Nikolai P. Pace

The Role of TLR2, TLR4, and TLR9 in the Pathogenesis of Atherosclerosis

Toll-like receptors (TLRs) are key players in the pathogenesis of inflammatory conditions including coronary arterial disease (CAD). They are expressed by a variety of immune cells where they recognize pathogen-associated molecular patterns (PAMPs). TLRs recruit adaptor molecules, including myeloid differentiation primary response protein (MYD88) and TIRF-related adaptor protein (TRAM), to mediate activation of MAPKs and NF-kappa B pathways. They are associated with the development of CAD through various mechanisms. TLR4 is expressed in lipid-rich and atherosclerotic plaques. In TLR2−/− and TLR4−/− mice, atherosclerosis-associated inflammation was diminished. Moreover, TLR2 and TLR4 may induce expression of Wnt5a in advanced staged atheromatous plaque leading to activation of the inflammatory processes. TLR9 is activated by CpG motifs in nucleic acids and have been implicated in macrophage activation and the uptake of oxLDL from the circulation. Furthermore, TLR9 also stimulates interferon-α (INF-α) secretion and increases cytotoxic activity of CD4+ T-cells towards coronary artery tunica media smooth muscle cells. This review outlines the pathophysiological role of TLR2, TLR4, and TLR9 in atherosclerosis, focusing on evidence from animal models of the disease.

The role of testosterone in colorectal carcinoma: pathomechanisms and open questions

Colorectal cancer (CRC) is the fourth commonest type of malignancy after breast, lung and prostate in the USA and accounts for approximately 49,190 deaths annually in USA alone. The 5-year survival rate of CRC has increased over the past decades, in part, due to greater awareness and the widespread implementation of national screening programmes. Recently, a number of studies reported that males have a higher risk of developing CRC due to the action of testosterone.Testosterone is an androgen that is responsible for the development of male secondary sex characteristics and for spermatogenesis. Studies on rats with mutated Apc tumour-suppressor gene subjected to either ovariectomy or orchidectomy exhibit different risks of CRC. Female rats subjected to ovariectomy are at higher risk of CRC, whereas orchidectomised male rats exhibit a lower risk of developing CRC. Sex hormones, in particular estrogen and testosterone, play a significant role in the development of CRC since the anti-neoplastic effect of estrogen lost during ovariectomy increases the risk of females developing CRC. Male mice exposed to testosterone after orchidectomy were also at greater risk than those who were orchidectomised but administered placebo only. Moreover, the recently established role of membrane androgen receptors in regression of CRC via non-genomic androgen-dependent action sets these receptors apart from intracellular androgen receptors (iARs) which themselves promote CRC development. In addition, testosterone-albumin conjugates are selective to membrane androgen receptors (mARs) and lead to apoptosis via caspase-3 activation. Akt kinases promote invasion of colon cancer cells when phosphorylated. These kinases are dephosphorylated upon activation of mARs, thereby reducing colon cancer cell motility and invasiveness.Testosterone similarly plays important roles in human CRC. Long cytosine-adenine-guanine (CAG) repeats in the gene for the androgen receptors have been associated with a poor 5-year survival compared to shorter CAG repeats. Very recently, the measurement of serum unbound testosterone has been suggested as a novel biomarker along with carcinoembryonic antigen in CRC. In conclusion, testosterone may promote the development of CRC via a number of pathways, which may place males at greater risk. Testosterone holds promise as a potential biomarker in CRC risk prediction; however, further studies are required to better define its role in colorectal neoplasia.

Testosterone and Cardiovascular Disease

Cardiovascular disease [CVD] is a leading cause of mortality accounting for a global incidence of over 31%. Atherosclerosis is the primary pathophysiology underpinning most types of CVD. Historically, modifiable and non-modifiable risk factors were suggested to precipitate CVD. Recently, epidemiological studies have identified emerging risk factors including hypotestosteronaemia, which have been associated with CVD. Previously considered in the realms of reproductive biology, testosterone is now believed to play a critical role in the cardiovascular system in health and disease. The actions of testosterone as they relate to the cardiac vasculature and its implication in cardiovascular pathology is reviewed.

Prevalence of obesity in Malta

Obesity is a global epidemic with the Mediterranean island of Malta being no exception. The World Health Organization (WHO) has identified Malta as one of the European countries with the highest obesity prevalence.

The Microbial Hypothesis: Contributions of Adenovirus Infection and Metabolic Endotoxaemia to the Pathogenesis of Obesity

The global obesity epidemic, dubbed “globesity” by the World Health Organisation, is a pressing public health issue. The aetiology of obesity is multifactorial incorporating both genetic and environmental factors. Recently, epidemiological studies have observed an association between microbes and obesity. Obesity-promoting microbiome and resultant gut barrier disintegration have been implicated as key factors facilitating metabolic endotoxaemia. This is an influx of bacterial endotoxins into the systemic circulation, believed to underpin obesity pathogenesis. Adipocyte dysfunction and subsequent adipokine secretion characterised by low grade inflammation, were conventionally attributed to persistent hyperlipidaemia. They were thought of as pivotal in perpetuating obesity. It is now debated whether infection and endotoxaemia are also implicated in initiating and perpetuating low grade inflammation. The fact that obesity has a prevalence of over 600 million and serves as a risk factor for chronic diseases including cardiovascular disease and type 2 diabetes mellitus is testament to the importance of exploring the role of microbes in obesity pathobiology. It is on this basis that Massachusetts General Hospital is sponsoring the Faecal Microbiota Transplant for Obesity and Metabolism clinical trial, to study the impact of microbiome composition on weight. The association of microbes with obesity, namely, adenovirus infection and metabolic endotoxaemia, is reviewed.

Diabetes, pre-diabetes and their risk factors in Malta : a study profile of national cross-sectional prevalence study

Background Type 2 diabetes mellitus constitutes a global epidemic and a major burden on health care systems across the world. Prevention of this disease is essential, and the development of effective prevention strategies requires validated information on the disease burden and the risk factors. Embarking on a nationally representative cross-sectional study is challenging and costly. Few countries undertake this process regularly, if at all. Method This paper sets out the evidence-based protocol of a recent cross-sectional study that was conducted in Malta. Data collection took place from November 2014 to January 2016. Results This study presents up-to-date national data on diabetes and its risk factors (such as obesity, smoking, physical activity and alcohol intake) that will soon be publicly available. Conclusion This protocol was compiled so that the study can be replicated in other countries. The protocol contains step-by-step descriptions of the study design, including details on the population sampling, the permissions required and the validated measurement tools used.

Molecular cytogenetic characterisation of a novel de novo ring chromosome 6 involving a terminal 6p deletion and terminal 6q duplication in the different arms of the same chromosome

BackgroundRing chromosome 6 is a rare sporadic chromosomal abnormality, associated with extreme variability in clinical phenotypes. Most ring chromosomes are known to have deletions on one or both chromosomal arms. Here, we report an atypical and unique ring chromosome 6 involving both a distal deletion and a distal duplication on the different arms of the same chromosome.Case presentationIn a patient with intellectual disability, short stature, microcephaly, facial dysmorphology, congenital heart defects and renovascular disease, a ring chromosome 6 was characterised using array-CGH and dual-colour FISH. The de-novo ring chromosome 6 involved a 1.8 Mb terminal deletion in the distal short arm and a 2.5 Mb duplication in the distal long arm of the same chromosome 6. This results in monosomy for the region 6pter to 6p25.3 and trisomy for the region 6q27 to 6qter. Analysis of genes in these chromosomal regions suggests that haploinsufficiency for FOXC1 and GMDS genes accounts for the cardiac and neurodevelopmental phenotypes in the proband. The ring chromosome 6 reported here is atypical as it involves a unique duplication of the distal long arm. Furthermore, the presence of renovascular disease is also a unique feature identified in this patient.ConclusionTo the best of our knowledge, a comparable ring chromosome 6 involving both a distal deletion and duplication on different arms has not been previously reported. The renovascular disease identified in this patient may be a direct consequence of the described chromosome rearrangement or a late clinical presentation in r(6) cases. This clinical finding may further support the implicated role of FOXC1 gene in renal pathology.

The effect of age, gender, TG/HDL-C ratio and behavioral lifestyles on the metabolic syndrome in the high risk Mediterranean Island population of Malta

AIMS Metabolic syndrome (MetS) is a public health epidemic, typically with female predominance. The aim was to analyse the effect of gender and age on MetS and its components; analyse effects of lifestyle, diabetes mellitus and identify predictors for MetS including TG/HDL ratio, on a national level in a Mediterranean island. Findings will provide evidence-based data for neighboring countries to aid in combat of this epidemic. METHOD A cross-sectional survey was conducted in Malta (2014-2016) on a randomized adults population sample. Various components of MetS were measured along with lifestyle habits (smoking, alcohol and physical activity) and family history (cardiovascular and diabetes). Both descriptive and statistical analyses were performed. RESULTS A total of 80,788 Maltese adults estimated to suffer from MetS. Males were predominantly affected with significant difference from females. All MetS components were found to be significant predictors along with alcohol habits but not smoking. Neither physical inactivity nor family history of cardiovascular disease, showed any predictive ability for MetS even after adjustment. Elevated triglyceride levels exhibited highest predictive effect on MetS. TG/HDL ratio showed predictive ability in the Maltese population. CONCLUSIONS Males were at higher risk for MetS in Malta. A number of predictors were established but not sedentary lifestyle. TG/HDL ratio may provide to be a good indicator for development of MetS.

Case Report: Identification of an HNF1B p.Arg527Gln mutation in a Maltese patient with atypical early onset diabetes and diabetic nephropathy

BackgroundThe diagnosis of atypical non-autoimmune forms of diabetes mellitus, such as maturity onset diabetes of the young (MODY) presents several challenges, in view of the extensive clinical and genetic heterogeneity of the disease. In this report we describe a case of atypical non autoimmune diabetes associated with a damaging HNF1β mutation. This is distinguished by a number of uncharacteristic clinical features, including early-onset obesity, the absence of renal cysts and diabetic nephropathy. HNF1β-MODY (MODY5) is an uncommon form of monogenic diabetes that is often complicated by a wide array of congenital morphological anomalies of the urinary tract, including renal cysts. This report expands on the clinical phenotypes that have been described in the context of HNF1β mutations, and is relevant as only isolated cases of diabetic nephropathy in the setting of MODY5 have been reported.Case presentationAn obese Maltese female with non-autoimmune diabetes, microalbuminuria, glomerular hyperfiltration, fatty liver and no renal cysts was studied by whole exome sequencing to investigate potential genes responsible for the proband’s phenotype. A rare missense mutation at a highly conserved site in exon 8 of HNF1β was identified (c.1580G > A, NM_000458.3, p.Arg527Gln), with multiple in-silico predictions consistent with pathogenicity. This mutation has not been previously characterised. Additionally, several common susceptibility variants associated with early-onset obesity, polygenic type 2 diabetes and nephropathy were identified in the proband that could impose additional effects on the phenotype, its severity or its clinical course.ConclusionThis report highlights several atypical features in a proband with atypical diabetes associated with an HNF1β missense mutation. It also reinforces the concept that monogenic causes of diabetes could be significant contributors to disease burden in obese individuals with atypical diabetes.

The Effects of Socioeconomic Determinants on Hypertension in a Cardiometabolic At-Risk European Country

Background A relationship has been established between socioeconomic status and hypertension. The aim of this study was to determine the prevalence of hypertension and to explore the links between hypertension and socioeconomic factors in the adult population of Malta. Methods A national representative cross-sectional health examination study was performed between 2014 and 2016. Sociodemographic and medical history data was gathered by validated questionnaires while blood pressure was measured. Prevalence rates of known hypertension, newly hypertension, and global hypertension were calculated. Associations between sociodemographic characteristics and hypertension were identified through logistic regression models. Results Hypertension contributed to 30.12% (CI 95%: 28.71–31.57) of the study population, with a male preponderance. The majority was known hypertensive (73.59% CI 95%: 71.01–76.02), with only three-quarters on medication. Multivariant analyses showed that increasing age and body mass index, male gender, and living in Gozo, Western district, and Northern Harbour district were associated with having hypertension. Conclusion Hypertension is a problem in Malta especially in the male population and with increasing age and body mass index. Education did not exhibit any associated risk for having hypertension, which is inconsistent with the literature, while habitat localities played a role in hypertension development.