Corticosteroids--from an idea to clinical use

Corticosteroids form the basis of treatment in many inflammatory rheumatic diseases, both as systemic treatment and as treatment with local injections to reduce inflammation. In 1948 the first systemic treatment of a patient with a rheumatic disease was given to a woman with severe rheumatoid arthritis (RA); the impressive effect in this patient, and in another 15 patients, was reported by Dr Hench and co-workers in 1949. Systemic corticosteroid treatment was rapidly adopted and used not only for patients with RA but also for those with other rheumatic diseases such as systemic lupus erythematosus-as well as other disorders such as asthma-with a similar positive effect. In the following year, 1950, the Nobel Prize was awarded for the discovery of the structure and biological effects of the adrenal cortex hormones. This open trial was followed by several controlled trials conducted in the UK in which the effects of cortisone were compared with the effects of aspirin in patients with RA-interestingly, without any significant clinical benefit for the cortisone-treated patients. It was not until 1959, in yet another multi-centre trial in Britain, that a significant effect on functional capacity and general well-being was reported after 2 years of treatment with prednisolone, compared to aspirin, in patients with early RA. Despite the dramatic effects that were observed in the severely ill RA patients reported by Hench and co-workers it took 10 years to demonstrate that this effect was superior to the effect of aspirin when the two compounds were compared in controlled trials. Why was this so? One explanation could be in the study designs and the different outcome measures used in the various studies. Perhaps the results in the first comparative studies would have been different if individual response criteria had been used. This is discussed in this chapter.     

Innate immune receptor NOD2 promotes vascular inflammation and formation of lipid‐rich necrotic cores in hypercholesterolemic mice

Atherosclerosis is an inflammatory disease associated with the activation of innate immune TLRs and nucleotide‐binding oligomerization domain‐containing protein (NOD)‐like receptor pathways. However, the function of most innate immune receptors in atherosclerosis remains unclear. Here, we show that NOD2 is a crucial innate immune receptor influencing vascular inflammation and atherosclerosis severity. 10‐week stimulation with muramyl dipeptide (MDP), the NOD2 cognate ligand, aggravated atherosclerosis, as indicated by the augmented lesion burden, increased vascular inflammation and enlarged lipid‐rich necrotic cores in Ldlr^?/? mice. Myeloid‐specific ablation of NOD2, but not its downstream kinase, receptor‐interacting serine/threonine‐protein kinase 2, restrained the expansion of the lipid‐rich necrotic core in Ldlr^?/? chimeric mice. In vitro stimulation of macrophages with MDP enhanced the uptake of oxidized low‐density lipoprotein and impaired cholesterol efflux in concordance with upregulation of scavenger receptor A1/2 and downregulation of ATP‐binding cassette transporter A1. Ex vivo stimulation of human carotid plaques with MDP led to increased activation of inflammatory signaling pathways p38 MAPK and NF‐κB‐mediated release of proinflammatory cytokines. Altogether, this study suggests that NOD2 contributes to the expansion of the lipid‐rich necrotic core and promotes vascular inflammation in atherosclerosis.     

Risk of renal disease in patients with both type 1 diabetes and coeliac disease

Aims/hypothesis

Our aim was to study the risk of renal disease in patients with type 1 diabetes (T1D) and coexisting coeliac disease (CD).

Methods

Individuals with T1D were defined as having a diagnosis of diabetes recorded at ≤30 years of age in the Swedish Patient Register between 1964 and 2009. Individuals with CD were identified through biopsy reports with villous atrophy (Marsh stage 3) from 28 pathology departments in Sweden between 1969 and 2008. We identified 954 patients with both T1D and CD. For each patient with T1D + CD, we selected five age- and sex-matched reference individuals with T1D only (n?=?4,579). Cox regression was used to estimate the following risks: (1) chronic renal disease and (2) end-stage renal disease in patients with CD + T1D compared with T1D patients only.

Results

Forty-one (4.3%) patients with CD + T1D and 143 (3.1%) patients with T1D only developed chronic renal disease. This corresponded to an HR of 1.43 for chronic renal disease (95% CI 0.94, 2.17) in patients with CD + T1D compared with T1D only. In addition, for end-stage renal disease there was a positive (albeit statistically non-significant) HR of 2.54 (95% CI 0.45, 14.2). For chronic renal disease, the excess risk was more pronounced after >10 years of CD (HR 2.03, 95% CI 1.08, 3.79). Risk estimates were similar when we restricted our cohort to the following T1D patients: (1) those who had an inpatient diagnosis of T1D; (2) those who had never received oral glucose-lowering medication; and (3) those who had not received their first diabetes diagnosis during pregnancy.

Conclusions/interpretation

Overall this study found no excess risk of chronic renal disease in patients with T1D and CD. However, in a subanalysis we noted a positive association between longstanding CD and chronic renal disease in T1D.     

Thioredoxin-related protein of 14 kDa is an efficient L-cystine reductase and S-denitrosylase

Thioredoxin-related protein of 14 kDa (TRP14, also called TXNDC17 for thioredoxin domain containing 17, or TXNL5 for thioredoxin-like 5) is an evolutionarily well-conserved member of the thioredoxin (Trx)-fold protein family that lacks activity with classical Trx1 substrates. However, we discovered here that human TRP14 has a high enzymatic activity in reduction of l-cystine, where the catalytic efficiency (2,217 min⁻¹⋅µM⁻¹) coupled to Trx reductase 1 (TrxR1) using NADPH was fivefold higher compared with Trx1 (418 min⁻¹⋅µM⁻¹). Moreover, the l-cystine reduction with TRP14 was in contrast to that of Trx1 fully maintained in the presence of a protein disulfide substrate of Trx1 such as insulin, suggesting that TRP14 is a more dedicated l-cystine reductase compared with Trx1. We also found that TRP14 is an efficient S-denitrosylase with similar efficiency as Trx1 in catalyzing TrxR1-dependent denitrosylation of S-nitrosylated glutathione or of HEK293 cell-derived S-nitrosoproteins. Consequently, nitrosylated and thereby inactivated caspase 3 or cathepsin B could be reactivated through either Trx1- or TRP14-catalyzed denitrosylation reactions. TRP14 was also, in contrast to Trx1, completely resistant to inactivation by high concentrations of hydrogen peroxide. The oxidoreductase activities of TRP14 thereby complement those of Trx1 and must therefore be considered for the full understanding of enzymatic control of cellular thiols and nitrosothiols.The redox or nitrosylation state of reactive cysteine (Cys) residues in proteins can affect a multitude of intracellular events, either beneficial or harmful, depending upon biological context (1, 2). Two major cellular systems that control the redox states of Cys residues are the thioredoxin (Trx) and the glutathione (GSH) systems. The Trx system includes isoforms of Trx, Trx reductase (TrxR), and NADPH together with several Trx-dependent enzymes and proteins (3). The GSH/GSH disulfide redox couple is kept reduced by the NADPH-dependent activity of GSH reductase (GR) and donates electrons to isoforms of glutaredoxin (Grx) and other GSH-dependent enzymes (4).In addition to Trx, many proteins have a Trx fold and a Trx-like active-site sequence. One such protein is thioredoxin-related protein of 14 kDa (TRP14, also known as TXNDC17 or TXNL5), which is an evolutionarily well-conserved cytosolic and widely expressed Trx-fold protein that can be reduced by TrxR1 (5). Its crystal structure, compared with Trx1, shows additional structural features in the active site, thereby explaining its lack of activity with most classical Trx1 protein disulfide substrates including ribonucleotide reductase, insulin, peroxiredoxins, or methionine sulfoxide reductase (5–7). TRP14 was suggested to have evolved to exert specific signaling roles in cells and was identified as a modulator of TNFα/NFκB signaling pathways through interactions with the dynein light chain LC8 protein (6, 8). We previously found that treatment of cells with cisplatin triggered the formation of covalent cross-links between TrxR1 and either Trx1 or TRP14, which suggests that TRP14 is tightly linked to TrxR1 within the cellular context (9). Recently, we also found that TRP14 is able to reactivate oxidized phosphotyrosine phosphatase 1B, thereby indeed implicating specific functions in modulation of cellular signaling pathways (10).In addition to having general protein disulfide reductase activities, Trx1 is also a denitrosylase for a broad spectrum of nitrosoproteins and nitrosothiols (11, 12). Substrates include S-nitrosocaspase 3 (13, 14), S-nitrosocaspase 8 (15), S-nitrosoglutathione (GSNO) (16, 17), and S-nitrosocysteine (l-CysSNO) (12). Nitrosylation and denitrosylation reactions provide a regulatory mechanism for protein function and are thereby also involved in a variety of cellular signal transduction pathways. For example, S-nitrosylation of caspases can inhibit their activity and thus regulate apoptosis in resting cells (18, 19). A full understanding of NO homeostasis and its pathways is of medical importance because an aberrant formation of nitrosylated proteins has been implicated in a variety of diseases. However, protein denitrosylation is a hitherto less studied part in NO-mediated signaling (20, 21). In addition to Trx1, another enzyme mediating cellular denitrosylation reactions is GSNO reductase (GSNOR). GSNOR is the same enzyme as class III alcohol dehydrogenase, mainly catalyzing denitrosylation of GSNO using NADH as an electron donor (22, 23). In addition, S-denitrosylation activities are supported by protein disulfide isomerase (PDI) (24), carbonyl reductase 1 (25), and lipoic acid (17).The high intracellular concentrations of GSH are also important in NO metabolism because of facilitated formation of GSNO by reaction of GSH with NO or by denitrosylation of cellular nitrosothiols (20, 26). Because the synthesis of GSH depends upon availability, cellular uptake and reduction of sulfur-containing precursors such as l-cystine, l-cystine homeostasis is also important for GSH functions (27). l-Cystine is taken up into cells using different transport systems, e.g., the oxidative stress-inducible cystine/glutamate antiporter (system ) (28). The mechanism behind the reduction of l-cystine still has not been fully elucidated, but has been implicated to include GSH itself or also TrxR1-dependent systems (29).In the present study, we wanted to further characterize the enzymatic properties of TRP14, which revealed that the protein is at least as efficient as Trx1 in supporting reduction of specific redox substrates, such as l-cystine. In that assay, TRP14 is a fivefold better substrate for TrxR1 than Trx1 itself and, furthermore, more dedicated as its activity is not diminished in the presence of other Trx1 substrates that are not reduced by TRP14. Furthermore, we discovered that TRP14 is yet another cytosolic oxidoreductase that can catalyze S-denitrosylation reactions.     

Cyclooxygenase-1, not cyclooxygenase-2, is responsible for physiological production of prostacyclin in the cardiovascular system

Prostacyclin is an antithrombotic hormone produced by the endothelium, whose production is dependent on cyclooxygenase (COX) enzymes of which two isoforms exist. It is widely believed that COX-2 drives prostacyclin production and that this explains the cardiovascular toxicity associated with COX-2 inhibition, yet the evidence for this relies on indirect evidence from urinary metabolites. Here we have used a range of experimental approaches to explore which isoform drives the production of prostacyclin in vitro and in vivo. Our data show unequivocally that under physiological conditions it is COX-1 and not COX-2 that drives prostacyclin production in the cardiovascular system, and that urinary metabolites do not reflect prostacyclin production in the systemic circulation. With the idea that COX-2 in endothelium drives prostacyclin production in healthy individuals removed, we must seek new answers to why COX-2 inhibitors increase the risk of cardiovascular events to move forward with drug discovery and to enable more informed prescribing advice.     

Effects of dietary inorganic nitrate on static and dynamic breath-holding in humans

Inorganic nitrate has been shown to reduce oxygen cost during exercise. Since the nitrate-nitrite-NO pathway is facilitated during hypoxia, we investigated the effects of dietary nitrate on oxygen consumption and cardiovascular responses during apnea. These variables were measured in two randomized, double-blind, placebo-controlled, crossover protocols at rest and ergometer exercise in competitive breath-hold divers. Subjects held their breath for predetermined times along with maximum effort apneas after two separate 3-day periods with supplementation of potassium nitrate/placebo.