Domenico Nuzzo

Inflammatory networks in ageing, age-related diseases and longevity.

Inflammation is considered a response set by the tissues in response to injury elicited by trauma or infection. It is a complex network of molecular and cellular interactions that facilitates a return to physiological homeostasis and tissue repair. The individual response against infection and trauma is also determined by gene variability. Ageing is accompanied by chronic low-grade inflammation state clearly showed by 2-4-fold increase in serum levels of inflammatory mediators. A wide range of factors has been claimed to contribute to this state; however, the most important role seems to be played by the chronic antigenic stress, which affects immune system thorough out life with a progressive activation of macrophages and related cells. This pro-inflammatory status, interacting with the genetic background, potentially triggers the onset of age-related inflammatory diseases as atherosclerosis. Thus, the analysis of polymorphisms of the genes that are key nodes of the natural immunity response might clarify the patho-physiology of age-related inflammatory diseases as atherosclerosis. On the other hand, centenarians are characterized by marked delay or escape from age-associated diseases that, on average, cause mortality at earlier ages. In addition, centenarian offspring have increased likelihood of surviving to 100 years and show a reduced prevalence of age-associated diseases, as cardiovascular disease (CVD) and less prevalence of cardiovascular risk factors. So, genes involved in CVD may play an opposite role in human longevity. Thus, the model of centenarians can be used to understand the role of these genes in successful and unsuccessful ageing. Accordingly, we report the results of several studies in which the frequencies of pro-inflammatory alleles were significantly higher in patients affected by infarction and lower in centenarians whereas age-related controls displayed intermediate values. These findings point to a strong relationship between the genetics of inflammation, successful ageing and the control of cardiovascular disease at least in men, in which these studies were performed. These data are also briefly discussed in the light of antagonistic pleiotropy theory and in order to pursuit a pharmacogenomics approach.

Inflammation, genes and zinc in Alzheimer's disease.

Alzheimers disease (AD) is a heterogeneous and progressive neurodegenerative disease which in Western society mainly accounts for clinical dementia. AD has been linked to inflammation and metal biological pathway. Neuro-pathological hallmarks are senile plaques, resulting from the accumulation of several proteins and an inflammatory reaction around deposits of amyloid, a fibrillar protein, Abeta, product of cleavage of a much larger protein, the beta-amyloid precursor protein (APP) and neurofibrillary tangles. Amyloid deposition, due to the accumulation of Abeta peptide, is the main pathogenetic mechanism. Inflammation clearly occurs in pathologically vulnerable regions of AD and several inflammatory factors influencing AD development, i.e. environmental factors (pro-inflammatory phenotype) and/or genetic factors (pro-inflammatory genotype) have been described. At the biochemical level metals such as zinc are known to accelerate the aggregation of the amyloid peptide and play a role in the control of inflammatory responses. In particular, zinc availability may regulate mRNA cytokine expression, so influencing inflammatory network phenotypic expression.

Mitochondrial Dysfunction: Different Routes to Alzheimer’s Disease Therapy

Mitochondria are dynamic ATP-generating organelle which contribute to many cellular functions including bioenergetics processes, intracellular calcium regulation, alteration of reduction-oxidation potential of cells, free radical scavenging, and activation of caspase mediated cell death. Mitochondrial functions can be negatively affected by amyloid β peptide (Aβ), an important component in Alzheimers disease (AD) pathogenesis, and Aβ can interact with mitochondria and cause mitochondrial dysfunction. One of the most accepted hypotheses for AD onset implicates that mitochondrial dysfunction and oxidative stress are one of the primary events in the insurgence of the pathology. Here, we examine structural and functional mitochondrial changes in presence of Aβ. In particular we review data concerning Aβ import into mitochondrion and its involvement in mitochondrial oxidative stress, bioenergetics, biogenesis, trafficking, mitochondrial permeability transition pore (mPTP) formation, and mitochondrial protein interaction. Moreover, the development of AD therapy targeting mitochondria is also discussed.

Are oxidative stress and mitochondrial dysfunction the key players in the neurodegenerative diseases

Abstract Oxidative stress has long been linked to neuronal cell death that is associated with certain neurodegenerative conditions. Whether it is a primary cause or merely a downstream consequence of the neurodegenerative and aging process is still an open question. Mitochondria are deeply involved in the production of reactive oxygen species through the electron carriers of the respiratory chain and their role in neurodegenerative diseases is discussed here. Moreover, the input of new technological approaches in the study of oxidative stress response or in the evidence of an oxidative stress component in neurodegeneration is reviewed in this paper.

Systemic Immune Responses in Alzheimer's Disease: In Vitro Mononuclear Cell Activation and Cytokine Production

To investigate the systemic signs of immune-inflammatory responses in Alzheimers disease (AD), in the present study we have analyzed blood lymphocyte subsets and the expression of activation markers on peripheral blood mononuclear cells (PBMCs) from AD patients and age-matched healthy controls (HC) activated in vitro by recombinant amyloid-beta peptide (rAbeta42). Our study of AD lymphocyte subpopulations confirms the already described decrease of the absolute number and percentage of B cells when compared to HC lymphocytes, whereas the other subsets are not significantly different in patients and controls. We report the increased expression of the activation marker CD69 and of the chemokine receptors CCR2 and CCR5 on T cells but no changes of CD25 after activation. B cells are also activated by rAbeta42 as demonstrated by the enhanced expression of CCR5. Moreover, rAbeta42 induces an increased expression of the scavenger receptor CD36 on monocytes. Some activation markers and chemokine receptors are overexpressed in unstimulated AD cells when compared to controls. This is evidence of the pro-inflammatory status of AD. Stimulation by rAbeta42 also induces the production of the pro-inflammatory cytokines IL-1beta, IL-6, IFN-gamma, and TNF-alpha, and of the anti-inflammatory cytokines IL-10 and IL-1Ra. The chemokines RANTES, MIP-1beta, and eotaxin as well as some growth factors (GM-CSF, G-CSF) are also overproduced by AD-derived PBMC activated by rAbeta42. These results support the involvement of systemic immunity in AD patients. However, our study is an observational one so we cannot draw a conclusion about its contribution to the pathophysiology of the disease.

Zinc and Inflammatory/Immune Response in Aging

Abstract:  Life‐long antigenic burden determines a condition of chronic inflammation, with increased lymphocyte activation and proinflammatory cytokine production. A large number of studies have documented changes in zinc metabolism in experimental animal models of acute and chronic inflammation and in human chronic inflammatory conditions. In particular, modification of zinc plasma concentration, as well as intracellular disturbance of antioxidant intracellular pathways, has been found in aging and in some age‐related diseases. Zinc deficiency is diffused in aged individuals in order to avoid meat and other high zinc content foods due to fear of cholesterol. Rather, they increase the consumption of refined wheat products that lack zinc and other critical nutrients as a consequence of the refining process. On the other hand, plasma zinc concentration is influenced by proinflammatory cytokines (IL‐6 and TNF‐α) and by metallothioneins (MT) homeostasis, which is in turn affected by proinflammatory cytokines. MT increase in aging and chronic inflammation allowing a continuous sequestration of intracellular zinc with subsequent low zinc ion availability against stressor agents and inflammation. This phenomenon leads to an impaired inflammatory/immune response in the elderly. A major target of zinc is NF‐κB, a transcription factor critical for the expression of proinflammatory cytokines whose production is regulated by extra‐ and intracellular activating and inhibiting factors interacting with the regulatory elements on cytokine genes. Effects of zinc on translocation of NF‐κB have been attributed to the suppression of phosphorylation and degradation of the inhibitory proteins (A20) that normally sequester it in the cytoplasm. Moreover, this factor and A20 are regulated by specific genes involved in inflammation and by intracellular zinc ion availability. So, it is not so surprising that zinc deficiency is constantly observed in chronic inflammation, such as in old individuals. On the other hand, cytokine genes are highly polymorphic and some of these polymorphisms are associated with atherosclerosis and diabetes type 2. Therefore, zinc turnover, via MT homeostasis, in individuals genetically predisposed to a dysregulation of the inflammatory/immune response may play a crucial role in causing possible adverse events with the appearance of age‐related diseases.

Immune-Inflammatory Responses and Oxidative Stress in Alzheimer's Disease: Therapeutic Implications

Alzheimers disease (AD) is a heterogeneous and progressive neurodegenerative disease which in Western society mainly accounts for clinical dementia. AD has been linked to inflammation and oxidative stress. Neuro-pathological hallmarks are senile plaques, resulting from the accumulation of several proteins and an inflammatory reaction around deposits of amyloid, a fibrillar protein, Abeta, product of cleavage of a much larger protein, the beta-amyloid precursor protein (APP) and neurofibrillary tangles. Inflammation clearly occurs in pathologically vulnerable regions of AD and several inflammatory factors influencing AD development, i.e. environmental factors (pro-inflammatory phenotype) and/or genetic factors (pro-inflammatory genotype) have been described. Irrespective of the source and mechanisms that lead to the generation of reactive oxygen species, mammalian cells have developed highly regulated inducible defence systems, whose cytoprotective functions are essential in terms of cell survival. When appropriately activated, each one of these systems has the possibility to restore cellular homeostasis and rebalance redox equilibrium. Increasing evidence, support the notion that reduction of cellular expression and activity of antioxidant proteins and consequent augment of oxidative stress are fundamental causes for ageing processes and neurodegenerative diseases., including AD. The better understanding of different molecular and cellular inflammatory mechanisms is crucial for complete knowledge of AD pathophysiology, hence for its prevention and drug therapy. Accordingly, two lines of preventive therapeutics can be outlined, the first based on anti-inflammatory drugs, the second one on anti-oxidative properties.

Metformin increases APP expression and processing via oxidative stress, mitochondrial dysfunction and NF-κB activation: Use of insulin to attenuate metformin's effect.

Clinical and experimental biomedical studies have shown Type 2 diabetes mellitus (T2DM) to be a risk factor for the development of Alzheimers disease (AD). This study demonstrates the effect of metformin, a therapeutic biguanide administered for T2DM therapy, on β-amyloid precursor protein (APP) metabolism in in vitro, ex vivo and in vivo models. Furthermore, the protective role of insulin against metformin is also demonstrated. In LAN5 neuroblastoma cells, metformin increases APP and presenilin levels, proteins involved in AD. Overexpression of APP and presenilin 1 (Pres 1) increases APP cleavage and intracellular accumulation of β-amyloid peptide (Aβ), which, in turn, promotes aggregation of Aβ. In the experimental conditions utilized the drug causes oxidative stress, mitochondrial damage, decrease of Hexokinase-II levels and cytochrome C release, all of which lead to cell death. Several changes in oxidative stress-related genes following metformin treatment were detected by PCR arrays specific for the oxidative stress pathway. These effects of metformin were found to be antagonized by the addition of insulin, which reduced Aβ levels, oxidative stress, mitochondrial dysfunction and cell death. Similarly, antioxidant molecules, such as ferulic acid and curcumin, are able to revert metformins effect. Comparable results were obtained using peripheral blood mononuclear cells. Finally, the involvement of NF-κB transcription factor in regulating APP and Pres 1 expression was investigated. Upon metformin treatment, NF-κB is activated and translocates from the cytoplasm to the nucleus, where it induces increased APP and Pres 1 transcription. The use of Bay11-7085 inhibitor suppressed the effect of metformin on APP and Pres 1 expression.

Ferulic Acid: a Natural Antioxidant Against Oxidative Stress Induced by Oligomeric A-beta on Sea Urchin Embryo

Alzheimer’s disease (AD) is a progressive, neurodegenerative disorder, characterized by loss of memory and impairment of multiple cognitive functions. Amyloid beta peptide (Aβ) is the main component of amyloid plaques observed in the brain of individuals affected by AD. Oxidative stress and mitochondrial dysfunction, induced by Aβ, are among the earliest events in AD, triggering neuronal degeneration and cell death. Use of natural molecules with antioxidant properties could be a suitable strategy for inhibiting the cell death cascade. Here, by employing the sea urchin Paracentrotus lividus as a model system, and Aβ oligomers, we tested the effectiveness of ferulic acid (FA), a natural antioxidant, as a putative AD neuroprotective compound. By microscopic inspection we observed that FA is able to reverse morphological defects induced by Aβ oligomers in P. lividus embryos. In addition, FA is able to neutralize reactive oxygen species (ROS), recover mitochondrial membrane potential, and block apoptotic pathways. Moreover, this model system has allowed us to obtain information about down- or up-regulation of some key molecules—Foxo3a, ERK, and p53—involved in the antioxidant mechanism.

Inflammatory Mediators as Biomarkers in Brain Disorders

Neurodegenerative diseases such as Alzheimer, Parkinson, amyotrophic lateral sclerosis, and Huntington are incurable and debilitating conditions that result in progressive death of the neurons. The definite diagnosis of a neurodegenerative disorder is disadvantaged by the difficulty in obtaining biopsies and thereby to validate the clinical diagnosis with pathological results. Biomarkers are valuable indicators for detecting different phases of a disease such as prevention, early onset, treatment, progression, and monitoring the effect of pharmacological responses to a therapeutic intervention. Inflammation occurs in neurodegenerative diseases, and identification and validation of molecules involved in this process could be a strategy for finding new biomarkers. The ideal inflammatory biomarker needs to be easily measurable, must be reproducible, not subject to wide variation in the population, and unaffected by external factors. Our review summarizes the most important inflammation biomarkers currently available, whose specificity could be utilized for identifying and monitoring distinctive phases of different neurodegenerative diseases.