The Role of Genetics and Epigenetic Regulation in the Pathogenesis of Osteoarthritis.

Osteoarthritis (OA) is progressive disease characterised by cartilage degradation, subchondral bone remodelling and inflammation of the synovium. The disease is associated with obesity, mechanical load and age. However, multiple pro-inflammatory immune mediators regulate the expression of metalloproteinases, which take part in cartilage degradation. Furthermore, genetic factors also contribute to OA susceptibility. Recent studies have highlighted that epigenetic mechanisms may regulate the expression of OA-associated genes. This review aims to present the mechanisms of OA pathogenesis and summarise current evidence regarding the role of genetics and epigenetics in this process.

Association Between Plasma Concentration of Klotho Protein, Osteocalcin, Leptin, Adiponectin, and Bone Mineral Density in Patients with Chronic Kidney Disease.

Patients with early-stage chronic kidney disease (CKD) are susceptible to changes in metabolic processes. Partial loss of kidney function leads to homoeostatic disturbances in bone and fatty tissue. The aim of this study was to investigate the association between plasma concentrations of Klotho protein, FGF23, leptin, adiponectin, osteocalcin, and bone mineral density (BMD) in patients with CKD in the pre-dialysis period. The study involved 52 patients with CKD and 23 patients with no kidney disease. In both groups, BMD, body mass index and serum or plasma concentrations of lipids, glucose, creatinine, calcium, phosphorus, parathormone, leptin, adiponectin, osteocalcin, Klotho, and FGF23 were measured. The group with CKD had statistically significant higher concentrations of leptin (p<0.001), parathormone (p<0.001), and osteocalcin (p<0.001) in comparison with the control group. Patients with CKD also had statistically significant lower BMD in the femoral neck in comparison with the control group. Osteocalcin correlated negatively with BMD. The results of our study suggest that elevated osteocalcin is the most sensitive marker of decreased bone mass in patients with CKD. Osteocalcin correlated negatively with BMD and GFR. The loss of bone mass in CKD patients was greatest in the femoral neck.

Association Study of SLCO1B3 and ABCC3 Genetic Variants in Gallstone Disease.

There is growing evidence that gallstone formation may be genetically determined. Recent studies have shown that polymorphism of genes encoding proteins involved in bile acid transport may be associated with the risk of gallstone disease. The aim of this study was to investigate the association between SLCO1B3 (rs4149117:G>T, rs7311358:A>G) and ABCC3 (rs4793665:T>C, rs11568591:G>A) genetic variants and susceptibility to cholesterol gallstone disease, as well as gallstone composition. The study included 317 patients suffering from cholelithiasis who underwent cholecystostomy and 249 controls with no evidence of stones, confirmed by ultrasound examination. There were no statistically significant differences in the distribution of studied gene polymorphisms between patients with gallstone disease and healthy controls. No significant associations were observed between studied genotypes and the content of analyzed gallstone components: total cholesterol, bilirubin, CaCO3, nor the total bile acids. There was also no association between bile acid content in gallstones and the polymorphisms studied. The results of this study suggest that polymorphisms of SLCO1B3 and ABCC3 genes are not a valuable marker of gallstone disease susceptibility and do not influence gallstone composition.

VAV1 Gene Polymorphism is Associated With Kidney Allograft Rejection.

BACKGROUND: VAV1 is an intracellular signal transduction protein that plays a significant role in signal transduction in T cells. Several studies suggest that VAV1 signaling plays significant roles in allograft rejection. The aim of this study was to examine the association between VAV1 gene polymorphisms and renal allograft function. METHODS: The study included 270 patients after allograft renal transplantation. We examined the associations between VAV1 gene polymorphisms and complications after transplantation, such as delayed graft function, acute rejection, and chronic allograft dysfunction. RESULTS: There were no statistically significant associations between VAV1 genotypes and delayed graft function and chronic allograft dysfunction. Among patients with acute allograft rejection, we observed decreased frequencies of VAV1 rs2546133 TT and CT genotypes (P = .03) and T allele (P = .02), as well as VAV1 rs2617822 GG and AG genotypes (P = .05) and G allele (P = 0.04). In the multivariate regression analysis, the higher number of VAV1 rs2546133 T alleles showed a protective effect against the acute rejection in kidney allograft recipients. CONCLUSIONS: The results of our study suggest that polymorphisms in the VAV1 gene are associated with kidney allograft rejection.

Effect of amiloride and bumetanide on transepithelial ion transport in isolated rabbit cecal and colonic wall.

INTRODUCTION: The aim of the study was to compare the effects of amiloride and bumetanide on the baseline transepithelial electrical potential difference (PD) and changes in PD during mechanical stimulation (dPD) in isolated cecal and colonic wall of rabbits. MATERIAL/METHODS: The experiments were performed with a modified Ussing chamber system. Isolated tissue specimens were incubated in Ringer's solution, in amiloride and/or bumetanide, or in dimethyl sulfoxide (DMSO). RESULTS: Under control conditions, i.e. when all the experimental fluids were Ringer's solution, the PD and R values of the rabbit cecum and colon were similar, while during mechanical stimulation, dPD of the colon was twice as high as that of the cecum. Addition of amiloride and/or bumetanide to all experimental fluids diminished the electrophysiological parameters of both tissues. DMSO added to all experimental fluids significantly diminished the values of the electrophysiological parameters of the cecum. Addition of amiloride to the stimulation fluid only diminished the PD and dPD values in the colon, whereas addition of bumetanide to the stimulation fluid only diminished the PD and dPD values in the cecum. It was found that the PD and dPD values of the rabbit cecum depend primarily on chloride ion transport, while those of the colon depend on sodium ion transport.

Ionic support of the cough reflex.

INTRODUCTION: The aim of this study was to determine the role ofintra-wall nervous and neurohormonal system in the control of airway transport of sodium and chloride ions, as well as to identify regulating mechanisms having an effect on the permanent electric potential of airway tissue, named the transepithelial electric potential (PD) and on reversible changes of this potential (dPD). Using amiloride, a sodium ion blocker, and bumetanide, a blocker of the chloride ion co-transport system, the importance oftransepithelial sodium and chloride ion transport for support of the cough reflex was determined. The conditions were identified for examination of chloride secretion in the airways presented as the chemical isolation of chloride currents with the use of amiloride. MATERIAL AND METHODS: The experimental material consisted of 135 fragments of trachea wall obtained from 45 animals. The experiments were directed at measurements of PD of the isolated tracheal wall placed in Ussing chamber where this tissue formed an interface between two half-chambers filled with an isoosmotic polyelectrolyte solution. The main procedure for irritation of sensory receptors in the airways utilized ajet from a peristaltic pump directed to the mucous surface of the isolated trachea. The jet fluid was analogous to the one in the chamber or it was modified as the experimental conditions required. RESULTS: Transepithelial transport of sodium ions in the trachea exerted a regulatory effect modulating the transepi- thelial difference of electric potentials, as well as inducing hyperpolarisation after mechanical stimulation when at 40% the sodium transport is the exclusive carrier of the hyperpolarisation reaction.

[Electrophysiological characteristics of ion transport in isolated rabbit trachea wall after in effect of mechanical stimuli and sodium transport inhibition]. / Elektrofizjologiczna charakterystyka transportu jonów w izolowanej scianie tchawicy po dzialaniu bodzców mechanicznych i hamowaniu transportu sodu.

INTRODUCTION: The aim of the study was to determine a role of intra-wall nervous and neurohormonal system in control of ion transport in airways, and to identify the control mechanisms, having effect on constant electric potential of this tissue named as PD, and the ones which have effect on reversible changes of this potential marked as dPD. Through the application of amiloride sodium ion transport blocker the importance of transepithelial sodium ion transport for transepithelial electric potential of airways was to be determined, as well as the other amiloride effects on isolated airways. The conditions for examination of secretion of the chlorides in airways have been determined and will be presented as chemical isolation of chloride currents with use of amiloride. MATERIAL AND METHODS: Experimental material consisted of 135 fragments of trachea wall obtained from 45 animals. Experiments consisted in measurements of transepithelial electric potential (PD) and resistance (R) of isolated trachea wall placed in Ussing apparatus, where the tissue separates two chambers filled up with isoosmotic complex electrolyte solution. The essential procedure applied in irritation of sensory receptors was directing the fluid jet from a peristaltic pump to mucous surface of isolated trachea. The jet consisted of fluid analogous to the one from the chamber, or it was modified as the experiment conditions required. RESULTS: Transepithelial transport way of sodium ions in trachea epithelium has the controlling effect in value modulation of transepithelial difference of electric potentials, as well as in induction of hyperpolarization after mechanical stimuli action, while at the same time the sodium transport at 40% is the exclusive carrier of hyperpolarization reaction.

Effect of amiloride and bumetanide on ionic currents in the epithelium of caecum from starved rabbits.

The aim of this study was to determine the effect of starvation on the transport of sodium and chloride ions in the epithelium of rabbit caecum. The experiment consisted in measuring transepithelial electrical potential (PD in mV) and the transepithelial electrical potential difference (dPD in mV) of an isolated fragment of rabbit caecum, before and after 4-day-long starvation. The studied tissue was incubated in Ringer solution and subsequently ion transport was modified through incubation in the Ringer solution supplemented with amiloride or/and bumetanide. It was demonstrated that the values of electrophysiological parameters of the tissue fragments of caecum from starved rabbits were substantially lower than the values for the fragments of control caecum. A similar relationship was observed also in the reaction of this tissue to mechanical stimuli. After the incubation of the caecum tissue fragments in the presence of amiloride or/and bumetanide, the value of transepithelial electrical potential and the sensitivity to mechanical stimuli decreased in both groups studied. Experimental data presented in this paper indicate that the starvation process has effect on lowering sodium and chloride ion transport and decreasing sensitivity of the epithelium of the caecum to mechanical stimuli.

Effect of capsaicin on ion transport in the caecum of rabbits.

Effect of capsaicin, a stimulator of C-fibres, on ion transport in the caecum of rabbits was studied using electrophysiological methods, designed to evaluate ionic currents occurring in epithelial tissues. The experiments consisted in measuring transepithelial electrical potential difference (dPD) of an isolated fragment of rabbit's caecum, placed in a Ussing apparatus. The ion transport was modified through incubation in Ringer solution, supplemented with amiloride, bumetanide, and capsaicin. Capsaicin was also administered with peristalting pump. The experiments demonstrated that the inhibition of sodium ions transport caused by incubation with amiloride and incubation with capsaicin slowed down mechanical reaction to electrical potential difference. On the other hand, immediately after the administration, the capsaicin effect on C-fibres modified electrophysiological reaction of the caecum to mechanical stimulation. Physiological and pharmacological experiments reveal that a component dependent on activation of C-fibres contributes to the reaction of ion transport activation following mechanical stimulation.

Effects of amiloride and bumetanide on ion transport in the caecum of rabbit.

Effect of selective blockers of sodium and chloride ion transport (amiloride and bumetanide) on transepithelial electrical potential (PD), transepithelial electrical potential difference (dPD), and electrical resistance of the tissue (R) of isolated fragment of the rabbit's caecum were determined using electrophysiological methods designed for measuring ionic currents occurring in epithelial tissues. A modified Ussing apparatus enabling application of mechanical and chemical stimuli on the isolated tissue was used in the experiment. It was demonstrated that amiloride used for incubation of the caecum fragments lowered by some 24% the value of PD and by 50% the value of dPD. Incubation of the caecum fragments with bumetanide resulted in a decrease in the PD value by 73% and in the value of dPD by some 83%. The results obtained with the tissue incubated in Ringer solution with addition of both compounds were comparable with those observed for the tissue incubated with bumetanide. As can be concluded from the above-mentioned experiments, both ion transport pathways contribute jointly to the induction of PD in the epithelium of the rabbits caecum.

Effect of antagonists of adrenergic and cholinergic receptors on ion transport in the isolated rabbit caecum wall.

A hypothesis was tested in this study that antagonists of adrenergic and cholinergic receptors affect sodium and chloride ion transport in the rabbit caecum. A modified Ussing chamber was used in the experiment. It was demonstrated that isolated caecum responded to a mechanical stimulus, which consisted in gentle rinsing of the mucous surface, with changes in transepithelial electrical potential difference. An application of ion transport inhibitors, amiloride for sodium and bumetanide for chloride ions, demonstrated that both sodium and chloride ion transport in part determined the response. Pharmaceuticals that are antagonistic at neural receptors (alpha- and beta-adrenergic, nicotinic, and muscarinic), applied both for incubation and stimulation, reduced electrical potential and inhibited responses to mechanical stimuli. Basing on the results of this experiment and literature data, one can presume that analogical responses occur in vivo, and the physiological role of the autonomic system includes regulation of the thickness and consistence of mucus that separates fecal masses from the caecum walls.

Effect of capsaicin and dimethyl sulfoxide on ion transport in the selected experimental models.

The aim of the present work was to determine the changes in ion transport in the selected epithelium-lined organs under influence of mechanical stimuli, and also to assess similarities and differences in reactions to capsaicin and dimethyl sulfoxide (DMSO) between trachea and caecum of rabbit and the skin of frog in this experimental setup. The experiments were conducted on rabbit trachea and caecum, and the skin of frog, Rana esculenta L. The experiments consisted in measuring transepithelial electrical potential (PD in mV) with Ussing apparatus, modified to enable testing of the effects of mechanical stimulation of organs and defined pharmacological treatments. It was demonstrated that the addition of DMSO to the stimulating fluid decreased reversible hyperpolarization (dPD) after mechanical stimulation by at least 50% in all studied groups. On the other hand, action of capsaicin was dependent on the organ studied as well as on experimental conditions (e.g. type of incubation). Capsaicin decreased PD and reaction to mechanical stimulation in trachea incubated in Ringer solution supplemented with amiloride. On the other hand, it did not influence electrophysiological parameters of the trachea following its incubation with bumetanide. Capsaicin did not change electrical potential or reactivity of rabbit caecum incubated with both amiloride and bumetanide. The administration of capsaicin on frog skin incubated with bumetanide caused inhibition of the reaction to mechanical stimulation, whereas during incubation with amiloride no changes were recorded in PD and dPD of the skin. The present study demonstrated that capsaicin and DMSO could modify processes of ion transport dependent on mechanical stimulation.