factors including plasma total homocysteine (tHcy), and other peripheral blood markers of vascular inflammation (leukocyte count, serum albumin, and plasma fibrinogen) were also assessed.

RESULTS

Risk for having sCRP in the highest decile (>0.7 mg/dl) was significantly higher in individuals with MMSE score 24-25 (odds ratio = 3.07, 95% confidence interval, 1.2-7.9) and 26-28 (odds ratio = 2.10, 95% confidence interval, 1.1-3.9) compared with those scoring above 28 (reference group). Results were unaffected by adjustment for all potential confounders. No association was found between MMSE and peripheral markers of vascular inflammation other than sCRP, but lower MMSE scores were also independently associated with hyperhomocysteinemia (plasma tHcy > 15 mmol/L).

CONCLUSION

In healthy, cognitively normal elderly community dwellers, increased sCRP levels are associated with concurrent cognitive impairment as measured by MMSE. The association is independent of sociodemographic status, lifestyle, health status, and traditional and nontraditional cardiovascular risk factors including hyperhomocysteinemia. Results support the hypothesis that chronic low-grade inflammation may be involved in age-related cognitive impairment.

Exaggerated neuroinflammation and sickness behavior in aged mice following activation of the peripheral innate immune system

Acute cognitive impairment (i.e., delirium) is common in elderly emergency department patients and frequently results from infections that are unrelated to the central nervous system. Since activation of the peripheral innate immune system induces brain microglia to produce inflammatory cytokines that are responsible for behavioral deficits, we investigated if aging exacerbated neuroinflammation and sickness behavior after peripheral injection of lipopolysaccharide (LPS). Microarray analysis revealed a transcriptional profile indicating the presence of primed or activated microglia and increased inflammation in the aged brain. Furthermore, aged mice had a unique gene expression profile in the brain after an intraperitoneal injection of LPS, and the LPS-induced elevation in the brain inflammatory cytokines and oxidative stress was both exaggerated and prolonged compared with adults. Aged mice were anorectic longer and lost more weight than adults after peripheral LPS administration. Moreover, reductions in both locomotor and social behavior remained 24 h later in aged mice, when adults had fully recovered, and the exaggerated neuroinflammatory response in aged mice was not reliably paralleled by increased circulating cytokines in the periphery. Taken together, these data establish that activation of the peripheral innate immune system leads to exacerbated neuroinflammation in the aged as compared with adult mice. This dysregulated link between the peripheral and central innate immune system is likely to be involved in the severe behavioral deficits that frequently occur in older adults with systemic infections.

The role of inflammation in Alzheimer's disease

Considerable evidence gained over the past decade has supported the conclusion that neuroinflammation is associated with Alzheimer's disease (AD) pathology. Inflammatory components related to AD neuroinflammation include brain cells such as microglia and astrocytes, the classic and alternate pathways of the complement system, the pentraxin acute-phase proteins, neuronal-type nicotinic acetylcholine receptors (AChRs), peroxisomal proliferators-activated receptors (PPARs), as well as cytokines and chemokines. Both the microglia and astrocytes have been shown to generate beta-amyloid protein (Abeta), one of the main pathologic features of AD. Abeta itself has been shown to act as a pro-inflammatory agent causing the activation of many of the inflammatory components. Further substantiation for the role of neuroinflammation in AD has come from studies that demonstrate patients who took non-steroidal anti-inflammatory drugs had a lower risk of AD than those who did not. These same results have led to increased interest in pursuing anti-inflammatory therapy for AD but with poor results. On the other hand, increasing amount of data suggest that AChRs and PPARs are involved in AD-induced neuroinflammation and in this regard, future therapy may focus on their specific targeting in the AD brain.

Developmental origins of aging in brain and blood vessels: an overview

Emerging evidence suggests a remarkable convergence of inflammatory mechanisms in the etiology of cardiovascular disease and Alzheimer disease. A broad set of NSAIDs and statins used to reduce the risk of vascular occlusion and to slow atherogensis may also be protective for Alzheimer disease. Elevated blood levels of C-reactive protein are risk factors for cardiovascular disease and possibly for Alzheimer disease. Monocyte-lineage cells are also fundamental to both conditions: in blood vessels, macrophages are important to atherogenesis for the accumulation of lipids (foam cells), whereas brain microglia show activation during aging and direct involvement in amyloid metabolism in the senile plaque. Genetic influences are recognized through the apoE4 allele, which is associated with hypercholesterolemia and is a risk factor in vascular events and Alzheimer disease, and is recognized for its proinflammatory profile. ApoE4 also accelerates Alzheimer disease pathogenesis in Down's syndrome and many other chronic neurodegenerative conditions, as is well-supported by animal models. Inflammatory changes are present at the earliest stages of vascular disease and Down's syndrome in human fetuses, and are also prominent early in Alzheimer disease. These findings give a basis for considering inflammatory processes early in life which can lead to fully fired pathogenesis of cardiovascular disease and possibly for Alzheimer disease.

Progressive changes in regulation of apolipoproteins E and J in glial cultures during postnatal development and aging

Apolipoprotein (Apo) E and ApoJ are lipid- and cholesterol-carriers in the central nervous system and are implicated in age-related neurodegenerative diseases. The primary source of secreted ApoE and ApoJ (clusterin) in the brain is glia. Regulation of these apolipoproteins in mixed glial cultures from rat cerebral cortex differed most strongly between neonatal- and adult-derived glia. Basal secretion of ApoJ was two-fold greater in neonatal than adult glia. Responses to cytokines also differed by donor age. In adult glia, IL-6 increased ApoE secretion, but slightly decreased ApoJ. Both IL-1 beta and TNFalpha treatments increased ApoJ secretion from adult glia, with little effect on ApoE. In contrast to adult glia, neonatal ApoJ secretion did not respond to IL-1 beta, IL-6, or TNFalpha, and ApoE secretion from neonatal glia was slightly increased by IL-6. These differences may contribute to age-related neuroinflammatory processes, and are pertinent to the general use of neonatal-derived primary glia in models for neurodegenerative disease.

Cognitive reserve and the neurobiology of cognitive aging

A hypothetical construct of "cognitive reserve" is widely used to explain how, in the face of neurodegenerative changes that are similar in nature and extent, individuals vary considerably in the severity of cognitive aging and clinical dementia. Intelligence, education and occupational level are believed to be major active components of cognitive reserve. Here, we summarize the main features of cognitive aging and their neuropathological correlates. We describe the neurobiology of cognitive aging and conclude that perturbations of neural health attributable to oxidative stress and inflammatory processes alone are insufficient to distinguish cognitive aging from Alzheimer's disease. We introduce the concept of cognitive reserve and illustrate its utility in explaining individual differences in cognitive aging. Structural and functional brain imaging studies suggest plausible neural substrates of cognitive reserve, probably involving processes that support neuroplasticity in the aging brain. The cognitive reserve hypothesis conforms with reported associations between early and mid life lifestyle choices, early education, lifelong dietary habit, leisure pursuits and the retention of late life mental ability.

Lack of association between vascular dementia and Chlamydia pneumoniae infection: a case-control study

Background

Chronic inflammation appears to play a role in the pathogenesis of vascular dementia. Given the association between Chlamydia pneumoniae and stroke, the possibility exists that previous exposure to C. pneumoniae may play a role in vascular dementia. The objective of this study was to determine if there was an association between serological evidence of C. pneumoniae infection or inflammatory markers with vascular dementia.

Methods

28 case-patients with vascular dementia at a geriatric clinic and 24 caregiver-controls were tested for C. pneumoniae IgG and IgA antibodies. The association between vascular dementia and C. pneumoniae titres as well as inflammatory markers was estimated by using both conditional logistic regression and stratified logistic regression.

Results

When matched cases were compared to controls, there was no significant difference in elevated C. pneumoniae specific IgG antibodies (titre ≥ 1:32), odds ratio [OR] 1.3 (95% confidence intervals [CI] 0.3 to 6.0), p = 0.71, or in elevated C. pneumoniae specific IgA antibodies (titre ≥ 1:16), OR 2.0 (95%CI 0.5 to 8.0), p = 0.33 indicative of past or persistent C. pneumoniae infection. Similarly, no difference in high IgG or IgA antibody levels (IgG titre ≥ 1:512 or IgA titre ≥ 1:64) between the two groups, indicative of recent C. pneumoniae infection, was found, OR 0.4 (95%CI 0.1 to 2.1), p = 0.27. For C-reactive protein (CRP), the mean difference between 18 matched pairs (case – control) was – 3.33 mg/L. There was no significant difference between cases and controls when comparing log transformed values, OR 0.03 (95%CI 0.00 to 2.89), p = 0.13 or comparing CRP values above or below the median, OR 0.8 (95%CI 0.2 to 3.4), p = 0.71. For fibrinogen, the mean difference between pairs (case – control) was -0.07 g/L. There was no statistical difference between cases and controls when comparing log transformed values, OR 0.6 (95%CI 0.0 to 31.2), p = 0.79 or between fibrinogen values above and below the median, OR = 0.5 (95%CI 0.1 to 2.0), p = 0.50.

Conclusion

We found no evidence for a significant association between C. pneumoniae infection, inflammatory markers such as CRP and fibrinogen, and vascular dementia.

Interleukin-10 and interleukin-6 gene polymorphisms as risk factors for Alzheimer’s disease

In the pathogenesis of Alzheimer disease (AD), it has been proposed that the anti-inflammatory interleukins such as IL-10 regulate beta-amyloid-induced microglial inflammatory responses inhibiting the proinflammatory cytokine IL-6. Since the promoters of the IL-10 and IL-6 genes show single nucleotide polymorphisms (SNPs) (IL-10: -1082 G --> A; IL-6: -174 G --> C), we investigated these SNPs and cytokine production by peripheral blood mononuclear cells in 65 AD patients and 65 controls (HC). In AD there was a significant increase of the -1082A IL-10 allele (P=0.009) and a decrease of -1082GG genotype (P=0.019). The frequency of the GG IL-6 genotype in AD was lower and the C allele significantly higher (P <0.005). The co-occurrence of IL-10 A and IL-6 C alleles significantly raised the odds ratio (OR 11.2, confidence interval: CI 1.3-97.3; P <0.05) independently of apolipoprotein E4 (adjusted OR 10.3, CI 1-108; P <0.05). Only amyloid-stimulated IL-10 production differed between the groups (P=0.023). These results raise questions regarding the inflammatory theory in AD, pointing to a pivotal role of IL-10 and IL-6 and a selective alteration in this network.

Radiation-induced impairment of hippocampal neurogenesis is associated with cognitive deficits in young mice

Advances in the management of pediatric brain tumors have increased survival rates in children, but their quality of life is impaired due to cognitive deficits that arise from irradiation. The pathogenesis of these deficits remains unknown, but may involve reduced neurogenesis within the hippocampus. To determine the acute radiosensitivity of the dentate subgranular zone (SGZ), 21-day-old C57BL/J6 male mice received whole brain irradiation (2-10 Gy), and 48 h later, tissue was assessed using immunohistochemistry. Proliferating SGZ cells and their progeny, immature neurons, were decreased in a dose-dependent fashion. To determine if acute changes translated into long-term alterations in neurogenesis, mice were given a single dose of 5 Gy, and 1 or 3 months later, proliferating cells were labeled with 5-bromo-2'-deoxyuridine (BrdU). Confocal microscopy was used to determine the percentage of BrdU-labeled cells that showed mature cell phenotypes. X-rays significantly reduced the production of new neurons at both time points, while glial components showed no change or small increases. Measures of activated microglia and infiltrating, peripheral monocytes indicated that reduced neurogenesis was associated with a chronic inflammatory response. Three months after irradiation, changes in neurogenesis were associated with spatial memory retention deficits determined using the Morris water maze. Behavioral training and testing increased the numbers of immature neurons, most prominently in irradiated animals. These data provide evidence that irradiation of young animals induces a long-term impairment of SGZ neurogenesis that is associated with hippocampal-dependent memory deficits.

Association of fear of terror with low-grade inflammation among apparently healthy employed adults

OBJECTIVE

Based on evidence that psychological stress may induce a chronic inflammatory process, we hypothesized that the stress caused by chronic fear of terror may be associated with low-grade inflammation. This hypothesis was examined in employed men and women with the presence of low-grade inflammation measured by high sensitivity C-reactive protein (CRP).

METHODS

Apparently healthy employed adults (N = 1153) undergoing periodic health check-ups in a tertiary hospital in Israel completed a questionnaire. Fear of terror (scored 1-5) was assessed by three items measuring the extent to which respondents have deep concern for personal safety, elevated tension in crowded places, and fear of terror strikes causing harm to one's self or one's family members. The main outcome measure was the presence or absence of an elevated CRP level (>3.0 mg/L).

RESULTS

Women scored significantly higher on fear of terror compared with men (M = 2.16 vs. M = 1.68, respectively; p <.0001). Most of the study participants who scored high (4 or 5) on fear of terror, reported having experienced this feeling for 1 year or more. In women only, there was a positive association between fear of terror and risk of elevated CRP level (adjusted OR = 1.7, 95% CI 1.2-2.4) in a multivariate model adjusting for generalized anxiety, depressive symptoms, and potentially confounding demographic and biomedical variables.

CONCLUSIONS

Chronic fear of terror in women, but not in men, is associated with elevated CRP levels, which suggests the presence of low-grade inflammation and a potential risk of cardiovascular disease.

Conditions of aging as manifestations of sympathetic bias unmasked by loss of parasympathetic function

We propose a unifying hypothesis that many clinical consequences of aging are pleiotropic manifestations of the loss of parasympathetic function that occurs during post-reproductive senescence. The loss of parasympathetic function unmasks the baseline sympathetic bias inherent in the end-organs, resulting in the familiar signs of aging including tachycardia, constipation, insomnia, erectile dysfunction, fluid retention, and systemic inflammation. These consequences in turn may contribute to many of the common diseases associated with aging including type-2 diabetes, Alzheimer's, atherosclerosis, and cancer. Maintenance and restoration of parasympathetic function may enable upstream control over the deleterious aspects of inherent end-organ adrenergic bias.

Common ancestors: chronic progressive diseases have the same pathogenesis

In multiple organ systems, chronic progressive disease is characterized at the tissue level by increase in inflammatory cytokines, cell apoptosis and progressive fibrosis, suggesting a possible commonality of pathogenesis. This speculation is supported by the observation that elevated systemic levels of cytokines and/or CRP predict the appearance of disease, progression of disease, and disease complications. Some therapeutic interventions that reduce the expression of inflammatory cytokines, such as HMG Co-A reductase inhibitors, slow the progression of a number of chronic diseases, independent of their effect on cholesterol level. Taken together, these data suggest a unifying hypothesis for many chronic progressive diseases. Diverse noxious stimuli activate a normal protective inflammatory response. This response typically defervesces with elimination of the stimulus, reestablishing homeostasis. When homeostasis is not restored, that is, the inflammatory response persists, cell apoptosis and tissue fibrosis can result. The universality of this tissue response derives from the fact that all cells derive from the same blastocyst. Since cell differentiation results in different tissue functions, however, the clinical manifestations of disease are also vastly different, obscuring the underlying disease process. The relevance of this insight is that it provides a potential framework for testing old and new therapies which might inhibit a diverse set of clinical conditions at several levels of the disease process.

A mechanistic model for the aging of human skin

The microinflammatory model of skin aging is described. This model accounts for the loss of elasticity, resiliene and flexibility of the dermis, as well as for the appearance of wrinkles and for the thinning of the epidermis which are associated with aging. The lack of appropriate apparatuses for the correct measurements of skin hydration does not allow one to test this model for its predictive capability of the appearance of dry skin with age. The micro-inflammatory model of skin aging fails to predict the appearance of age spots on the surface of the skin.

Reduced susceptibility to kainic acid-induced excitoxicity in T-cell deficient CD4/CD8(-/-) and middle-aged C57BL/6 mice

Kainic acid (KA)-induced hippocampal injury is a good model for studying human neurodegenerative diseases. To investigate the roles of immune cells and age related changes in neurodegeneration, we used this model to assess reactions in young and middle-aged wild-type and CD4/CD8(-/-) mice by intranasal administration of KA. We found that CD4/CD8-deficiency resulted in a significant reduction of the severity of clinical signs and pathological changes in KA-treated young, but not in KA-treated middle-aged mice. Middle-aged wild-type mice had a similar reaction to KA insult as young and middle-aged CD4/CD8(-/-) mice. CD4/CD8(-/-) mice exhibited decreased locomotor and rearing activities as they approached to middle-aged state, which was not seen in wild-type mice. In addition, CD4/CD8-deficiency and increased age prevented KA-induced increase of both locomotor and rearing activities. The results suggest that a decline of immunological function is associated with aging, and both of them may contribute to the relative resistance to KA-induced neurotoxicity.

Cross-linked fibrin degradation products (D-dimer), plasma cytokines, and cognitive decline in community-dwelling elderly persons

OBJECTIVES

To investigate the effect of coagulation and inflammatory pathway activation on future cognitive decline in older persons.

DESIGN

Prospective cohort study.

SETTING

Rural and urban communities in North Carolina.

PARTICIPANTS

Community-dwelling older people enrolled in the Duke Established Populations for Epidemiologic Studies of the Elderly in 1986.

MEASUREMENTS

In 1992, blood was drawn for assay of D-dimer (1,723 subjects), Interleukin-6 (1,726 subjects), and other cytokines (1,551 subjects). Cognitive and functional assessments were performed in 1986, 1989, 1992, and 1996. Cognition was measured using the Short Portable Mental Status Questionnaire.

RESULTS

Cognitive decline over a 4-year period was significantly correlated (P<.001) with D-dimer, age, race, and physical performance status as measured using the Rosow-Breslau and Nagi instruments. After controlling for demographics, functional status, and comorbidities, D-dimer remained predictive of cognitive decline. Proinflammatory cytokines were not associated with current cognitive status in cross-sectional analyses or with incident cognitive decline in prospective analyses.

CONCLUSION

In a large sample of community-dwelling elders, higher levels of D-dimer were predictive of cognitive decline over a 4-year period. No clinically significant associations were found between age-related peripheral cytokine dysregulation and cognition.

Protective effect of vitamin C against the ethanol mediated toxic effects on human brain glial cells

It is now known that chronic consumption of excessive amounts of alcohol is a major source of social and medical problems. Ethanol-mediated glial cell activation may lead to neuron damage in many ways, including the formation of free radicals and production of pro-inflammatory molecules. Vitamin C (vit-C) is an essential dietary nutrient required as a co-factor for many enzymes and a very efficient antioxidant, protecting cells against free radical-mediated damage. The objective of this study was to evaluate the protective effects of vit-C on glial cell activation and viability against ethanol-mediated toxicity. Human brain astrocyte cells (HA) were exposed to ethanol (0, 50, and 350 mmol/L) for 24 h. We found that glial cells incubated with different concentrations of vit-C increase their vit-C in a dose-dependent manner. HA incubated with 0, 50 or 350 mmol/L of ethanol for up to 24 h showed toxic effects that were proportional to the levels of ethanol in the medium, HA showed increased levels of heat shock protein (Hsp70). However, cells enriched with vit-C before being exposed to ethanol, were better protected against the alcohol-mediated toxicity than non-supplemented cells, and showed significantly lower concentrations of Hsp70. Ethanol also caused increased expression of cyclooxygenase-2 (COX-2) and synthesis of prostaglandin E2 (PGE2), which were reduced by vit-C. In summary, HA supplemented with vit-C were significantly more resistant to the ethanol-mediated toxic effects.