The neuromuscular and multisystem features of RYR1-related malignant hyperthermia and rhabdomyolysis: A study protocol

INTRODUCTION

Malignant hyperthermia (MH) and exertional rhabdomyolysis (ERM) have long been considered episodic phenotypes occurring in response to external triggers in otherwise healthy individuals with variants in RYR1. However, recent studies have demonstrated a clinical and histopathological continuum between patients with RYR1-related congenital myopathies and those with ERM or MH susceptibility. Furthermore, animal studies have shown non-neuromuscular features such as a mild bleeding disorder and an immunological gain-of-function associated with MH/ERM related RYR1 variants raising important questions for further research. Awareness of the neuromuscular disease spectrum and potential multisystem involvement in RYR1-related MH and ERM is essential to optimize the diagnostic work-up, improve counselling and and future treatment strategies for patients affected by these conditions. This study will examine in detail the nature and severity of continuous disease manifestations and their effect on daily life in patients with RYR1-related MH and ERM.

METHODS

The study protocol consists of four parts; an online questionnaire study, a clinical observational study, muscle imaging, and specific immunological studies. Patients with RYR1-related MH susceptibility and ERM will be included. The imaging, immunological and clinical studies will have a cross-sectional design, while the questionnaire study will be performed three times during a year to assess disease impact, daily living activities, fatigue and pain. The imaging study consists of muscle ultrasound and whole-body magnetic resonance imaging studies. For the immunological studies, peripheral mononuclear blood cells will be isolated for in vitro stimulation with toll-like receptor ligands, to examine the role of the immune system in the pathophysiology of RYR1-related MH and ERM.

DISCUSSION

This study will increase knowledge of the full spectrum of neuromuscular and multisystem features of RYR1-related MH and ERM and will establish a well-characterized baseline cohort for future studies on RYR1-related disorders. The results of this study are expected to improve recognition of RYR1-related symptoms, counselling and a more personalized approach to patients affected by these conditions. Furthermore, results will create new insights in the role of the immune system in the pathophysiology of MH and ERM.

TRIAL REGISTRATION

This study was pre-registered at ClinicalTrials.gov (ID: NCT04610619).

Stewart analysis unmasks acidifying and alkalizing effects of ionic shifts during acute severe respiratory alkalosis

PURPOSE

Although both the Henderson-Hasselbalch method and the Stewart approach can be used to analyze acid-base disturbances and metabolic and respiratory compensation mechanisms, the latter may be superior in detecting subtle metabolic changes.

MATERIALS AND METHODS

We analyzed acid-base disturbances using both approaches in six healthy male volunteers practicing extreme voluntary hyperventilation. Arterial blood gas parameters were obtained during a breathing exercise consisting of approximately 30 cycles of powerful hyperventilation followed by breath retention for approximately 2 min.

RESULTS

Hyperventilation increased pH from 7.39 ± 0.01 at baseline to 7.74 ± 0.06, PaCO₂ decreased from 34.1 ± 1.1 to 12.6 ± 0.7 mmHg, PaO₂ increased from 116 ± 4.6 to 156 ± 4.3 mmHg. Baseline apparent strong ion difference was 42.3 ± 0.5 mEq/L, which decreased to 37.1 ± 0.7 mEq/L following hyperventilation. The strong ion gap significantly decreased following hyperventilation, with baseline levels of 10.0 ± 0.9 dropping to 6.4 ± 1.1 mEq/L.

CONCLUSIONS

Henderson-Hasselbalch analysis indicated a profound and purely respiratory alkalosis with no metabolic compensation following extreme hyperventilation. The Stewart approach revealed metabolic compensation occurring within minutes. These results challenge the long-held axiom that metabolic compensation of acute respiratory acid-base changes is a slow process.

Pharmacokinetics, safety and tolerability of the novel β-hCG derived immunomodulatory compound, EA-230

Aims

EA‐230 is a newly developed synthetic linear tetrapeptide (AQGV) derived from the chorionic gonadotropin hormone (β‐hCG). We investigated the pharmacokinetics, safety and tolerability of EA‐230 in healthy subjects using different administration strategies.

Methods

Double‐blind, randomized, placebo‐controlled, dose‐escalating phase I studies in healthy subjects using intravenous administration were conducted. In the single dosage study, 32 subjects were assigned to four single dosage groups (1, 3, 10 or 30 mg/kg). In the multiple dosage study, 24 subjects were assigned to three dosage groups (10, 20 or 30 mg/kg, thrice daily for 3 days). In the continuous dosage study, 24 subjects were assigned to three dosage groups (15, 30, or 90 mg/kg/hour for 2 hours). Pharmacokinetics, safety and tolerability assessments were performed up to 14 days.

Results

The highest dosage of EA‐230 (continuous infusion of 90 mg/kg/hour for 2 hours) showed more than proportional increases in exposure (C_max136%; AUC_0‐last137%), a large volume of distribution (geometric mean and 95% CI: 13 [3–58] L/kg), a high clearance rate (26 [15–43] L/h/kg), and a short half‐life (0.35 [0.13–1.0] minutes). EA‐230 was well tolerated and no safety concerns were observed.

Conclusion

These dose‐escalating phase I studies with different administration strategies reveal a pharmacokinetic profile of EA‐230 with a large volume of distribution and a short half‐life. Furthermore, EA‐230 was well tolerated and no safety issues emerged. These results have enabled further clinical development in a phase IIa trial assessing the pharmacodynamics of this compound during systemic inflammation described elsewhere in this issue.

A randomized double-blind, placebo-controlled clinical phase IIa trial on safety, immunomodulatory effects and pharmacokinetics of EA-230 during experimental human endotoxaemia

AIMS

EA-230 is a human chorionic gonadotropin hormone-derived linear tetrapeptide, developed for the treatment of systemic inflammation-related disorders. EA-230 has shown promising immunomodulatory and tissue-protective effects in animals and an excellent safety profile in human phase I studies that we performed. The present phase IIa study follows-up on these results by investigating the safety, efficacy and pharmacokinetics of EA-230 under systemic inflammatory conditions induced by experimental human endotoxaemia.

METHODS

In this randomized, double blind, placebo-controlled phase IIa study, systemic inflammation was induced by intravenous administration of Escherichia coli-derived lipopolysaccharide (LPS). At t = 0 hours, 36 healthy male volunteers received 2 ng/kg LPS, followed by a 2-hour continuous infusion of EA-230 (15, 45 and 90 mg/kg/h, n = 8 per group) or placebo (n = 12).

RESULTS

EA-230 was well tolerated and showed a favourable safety profile. Treatment with the highest dose of EA-230 resulted in a significant attenuation of the LPS-induced increase in plasma levels of inflammatory mediators interleukin (IL)-6, IL-8, IL-1 receptor antagonist, monocyte chemoattractant protein-1, macrophage inflammatory proteins-1α and -1β, and vascular cell adhesion protein-1 (% reduction of 48, 28, 33, 28, 14, 16 and 19 respectively, p < .01), and reduced fever (peak decrease from 1.8 ± 0.1°C to 1.3 ± 0.2°C, P < .05) and symptom scores (peak decrease from 7.4 ± 1.0 to 4.0 ± 1.2 points, P < .05). EA-230 exhibited a very short elimination half-life and a large volume of distribution in the highest dosage group (geometric mean and 95% confidence interval: 0.17 [0.12-0.24] hours and 2.2 [1.3-3.8] L/kg, respectively).

CONCLUSION

Administration of EA-230 is safe and results in attenuation of the systemic inflammatory response in humans.

Vascular endothelial growth factor is increased during the first 48 hours of human septic shock and correlates with vascular permeability

Meningococcal septic shock is an important cause of morbidity and mortality in children and young adults worldwide and is the prototypical gram-negative septic shock. One of the key factors in the development of shock is increased microvascular permeability. Vascular endothelial growth factor (VEGF) is a central factor in angiogenesis and is an important mediator of vascular permeability. Thirteen patients with meningococcal infection (eight presenting with shock) were investigated in the early phase of invasive meningococcal disease. Cytokines, complement activation, and VEGF plasma concentrations were measured during the first 48 h on the pediatric intensive care unit. Increased cytokine concentrations and activation of the complement system were observed. VEGF plasma concentrations were increased (median 193 pg/mL, range 71-1082) and were highest in the presence of shock (208 pg/mL, 169-1082) compared with patients presenting without shock (92 pg/mL range 71-299). VEGF concentration at admission correlated with the severity of disease (pediatric risk of mortality score, R=0.90 [Spearman], P=0.0001) and the amount of fluids administered within the first 24 h (R=0.90, P<0.0001). In all patients, a decrease in VEGF was associated with a decrease in fluid intake during t=24 to 48 h. The results suggest that apart from correlation with IL-1 beta, -10, -12, and complement activation, microvascular permeability in sepsis is also closely linked to the plasma concentration of VEGF. The role of VEGF in sepsis-associated increased microvascular permeability needs further exploration and may represent a new therapeutic target.