Human genetics of meningococcal infections

Neisseria meningitidis is a leading cause of bacterial septicaemia and meningitis worldwide. Meningococcal disease is rare but can be life threatening with a tendency to affect children. Many studies have investigated the role of human genetics in predisposition to N. meningitidis infection. These have identified both rare single-gene mutations as well as more common polymorphisms associated with meningococcal disease susceptibility and severity. These findings provide clues to the pathogenesis of N. meningitidis, the basis of host susceptibility to infection and to the aetiology of severe disease. From the multiple discoveries of monogenic complement deficiencies to the associations of complement factor H and complement factor H-related three polymorphisms to meningococcal disease, the complement pathway is highlighted as being central to the genetic control of meningococcal disease. This review aims to summarise the current understanding of the host genetic basis of meningococcal disease with respect to the different stages of meningococcal infection

A Rare Mutation in SPLUNC1 Affects Bacterial Adherence and Invasion in Meningococcal Disease

BACKGROUND Neisseria meningitidis (Nm) is a nasopharyngeal commensal carried by healthy individuals. However, invasive infections occurs in a minority of individuals, with devastating consequences. There is evidence that common polymorphisms are associated with invasive meningococcal disease (IMD), but the contributions of rare variants other than those in the complement system have not been determined. METHODS We identified familial cases of IMD in the UK meningococcal disease study and the European Union Life-Threatening Infectious Disease Study. Candidate genetic variants were identified by whole-exome sequencing of 2 patients with familial IMD. Candidate variants were further validated by in vitro assays. RESULTS Exomes of 2 siblings with IMD identified a novel heterozygous missense mutation in BPIFA1/SPLUNC1. Sequencing of 186 other nonfamilial cases identified another unrelated IMD patient with the same mutation. SPLUNC1 is an innate immune defense protein expressed in the nasopharyngeal epithelia; however, its role in invasive infections is unknown. In vitro assays demonstrated that recombinant SPLUNC1 protein inhibits biofilm formation by Nm, and impedes Nm adhesion and invasion of human airway cells. The dominant negative mutant recombinant SPLUNC1 (p.G22E) showed reduced antibiofilm activity, increased meningococcal adhesion, and increased invasion of cells, compared with wild-type SPLUNC1. CONCLUSIONS A mutation in SPLUNC1 affecting mucosal attachment, biofilm formation, and invasion of mucosal epithelial cells is a new genetic cause of meningococcal disease

Stakeholders' perspectives on the regulation and integration of complementary and alternative medicine products in Lebanon: a qualitative study

<p>Abstract</p> <p>Background</p> <p>The regulation of the markets for Complementary and Alternative Medicine (CAM) products presents a global challenge. There is a dearth of studies that have examined or evaluated the regulatory policies of CAM products in the Eastern Mediterranean Region (EMR). We investigate the regulatory frameworks and the barriers for the proper regulation and integration of CAM products in Lebanon, as an example of an EMR country with a weak public infrastructure.</p> <p>Methods</p> <p>We utilized a qualitative study design involving a series of semi-structured interviews with stakeholders of the CAM market in Lebanon. Snowball sampling was used to identify interviewees; interviews continued until the "saturation" point was reached. A total of 16 interviews were carried out with decision makers, representatives of professional associations, academic researchers, CAM product importers, policy makers and a media representative. Interviews were transcribed and thematic analysis of scripts was carried out.</p> <p>Results</p> <p>There was a consensus among all stakeholders that the regulation of the market for CAM products in Lebanon needs to be strengthened. Thematic analysis identified a number of impediments jeopardizing the safety of public consumption and hindering the integration of CAM therapies into mainstream medicine; including: weak infrastructure, poor regulation, ineffective policies and politics, weak CAM awareness and sub-optimal coordination and cooperation among stakeholders. With respect to policy instruments, voluntary instruments (self regulation) were deemed ineffective by stakeholders due to poor awareness of both users and providers on safe use of CAM products. Stakeholders' rather recommended the adoption of a combination of mixed (enhancing public awareness and integration of CAM into medical and nursing curricula) and compulsory (stricter governmental regulation) policy instruments for the regulation of the market for CAM products.</p> <p>Conclusions</p> <p>The current status quo with respect to the regulation of CAM products in Lebanon is not conducive to public safety, nor does it support the integration of CAM products into the healthcare system. The Ministry of Health indeed plays a dominant role in the regulation of these products through a combination of mixed and compulsory policy instruments. Yet, the proper implementation of these regulations requires political resolve coupled with the cooperation of all CAM stakeholders.</p

Heterozygous BTNL8 variants in individuals with multisystem inflammatory syndrome in children (MIS-C)

\ua9 2024 Bellos et al.Multisystem inflammatory syndrome in children (MIS-C) is a rare condition following SARS-CoV-2 infection associated with intestinal manifestations. Genetic predisposition, including inborn errors of the OAS-RNAseL pathway, has been reported. We sequenced 154 MIS-C patients and utilized a novel statistical framework of gene burden analysis, “burdenMC,” which identified an enrichment for rare predicted-deleterious variants in BTNL8 (OR = 4.2, 95% CI: 3.5-5.3, P &lt; 10-6). BTNL8 encodes an intestinal epithelial regulator of Vγ4+γδ T cells implicated in regulating gut homeostasis. Enrichment was exclusive to MIS-C, being absent in patients with COVID-19 or bacterial disease. Using an available functional test for BTNL8, rare variants from a larger cohort of MIS-C patients (n = 835) were tested which identified eight variants in 18 patients (2.2%) with impaired engagement of Vγ4+γδ T cells. Most of these variants were in the B30.2 domain of BTNL8 implicated in sensing epithelial cell status. These findings were associated with altered intestinal permeability, suggesting a possible link between disrupted gut homeostasis and MIS-C-associated enteropathy triggered by SARS-CoV-2

Inborn errors of type I IFN immunity in patients with life-threatening COVID-19.

Clinical outcome upon infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ranges from silent infection to lethal coronavirus disease 2019 (COVID-19). We have found an enrichment in rare variants predicted to be loss-of-function (LOF) at the 13 human loci known to govern Toll-like receptor 3 (TLR3)- and interferon regulatory factor 7 (IRF7)-dependent type I interferon (IFN) immunity to influenza virus in 659 patients with life-threatening COVID-19 pneumonia relative to 534 subjects with asymptomatic or benign infection. By testing these and other rare variants at these 13 loci, we experimentally defined LOF variants underlying autosomal-recessive or autosomal-dominant deficiencies in 23 patients (3.5%) 17 to 77 years of age. We show that human fibroblasts with mutations affecting this circuit are vulnerable to SARS-CoV-2. Inborn errors of TLR3- and IRF7-dependent type I IFN immunity can underlie life-threatening COVID-19 pneumonia in patients with no prior severe infection

Genetic Determinants of the Complement and Coagulation Pathways in Invasive Meningococcal Disease.

BackgroundThe complement and coagulation pathways are implicated in the systemic manifestations of invasive meningococcal disease (MD) However, the genetic landscape of these two interconnected plasma proteolytic pathways has not been systematically explored.ObjectiveWe investigated how genetic variation in the complement and coagulation pathways contributes to invasive meningococcal disease.MethodsWhole Exome Sequencing (WES) and high-coverage amplicon-based sequencing were performed in a large series of 229 MD patients. As a control cohort we used 275 patients with other invasive bacterial infections.ResultsOur WES data show an enrichment of rare variants in the complement and coagulation genes in MD, namely CFP and FCGR2A. In a subcohort of severe MD, CFP and SERPINE1 were enriched for rare variants compared to the control infection cohorts. Combining the amplicon panel and the WES datasets, we identified a mild hemophilia A case, five properdin mutated individuals and four digenic complement deficiencies. In addition, we report a significant copy number variant association in the CFH/CFHR1-5 gene cluster. This provides strong support for the role of complement regulation in MD. Furthermore, there are pathogenic variants in VWF, PROS1 and SERPINC1, relevant to coagulation and fibrinolysis.ConclusionThe study demonstrates the value of a mechanistic pathway approach to describe the genetic landscape of infectious disease, particularly in understanding its course and outcome. Notably, we identify complement-mediated thrombotic microangiopathy (CM-TMA) as a key pathophysiologic mechanism involved, particularly in MD.Clinical implicationUnderstanding the genetic landscape may enable further exploration of novel complement- and TMA-directed therapies

The mechanism of DNA unwinding by the eukaryotic replicative helicase

Accurate DNA replication is tightly regulated in eukaryotes to ensure genome stability during cell division and is performed by the multi-protein replisome. At the core an AAA+ hetero-hexameric complex, Mcm2-7, together with GINS and Cdc45 form the active replicative helicase Cdc45/Mcm2-7/GINS (CMG). It is not clear how this replicative ring helicase translocates on, and unwinds, DNA. We measure real-time dynamics of purified recombinant Drosophila melanogaster CMG unwinding DNA with single-molecule magnetic tweezers. Our data demonstrates that CMG exhibits a biased random walk, not the expected unidirectional motion. Through building a kinetic model we find CMG may enter up to three paused states rather than unwinding, and should these be prevented, in vivo fork rates would be recovered in vitro. We propose a mechanism in which CMG couples ATP hydrolysis to unwinding by acting as a lazy Brownian ratchet, thus providing quantitative understanding of the central process in eukaryotic DNA replication

Progranulin/Tumor Necrosis Factor-α\alpha ratio in Psoriasis Vulgaris

Background and Aim: In psoriasis, the proteins Tumor Necrosis Factor (TNF) and interleukin-6 (IL-6) are overexpressed and play important roles in the disease's progression. For treating psoriasis, biological drugs that target TNF signaling are quite successful. Embryogenesis, tissue repair, cancer, neuronal survival, host defense, and inflammation are all dependent on progranulin (PGRN). By competing with TNF binding to TNFR1/2, PGRN inhibits TNF-mediated signaling pathways and has anti-inflammatory properties in inflammatory arthritis models. The current research seeks to study the relationship between serum PGRN / TNF - $\alpha$and psoriasis vulgaris activity.&#x0D; Subjects &amp; Methods: This study’s subjects were categorized into 2 groups: group 1 with 35 patients with psoriasis vulgaris, and group 2 of 30 healthy subjects with matched age and sex.&#x0D; Results: We discovered a significant increase in PGRN and TNF-$\alpha$in cases versus control. And we have found a significant decrease in PGRN/TNF-$\alpha$ratio in cases versus control. We also detected significant differences between the Psoriasis Area Severity Index (PASI) degree and the levels of PGRN and TNF-$\alpha$, as well as the PGRN/TNF-$\alpha$ratio. We discovered a negative significant correlation between PASI and PGRN/TNF-$\alpha$ratio.&#x0D; Conclusion: Atsttrin exhibited potent anti-inflammatory properties due to its three modified granulin motifs and their associated linker regions. In the treatment of rheumatoid arthritis and contact dermatitis, PGRN and its derivative Atsttrin may be a potential therapeutic drug.</jats:p