Transportable normothermic kidney perfusion for 24 hours or longer could enable viability assessment of marginal grafts, increased organ utilization and improved transplantation logistics. Eleven clinically‐declined kidneys were perfused normothermically, six from donors after brain stem death (DBD, median cold ischemia time 33±36.9 hours) and five from donors after circulatory death (DCD, 36.2±38.3 hours): n=3 kidneys were perfused using Ringer's lactate to replace excreted urine volume, and n=8 using urine recirculation to maintain perfusate volume without fluid replenishment. In all cases normothermic perfusion either maintained or slightly improved the histopathologically assessed tubular condition and there was effective urine production in both DBDs and DCDs (2367±1798 ml vs. 744.4±198.4 ml p=0.44). Biomarkers, neutrophil gelatinase‐associated lipocalin (NGAL) and kidney injury molecule‐1 (KIM‐1) were successfully detected and quantified in the perfusate. All kidneys with urine recirculation were readily perfused for 24 hours (n=8) and exhibited physiological perfusate sodium levels (140.7±1.2 mmol/l), whilst kidneys without urine recirculation (n=3) achieved a reduced normothermic perfusion time of 7.7±1.5 hours and significantly higher perfusate sodium levels (159.6±4.63 mmol/l, p<0.01). Normothermic machine perfusion for 24 hours of human kidneys appears to be feasible and urine recirculation was found to facilitate maintenance of perfusate volume and homeostasis.

Reactive species of oxygen, nitrogen and sulfur play cell signalling roles in human health, e.g. recent studies have shown that increased dietary nitrate, which is a source of RNS (reactive nitrogen species), lowers resting blood pressure and the oxygen cost of exercise. In such studies, plasma nitrite and nitrate are readily determined by chemiluminescence. At sites of inflammation, such as the joints of RA (rheumatoid arthritis) patients, the generation of ROS (reactive oxygen species) and RNS overwhelms antioxidant defences and one consequence is oxidative/nitrative damage to proteins. For example, in the inflamed joint, increased RNS-mediated protein damage has been detected in the form of a biomarker, 3-nitrotyrosine, by immunohistochemistry, Western blotting, ELISAs and MS. In addition to NO^•, another cell-signalling gas produced in the inflamed joint is H₂S (hydrogen sulfide), an RSS (reactive sulfur species). This gas is generated by inflammatory induction of H₂S-synthesizing enzymes. Using zinc-trap spectrophotometry, we detected high (micromolar) concentrations of H₂S in RA synovial fluid and levels correlated with clinical scores of inflammation and disease activity. What might be the consequences of the inflammatory generation of reactive species? Effects on inflammatory cell-signalling pathways certainly appear to be crucial, but in the current review we highlight the concept that ROS/RNS-mediated protein damage creates neoepitopes, resulting in autoantibody formation against proteins, e.g. type-II collagen and the complement component, C1q. These autoantibodies have been detected in inflammatory autoimmune diseases.

Ischaemia and reperfusion injury (IRI) is the leading cause of acute kidney injury (AKI), which contributes to high morbidity and mortality rates in a wide range of injuries as well as the development of chronic kidney disease. The cellular and molecular responses of the kidney to IRI are complex and not fully understood. Here, we used an integrated proteomic and metabolomic approach to investigate the effects of IRI on protein abundance and metabolite levels. Rat kidneys were subjected to 45 min of warm ischaemia followed by 4 h and 24 h reperfusion, with contralateral and separate healthy kidneys serving as controls. Kidney tissue proteomics after IRI revealed elevated proteins belonging to the acute phase response, coagulation and complement pathways, and fatty acid (FA) signalling. Metabolic changes were already evident after 4 h reperfusion and showed increased level of glycolysis, lipids and FAs, whilst mitochondrial function and ATP production was impaired after 24 h. This deficit was partially compensated for by the contralateral kidney. Such a metabolic balance counteracts for the developing energy deficit due to reduced mitochondrial function in the injured kidney.

Peroxiredoxin 2 has immune regulatory functions, but its expression in human peripheral blood lymphocytes and levels in extracellular fluid in healthy subjects and rheumatoid arthritis patients are poorly described. In the present study, the median intracellular peroxiredoxin 2 protein content of lymphocytes from rheumatoid arthritis patients was more than two-fold higher compared with healthy subjects' lymphocytes. Intracellular peroxiredoxin 3 levels were similar in healthy and rheumatoid arthritis lymphocytes. Flow cytometry detected peroxiredoxin 2 on the surface of ca. 8% of T cells and ca. 56% of B cells (median % values) of all subjects analyzed. Exofacial thioredoxin-1 was also observed. In the total lymphocyte population from rheumatoid arthritis patients, few cells (median, 6%) displayed surface peroxiredoxin 2. In contrast, a significantly increased proportion of interleukin-17(+ve) lymphocytes were exofacially peroxiredoxin 2(+ve) (median, 39%). Prdx2 was also detected in human extracellular fluids. We suggest that crucial inflammatory cell subsets, i.e. interleukin-17(+ve) T cells, exhibit increased exofacial redox-regulating enzymes and that peroxiredoxin 2 may be involved in the persistence of pro-inflammatory cells in chronic inflammation.