Michelino Di Rosa

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.

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.

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.

Osteoarthritis in the XXIst Century: Risk Factors and Behaviours that Influence Disease Onset and Progression

Osteoarthritis (OA) is a growing public health problem across the globe, affecting more than half of the over 65 population. In the past, OA was considered a wear and tear disease, leading to the loss of articular cartilage and joint disability. Nowadays, thanks to advancements in molecular biology, OA is believed to be a very complex multifactorial disease. OA is a degenerative disease characterized by “low-grade inflammation” in cartilage and synovium, resulting in the loss of joint structure and progressive deterioration of cartilage. Although the disease can be dependent on genetic and epigenetic factors, sex, ethnicity, and age (cellular senescence, apoptosis and lubricin), it is also associated with obesity and overweight, dietary factors, sedentary lifestyle and sport injuries. The aim of this review is to highlight how certain behaviors, habits and lifestyles may be involved in the onset and progression of OA and to summarize the principal risk factors involved in the development of this complicated joint disorder.

Interleukin-18 and transforming growth factor-beta 1 plasma levels in Alzheimer's disease and vascular dementia

Inflammation has been involved in the development of dementia in cerebrovascular diseases. To investigate the cellular activation of the peripheral immune system in patients with Alzheimer’s disease (AD) and vascular dementia (VaD), we determined the presence of IL‐18 and TGF‐β1 in the plasma by using ELISA. The levels of IL‐18 and TGF‐β1 were significantly elevated in patients with AD and VaD compared to non‐demented, age‐matched subjects. We found an inverse correlation between the levels of IL‐18 and TGF‐β1 in AD patients. In VaD patients, the correlation between IL‐18 and TGF‐β1 reached a borderline positive value. Whereas, in the non‐demented, age‐matched subjects, a positive correlation between IL‐18 and TGF‐β1 levels was observed. These findings indicate that IL‐18 and TGF‐β1 elevation is associated with AD and VaD patients, confirming that the immune system might exert a remarkable role in the development and progression of neurodegenerative disorders. Moreover, as different modifications were detected in the patients affected by AD and VaD, we propose that IL‐18 and TGF‐ β1 plasma levels might represent possible differential biomarkers.

Evaluation of CHI3L-1 and CHIT-1 Expression in Differentiated and Polarized Macrophages

Chitinase 3-like protein 1 (CHI3L-1) and chitotriosidase (CHIT-1) are members of the chitinase family. CHI3L-1 is a newly recognized protein that is secreted by activated macrophages and neutrophils and expressed in a broad spectrum of inflammatory conditions and cancers. In human plasma, CHIT-1 activity has been proposed as a biochemical marker of macrophage activation. Although CHI3L-1 expression in inflammation is under examination, little is known regarding its regulation during macrophages’ full maturation and polarization. In this study, we compared CHI3L-1 and CHIT-1 modulation during monocyte to macrophage transition and polarization. Gene expression analysis was investigated by real-time PCR. We found that during the maturation of monocytes into macrophages, the expression of both CHI3L-1 and CHIT-1 increased exponentially over time. Additionally, we observed a different regulation of CHI3L-1 and CHIT-1 in undifferentiated monocytes under stimulation with lipopolysaccharide, interferon-γ, and interleukin-4, at the same concentration used to polarize macrophages. Our finding suggests that in the immune response, the role of CHI3L-1 and CHIT-1 is not restricted to innate immunity, but they are also protagonists in acquired immunity.

HIV RNA suppression and immune restoration: can we do better?

HAART has significantly changed the natural history of HIV infection: patients receiving antiretrovirals are usually able to control viremia, even though not all virological responders adequately recover their CD4+ count. The reasons for poor immune restoration are only partially known and they include genetic, demographic and immunologic factors. A crucial element affecting immune recovery is immune activation, related to residual viremia; indeed, a suboptimal virological control (i.e., low levels of plasma HIV RNA) has been related with higher levels of chronic inflammation and all-cause mortality. The sources of residual viremia are not yet completely known, even though the most important one is represented by latently infected cells. Several methods, including 2-LTR HIV DNA and unspliced HIV RNA measurement, have been developed to estimate residual viremia and predict the outcome of antiretroviral therapy. Considering that poor immunologic responders are exposed to a higher risk of both AIDS-related and non-AIDS-related diseases, there is a need of new therapeutic strategies, including immunomodulators and drugs targeting the latent viral reservoirs, in order to face residual viremia but also to “drive” the host immunologic responses.

Modulation of Chitotriosidase During Macrophage Differentiation

Macrophages as a principal component of immune system play an important role in the initiation, modulation, and final activation of the immune response against pathogens. Upon stimulation with different cytokines, macrophages can undergo classical or alternative activation to become M1 or M2 macrophages, which have different functions during infections. Although chitotriosidase is widely accepted as a marker of activated macrophages and is thought to participate in innate immunity, particularly in defense mechanisms against chitin containing pathogens, little is known about its expression during macrophages full maturation and polarization. In this study we analyzed CHIT-1 modulation during monocyte-to-macrophage maturation and during their polarization. The levels of CHIT-1 expression was investigated in human monocytes obtained from buffy coat of healthy volunteers, polarized to classically activated macrophages (or M1), whose prototypical activating stimuli are interferon-γ and lipopolysaccharide, and alternatively activated macrophages (or M2) obtained by interleukin-4 exposure by real-time PCR and by Western blot analysis. During monocyte–macrophage differentiation both protein synthesis and mRNA analysis showed that CHIT-1 rises significantly and is modulated in M1 and M2 macrophages.Our results demonstrated that variations of CHIT-1 production are strikingly associated with macrophages polarization, indicating a different rule of this enzyme in the specialized macrophages.

Genetic variants in candidate genes influencing NAFLD progression

Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder including simple steatosis and nonalcoholic steatohepatitis (NASH). Advanced stages of NASH result ultimately in fibrosis, cirrhosis, and hepatocarcinoma. A diagnosis of NASH entails an increased risk of both liver-related and cardiovascular mortality as worsening of the metabolic syndrome. Because of its escalation, many investigations have been performed to elucidate the pathophysiologic origins of the disease progression. Human epidemiologic studies describing polymorphisms in a number of genes involved in metabolic dysfunctions have contributed to clarify the causes leading to the disease evolution. In this review, we attempt to outline critically the most recently identified genetic variants in NAFLD patients to identify possible risk factors promoting the progression of the disease. The evaluation of altered genotypes together with other clinical variables may facilitate the clinical management of these patients.