CX3CL1 Pathway as a Molecular Target for Treatment Strategies in Alzheimer's Disease.

Alzheimer's disease (AD) is a scourge for patients, caregivers and healthcare professionals due to the progressive character of the disease and the lack of effective treatments. AD is considered a proteinopathy, which means that aetiological and clinical features of AD have been linked to the deposition of amyloid ß (Aß) and hyperphosphorylated tau protein aggregates throughout the brain, with Aß and hyperphosphorylated tau representing classical AD hallmarks. However, some other putative mechanisms underlying the pathogenesis of the disease have been proposed, including inflammation in the brain, microglia activation, impaired hippocampus neurogenesis and alterations in the production and release of neurotrophic factors. Among all, microglia activation and chronic inflammation in the brain gained some attention, with researchers worldwide wondering whether it is possible to prevent and stop, respectively, the onset and progression of the disease by modulating microglia phenotypes. The following key points have been established so far: (i) Aß deposition in brain parenchyma represents repeated stimulus determining chronic activation of microglia; (ii) chronic activation and priming of microglia make these cells lose neuroprotective functions and favour damage and loss of neurons; (iii) quiescent status of microglia at baseline prevents chronic activation and priming, meaning that the more microglia are quiescent, the less they become neurotoxic. Many molecules are known to modulate the quiescent baseline state of microglia, attracting huge interest among scientists as to whether these molecules could be used as valuable targets in AD treatment. The downside of the coin came early with the observation that quiescent microglia do not display phagocytic ability, being unable to clear Aß deposits since phagocytosis is crucial for Aß clearance efficacy. A possible solution for this issue could be found in the modulation of microglia status at baseline, which could help maintain both neuroprotective features and phagocytic ability at the same time. Among the molecules known to influence the baseline status of microglia, C-X3-chemokine Ligand 1 (CX3CL1), also known as Fractalkine (FKN), is one of the most investigated. FKN and its microglial receptor CX3CR1 are crucial players in the interplay between neurons and microglia, modulating the operation of some neural circuits and the efficacy and persistence of immune response against injury. In addition, CX3CL1 regulates synaptic pruning and plasticity in the developmental age and in adulthood, when it strongly impacts the hippocampus neurogenesis of the adult. CX3CL1 has an effect on Aß clearance and tau phosphorylation, as well as in microglia activation and priming. For all the above, CX3CL1/CX3CR1 signalling has been widely studied in relation to AD pathogenesis, and its biochemical pathway could hide molecular targets for novel treatment strategies in AD. This review summarizes the possible role of CX3CL1 in AD pathogenesis and its use as a potential target for AD treatment.

Biomarkers for Prognosis and Treatment Response in COVID-19 Patients.

During a severe infection such as coronavirus disease 2019 (COVID-19), the level of almost all analytes can change, presenting a correlation with disease severity and survival; however, a biomarker cannot be translated into clinical practice for treatment guidance until it is proven to have a significant impact. Several studies have documented the association between COVID-19 severity and circulating levels of C-reactive protein (CRP) and interleukin-6, and the accuracy of the CRP level in predicting treatment responses has been evaluated. Moreover, promising findings on prothrombin and D-dimer have been reported. However, the clinical usefulness of these biomarkers in COVID-19 is far from proven. The burst of data generation during this pandemic has led to the publication of numerous studies with several notable drawbacks, weakening the strength of their findings. We provide an overview of the key findings of studies on biomarkers for the prognosis and treatment response in COVID-19 patients. We also highlight the main drawbacks of these studies that have limited the clinical use of these biomarkers.

Clinical Utility of Midregional Proadrenomedullin in Patients with COVID-19.

OBJECTIVE: The aim of the study was to assess the role of midregional proadrenomedullin (MR-proADM) in patients with COVID-19. METHODS: We included 110 patients hospitalized for COVID-19. Biochemical biomarkers, including MR-proADM, were measured at admission. The association of plasma MR-proADM levels with COVID-19 severity, defined as a requirement for mechanical ventilation or in-hospital mortality, was evaluated. RESULTS: Patients showed increased levels of MR-proADM. In addition, MR-proADM was higher in patients who died during hospitalization than in patients who survived (median, 2.59 nmol/L; interquartile range, 2.3-2.95 vs median, 0.82 nmol/L; interquartile range, 0.57-1.03; P <.0001). Receiver operating characteristic curve analysis showed good accuracy of MR-proADM for predicting mortality. A MR-proADM value of 1.73 nmol/L was established as the best cutoff value, with 90% sensitivity and 95% specificity (P <.0001). CONCLUSION: We found that MR-proADM could represent a prognostic biomarker of COVID-19.

Presepsin and Midregional Proadrenomedullin in Pediatric Oncologic Patients with Febrile Neutropenia.

OBJECTIVE: In this study, we investigated the roles of presepsin (PSP) and midregional proadrenomedullin (mr-proADM) in children with febrile neutropenia (FN) due to chemotherapy. METHODS: We assessed 36 FN episodes in 26 children. Patients were classified into bacteremia (B) and fever of unknown origin (FUO) groups. We evaluated PSP and mr-proADM at admission (T0), after 24/48 h (T1), and after 5 days (T2). RESULTS: PSP and mr-proADM levels were elevated at T0 and significantly decreased at T2. mr-proADM levels did not significantly differ between the B and FUO groups. PSP levels significantly differed between the B and FUO groups only at T1. Both PSP and mr-proADM levels at T0 were a predictor of length of hospital stay but not of the duration of fever. Finally, receiver operating characteristic curve analysis showed that PSP and mr-proADM had low diagnostic accuracy for blood culture positivity. CONCLUSION: PSP and mr-proADM display poor clinical usefulness for FN in oncologic children.

Clinical Use of κ Free Light Chains Index as a Screening Test for Multiple Sclerosis.

OBJECTIVE: To assess the usefulness of the κ free light chain index (κFLCi) as a screening test to identify patients with suspected MS. METHODS: The study included 56 patients with a request to test for oligoclonal bands (OCBs). OCBs were detected by isoelectric focusing, followed by immunofixation. Cerebrospinal fluid (CSF) and serum κFLC were measured by a turbidimetric assay. Also, the κFLC index (κFLCi) was calculated. RESULTS: CSF κFLC levels and κFLCi were significantly higher in patients with multiple sclerosis (MS) than in patients with other neurological diseases (NDs; P < .001 and P < .001, respectively). At the cutoff value of 2.9, the κFLCi detected MS with sensitivity of 97% and specificity of 65%. Overall, 92% patients with κFLCi of 2.9 or greater and who had tested positive for OCBs were diagnosed as having MS. CONCLUSION: Our findings support the use of κFLCi as a screening test when MS is suspected, followed by OCB detection as a confirmatory test for the diagnosis of MS.

Vitamin K deficiency bleeding leading to the diagnosis of Crohn's disease.

We report the case of a 45 year old man who came to Emergency Room of Polyclinic for sudden onset of localized ecchymosis and widespread hematomas. He was subjected to blood count and first level investigations to assess coagulation. Based on the results, second level investigations were performed. Endoscopy of the gastrointestinal tract with histological examination revealed a diagnosis of Crohn's disease. Vitamin K deficiency causes the formation of vitamin K-dependent clotting factors that cannot perform their pro-coagulant action. Consequently, patients present with hemorrhagic manifestations. Clinical and laboratory features observed in this patient show that the deficiency of vitamin K-dependent coagulation factors may reveal a complex clinical condition such as an inflammatory bowel disease.

Carotid restenosis is associated with plasma ADMA concentrations in carotid endarterectomy patients.

BACKGROUND: The aim of this work has been to study the association between plasma asymmetric dimethylarginine (ADMA) concentrations and carotid stenosis in a group of 64 patients undergoing carotid endarterectomy (CEA). METHODS: Arginine, ADMA and symmetric dimethylarginine (SDMA) were measured using capillary electrophoresis with UV detection. An evaluation of plasma concentrations of total cysteine (tCys) and total homocysteine (tHcy) was also performed. RESULTS: Pearson's analysis show a positive correlation between ADMA and carotid stenosis (r=0.37, p=0.003), which is also confirmed after stepwise multiple linear regression analysis. ADMA plasma concentrations were significantly associated with tHcy (r=0.40, p=0.001) and to a lesser extent, even if not significantly, with tCys (r=0.23, p=0.07). CONCLUSIONS: Our data suggest that plasma ADMA is involved in carotid narrowing after CEA intervention. This suggests that this molecule may have an important role in the events that lead to stenosis.

C-reactive protein but not soluble CD40 ligand and homocysteine is associated to common atherosclerotic risk factors in a cohort of coronary artery disease patients.

OBJECTIVES: One third to one half of the variation in vascular disease occurrence remains unexplained by traditional risk factors. Since atherosclerosis may, in part, be an inflammatory disease, circulating factors related to inflammation may be predictors of cardiovascular disease. The aim of this study was to evaluate the association between common atherosclerotic risk factors and markers of inflammation. DESIGN AND METHODS: Serum levels of soluble CD40 (sCD40L), high-sensitive C-reactive protein (hs-CRP) and homocysteine (Hcy) were measured in 251 patients selected from a series of 438 subjects affected by previous myocardial infarction, angina or other cardiovascular diseases. RESULTS: sCD40L levels were lower in patients with previous myocardial infarction while no association was observed between sCD40L and Hcy levels and other risk factors. Only hs-CRP levels positively correlated with increased number of risk factors. CONCLUSION: In a setting of patients affected with coronary artery disease no association between sCD40L and homocysteine levels and atherosclerotic risk factors was observed; only hs-CRP showed increased levels according to the number of risk factors. Future studies using larger cohorts will be needed to validate the clinical use of markers of inflammation in the prediction of cardiovascular events.

Procalcitonin levels in plasma in oncohaematologic patients with and without bacterial infections.

BACKGROUND: The flogosis markers currently in use show both low sensitivity and specificity, particularly in neoplastic and degenerative diseases. Procalcitonin (PCT) is a pro-peptide of calcitonin produced mainly but not only in the C-cells of the thyroid glands and, as several studies show, PCT levels in plasma increase during infections. Bacterial infections are also the main cause of death in oncological patients. Furthermore, in patients with leukaemia in chemotherapy recovery, infections often induce relapses. The aim of the present study is to detect PCT levels in plasma in oncohaematologic patients with and without infections. METHODS: The study was carried out on 54 patients by a quantitative automated immunoassay. RESULTS: PCT plasma levels > or =0.5 ng were detected in 27 out of 30 patients (90,0%) with bacterial infections; 8 out of 9 patients (88,9%) with viral infections and in 12 out of 15 patients in the control group without statistically significant differences. CONCLUSIONS: The results, which differ from those in the literature, are discussed.