Complement and coagulation crosstalk - Factor H in the spotlight

The immune complement and the coagulation systems are blood-based proteolytic cascades that are activated by pathway-specific triggers, based on protein-protein interactions and enzymatic cleavage reactions. Activation of these systems is finely balanced and controlled through specific regulatory mechanisms. The complement and coagulation systems are generally viewed as distinct, but have common evolutionary origins, and several interactions between these homologous systems have been reported. This complement and coagulation crosstalk can affect activation, amplification and regulatory functions in both systems. In this review, we summarize the literature on coagulation factors contributing to complement alternative pathway activation and regulation and highlight molecular interactions of the complement alternative pathway regulator factor H with several coagulation factors. We propose a mechanism where factor H interactions with coagulation factors may contribute to both complement and coagulation activation and regulation within the haemostatic system and fibrin clot microenvironment and introduce the emerging role of factor H as a modulator of coagulation. Finally, we discuss the potential impact of these protein interactions in diseases associated with factor H dysregulation or deficiency as well as evidence of coagulation dysfunction.

MAGT1 deficiency in XMEN disease is associated with severe platelet dysfunction and impaired platelet glycoprotein N-glycosylation

BACKGROUND

X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia (XMEN) disease is a primary immunodeficiency due to loss-of-function mutations in the gene encoding for magnesium transporter 1 (MAGT1). Furthermore, as MAGT1 is involved in the N-glycosylation process, XMEN disease is classified as a congenital disorder of glycosylation. Although XMEN-associated immunodeficiency is well described, the mechanisms underlying platelet dysfunction and those responsible for life-threatening bleeding events have never been investigated.

OBJECTIVES

To assess platelet functions in patients with XMEN disease.

METHODS

Two unrelated young boys, including one before and after hematopoietic stem cell transplantation, were investigated for their platelet functions, glycoprotein expression, and serum and platelet-derived N-glycans.

RESULTS

Platelet analysis highlighted abnormal elongated cells and unusual barbell-shaped proplatelets. Platelet aggregation, integrin αIIbβ3 activation, calcium mobilization, and protein kinase C activity were impaired between both patients. Strikingly, platelet responses to protease-activated receptor 1 activating peptide were absent at both low and high concentrations. These defects were also associated with decreased molecular weights of glycoprotein Ibα, glycoprotein VI, and integrin αIIb due to partial impairment of N-glycosylation. All these defects were corrected after hematopoietic stem cell transplantation.

CONCLUSION

Our results highlight prominent platelet dysfunction related to MAGT1 deficiency and defective N-glycosylation in several platelet proteins that could explain the hemorrhages reported in patients with XMEN disease.

Zonisamide safety in pregnancy: Data from the UK and Ireland epilepsy and pregnancy register

BACKGROUND

Animal data suggest teratogenic effects with zonisamide use and risk of pregnancy losses. Human data following zonisamide exposure are presently limited, but suggest low risk of malformation with elevated risk of low birth weight.

OBJECTIVE

To calculate the major congenital malformation (MCM) rate of zonisamide in human pregnancy and assess for a signal of any specific malformation pattern and associations with birth weight.

METHODS AND MATERIALS

Data were obtained from the UK and Ireland Epilepsy and Pregnancy register (UKIEPR) which is an observational, registration, and follow up study from December 1996 to July 2020. Eligibility criteria were use of zonisamide and to have been referred to the UKIEPR before the outcome of the pregnancy was known. Primary outcome was evidence of MCM.

RESULTS

From December 1996 through July 2020 there were 112 cases of first trimester exposure to zonisamide, including 26 monotherapy cases. There were 3 MCM for monotherapy cases (MCM rate 13.0% (95% confidence interval 4.5-32.1)), and 5 MCM for polytherapy cases (MCM rate 6.9% (95% confidence interval 3.0-15.2)). While the median birth weight was on 71st and 44th centile for monotherapy and polytherapy cases respectively, there was a high rate of infants born small for gestational age (21% for both).

CONCLUSION

These data raise concerns about a signal for potential teratogenicity with zonisamide in human pregnancy. Given the low numbers reported, further data will be required to adequately counsel women who use zonisamide in pregnancy.

Meta-analysis and systematic review of population-based epidemiological studies in idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is positively associated with obesity, mostly in young women. The global increase in obesity may influence the burden of IIH. Using the PubMed, Embase, MEDLINE and Web of Science databases, a meta-analysis and systematic review of epidemiological studies of IIH were performed up to June 2017. Temporal changes in IIH incidence were measured, and incidence rates of IIH were correlated with country-specific World Health Organization obesity rates. Prevalence data and shunting rates of IIH were recorded. The quality of epidemiological studies was assessed using the Standards of Reporting of Neurological Disorders (STROND) criteria. In 15 identified studies, there were 889 patients (87% women), mean age 29.8 years. The incidence of IIH ranged from 0.03 to 2.36 per 100 000 per year. The pooled incidence of IIH was 1.20 per 100 000 per year although there was very high heterogeneity (I² 98%). The incidence rates of IIH were correlated with country-specific prevalence of obesity (Spearman's correlation 0.82, P < 0.01). The prevalence of IIH was rarely recorded. A shunting procedure was reported in 8% of patients. STROND criteria were variably reported, median of 26.5 of 43 (range 16-35). IIH is a public health concern as increased obesity prevalence is associated with increased incidence of IIH. A better quality of epidemiological studies is required to improve understanding of IIH and inform health policy for IIH management.

Valgus extension overload in the pitching elbow

Five baseball pitchers, three college and two professional, with an average age of 24 years, exhibited pain between the acceleration phase and follow-through phase of the pitching motion. This caused the players to be unable to continue at the level of competition necessary to play. A significant osteophyte on the posteromedial aspect of the olecranon process was identified in all pitchers. This caused impingement with the articular wall of the olecranon fossa and often created an area of chondromalacia. The more commonly identified posterior osteophyte was present in all cases. However, if just this posterior osteophyte is removed, the described lesion will be missed, with resultant persistent disability. Surgical excision of the posteromedial osteophyte through a relatively atraumatic posterolateral approach allowed early return of function without morbidity. With an average follow up of 1 year, all of the pitchers returned for one full season at maximum effectiveness.

Classification of knee ligament instabilities

1) The intactness of the posterior cruciate ligament is a key to the basic classification system of the knee. 2) With an intact posterior cruciate ligament, single or combined rotatory instability may occur. 3) With a tear of the posterior cruciate ligament, straight instability may be found. 4) An intact posterior cruciate ligament limits the instability of the knee in full extension (adduction or abduction stress test). 5) The anterior drawer test is somewhat equivocal. A strongly positive result of the anterior drawer test does suggest that the anterior cruciate ligament is not intact, although a moderately positive result may not implicate this ligament.