Lucia Malaguarnera

Molecular mechanisms involved in NAFLD progression

Non-alcoholic fatty liver disease (NAFLD) is an emerging metabolic-related disorder characterized by fatty infiltration of the liver in the absence of alcohol consumption. NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis (NASH), which might progress to end-stage liver disease. This progression is related to the insulin resistance, which is strongly linked to the metabolic syndrome consisting of central obesity, diabetes mellitus, and hypertension. Earlier, the increased concentration of intracellular fatty acids within hepatocytes leads to steatosis. Subsequently, multifactorial complex interactions between nutritional factors, lifestyle, and genetic determinants promote necrosis, inflammation, fibrosis, and hepatocellular damage. Up to now, many studies have revealed the mechanism associated with insulin resistance, whereas the mechanisms related to the molecular components have been incompletely characterized. This review aims to assess the potential molecular mediators initiating and supporting the progression of NASH to establish precocious diagnosis and to plan more specific treatment for this disease.

Vitamin D3: a helpful immuno-modulator

The active metabolite of vitamin D, 1α, 25‐dihydroxyvitamin D3 [1,25(OH)2D3], is involved in calcium and phosphate metabolism and exerts a large number of biological effects. Vitamin D3 inhibits parathyroid hormone secretion, adaptive immunity and cell proliferation, and at the same time promotes insulin secretion, innate immunity and stimulates cellular differentiation. The role of vitamin D3 in immunoregulation has led to the concept of a dual function as both as an important secosteroid hormone for the regulation of body calcium homeostasis and as an essential organic compound that has been shown to have a crucial effect on the immune responses. Altered levels of vitamin D3 have been associated, by recent observational studies, with a higher susceptibility of immune‐mediated disorders and inflammatory diseases. This review reports the new developments with specific reference to the metabolic and signalling mechanisms associated with the complex immune‐regulatory effects of vitamin D3 on immune cells.

The immune response to Plasmodium falciparum malaria

Malaria is still a major cause of severe disease which is responsible for millions of deaths, mostly in children under 5 years old, in tropical countries, especially sub-Saharan Africa. Complications of severe anaemia and cerebral malaria are thought to be the major cause of morbidity and mortality but recent evidence suggests that the hosts immunological response could also contribute to the pathophysiology of the disease in human beings. Intensive studies of the immune response to malaria parasites in human beings have provided a wealth of information about the cells and cytokines implicated in the pathophysiology of survival and fatal outcome in severe infections. This review focuses on the pivotal role of macrophages and other important cellular effectors, molecules, and cytokines involved in the activation of the immune response at the different stages of human falciparum malaria. Our understanding of the putative mechanisms by which cytokines may mediate beneficial and harmful effects, through activation of phagocytic cells, could help to develop new treatment strategies, regardless of the emergence of parasite multidrug resistance.

Plasma chitotriosidase activity in acute Plasmodium falciparum malaria.

BACKGROUND Chitotriosidase is a functional chitinase secreted by activated macrophages. It is encoded by a gene located on chromosome 1q31-32, whose mutations may be responsible for chitotriosidase deficiency, encountered in almost 6% of Caucasian population. OBJECTIVE This study reports firstly plasma chitotriosidase activity in African children with acute Plasmodium falciparum malaria. The chitotriosidase activity was correlated to objective parameters reflecting the status of the disease and compared with those found in healthy African children. RESULTS We found that plasma chitotriosidase levels are significantly increased in African children with acute malaria (185.0+/-141.0 nmol/h/ml; median 150; range 11-521) with respect to reference values obtained in age matched African children (84.4.5+/-72.8 nmol/ml/h; median 63; range 4-350) (P<0.001). Moreover the levels of chitotriosidase were higher in African children than in Caucasian children matched for age (28.86+/-18.7 nmol/h/ml; median 24; range 1-98) (P<0.0001). A remarkable significant correlation was found between plasma chitotriosidase and reticulo-endothelial activation, as judged by thrombocytopenia degree and serum ferritin level in children with acute malaria. CONCLUSION Based on this study, it appears that genetic and environmental features might be responsible for diversity of plasma chitotriosidase activity in black children living in Burkina Faso.

A 24-bp duplication in exon 10 of human chitotriosidase gene from the sub-Saharan to the Mediterranean area: role of parasitic diseases and environmental conditions

Human chitotriosidase (Chit) is a member of the chitinase family and it is synthesized by activated macrophages. Recently, a genetic polymorphism was found to be responsible for the common deficiency in Chit activity, frequently encountered in different populations. We analyzed the Chit gene in some ethnic groups from the Mediterranean and African areas, to evaluate whether the Chit gene polymorphism correlates with the changes in environmental features and the disappearance of parasitic diseases. We found a heterozygote frequency for the duplication of 24 bp in exon 10 of 44% in Sicily and 32.71% in Sardinia, whereas those homozygous Chit deficient were 5.45 and 3.73%, respectively. In contrast, in Benin and Burkina Faso, both mesoendemic regions for Plasmodium falciparum malaria and other infections due to intestinal parasites, a low incidence of Chit mutation was found (heterozygous 0 and 2%, respectively) and no subject was homozygous for Chit deficiency. Our results provide evidence of the fact that the low frequency or the absence of mutant Chit gene may represent a protective factor in the population still living in disadvantaged environmental conditions. The present study suggests that the disappearance of parasitic diseases and the improved environmental conditions may have ensued the occurrence of a high percentage of 24-bp mutation in Sicily, in Sardinia and in other Mediterranean countries, whereas in the sub-Saharan regions (Benin and Burkina Faso), the widespread parasitic diseases and the poor social status have contributed to maintenance of the wild-type Chit gene.

Immuno-modulatory effects of vitamin D3 in human monocyte and macrophages.

Vitamin D3 [1α,25-(OH)(2)D(3)], involved in the regulation of body calcium homeostasis, promotes immature myeloid precursor cells differentiation into monocytes/macrophages. In this study we compared the regulatory interaction between 1α,25-(OH)(2)D(3) and tumor necrosis factor (TNF)-α or lipopolysaccharide (LPS) in the mRNA expression of interleukin (IL)-1β, (IL)-6, TNF-α, toll like receptors (TLR)-2 and (TLR)-4 in freshly isolated human monocyte (MonoT0) and in macrophages cultured for seven days (MØT7). Additionally, we detected the effect of 1α,25-(OH)(2)D(3) on macrophages chemotaxis. The expression of IL-1β, IL-6 and TNF-α, as well as TLR-2 and TLR-4 in MonoT0 and in MØT7 was examined by real time RT-PCR. Macrophages chemotaxis was analyzed by using horizontal chemotaxis agarose spot assay. We found that 1α,25-(OH)(2)D(3) influences macrophages chemotaxis and differently modulates the expression of IL-1β, IL-6, TNF-α and TLRs in the two different stages of monocytes/macrophage maturation. In conclusion our data add new information about the role of 1α,25-(OH)(2)D(3) on the expression of inflammatory mediators in human monocyte/macrophages, underlying the complex function of these cells. Investigating the differences in the pattern of expression of immune-mediators produced by MonoT0 and MØT7 may provide a new way to examine their biochemical and molecular function and may constitute a model system with well-defined behavior with respect to early or tardive events in the innate immune response.

Chitotriosidase and inflammatory mediator levels in Alzheimer's disease and cerebrovascular dementia

Inflammation has been reported to be involved in the pathogenesis of cerebrovascular dementias (CvDs). This study investigated the involvement of Chitotriosidase (ChT), a chinolitic enzyme mainly produced by activated macrophages, in the pathophysiology of Alzheimers disease (AD) and ischemic CvD. In addition, the levels of interleukin (IL)‐16, IL‐18, transforming growth factor (TGF) ‐β1 and superoxide anion (O2–) were determined to evaluate the relationship between ChT levels, these cytokines and oxidative stress in both AD and ischemic CvD patients. The levels of ChT and IL‐16, IL‐18, and TGF‐β1 mRNA were investigated using quantitative real‐time polymerase chain reaction on macrophages of peripheral blood of 40 patients with AD, 40 patients with ischemic CvD and 40 non‐demented age‐matched subjects. The results show that ChT, IL‐16 and O2– levels significantly increased in ischemic CvD patients compared with AD patients and were significantly and positively correlated with IL‐18 and O2–. The production of IL‐18 was increased in both AD and ischemic CvD patients. TGF‐β1 expression was higher in AD patients and was inversely correlated with the expression of ChT, IL‐16 and IL‐18, respectively. In non‐demented age‐matched subjects no significant changes in ChT and IL‐16, IL‐18, and TGF‐β1 expression were found. Our results indicate that ChT, IL‐16, IL‐18 and TGF‐β1 are increased in ischemic CvD and AD, confirming that the immune system may play an important role in the development and progression of neurodegenerative disorders. In addition, the present findings suggest that ChT could also play a crucial role in pathological conditions such as CvD in which the inflammatory process is activated.

Chitotriosidase gene expression in Kupffer cells from patients with non-alcoholic fatty liver disease

Background and aims: Non-alcoholic steatohepatitis (NASH) is a clinicopathological condition characterised by a necroinflammatory disorder with fatty infiltration of the hepatocytes. The molecular mechanisms involved in the anomalous behaviour of liver cells have only partially been determined. Human chitotriosidase (Chit) is a chitinolytic enzyme mainly produced by activated macrophages. The aim of this study was to investigate the expression of the chitinase-like gene in Kupffer cells, to determine how chitotriosidase may be implicated in the progression from uncomplicated steatosis to steatohepatitis with progressive fibrosis. Methods: 75 subjects were studied: 40 with NASH, 20 with simple steatosis, and 15 normal controls. Kupffer cells obtained from liver biopsies were used to detect CHIT expression, superoxide anion (O2−), lipid peroxidation, and tumour necrosis factor α (TNFα) and ferritin levels. Results: CHIT expression differed markedly in livers from normal controls and in those from patients with simple steatosis or non-alcoholic steatohepatitis. A significant correlation between mRNA CHIT and O2−, lipid peroxidation, TNFα, and ferritin levels was observed in both NASH and simple steatosis. Conclusions: Human Kupffer cells in NASH patients overproduce chitotriosidase. At the highest levels of production, this enzyme may play a role in increasing the risk for a poor outcome in steatohepatitis.

Effect of interferon-γ, interleukin-10, lipopolysaccharide and tumor necrosis factor-α on chitotriosidase synthesis in human macrophages

Abstract Human chitotriosidase is a chitinolytic enzyme and mainly produced by activated macrophages. Recently, we observed that prolactin, which is structurally related to several cytokines and is involved in regulating monocyte/macrophage functions, upregulates chitotriosidase gene expression in human macrophages, suggesting that chitotriosidase is not only a biochemical marker of macrophage activation in lysosomal diseases and hematological disorders, but also may reflect induction of an immunological response. To confirm this hypothesis we evaluated by quantitative real-time PCR the mRNA chitotriosidase levels in human monocytes/macrophages following treatment with pro-inflammatory stimuli such as interferon-γ, tumor necrosis factor-α, lipopolysaccharide, and interleukin-10, an anti-inflammatory cytokine. Stimulation of macrophages with interferon-γ, tumor necrosis factor-α and lipopolysaccharide resulted in increased levels of chitotriosidase mRNA, as well as chitotriosidase activity, whereas interleukin-10 decreased chitotriosidase synthesis. This finding is consistent with the hypothesis that the production of chitotriosidase by macrophages could have biological relevance in the immune response.

The role of immunity in elderly cancer

The increased incidence of malignancies in elderly patients living in industrialized countries has led to both identify the causes that alter the normal homeostatic balance in elderly and designate the specific treatments. The progressive decline of the immune system (immunosenescence) involving cellular and molecular alterations impact both innate and adaptive immunity. The immunosenescence leads to increased incidence of infectious diseases morbidity and mortality as well as heightened rates of other immune disorders such as autoimmunity, cancer, and inflammatory conditions. Here, we summarize the knowledge on the major changes in the immune system associated with aging in primary lymphoid organs as well as a description of molecular mechanisms, and the impact on cancer development.