Patterns of C1-Inhibitor Plasma Levels and Kinin-Kallikrein System Activation in Relation to COVID-19 Severity.

Background: Although more than four years have passed since the pandemic began, SARS-CoV-2 continues to be of concern. Therefore, research into the underlying mechanisms that contribute to the development of the disease, especially in more severe forms, remains a priority. Sustained activation of the complement (CS), contact (CAS), and fibrinolytic and kinin-kallikrein systems (KKS) has been shown to play a central role in the pathogenesis of the disease.

Proof of concept of a new plasma complement Factor H from waste plasma fraction.

Introduction: Complement factor H (FH) is a major regulator of the complement alternative pathway, its mutations predispose to an uncontrolled activation in the kidney and on blood cells and to secondary C3 deficiency. Plasma exchange has been used to correct for FH deficiency and although the therapeutic potential of purified FH has been suggested by experiments in animal models, a clinical approved FH concentrate is not yet available. We aimed to develop a purification process of FH from a waste fraction rather than whole plasma allowing a more efficient and ethical use of blood and plasma donations.

Venous Thromboembolism Management throughout the COVID-19 Era: Addressing Acute and Long-Term Challenges.

COVID-19 increases the risk of venous thromboembolism (VTE) through a complex interplay of mechanisms collectively referred to as immunothrombosis. Limited data exist on VTE challenges in the acute setting throughout a dynamic long-term follow-up of COVID-19 patients compared to non-COVID-19 patients. The aim of the study was to investigate acute and long-term management and complications in VTE patients with and without COVID-19.

A New Ultrasensitive Bioluminescence-Based Method for Assaying Monoacylglycerol Lipase.

A novel bioluminescent Monoacylglycerol lipase (MAGL) substrate 6-O-arachidonoylluciferin, a D-luciferin derivative, was synthesized, physico-chemically characterized, and used as highly sensitive substrate for MAGL in an assay developed for this purpose. We present here a new method based on the enzymatic cleavage of arachidonic acid with luciferin release using human Monoacylglycerol lipase (MAGL) followed by its reaction with a chimeric luciferase, PLG2, to produce bioluminescence. Enzymatic cleavage of the new substrate by MAGL was demonstrated, and kinetic constants Km and Vmax were determined.

Anti-C1-Inhibitor Autoantibody Detection by ELISA.

Enzyme-linked immunosorbent assay (ELISA) is a quantitative analytical method used to measure the concentration of molecules in biological fluids through antigen-antibody reactions. Here we describe the measurement of anti-C1-inhibitor autoantibodies by an indirect ELISA. In this method patients' sera are incubated in a microplate coated with plasma derived C1-inhibitor.

IgM Autoantibodies to Complement Factor H in Atypical Hemolytic Uremic Syndrome.

Background: Atypical hemolytic uremic syndrome (aHUS), a severe thrombotic microangiopathy, is often related to complement dysregulation, but the pathomechanisms remain unknown in at least 30% of patients. Researchers have described autoantibodies to complement factor H of the IgG class in 10% of patients with aHUS but have not reported anti-factor H autoantibodies of the IgM class.

Methods: In 186 patients with thrombotic microangiopathy clinically presented as aHUS, we searched for anti-factor H autoantibodies of the IgM class and those of the IgG and IgA classes.

The central role of endothelium in hereditary angioedema due to C1 inhibitor deficiency.

An impairment of the endothelial barrier function underlies a wide spectrum of pathological conditions. Hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE) can be considered the "pathophysiological and clinical paradigm" of Paroxysmal Permeability Diseases (PPDs), conditions characterized by recurrent transient primitively functional alteration of the endothelial sieving properties, not due to inflammatory-ischemic-degenerative injury and completely reversible after the acute flare. It is a rare yet probably still underdiagnosed disease which presents with localized, non-pitting swelling of the skin and submucosal tissues of the upper respiratory and gastrointestinal tracts, without significant wheals or pruritus.

Intermittent C1-Inhibitor Deficiency Associated with Recessive Inheritance: Functional and Structural Insight.

C1-inhibitor is a serine protease inhibitor (serpin) controlling complement and contact system activation. Gene mutations result in reduced C1-inhibitor functional plasma level causing hereditary angioedema, a life-threatening disorder. Despite a stable defect, the clinical expression of hereditary angioedema is unpredictable, and the molecular mechanism underlying this variability remains undisclosed.

Acquired Complement Regulatory Gene Mutations and Hematopoietic Stem Cell Transplant-Related Thrombotic Microangiopathy.

Hematopoietic stem cell transplant-related thrombotic microangiopathy (HSCT-TMA) is a severe complication whose pathophysiology is unknown. We describe 6 patients in which the disease was associated with complement regulatory gene abnormalities received from their respective donors. It is suggested that mutated and transplanted monocyte-derived cells are responsible for production of abnormal proteins, complement dysregulation, and, ultimately, for the disease.

Rapid isolation of pure Complement Factor H from serum for functional studies by the use of a monoclonal antibody that discriminates FH from all the other isoforms.

Several mutations have been identified in the gene coding for Complement Factor H (FH) from patients with atypical Hemolytic Uraemic Syndrome (aHUS), Age-related Macular Degeneration (AMD) and Membranoproliferative Glomerulonephritis (MPGN). These data allow for a precise description of the structural changes affecting FH, but a simple test for specifically assessing FH function routinely is not yet of common use. We have produced and characterised a monoclonal antibody (5H5) which discriminates between FH and the smaller FH-like 1 and FH-related proteins and show here that it specifically binds to FH without detecting the smaller isoforms.

BDNF repairs podocyte damage by microRNA-mediated increase of actin polymerization.

Idiopathic focal segmental glomerulosclerosis (FSGS) is a progressive and proteinuric kidney disease that starts with podocyte injury. Podocytes cover the external side of the glomerular capillary by a complex web of primary and secondary ramifications. Similar to dendritic spines of neuronal cells, podocyte processes rely on a dynamic actin-based cytoskeletal architecture to maintain shape and function.

Podocyte glutamatergic signaling contributes to the function of the glomerular filtration barrier.

Podocytes possess the complete machinery for glutamatergic signaling, raising the possibility that neuron-like signaling contributes to glomerular function. To test this, we studied mice and cells lacking Rab3A, a small GTPase that regulates glutamate exocytosis. In addition, we blocked the glutamate ionotropic N-methyl-d-aspartate receptor (NMDAR) with specific antagonists.

Interstitial vascular rarefaction and reduced VEGF-A expression in human diabetic nephropathy.

Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN.

Glomerular podocytes contain neuron-like functional synaptic vesicles.

Although patients with chronic renal failure are increasing worldwide, many aspects of kidney biology remain to be elucidated. Recent research has uncovered several molecular properties of the glomerular filtration barrier, in which podocytes, highly differentiated, ramified cells that enwrap the glomerular basement membrane, have been reported to be mainly responsible for filter's selectivity. We previously described that podocytes express Rab3A, a GTPase restricted to cell types that are capable of highly regulated exocytosis, such as neuronal cells.

Glomerular podocytes possess the synaptic vesicle molecule Rab3A and its specific effector rabphilin-3a.

Several recent studies have focused on similarities between glomerular podocytes and neurons because the two cells share a specialized cytoskeletal organization and several expression-restricted proteins, such as nephrin and synaptopodin. In neurons, the small guanosine triphosphatase Rab3A and its effector rabphilin-3A form a complex required for the correct docking of synaptic vesicles to their target membrane. Because rabphilin-3A binds in neurons to cytoskeletal proteins also important for podocyte homeostasis, and the complex rabphilin-3A-Rab3A has been demonstrated in neurons and neuroendocrine cells, the aim of our work was to investigate their possible expression and regulation in podocytes.