Kidney failure and associated uraemia have implications for the cardiovascular system, brain, and blood–brain barrier (BBB). We aim to examine BBB disruption, by assessing brain-derived neurotropic factor (BDNF), neuron-specific enolase (NSE) levels, and gut-blood barrier (GBB) disruption by trimethylamine N-oxide (TMAO), in chronic kidney disease (CKD) patients. Additionally, endothelial tight-junction protein expressions and modulation via TMAO were assessed. Serum from chronic kidney disease (CKD) female and male haemodialysis (HD) patients, and controls, were used to measure BDNF and NSE by enzyme-linked immunosorbent assays, and TMAO by mass spectrometry. Immunofluorescent staining of subcutaneous fat biopsies from kidney transplant recipients, and controls, were used to measure microvascular expression of tight-junction proteins (claudin-5, occludin, JAM-1), and control microvasculature for TMAO effects. HD patients versus controls, had significantly lower and higher serum levels of BDNF and NSE, respectively. In CKD biopsies versus controls, reduced expression of claudin-5, occludin, and JAM-1 were observed. Incubation with TMAO significantly decreased expression of all tight-junction proteins in the microvasculature. Uraemia affects BBB and GBB resulting in altered levels of circulating NSE, BDNF and TMAO, respectively, and it also reduces expression of tight-junction proteins that confer BBB maintenance. TMAO serves as a potential candidate to alter BBB integrity in CKD.

The pathophysiology of vascular disease is linked to accelerated biological aging and a combination of genetic, lifestyle, biological, and environmental risk factors. Within the scenario of uncontrolled artery wall aging processes, CKD (chronic kidney disease) stands out as a valid model for detailed structural, functional, and molecular studies of this process. The cardiorenal syndrome relates to the detrimental bidirectional interplay between the kidney and the cardiovascular system. In addition to established risk factors, this group of patients is subjected to a plethora of other emerging vascular risk factors, such as inflammation, oxidative stress, mitochondrial dysfunction, vitamin K deficiency, cellular senescence, somatic mutations, epigenetic modifications, and increased apoptosis. A better understanding of the molecular mechanisms through which the uremic milieu triggers and maintains early vascular aging processes, has provided important new clues on inflammatory pathways and emerging risk factors alike, and to the altered behavior of cells in the arterial wall. Advances in the understanding of the biology of uremic early vascular aging opens avenues to novel pharmacological and nutritional therapeutic interventions. Such strategies hold promise to improve future prevention and treatment of early vascular aging not only in CKD but also in the elderly general population.

Background Chronic kidney disease (CKD) is linked to an increased cardiovascular disease (CVD) burden. Albeit underappreciated, sex differences are evident in CKD with females being more prone to CKD development, but males progressing more rapidly to kidney failure (KF). Cardiovascular remodelling is a hallmark of CKD with increased arterial and valvular calcification contributing to CKD. However, little is known regarding sex differences in calcific cardiovascular remodelling in KF patients. Thus, we hypothesise that sex differences are present in coronary artery calcification (CAC) and aortic valve calcification (AVC) in patients with KF. Methods KF patients, males (n = 214) and females (n = 107), that had undergone computer tomography (CT) assessment for CAC and AVC were selected from three CKD cohorts. All patients underwent non-contrast multi-detector cardiac CT scanning, with CAC and AVC scoring based on the Agatston method. Baseline biochemical measurements were retrieved from cohort databases, including plasma analyses for inflammation markers (IL-6, TNF, hsCRP) and oxidative stress by skin autofluorescence measuring advanced glycation end-products (AGE), amongst other variables. Results Sex-disaggregated analyses revealed that CAC score was associated with age in both males and females (both p < 0.001). Age-adjusted analyses revealed that in males CAC was associated with diabetes mellitus (DM) (p = 0.018) and CVD (p = 0.011). Additionally, for females CAC associated with IL-6 (p = 0.005) and TNF (p = 0.004). In both females and males CAC associated with AGE (p = 0.042 and p = 0.05, respectively). CAC was associated with mortality for females (p = 0.015) independent of age. AVC in females was not reviewed due to low AVC-positive samples (n = 14). In males, in multivariable regression AVC was associated with age (p < 0.001) and inflammation, as measured by IL-6 (p = 0.010). Conclusions In female KF patients inflammatory burden and oxidative stress were associated with CAC. Whereas in male KF patients oxidative stress and inflammation were associated with CAC and AVC, respectively. Our findings suggest a sex-specific biomarker signature for cardiovascular calcification that may affect the development of cardiovascular complications in males and females with KF.

Background Sex differences are underappreciated in the current understanding of cardiovascular disease (CVD) in association with chronic kidney disease (CKD). A hallmark of CKD is vascular aging that is characterised, amongst others, by; systemic inflammation, microbiota disbalance, oxidative stress, and vascular calcification—features linked to atherosclerosis/arteriosclerosis development. Thus, it is the necessary to introduce novel biomarkers related to athero-/arteriosclerotic damage for better assessment of vascular ageing in patients CKD. However, little is known about the relationship between uraemia and novel CVD biomarkers, such as growth differentiation factor-15 (GDF-15), cartilage glycoprotein-39 (YKL-40) and matrix metalloproteinase-9 (MMP-9). Therefore, we hypothesise that there are sex-specific relationships between GDF-15, YKL-40, MMP-9 levels in end-stage kidney disease (ESKD) patients in relation to gut microbiota, vascular calcification, inflammation, comorbidities, and all-cause mortality. Methods ESKD patients, males (n = 151) and females (n = 79), not receiving renal replacement therapy were selected from two ongoing prospective ESKD cohorts. GDF-15, YKL-40 and MMP9 were analysed using enzyme-linked immunosorbent assay kits. Biomarker levels were analysed in the context of gut microbiota-derived trimethylamine N-oxide (TMAO), vascular calcification, inflammatory response, oxidative stress, comorbidities, and all-cause mortality. Results Increased GDF-15 correlated with higher TMAO in females only, and with higher coronary artery calcification and IL-6. In females, diabetes was associated with elevated GDF-15 and MMP-9, whilst males with diabetes only had elevated GDF-15. No associations were found between biomarkers and CVD comorbidity. Deceased males and females had higher GDF-15 concentrations (p = 0.01 and p < 0.001, respectively), meanwhile only YKL-40 was increased in deceased males (p = 0.02). Conclusions In conclusion, in males GDF-15 and YKL-40 were related to vascular calcification, inflammation, and oxidative stress, whilst in females GDF-15 was related to TMAO. Increased levels of YKL-40 and GDF-15 in males, and only GDF-15 in females, were associated with all-cause mortality. Our findings suggest that sex-specific associations of novel CVD biomarkers have a potential to affect development of cardiovascular complications in patients with ESKD.

Background Individuals with chronic kidney disease are affected by acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) due to multiple comorbidities and altered immune system. The first step of the infection process is the binding of SARS‐CoV‐2 with angiotensin‐converting enzyme 2 (ACE2) receptor, followed by its priming by transmembrane protease serine 2 (TMPRSS2). We hypothesized that circulating soluble ACE2 levels, as well as the expressions of ACE2 and TMPRSS2 in the microvasculature, are increased in patients with end‐stage kidney disease (ESKD). Methods A total of 210 participants were enrolled, representing 80 ESKD patients and 73 non‐CKD controls for soluble ACE2, and 31 ESKD and 26 non‐CKD controls for vasculature and fat tissue bioassays. We have assessed ACE2 expression in blood using ELISA and in tissue using immunofluorescence. Results Soluble ACE2 levels were higher in ESKD patients compared to controls; however, there is no sex difference observed. In ESKD and controls, soluble ACE2 positively correlated with Interleukin 6 (IL‐6) and C‐reactive protein (CRP), respectively. Similarly, ACE2 tissue expression in the vasculature was higher in ESKD patients; moreover, this higher ACE2 expression was observed only in male ESKD patients. In addition, TMPRSS2 expression was observed in vessels from males and females but showed no sex difference. The expression of ACE2 receptor was higher in ESKD patients on ACE‐inhibitor/angiotensin blocker treatment. Conclusion ESKD is associated with increased ACE2 levels in the circulation and pronounced in male vasculature; however, further studies are warranted to assess possible sex differences on specific treatment regime(s) for different comorbidities present in ESKD.

Kidney transplantation (KTx) is the preferred form of renal replacement therapy in chronic kidney disease (CKD) patients, owing to increased quality of life and reduced mortality when compared to chronic dialysis. Risk of cardiovascular disease is reduced after KTx; however, it is still a leading cause of death in this patient population. Thus, we aimed to investigate whether functional properties of the vasculature differed two years post-KTx (postKTx) compared to baseline (time of KTx). Using the EndoPAT device in 27 CKD patients undergoing living-donor KTx, we found that vessel stiffness significantly improved while endothelial function worsened postKTx vs. baseline. Furthermore, baseline serum indoxyl sulphate (IS), but not p-cresyl sulphate, was independently negatively associated with reactive hyperemia index, a marker of endothelial function, and independently positively associated with P-selectin postKTx. Finally, to better understand the functional effects of IS in vessels, we incubated human resistance arteries with IS overnight and performed wire myography experiments ex vivo. IS-incubated arteries showed reduced bradykinin-mediated endothelium-dependent relaxation compared to controls via reduced nitric oxide (NO) contribution. Endothelium-independent relaxation in response to NO donor sodium nitroprusside was similar between IS and control groups. Together, our data suggest that IS promotes worsened endothelial dysfunction postKTx, which may contribute to the sustained CVD risk.

Background and Aims Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to dramatic loss of lives due to COVID-19. Individuals with chronic conditions, including patients with kidney failure and/or kidney transplants, are affected more substantially due to multiple comorbidities and altered immune system. The first step of this infection process is the binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE-2) receptor, followed by its priming by transmembrane protease serine 2 (TMPRSS2). We hypothesized that the expressions of ACE-2 and TMPRSS2 are increased in microvasculature, in addition to increased circulating soluble ACE-2 levels in patients with end stage kidney disease (ESKD); i.e. prerequisites to explain to why ESKD patients are susceptible to SARS-CoV-2 infection. Therefore, we assessed if there is a difference in the expression of ACE-2 and TMPRSS2 receptors in the resistance artery and subcutaneous adipose tissue, alongside circulating soluble ACE-2 levels in ESKD patients versus controls. Method A total of 210 participants were enrolled, representing 80 ESKD and 73 healthy controls for soluble ACE-2 analysis, and 31 ESKD and 26 healthy controls for isolated subcutaneous vasculature bioassay. Immunofluorescence techniques were performed for the detection and evaluation of ACE-2 and TMPRSS2 in isolated subcutaneous resistance artery (200-300 µm of internal âCE€) and adipose tissue. Soluble ACE-2 protein concentration was detected using commercially available ELISA kits. Results Soluble ACE-2 levels were significantly higher in ESKD (3.8 ng/mL, IQR 2.4-5.5, n=80) vs control groups (2.7 ng/mL, IQR 2.1-3.7 ng/mL, n=73). There was no difference in soluble ACE-2 between females and males in either group. Soluble ACE-2 was positively correlated with IL-6 (rho=0.257, p=0.02, n=80), while it was negatively correlated with cholesterol (rho= -0.248, p=0.02, n=78) in ESKD patients. The expression of ACE-2 receptor was observed both on endothelium and vascular smooth muscle cells (VSMCs) in arteries from both groups. The expression was higher in ESKD patients (19.1%, n=23) vs controls (15.4%, n=15). Patients with ESKD on ACE-inhibitor/angiotensin receptor blocker treatment showed higher expression of ACE-2 vs. non-treatment group (treatment: 20.2%, n=12 vs non-treatment: 12.8%, n=11) in resistance artery. In subcutaneous adipose tissue the ACE-2 staining was not statistically different among the groups (ESKD: 2.9%, n=10 vs controls: 3.6%, n=10). In addition, TMPRSS2 was expressed both on endothelium and VSMCs in resistance artery, however there was no difference in the expression (ESKD: 8.4%, n=23 vs controls: 10.2%, n=15) between the groups. Conclusion Soluble ACE-2 levels and ACE-2 receptor expression in the vasculature were higher in patients with ESKD as compared to controls. The ACE-2 receptor is present both in the endothelium and VSMCs from arteries in peripheral microcirculation. This supports the suggestion that the uremic milieu induces an optimal environment for SARS-CoV-2 entrance in microcirculation with following consequence on the vasculature during the COVID-19. Similarly, TMPRSS2 expression was observed in vessels from both groups, while increased expression of ACE-2 receptor was observed in those ESKD patients receiving ACE-inhibitor/angiotensin receptor blocker treatment. Further studies are warranted to assess possible sex differences in the target receptor expressions with further elaboration on specific treatment regime(s) for different comorbidities present in patients with ESKD.

Cardio-pulmonary diseases, which were once regarded as a man's illness, have been one of the leading causes of morbidity and mortality for both men and women in many countries in recent years. Both gender and sex influence the functional and structural changes in the human body and therefore play an important role in disease clinical manifestation, treatment choice, and/or response to treatment and prognosis of health outcomes. The gender dimension integrates sex and gender analysis in health sciences and medical research, however, it is still relatively overlooked suggesting the need for empowerment in the medical research community. Latest advances in the field of cardiovascular research have provided supportive evidence that the application of biological variables of sex has led to the understanding that heart disease in females may have different pathophysiology compared to males, particularly in younger adults. It has also resulted in new diagnostic techniques and a better understanding of symptomatology, while gender analysis has informed more appropriate risk stratification and prevention strategies. The existing knowledge in the pulmonary field shows the higher prevalence of pulmonary disorders among females, however, the role of gender as a socio-cultural construct has yet to be explored for the implementation of targeted interventions. The purpose of this review is to introduce the concept of gender dimension and its importance for the cardiopulmonary continuum with a focus on shared pathophysiology and disease presentation in addition to interrelation with chronic kidney disease. The review presents basic knowledge of what gender dimension means, and the application of sex and gender aspects in cardiovascular medicine with a specific focus on early pulmonary development, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). Early vascular aging and inflammation have been presented as a potential pathophysiological link, with further interactions between the cardiopulmonary continuum and chronic kidney disease. Finally, implications for potential future research have been provided to increase the impact of gender dimension on research excellence that would add value to everybody, foster toward precision medicine and ultimately improve human health.