What Have We Learnt About the Treatment of Juvenile-Onset Systemic Lupus Erythematous Since Development of the SHARE Recommendations 2012?

Introduction

Juvenile-onset systemic lupus erythematous (JSLE) is a rare multisystem autoimmune disorder. In 2012, the Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) initiative developed recommendations for the diagnosis/management of JSLE, lupus nephritis (LN) and childhood-onset anti-phospholipid syndrome (APS). These recommendations were based upon available evidence informing international expert consensus meetings.

Objective

To review new evidence published since 2012 relating to the management of JSLE, LN and APS in children, since the original literature searches informing the SHARE recommendations were performed.

Method

MEDLINE, EMBASE and CINAHL were systematically searched for relevant literature (2012-2021) using the following criteria: (1) English language studies; (2) original research studies regarding management of JSLE, LN, APS in children; (3) adult studies with 3 or more patients <18-years old, or where the lower limit of age range ≤16-years and the mean/median age is ≤30-years; (4) randomized controlled trials (RCTs), cohort studies, case control studies, observational studies, case-series with >3 patients. Three reviewers independently screened all titles/abstracts against predefined inclusion/exclusion criteria. All relevant manuscripts were reviewed independently by at least two reviewers. Data extraction, assessment of the level of evidence/methodological quality of the manuscripts was undertaken in-line with the original SHARE processes. Specific PUBMED literature searches were also performed to identify new evidence relating to each existing SHARE treatment recommendation.

Results

Six publications met the inclusion/exclusion criteria for JSLE: three RCTs, one feasibility trial, one case series. For LN, 16 publications met the inclusion/exclusion criteria: eight randomized trials, three open label prospective clinical trials, five observational/cohort studies. For APS, no publications met the inclusion criteria. The study with the highest evidence was an RCT comparing belimumab vs. placebo, including 93 JSLE patients. Whilst the primary-endpoint was not met, a significantly higher proportion of belimumab-treated patients met the PRINTO/ACR cSLE response to therapy criteria. New evidence specifically addressing each SHARE recommendation remains limited.

Conclusion

Since the original SHARE literature searches, undertaken >10-years ago, the main advance in JSLE treatment evidence relates to belimumab. Additional studies are urgently needed to test new/existing agents, and assess their long-term safety profile in JSLE, to facilitate evidence-based practice.

Inside the alkalinity engine: the role of electron donors in the organomineralization potential of sulfate-reducing bacteria

Mineral precipitation in microbial mats may have been the key to their preservation as fossil stromatolites, potentially documenting evidence of the earliest life on Earth. Two factors that contribute to carbonate mineral precipitation are the saturation index (SI) and the presence of nucleation sites. Both of these can be influenced by micro-organisms, which can either alter SI through their metabolisms, or produce and consume organic substances such as extracellular polymeric substances (EPS) that can affect nucleation. It is the balance of individual metabolisms within the mat community that determines the pH and the dissolved inorganic carbon concentration, thereby potentially increasing the alkalinity and consequently the SI. Sulfate-reducing bacteria (SRB) are an important component of this 'alkalinity engine.' The activity of SRB often peaks in layers where CaCO(3) precipitates, and mineral precipitation has been demonstrated in SRB cultures; however, the effect of their metabolism on the alkalinity engine and actual contribution to mineral precipitation is the subject of controversy. Here, we show through culture experiments, theoretical calculations, and geochemical modeling studies that the pH, alkalinity, and organomineralization potential will vary depending on the type of electron donor. Specifically, hydrogen and formate can increase the pH, but electron donors like lactate and ethanol, and to a lesser extent glycolate, decrease the pH. The implication of this for the lithification of mats is that the combination of processes supplying electron donors and the utilization of these compounds by SRB may be critical to promoting mineral precipitation.

Expression of the ryanodine receptor isoforms in immune cells

Ryanodine receptor (RYR) is a Ca(2+) channel that mediates Ca(2+) release from intracellular stores. We have used RT-PCR analysis and examined its expression in primary peripheral mononuclear cells (PBMCs) and in 164 hemopoietic cell lines. In PBMCs, type 1 RYR (RYR1) was expressed in CD19(+) B lymphocytes, but less frequently in CD3(+) T lymphocytes and in CD14(+) monocytes. Type 2 RYR (RYR2) was mainly detected in CD3(+) T cells. Induction of RYR1 and/or RYR2 mRNA was found after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1alpha (MIP1alpha) or TGF-beta. Type 3 RYR (RYR3) was not detected in PBMCs. Many hemopoietic cell lines expressed not only RYR1 or RYR2 but also RYR3. The expression of the isoforms was not associated with specific cell lineage. We showed that the RYR-stimulating agent 4-chloro-m-cresol (4CmC) induced Ca(2+) release and thereby confirmed functional expression of the RYR in the cell lines expressing RYR mRNA. Moreover, concordant induction of RYR mRNA with Ca(2+) channel function was found in Jurkat T cells. In untreated Jurkat T cells, 4CmC (>1 mM) had no effect on Ca(2+) release, whereas 4CmC (<400 microM) caused Ca(2+) release after the induction of RYR2 and RYR3 that occurred after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1alpha, or TGF-beta. Our results demonstrate expression of all three isoforms of RYR mRNA in hemopoietic cells. Induction of RYRs in response to chemokines and TGF-beta suggests roles in regulating Ca(2+)-mediated cellular responses during the immune response.

North American malignant hyperthermia population: screening of the ryanodine receptor gene and identification of novel mutations

BACKGROUND

Malignant hyperthermia (MH) is a disorder of skeletal muscle manifested as a life-threatening hypermetabolic crisis in susceptible individuals after exposure to inhalational anesthetics and depolarizing muscle relaxants. Mutations in the gene encoding the skeletal muscle ryanodine receptor (RYR1) are considered a common cause of the disorder, and, to date, more than 20 RYR1 mutations have been reported in European and Canadian families. Some studies suggest that differences may exist in the frequencies and distribution of mutations in the RYR1 gene between European and North American MH families the frequency and distribution of mutations in the RYR1 gene.

METHODS

Skeletal muscle samples from 73 unrelated individuals diagnosed as MH susceptible according to the North American MH caffeine-halothane contracture test were studied. Genomic DNA of MH-susceptible patients was investigated by polymerase chain reaction-based restriction fragment length polymorphism, single-strand conformation polymorphism, and sequencing analysis. The majority of known RYR1 mutations were analyzed using the restriction fragment length polymorphism method, whereas new mutations were searched by single-strand conformation polymorphism in exons 12, 15, 39, 40, 44, 45, and 46 of the gene.

RESULTS

Seven known RYR1 mutations (Arg163Cys, Gly248Arg, Arg614Cys, Val2168Met, Thr2206Met, Gly2434Arg, and Arg2454His) were detected at frequencies of 2.7, 1.4, 1.4, 1.4, 1.4, 5.5, and 4.1%, respectively. In addition, three novel amino acid substitutions (Val2214Ile, Ala2367Thr, and Asp2431Asn) were detected at frequency of 1.4% each. These 10 mutations account for 21.9% of the North American MH-susceptible population.

CONCLUSION

Three novel candidate mutations in the RYR1 gene were identified in these MH patients. The frequency and distribution of RYR1 mutations observed in this North American MH population was markedly different from that previously identified in Europe. Larger-scale studies are necessary to clarify the type and frequency of mutations in RYR1 associated with MH in North American families.

Multiple effects of caffeine on Ca2+ release and influx in human B lymphocytes

Caffeine has been used as a pharmacological tool to study the ryanodine receptor (RYR)-mediated Ca2+ release from caffeine-sensitive, inositol 1,4,5,-trisphosphate (IP3)-insensitive pools. In the present study, we demonstrate multiple effects of caffeine on Ca2+ homeostasis in human B lymphocytes. Although B cells express a functional RYR, which can be activated by 4-chloro-m-cresol following depletion of IP(3)-sensitive pools, caffeine does not activate RYR-mediated Ca2+ release. Instead, caffeine dose-dependently inhibited IP3 receptor (IP3R)-mediated Ca2+ release, RYR-mediated Ca2+ release and B cell receptor-initiated Ca2+ influx, while high concentrations of caffeine (> or = 25 mM) induced a Ca2+ influx. In contrast with its ability to suppress receptor-stimulated Ca2+ influx, caffeine had no significant effect on the store-operated Ca2+ (SOC) channel-dependent Ca2+ influx induced by thapsigargin. Thus, caffeine may act as an inhibitor on a single or multiple site(s) responsible for regulating the IP3R channel, RYR channel and presumably the receptor-mediated SOC channel. The present report may be the first demonstration of multiple effects of caffeine on Ca2+ mobilization in single cell type. Our results suggest the need for caution regarding use of caffeine simply as a RYR-activator to study Ca2+ homeostasis in eucaryotic cells.

Location of the ureters in relation to the uterine cervix by computed tomography

OBJECTIVE

Our aim was to determine the distance of the ureter from the cervix and the influence of age and weight on this distance.

STUDY DESIGN

The distance of the ureter from the uterine cervix was determined by evaluating the computed pelvic tomograms from 52 women. Age and body mass index were compared to this distance by means of regression analysis.

RESULTS

At the most dorsal reflection of the ureter, the average distance from ureter to cervical margin was 2.3 +/- 0.8 cm (range, 0.1-5.3 cm). There was no relationship to age, but there was a linear relationship between this distance and body mass index (R2 = 0.075; P = .049); thus the ureter was slightly more proximal to the cervical margin in heavier women.

CONCLUSIONS

In women with apparently normal pelvic anatomy, the average distance between the ureter and cervix is >2 cm. The finding that this distance is <0.5 cm in 12% of the women studied may explain the relatively common occurrence of ureteral injury during hysterectomy. The relationship between body mass index and location is clinically insignificant.

Phosphatidylinositol 3-kinase and focal adhesion kinase are early signals in the growth factor-like responses to thrombospondin-1 seen in human vascular smooth muscle

Thrombospondin-1 (TSP-1) is a matricellular protein that is expressed in negligible amounts in normal blood vessels but is markedly upregulated in vascular injury. Although TSP-1 can act as a pleiotropic regulator for human vascular smooth muscle cells (HVSMCs), the intracellular signaling pathways stimulated by this protein remain obscure. In cultured HVSMCs derived from saphenous vein, TSP-1 induces tyrosine phosphorylation of a number of cellular proteins, with a complex temporal pattern of activation. Immunoprecipitation techniques have identified the early tyrosine-phosphorylated signals as being the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI 3-K) and focal adhesion kinase (FAK). Tyrosine phosphorylation of the p85 subunit of PI 3-K showed a biphasic response to TSP-1 stimulation, which corresponded to a biphasic activation of the lipid kinase. Treatment with both wortmannin and LY294002 inhibited PI 3-K activity of HVSMCs but did not affect tyrosine phosphorylation of the p85 regulatory subunit. TSP-1-stimulated FAK phosphorylation, however, was substantially reduced by these inhibitors, as was the TSP-1-induced chemotaxis of these cells. These results suggest that activation of PI 3-K is an early signal induced by TSP-1 and is critical for chemotaxis. Activation of this kinase precedes and may occur upstream from FAK phosphorylation, although the nature of the interaction between these 2 enzymes remains obscure.

Skeletal muscle type ryanodine receptor is involved in calcium signaling in human B lymphocytes

The regulation of intracellular free Ca2+ concentration ([Ca2+]i) in B cells remains poorly understood and is presently explained almost solely by inositol 1,4,5-triphosphate (IP3)-mediated Ca2+ release, followed by activation of a store-operated channel mechanism. In fact, there are reports indicating that IP3 production does not always correlate with the magnitude of Ca2+ release. We demonstrate here that human B cells express a ryanodine receptor (RYR) that functions as a Ca2+ release channel during the B cell antigen receptor (BCR)-stimulated Ca2+ signaling process. Immunoblotting studies showed that both human primary CD19(+) B and DAKIKI cells express a 565-kDa immunoreactive protein that is indistinguishable in molecular size and immunoreactivity from the RYR. Selective reverse transcription-polymerase chain reaction, restriction fragment length polymorphism, and sequencing of cloned cDNA indicated that the major isoform of the RYR expressed in primary CD19(+) B and DAKIKI cells is identical to the skeletal muscle type (RYR1). Saturation analysis of [3H]ryanodine binding yielded Bmax = 150 fmol/mg of protein and Kd = 110 nM in DAKIKI cells. In fluo-3-loaded CD19(+) B and DAKIKI cells, 4-chloro-m-cresol, a potent activator of Ca2+ release mediated by the ryanodine-sensitive Ca2+ release channel, induced Ca2+ release in a dose-dependent and ryanodine-sensitive fashion. Furthermore, BCR-mediated Ca2+ release in CD19(+) B cells was significantly altered by 4-chloro-m-cresol and ryanodine. These results indicate that RYR1 functions as a Ca2+ release channel during BCR-stimulated Ca2+ signaling and suggest that complex Ca2+ signals that control the cellular activities of B cells may be generated by cooperation of the IP3 receptor and RYR1.

Two cases of clarithromycin-induced digoxin toxicity

Two patients experienced clarithromycin-induced digoxin toxicity. Both had stable renal function within normal limits and had been maintained on a consistent dosage of digoxin. No changes in drug therapy had been made except for the addition of clarithromycin. Administration of clarithromycin to patients receiving long-term digoxin therapy may induce digoxin toxicity. When concomitant therapy is employed, patients should be closely monitored for clinical signs and symptoms of digoxin toxicity, and digoxin concentrations should be measured to avoid it.

Dietary intakes and biochemical profiles of nutritional status of ultramarathoners

Nutritional status was determined in 17 ultramarathoners registered to participate in the Old Dominion 100-Miler. They had a mean age of 40 +/- 2 yr and ran 67.7 +/- 9.0 miles.wk-1. Subjects maintained 4-d dietary records on two occasions: usual and prerace. Fasting blood samples and 24-h urine collections were also obtained, and concentrations of selected vitamins and minerals were analyzed. Usual and prerace energy, carbohydrate and fat intakes of the ultramarathoners were not significantly different, but usual protein and alcohol intakes were significantly (P < 0.05) higher than prerace intakes. The amount of energy supplied by carbohydrates rose from a usual intake of 54.2 +/- 2.3% to 60.1 +/- 2.4% in the prerace period. Twelve subjects reported taking vitamin/mineral supplements and mean usual and prerace intakes of vitamin and minerals from food and supplements combined met the current recommendations. Biochemical indices of vitamin and mineral status were normal. However, our findings suggest that vitamin B12 metabolism may be altered in ultraendurance runners. Further research is required to determine whether ultraendurance athletes have special nutrition needs.

Consumption of a dehydrated ration for 31 days at moderate altitudes: status of zinc, copper, and vitamin B-6

Intake of energy zinc, copper, and vitamin B-6 and indexes of zinc, copper and vitamin B-6 status were determined for eight men who consumed a high-carbohydrate dehydrated ration for 31 days of high activity at moderate altitudes (2,400 to 4,300 m). Data were collected 2 months before exposure (PRE), four times during the month at moderate altitudes (ALT), and 1 month after return (RET). Mean (+/- standard error) energy intake was 2,725 +/- 215, 3,430 +/- 79, and 3,370 +/- 215 kcal/day during PRE, ALT, and RET, respectively. Zinc and copper intakes averaged 10.6 +/- 1.6 and 1.0 +/- 0.1 mg/day during PRE and increased significantly to 16.9 +/- 0.7 and 3.5 +/- 0.1 mg/day during ALT; zinc and copper intakes were 15.5 +/- 1.6 and 1.9 +/- 0.3 mg/day for RET, respectively. Similarly, vitamin B-6 intake was significantly higher during ALT (PRE = 2.2 +/- 0.5 mg/day; ALT = 4.2 +/- 0.4 mg/day; and RET = 2.6 +/- 0.4 mg/day) as compared with PRE and RET. No significant changes were noted for plasma zinc, copper, or their related proteins or plasma or erythrocyte pyridoxal-5'-phosphate. Finally, no changes in urinary excretion of zinc were observed. The results indicate that dehydrated rations provide zinc, copper, and vitamin B-6 in amounts above the Recommended Dietary Allowances. Such diets may be consumed for at least 1 month without compromising status for these nutrients.

Measurement of intracellular magnesium in a vascular smooth muscle cell line using a fluorescent probe

Until recently, direct measurement of intracellular free magnesium has been complex and difficult. However, fluorescent probes are now available, based on the same principle as well-established probes for free calcium. Using one such probe, mag-fura-2, we have estimated basal intracellular magnesium concentrations in the A7r5 rat vascular smooth muscle cell line. This level was unaffected by numerous pharmacological manipulations, including agonist stimulation and depolarisation. The possible implications of these findings are discussed.