Post-translational modifications (PTMs) of proteins and peptides have recently gained much attention, as they are involved in the pathogenesis of cardiovascular disease and eventually also play a role in the progression of chronic kidney disease (CKD). In this review, we provide an overview of post-translational protein modifications such as carbamylation, glycation and oxidation, starting with their definitions, mechanisms and clinical relevance in the setting of CKD and cardiovascular disease. The methods currently used for the identification and, in particular, quantification of PTMs are described and potential treatment options in the context of PTMs are reviewed. We foresee that advancements in mass spectrometry-based methods leading to the identification of novel disease markers and/or pathophysiologically relevant factors will certainly boost the clinical utility in sample analyses.

Chronic kidney disease (CKD), diabetes mellitus (DM), and cardiovascular diseases (CVD) are complex disorders of partly unknown genesis and mostly known progression factors. CVD and DM are the risk factors of CKD and are strongly intertwined since DM can lead to both CKD and/or CVD, and CVD can lead to kidney disease. In recent years, our knowledge of CKD, DM, and CVD has been expanded and several important experimental, clinical, and epidemiological associations have been reported. The tight cellular and molecular interactions between the renal, diabetic, and cardiovascular systems in acute or chronic disease settings are becoming increasingly evident. However, the (patho-) physiological basis of the interactions of CKD, DM, and CVD with involvement of multiple endogenous and environmental factors is highly complex and our knowledge is still at its infancy. Not only single pathways and mediators of progression of these diseases have to be considered in these processes but also the mutual interactions of these factors are essential. The recent advances in proteomics and integrative analysis technologies have allowed rapid progress in analyzing complex disorders and clearly show the opportunity for new efficient and specific therapies. More than a dozen pathways have been identified so far, including hyperactivity of the renin–angiotensin (RAS)–aldosterone system, osmotic sodium retention, endothelial dysfunction, dyslipidemia, RAS/RAF/extracellular-signal-regulated kinase pathway, modification of the purinergic system, phosphatidylinositol 3-kinase (PI 3-kinase)-dependent signaling pathways, and inflammation, all leading to histomorphological alterations of the kidney and vessels of diabetic and non-diabetic patients. Since a better understanding of the common cellular and molecular mechanisms of these diseases may be a key to successful identification of new therapeutic targets, we review in this paper the current literature about cellular and molecular mechanisms of CKD.

We used a mass spectrometry-based method for the characterization of post-translational modification and demonstrated the pathophysiological impact of a representative post-translational modification of plasma albumin. The data described in this study may help to elucidate the pathophysiological role of protein modifications.

Protein-bound uremic retention solutes accumulate in patients suffering from chronic kidney disease, and the removal of these solutes by hemodialysis is hampered. Therefore, we developed a dialysis technique where the protein-bound uremic retention solutes are removed more efficiently under high ionic strength. Protein-bound uremic solutes such as phenylacetic acid, indoxyl sulfate, and p-cresyl sulfate were combined with plasma in the presence of increased ionic strength. The protein integrity of proteins and enzymatic activities were analyzed. In vitro dialysis of albumin solution was performed to investigate the clearance of the bound uremic retention solutes. In vitro hemodiafiltrations of human blood were performed to investigate the influence of increased ionic strength on blood cell survival. The protein-bound fraction of phenylacetic acid, indoxyl sulfate, and p-cresyl sulfate was significantly decreased from 59.4% ± 3.4%, 95.7% ± 0.6%, 96.9% ± 1.5% to 36.4% ± 3.7%, 87.8% ± 0.6%, and 90.8% ± 1.3%, respectively. The percentage of phenylacetic acid, indoxyl sulfate, and p-cresyl sulfate released from protein was 23.0% ± 5.7%, 7.9% ± 1.1%, and 6.1% ± 0.2%, respectively. The clearance during in vitro dialysis was increased by 13.1% ± 3.6%, 68.8% ± 15.1%, and 53.6% ± 10.2%, respectively. There was no difference in NaCl concentrations at the outlet of the dialyzer using isotonic and hypertonic solutions. In conclusion, this study forms the basis for establishing a novel therapeutic approach to remove protein-bound retention solutes.

In patients with chronic kidney disease (CKD), adequate renal clearance is compromised, resulting in the accumulation of a plethora of uremic solutes. These uremic retention solutes, also named uremic toxins, are a heterogeneous group of organic compounds with intrinsic biological activities, many of which are too large to be filtered and/or are protein bound. The renal excretion of protein-bound toxins depends largely on active tubular secretion, which shifts the binding and allows for active secretion of the free fraction. To facilitate this process, renal proximal tubule cells are equipped with a range of transporters that co-operate in basolateral uptake and luminal excretion. Many of these transporters have been characterized as mediators of drug disposition, but have recently been recognized for their importance in the proximal renal tubular transport of uremic toxins as well. This also indicates that during uremia, drug disposition may be severely affected as a result of drug-uremic toxin interaction. In addition, CKD patients receive various drugs to treat their complications potentially resulting in drug-drug interactions (DDIs), also for drugs that are non-renally excreted. This review discusses the current knowledge on formation, disposition and removal of protein-bound uremic toxins. Furthermore, implications associated with drug treatment in kidney failure, as well as innovative renal replacement therapies targetting the protein-bound uremic toxins are being discussed. It will become clear that the complex problems associated with uremia warrant a transdisciplinary approach that unites research experts in the area of fundamental biomedical research with their colleagues in clinical nephrology.

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease associated with unremitting fibroblast activation including fibroblast-to-myofibroblast transformation (FMT), migration, resistance to apoptotic clearance, and excessive deposition of extracellular matrix (ECM) proteins in the distal lung parenchyma. Aberrant activation of lung-developmental pathways is associated with severe fibrotic lung disease; however, the mechanisms through which these pathways activate fibroblasts in IPF remain unclear.Sox9 is a member of the HMG box family of DNA-binding transcription factors that are selectively expressed by epithelial cell progenitors to modulate branching morphogenesis during lung development. We demonstrate that Sox9 is upregulated via MAPK/PI3Kdependent signaling and by the transcription factor Wilms' tumor 1 in distal lung-resident fibroblasts in IPF. Mechanistically, using fibroblast activation assays, we demonstrate that Sox9 functions as a positive regulator of FMT, migration, survival, and ECM production. Importantly, our in vivo studies demonstrate that fibroblast-specific deletion of Sox9 is sufficient to attenuate collagen deposition and improve lung function during TGFαinduced pulmonary fibrosis. Using a mouse model of bleomycin-induced pulmonary fibrosis, we show that myofibroblast-specific Sox9 overexpression augments fibroblast activation and pulmonary fibrosis. Thus, Sox9 functions as a profibrotic transcription factor in activating fibroblasts, illustrating the potential utility of targeting Sox9 in IPF treatment.

1 has shown that despite the availability of several effective blood pressure (BP)-lowering drugs, the burden of disease caused by hypertension rather than decreasing has continuously incremented worldwide. This indicates limitations of the diagnostic and therapeutic strategies to date implemented in managing hypertension and underscores the urgent need of new strategies for overcoming these limitations and reducing their consequences on public health.Under the diagnostic aspect, hypertension is identified on the simple basis of several BP measurements taken under standard conditions, but it is well-known that BP is extremely variable, and its measurements are scarcely reproducible.2 This has brought to a long-lasting and continuing discussion on the Abstract-Despite advancements in lowering blood pressure, the best approach to lower it remains controversial because of the lack of information on the molecular basis of hypertension. We, therefore, performed plasma proteomics of plasma from patients with hypertension to identify molecular determinants detectable in these subjects but not in controls and vice versa. Plasma samples from hypertensive subjects (cases; n=118) and controls (n=85) from the InGenious HyperCare cohort were used for this study and performed mass spectrometric analysis. Using biostatistical methods, plasma peptides specific for hypertension were identified, and a model was developed using least absolute shrinkage and selection operator logistic regression. The underlying peptides were identified and sequenced offline using matrix-assisted laser desorption ionization orbitrap mass spectrometry. By comparison of the molecular composition of the plasma samples, 27 molecular determinants were identified differently expressed in cases from controls. Seventy percent of the molecular determinants selected were found to occur less likely in hypertensive patients. In cross-validation, the overall R 2 was 0.434, and the area under the curve was 0.891 with 95% confidence interval 0.8482 to 0.9349, P<0.0001. The mean values of the cross-validated proteomic score of normotensive and hypertensive patients were found to be −2.007±0.3568 and 3.383±0.2643, respectively, P<0.0001. The molecular determinants were successfully identified, and the proteomic model developed shows an excellent discriminatory ability between hypertensives and normotensives. The identified molecular determinants may be the starting point for further studies to clarify the molecular causes of hypertension. 2 Although the use of these subtypes of hypertension has become popular in the management of hypertension, there are no agreements yet on strategies for their management.3 Under the therapeutic aspect, several classes and compounds have been shown to effectively lower BP, thus reducing cardiovascular disease risk. 4,5 However, each of these classes is known to be effective only in a proportion of hypertensive patients, and in the absence of proven predictors of their effect, they are commonly prescribed by a trial and error str...

Introduction: Fibrosis is an irreversible pathological endpoint in many chronic diseases, including pulmonary fibrosis. Idiopathic pulmonary fibrosis (IPF) is a progressive and often fatal condition characterized by (myo)fibroblast proliferation and transformation in the lung, expansion of the extracellular matri and extensive remodeling of the lung parenchyma. Recent evidence indicates that IPF prevalence and mortality rates are growing in the United States and elsewhere. Despite decades of research on the pathogenic mechanisms of pulmonary fibrosis, few therapeutics have succeeded in the clinic, and they have failed to improve IPF patient survival. Areas Covered: Based on a literature search and our own results, we discuss the key cellular and molecular responses that contribute to (myo)fibroblast actions and pulmonary fibrosis pathogenesis; this includes signaling pathways in various cells that aberrantly and persistently activate (myo)fibroblasts in fibrotic lesions and promote scar tissue formation in the lung. Expert Opinion: Lessons learned from recent failures and successes with new therapeutics point toward approaches that can target multiple pro-fibrotic processes in IPF. Advances in preclinical modeling and single-cell genomics will also accelerate novel discoveries for effective treatment of IPF.