Skeletal muscle overexpression of sAnk1.5 in transgenic mice does not predispose to type 2 diabetes

Genome-wide association studies (GWAS) and cis-expression quantitative trait locus (cis-eQTL) analyses indicated an association of the rs508419 single nucleotide polymorphism (SNP) with type 2 diabetes (T2D). rs508419 is localized in the muscle-specific internal promoter (P2) of the ANK1 gene, which drives the expression of the sAnk1.5 isoform. Functional studies showed that the rs508419 C/C variant results in increased transcriptional activity of the P2 promoter, leading to higher levels of sAnk1.5 mRNA and protein in skeletal muscle biopsies of individuals carrying the C/C genotype. To investigate whether sAnk1.5 overexpression in skeletal muscle might predispose to T2D development, we generated transgenic mice (TgsAnk1.5/+) in which the sAnk1.5 coding sequence was selectively overexpressed in skeletal muscle tissue. TgsAnk1.5/+ mice expressed up to 50% as much sAnk1.5 protein as wild-type (WT) muscles, mirroring the difference reported between individuals with the C/C or T/T genotype at rs508419. However, fasting glucose levels, glucose tolerance, insulin levels and insulin response in TgsAnk1.5/+ mice did not differ from those of age-matched WT mice monitored over a 12-month period. Even when fed a high-fat diet, TgsAnk1.5/+ mice only presented increased caloric intake, but glucose disposal, insulin tolerance and weight gain were comparable to those of WT mice fed a similar diet. Altogether, these data indicate that sAnk1.5 overexpression in skeletal muscle does not predispose mice to T2D susceptibility.

Evidence for hydrogen-sulfide as a novel modulator of Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels in human atrial cardiomyocytes

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): M.I.U.R. PRIN 2017

Evidence for hydrogen-sulfide as a novel modulator of Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels in human atrial cardiomyocytes

Background

Hydrogen sulfide (H2S) is an endogenous gasotransmitter that controls several physiological and pathological processes in mammalian organs. H2S is synthesized by endogenous enzymes and directly regulates the function of target proteins by sulfhydration of cysteine residues and/or indirect effects mediated by modification of intracellular cyclic nucleotide (cAMP/cGMP) levels. In the cardiovascular system, H2S activates protective responses aimed to counterbalance pathological processes, such as those involved in glucose dysmetabolism, vasal constriction, oxidative stress and cytotoxicity. In cardiac cells, H2S regulates electrogenesis through the modulation of different ion channels, comprising potassium, calcium and TRP channels. No information is available on the effects of H2S on the funny current (If), which is involved in cardiac pacemaking and working myocyte electrogenesis.

Purpose

The aim of this study was to assess whether H2S modulates the properties of If in human atrial myocytes. If is mediated by Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels, which are expressed in human atria and are directly regulated by intracellular cAMP/cGMP levels.

Methods

Human atrial cardiomyocytes were isolated by enzymatic and mechanical digestion from atrial specimens of patients undergoing cardiac surgery. The acute effects of H2S on If were tested by single-cell patch-clamp recordings using increasing concentrations of NaHS as H2S donor.

Results

High NaHS concentrations increased If conductance at all potential tested. At physiological potential (-80 mV), relative If conductance changed from 0.33±0.08 to 0.45±0.11 and 0.60±0.11 at 10 and 100 µM concentrations, respectively (p<0.05, n=5-7), while half-maximal activation potential (V½) was shifted from -92.4±0.9 to -83.9±0.7 and -82.4±0.4 mV, respectively (p<0.05, n=5-7). Conversely, low NaHS concentrations reduced If conductance that at -80 mV changed to 0.23±0.07 and 0.25±0.06 at 1 and 5 µM concentrations, respectively (p<0.05, n=5-7). Accordingly, at low NaHS concentration If V½ showed a trend toward less positive potentials. Both high and low concentrations did not modify If kinetics.

Conclusions

H2S exerts a dual, concentration-dependent effect on If expressed in human atrial cardiomyocytes. This response is similar to that induced by NO, a different gas signaling molecule. The effect of H2S on If properties may be caused by direct S-sulfhydration of HCN proteins and/or to modifications of intracellular cAMP/cGMP levels resulting from phosphodiesterase inhibition by H2S. These findings may open novel perspectives to modulate If function and dysfunction in cardiac pacemaker cells and working myocytes.

A combined molecular and electrophysiological approach to understand the effect of interleukin 6 in cardiac myocytes

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): M.I.U.R. PRIN 2017

Background and purpose

Increased inflammatory cytokines, including interleukin 6 (IL-6), are associated to enhanced arrhythmogenic risk, including atrial fibrillation [1]. Moreover, direct effects of cytokines on ion channels are emerging as important mediators of arrhythmogenic remodeling [2]. In line with this, enhanced arrhythmogenesis in COVID-19 patients is hypothesized to be driven by cytokine storms, a well demonstrated condition in this setting [3]. To dissect the underlying mechanisms explaining such an association, we evaluated the proarrhythmogenic alterations of IL-6, assessing the impact on the expression of Hyperpolarization-activated cyclic nucleotide–gated (HCN) channels, of the regulatory subunits MiRP1, and on the action potential (AP) profile in HL-1 cardiomyocytes (CMs). In human left atrial samples we studied the relation occurring between the expression levels of IL-6 and of HCN channels. In human induced pluripotent stem cell (hiPSC)-derived CMs we evaluated the acute effects of IL-6 on pacemaker activity.

Methods

HL-1 CMs exposed to 50 ng/ml IL-6 or vehicle were collected after 0, 0.5, 6, 12, 24 and 48 h to study intracellular signaling, ion channel expression and AP profile. The latter was assessed through a high-throughput system allowing optical detection of APs with optical stimulation. In human atrial samples obtained from patients undergoing surgery, IL-6 and HCN mRNA expression were analyzed by quantitative RT-PCR. The acute effects on pacemaker activity were evaluated in hiPSC-derived CMs exposed to increasing concentrations of IL-6.

Results

In HL1 CMs IL-6 rapidly induces STAT3 phosphorylation, demonstrating the activation of IL-6 signaling cascade. IL-6 modifies HCN channel transcript and proteins at different time points, evidencing a significant downregulation of HCN4 isoform and significant upregulations of HCN1, HCN2 and MiRP1. In line with this, in human left atrial samples, expression levels of IL-6 were linearly and directly related to HCN1 channel, while they were linearly and inversely related to HCN4. Electrophysiological recordings on HL-1 CMs showed a decreasing trend of AP amplitude and of maximum diastolic potential, while AP durations tended to increase. In hiPSC-derived CMs IL-6 reduces the frequency of AP in a concentration-dependent manner.

Conclusions

Our data demonstrate that in HL-1 CMs IL-6 activates a STAT3 dependent intracellular signaling that is associated to subsequent variation of HCN channel expression and a concurrent alteration of AP profile. The relation between IL-6 and HCN1,4 expression in human samples suggests a mechanistic link between IL-6 levels and ionic channel targets, including HCN channels. The reduction of AP frequency in hiPSC-derived CMs suggests a direct interaction with ion channels. We hypothesize that these modifications may lay the basis to enhance the propensity of atria to develop arrhythmias in condition of elevate IL-6 levels.

Blockers of Hyperpolarization-activated Cyclic Nucleotide-gated channels exhibit antimuscarinic properties in human atrial cardiomyocytes

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): M.I.U.R. PRIN 2017 to E.C and ECRF to L.S.

Introduction

Ivabradine (Iva), Zatebradine (Zat) and ZD7288 (ZD) are blockers of Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels, which play definite electrophysiological functions in cardiac pacemakers, working cardiomyocytes, peripheral and central neurons [1]. Among them, Iva is in clinical use as bradycardic agent for uncontrolled angina and heart failure with reduced ejection fraction. Accumulating evidence suggests Iva may have a more complex pharmacological profile, including targets different from HCN channels [2, 3]. Reports on experimental atrial fibrillation, detrusor contraction and bladder overactivity [4] led us to hypothesize that muscarinic receptors (mAChRs) may represent still unexplored targets of Iva and analogues. Present study was designed to identify the effect of Iva on acetylcholine-gated inward-rectifier K+-current (IKACh), the main effector of atrial mAChRs, and to assess whether Iva and analogues interact directly with human atrial and recombinant mAChRs.

Methods

Patch-clamp recordings were performed on human atrial myocytes (hAMs) isolated from atrial appendages of patients in sinus rhythm. Competition and kinetic radioligand binding assays were performed on hAM preparations and on mAChR(1,2,3) expressed in heterologous systems.

Results

Patch-clamp recordings on hAMs demonstrated Iva is able to suppress IKAch similarly to atropine, thus suggesting a functional antagonism of Iva on atrial mAChRs.  Competition binding assays on hAM membranes revealed Iva, Zat and ZD bind to mAChRs with affinity values close to those of muscarinic ligands carbachol (Cch) and gallamine (Gal). Competition binding assays on recombinant mAChR(1,2,3), which are functionally relevant in hAMs, showed all blockers are ligands for each single mAChR type with affinity values close to those of CCh and Gal. Finally, using dissociation binding assays on mAChR(2) lacking the allosteric binding site, we showed Iva and Zat behave as allosteric ligands with affinity values similar to Gal. Doking studies confirmed Iva and Zat, but not ZD, have the structural requirements necessary to interact with the allosteric and the orthosteric site of mAChR(2).

Conclusions

This study demonstrates Iva directly interacts with mAChR expressed in hAMs, showing antimuscarinic activity on IKAch. This property is likely dependent on a double interaction of Iva with the orthosteric and the allosteric site of mAChR(2). Zat, but not ZD, shows similar binding properties compared to Iva. Our results identify a novel pharmacological target for Iva and analogues in human atria, which may have important consequences for the function of the healthy and diseased atrium.

Selective HCN1 block as a strategy to control oxaliplatin-induced neuropathy

Chemotherapy-Induced Peripheral Neuropathy (CIPN) is the most frequent adverse effect of pharmacological cancer treatments. The occurrence of neuropathy prevents the administration of fully-effective drug regimen, affects negatively the quality of life of patients, and may lead to therapy discontinuation. CIPN is currently treated with anticonvulsants, antidepressants, opioids and non-opioid analgesics, all of which are flawed by insufficient anti-hyperalgesic efficacy or addictive potential. Understandably, developing new drugs targeting CIPN-specific pathogenic mechanisms would dramatically improve efficacy and tolerability of anti-neuropathic therapies. Neuropathies are associated to aberrant excitability of DRG neurons due to the alteration in the expression or function of a variety of ion channels. In this regard, Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels are overexpressed in inflammatory and neuropathic pain states, and HCN blockers have been shown to reduce neuronal excitability and to ameliorate painful states in animal models. However, HCN channels are critical in cardiac action potential, and HCN blockers used so far in pre-clinical models do not discriminate between cardiac and non-cardiac HCN isoforms. In this work, we show an HCN current gain of function in DRG neurons from oxaliplatin-treated rats. Biochemically, we observed a downregulation of HCN2 expression and an upregulation of the HCN regulatory beta-subunit MirP1. Finally, we report the efficacy of the selective HCN1 inhibitor MEL57A in reducing hyperalgesia and allodynia in oxaliplatin-treated rats without cardiac effects. In conclusion, this study strengthens the evidence for a disease-specific role of HCN1 in CIPN, and proposes HCN1-selective inhibitors as new-generation pain medications with the desired efficacy and safety profile.

Neuropsychiatric effects and type of IFN-alpha in chronic hepatitis C

Chronic hepatitis is often associated with neuropsychiatric disorders. Interferon (IFN) is the drug most widely used to treat this disease, and its side effects, such as depression, often involve the central nervous system (CNS). Symptoms include a slowing down of psychomotor functions, loss of interest, frontal lobe dysfunction, parkinsonism, and delirium. The occurrence of these complications calls for dropping out of IFN treatment or for a significant dose reduction and administration of antidepressants. Efficacy and side effects vary on the basis of the IFN type employed. The aim of our study was to evaluate if the frequency, form, and degree of depression induced are related to the type of IFN employed. We studied 96 patients with chronic hepatitis C. Our study series was divided into four groups according to the type of IFN-alpha administered. Depression degree was clinically evaluated using the Hamilton Depression Rating Scale (HAM-D). All patients were tested before treatment and 1, 3, and 6 months (15 days after the end of treatment) later. Our results showed that the type of IFN used seemed to influence the depression onset rate, with the leukocyte type inducing the lowest level of depression. However, when a number of symptoms associated with the depression were considered, the results of other types of IFN-alpha were found to be better. Use of the most suitable type of IFN-alpha could thus lead to more personalized treatment, with fewer side effects. The type of IFN used seems to influence the psychological side effects and the adaptation rate to therapy. It would be appropriate to choose the type of IFN on the basis of a neuropsychiatric assessment carried out before treatment.

Increase of serum beta2-microglobulin in patients affected by HCV correlated hepatocellular carcinoma

OBJECTIVE

HLA antigens influence tumour growth and spreading, but the mechanism is still unclear. Increased serum levels of beta2-microglobulin (beta2MG) have been found in several chronic inflammatory and tumour diseases. The aim of the present study was to analyse the relationship between serum beta2MG levels and some markers of tumour progression, to verify the reliability of this parameter as a marker of hepatocellular carcinoma (HCC) progression.

DESIGN

We studied 50 patients with hepatitis C virus (HCV) correlated HCC, 50 patients affected by chronic hepatitis C and 20 healthy controls. We performed a statistical analysis on the data obtained from haematological withdrawals in patients and healthy subjects.

METHODS

Serum beta2MG levels were determined by an immunoturbidimetric method (normal values range from 0.8 to 27 microg/ml). Diagnosis of HCC was performed on the basis of haematochemical parameters (alpha-fetoprotein) and instrumental examinations (ultrasonography and computed tomography). In order to perform the statistical analysis we used the Wilcoxon non-parametric rank test and the Spearman log-rank correlation test

RESULTS

Patients with HCC showed higher serum beta2MG levels than did chronic hepatitis C patients (36+/-16.5 microg/ ml versus 2.3+/-0.8 microg/ml; P<0.0001) or healthy subjects (36+/-16.5 microg/ml versus 1.6+/-0.4 microg/ml; P<0.0001). We found a positive correlation between beta2MG and interleukin-6 (IL-6) (r = +0.3; P = 0.05), beta2MG and alpha-fetoprotein (r = +0.4; P = 0.005), beta2MG and tumour size (r = +0.3; P = 0.02).

CONCLUSIONS

An increase in the beta2MG serum level reflects the tumour size and seems to be a consequence of the stimulation on hepatocytes by humoral components of immunological response, such as IL-6. Weakening of the immune system, due to IL-6, may be responsible for a more severe progression of HCC and the hyperexpression of beta2MG.

The comorbidities of elderly oncologic patients

The scope of this study was to evaluate the prevalence of comorbidity in elderly subjects with neoplastic diseases, and to compare it to those without tumor pathologies. Three groups of patients have been considered: (A)35 elderly oncological patients; (B)38 young/adult oncological patients; (C)25 elderly patients without oncological pathology. After clinical evaluation and pathohistological diagnostic analysis, the concomitant pathologies have been estimated by means of two methods: (i)the Satariano's score; and (ii)the Charlson Comorbidity Index (CCI). Statistical analyses performed by using the Chi-square and the Student's t-test gave coherent results, and revealed that the prevalence of comorbidities was the highest in Group C, and displayed significantly reduced prevalences in the sequence Group B, Group A.

Extralymphonodal Castleman's disease. A case report

Castleman's disease is a rare lymph node pathology characterized by angiofollicular hyperplasia. There are two forms of the disease: localized and systemic, with different features, symptoms and prognosis. Three are the histological types of disease: plasma cell, hyaline-vascular and mixed variants. We report the case of a 65-year-old female affected by localized plasma cell variant of Castleman's disease. The singularity of our case lies in its localization on the breast and monoclonal plasma cell proliferation inside the nodule.

Decrease of interferon gamma serum levels in patients with chronic hepatitis C

Cytokines can play a crucial role in defending the organism from viral infections. One of these, interferon gamma (IFN-gamma), possesses marked immunomodulating activity. As cell immunity seems to be involved in chronic hepatitis C virus (HCV), study of the events regulated by IFN-gamma may be useful in evaluating the host's immunological response. We studied 63 patients (36 males, 27 females) affected by chronic HCV and 28 (14 males, 14 females) healthy controls. IFN-gamma concentrations were significantly lower in the former, and were positively correlated with the histological activity index, suggesting that low IFN-gamma values play a part in determining chronicity. We believe they may be an unfavorable factor and may be useful in detecting patients who are not capable of eradicating the virus.

Serum interleukin 6 concentrations in chronic hepatitis C patients before and after interferon-alpha treatment

IFN-alpha represents the treatment of choice in chronic hepatitis C. It acts directly on the cells infected by the virus and indirectly via the cytokine network. We studied the behavior of interleukin 6 (IL-6), a cytokine that is particularly active in the liver and considered an index of liver inflammation and necrosis, in order to evaluate the relationships between IFN-alpha administration and serum levels of this cytokine. Our study series was composed of 60 patients (32 males, 28 females, mean age 53.03 +/- 12.7 years) affected by chronic hepatitis C and 24 healthy controls (14 males, 13 females, mean age 45.8 +/- 5.9 years). We determined serum IL-6 concentrations before and after 3,000,000 IU of IFN-alpha t.i.w./6 months in the former and compared them with levels observed in the controls. Pre- and post-treatment serum IL-6 levels were higher in chronic hepatitis patients and correlated with HAI score and HCV RNA prior to treatment. Diversely, this correlation was less significant after completion of the treatment. Furthermore, IL-6 concentrations depended on the type of response to treatment, i.e. they decreased in complete responders, while increased in partial and non-responders. Our data indicate that IL-6 concentrations, before treatment, are expression of viral-induced inflammation and that, after treatment, may be increased by the action of IFN-alpha treatment.

[Malignant anorectal melanoma: description of a clinical case and review of the literature]

Malignant ano-rectal melanoma is a rare pathology without characteristic symptoms. It is more frequent in females than in males (ratio 2:1) and represents 3-15% of anal canal tumours. A case of a woman who recently came to us complaining of painful defecation, tenesmus and rectal bleeding induced us to reconsider the diagnostic and therapeutic implications in ano-rectal melanoma. The low incidence of cases reported and the negative 5-year prognosis are due to late, often incidental, diagnosis during clinical observation for hemorrhoids, rectal polyps or rhagades, together with the aspecificity of the tumour symptoms. We hope our case report emphasizes the importance of conducting early diagnosis in patients at risk of ano-rectal melanoma.

Elevation of interleukin 6 levels in patients with chronic hepatitis due to hepatitis C virus

Interleukin 6 (IL-6) is a pleiotropic cytokine produced by a wide variety of lymphoid and non-lymphoid tissues. We studied the relationship between IL-6 and the liver in an attempt to elucidate this cytokine's role in hepatitis C-induced liver inflammation. We investigated the behavior of serum IL-6 in 25 patients with chronic hepatitis C (divided into three groups depending on severity) and in 27 healthy controls. Our results showed a significant elevation (P < 0.0001) in serum IL-6 levels in the patients with chronic hepatitis C, correlated with the histological activity index (HAI) and their HCV-RNA serum levels. This rise may represent the expression of the hepatitis C virus-induced inflammatory state.

[Erythropoietin in hepatocellular carcinoma]

Hemopoietic alterations may occur during tumoral diseases, determining anemia. In most cases, serum EPO levels were lower than normal values. Hepatocellular carcinoma (HCC), one of the most frequent malignancies world-wide, is often characterized by mild anemia and increased serum EPO levels. We studied 30 HCC patients and 20 healthy subjects. We found that HCC patients presented higher serum EPO levels than healthy controls. In HCC patients, there was a significant inverse correlation between serum EPO levels and red blood cell count or hemoglobin levels. We postulated that the elevated serum EPO levels observed in these patients may be due to reduced hepatic clearance of EPO, and to the influence of cytokine-mediated inflammatory factors.

Interleukin-6 in hepatitis C cirrhosis

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in numerous diseases but the correlation between liver fibrosis and IL-6 role is not clear. We studied IL-6 levels in 50 HCVAb+ patients with liver cirrhosis (grouped into A, B and C, Child classes) and in 27 healthy control subjects. IL-6 serum levels were significantly increased in the former (p < 0.005) suggesting that IL-6 stimulates and sustains liver fibrosis. In cirrhotic subjects, the rise in IL-6 serum levels is due to impaired hepatic clearance of this cytokine, while its production remains steady.

[Role of interleukin 6 in hepatocellular carcinoma]

Interleukin 6 (IL-6) is a pleiotropic cytokine which possesses a broad spectrum of action in diverse pathological conditions. It is mainly produced and metabolised in the liver where it carries out one of its best known actions in the mediation of the acute phase response. We studied its behaviour in hepatocellular carcinoma to evaluate its clinical prognostic role. We determined serum IL-6 concentrations in 39 patients with hepatocarcinoma (27 males and 12 females) and 25 healthy controls (15 males and ten females). Our results showed a significant increase in serum IL-6 concentrations in hepatocarcinoma subjects compared with controls (P < 0.005) and an elevated positive correlation (r = 0.616) between IL-6 and size of the hepatocarcinoma. Our study demonstrated that IL-6 is able to influence hepatocarcinoma progression by acting as an autocrine tumoral growth factor and depleting immune surveillance.

[Immunologic diseases and hepatitis C virus]

Active chronic hepatitis may be associated with various immunologic diseases. In the Mediterranean area and to a lesser extent elsewhere, hepatitis C virus, has often been detected in patients affected by mixed cryoglobulinemia, membranoproliferative glomerulonephritis, polyarteritis nodosa autoimmune type 2b hepatitis, Hashimoto's disease, Sjögren's syndrome and lichen ruber planus. These findings should not be considered fortuitous due to the elevated prevalence of autoantibodies and immunologic abnormalities observed in hepatitis C patients compared with subjects presenting other liver diseases. The pathogenetic evaluation of the association between these immunologic diseases and chronic hepatitis C has led us to suggest that diverse virus C and host induced factors may play a fundamental role in determining these immunologic diseases.