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This study seeks to discover how the concentration of complement proteins, factors B and P are affected in HIV-associated PE. This study included 72 pregnant women: 36 preeclamptic and 36 normotensive. Serum concentrations of factors B and P were measured using a Bioplex immunoassay. A significant decrease of factor B in the HIV+ compared to the HIV- group was noted. No significant difference across all groups for both analytes was observed. Our results suggest the alternative pathway (AP) is inhibited by HIV evading immune detection. The AP is not excessively activated in PE during the third trimester. [ABSTRACT FROM AUTHOR]

The article presents a study related to an increased alternative complement pathway function and improved survival during critical illness. It mentions that patients with elevated alternative pathway (AH50) had an increased levels of activator protein (AP) factors B, H, and properdin, and some patients showed a "hyperinflammatory" subphenotype. It mentions overexuberant activation of complement system is thought to contribute to the pathogenesis of sepsis despite its role in immune function.

Ocular inflammation is a defining feature of sight threating diseases and its dysregulation can catalyze and or propagate ocular neurodegenerative maladies such as age-related macular degeneration (AMD). The complement system, an intrinsic component of the innate immunity, has an integral role in maintaining immune-surveillance and homeostasis in the ocular microenvironment; however, overstimulation can drive ocular inflammatory diseases. The mechanism for complement disease propagation in AMD is not fully understood, although there is accumulating evidence showing that targeted modulation of complement-specific proteins has the potential to become a viable therapeutic approach. To date, a major focus of complement therapeutics has been on targeting the alternative complement system in AMD. Recent studies have outlined potential complement cascade inhibitors that might mitigate AMD disease progression. First-in-class complement inhibitors target the modulation of complement proteins C3, C5, factor B, factor D, and properdin. Herein, we will summarize ocular inflammation in the context of AMD disease progression, current clinical outcomes and complications of complement-mediated therapeutics. Given the need for additional therapeutic approaches for ocular inflammatory diseases, targeted complement modulation has emerged as a leading candidate for eliminating inflammation-driven ocular maladies. [ABSTRACT FROM AUTHOR]

The alternative pathway of complement originated from the Properdin pathway originally described by the Pillemer laboratory in the 1950s. This work generated great controversy and it took several decades for a consensus on its components, its reaction sequence and its functions to emerge. This paper reviews this history and attempts to clarify some of the ambiguities that remain. [ABSTRACT FROM AUTHOR]

Background Heart transplantation (HT) is a life-saving treatment for patients with end-stage heart failure. One of the main problems after HT is the humoral response termed antibody-mediated rejection (AMR). Complement activation plays a key role in AMR contributing to graft damage. The aim of this study was to analyze genetic variants in genes related to the complement pathways that could be associated with the development of AMR. Methods Analysis of 51 genes related to the complement pathway was performed by next-generation sequencing in 46 HT recipients, 23 with and 23 without AMR. Statistical analysis was performed with SNPstats and R. Results We identified 2 single nucleotide polymorphisms, 1 in the mannose-binding lectin 2 gene (p.Gly54Asp- MBL2 ) and 1 in the complement factor properdin gene (p.Asn428(p=)- CFP ), that showed significant association with the absence and development of AMR, respectively. Moreover, the presence of the rare allele in p.Gly54Asp- MBL2 control patients correlated with an immunodeficiency of mannose-binding lectin (6.24 ng/ml vs 207.50 ng/ml, p < 0.01), whereas the presence of the rare allele p.Asn428(p=)- CFP in patients with AMR correlated with higher levels of properdin protein (14.65 μg/ml vs 10.77 μg/ml, p < 0.05). Conclusions AMR is a complex phenotype affected by many recipient factors. Variants in p.Gly54Asp- MBL2 and p.Asn428(p=)- CFP genes, encoding mannose-binding lectin 2 and properdin, may influence the risk of AMR. [ABSTRACT FROM AUTHOR]

This review is not intended to cover in detail all aspects of the discovery and evolution of our understanding of the “alternative pathway” of complement activation, there are many excellent reviews that do this (see Fearon (CRC Crit Rev Immunol 1:1–32, 1979), Pangburn and Müller-Eberhard (Springer Semin Immunopathol 7:163–192, 1984)), but instead to give sufficient background for current concepts to be put in context. The prevailing textbook view, of components having a primary role as an alternative “pathway” for C3 activation, is challenged, with an argument developed for the primary role of the system being that of providing a surface-dependent amplification loop for both C3 and C5 activation. Whatever the mechanism by which the initial C3b molecule is generated, deposition onto a surface has the potential to target that surface for elimination. Elimination or escape from initial targeting is determined by a sophisticated and highly regulated amplification loop for C3 activation. This viewpoint of the system is then briefly developed to provide a context for therapeutic treatment of disease caused, at least in part, by dysregulated amplification of C3 activation, and to highlight some of the challenges that such therapies will face and need to address. [ABSTRACT FROM AUTHOR]

A key component of both innate and adaptive immunity, new understandings of the complement system are expanding its roles beyond that traditionally appreciated. Evidence is accumulating that complement has an intracellular arsenal of components that provide not only immune defense, but also assist in key interactions for host cell functions. Although early work has primarily centered on T cells, the intracellular complement system likely functions in many if not most cells of the body. Some of these functions may trace their origins to the primitive complement system that began as a primeval form of C3 likely tasked for protection from intracellular pathogen invasion. This later expanded to include extracellular defense as C3 became a secreted protein to patrol the vasculature. Other components were added to the growing system including regulators to protect host cells from the indiscriminate effects of this potent system. Contemporary cells may retain some of these vestigial remnants. We now know that a) C3 serves as a damage-associated molecular pattern (in particular by coating pathogens that translocate into cells), b) most cells store C3 and recycle C3(H 2 O) for immediate use, and c) C3 assists in cellular survival and metabolic reprogramming. Other components also are part of this hidden arsenal including C5, properdin, factors H and B, and complement receptors. Importantly, better definition of the intracellular complement system may translate into new target discovery to assist in creating the next generation of complement therapeutics. [ABSTRACT FROM AUTHOR]

Two functions have been assigned to properdin; stabilization of the alternative convertase, C3bBb, is well accepted, whereas the role of properdin as pattern recognition molecule is controversial. The presence of nonphysiological aggregates in purified properdin preparations and experimental models that do not allow discrimination between the initial binding of properdin and binding secondary to C3b deposition is a critical factor contributing to this controversy. In previous work, by inhibiting C3, we showed that properdin binding to zymosan and Escherichia coli is not a primary event, but rather is solely dependent on initial C3 deposition. In the present study, we found that properdin in human serum bound dose-dependently to solid-phase myeloperoxidase. This binding was dependent on C3 activation, as demonstrated by the lack of binding in human serum with the C3-inhibitor compstatin Cp40, in C3-depleted human serum, or when purified properdin is applied in buffer. Similarly, binding of properdin to the surface of human umbilical vein endothelial cells or Neisseria meningitidis after incubation with human serum was completely C3-dependent, as detected by flow cytometry. Properdin, which lacks the structural homology shared by other complement pattern recognition molecules and has its major function in stabilizing the C3bBb convertase, was found to bind both exogenous and endogenousmolecular patterns in a completely C3-dependent manner. We therefore challenge the view of properdin as a pattern recognition molecule, and argue that the experimental conditions used to test this hypothesis should be carefully considered, with emphasis on controlling initial C3 activation under physiological conditions. [ABSTRACT FROM AUTHOR]

Previous studies have shown that complement activation on renal tubular cells is involved in the induction of interstitial fibrosis and cellular injury. Evidence suggests that the tubular cell damage is initiated by the alternative pathway (AP) of complement with properdin having an instrumental role. Properdin is a positive regulator of the AP, which can bind necrotic cells as well as viable proximal tubular epithelial cells (PTECs), inducing complement activation. Various studies have indicated that in the circulation there is an unidentified inhibitor of properdin. We investigated the ability of C-reactive protein (CRP), both in its monomeric (mCRP) and pentameric (pCRP) form, to inhibit AP activation and injury in vitro on renal tubular cells by fluorescent microscopy, ELISA, and flow cytometry. We demonstrated that preincubation of properdin with normal human serum inhibits properdin binding to viable PTECs. We identified mCRP as a factor able to bind to properdin in solution, thereby inhibiting its binding to PTECs. In contrast, pCRP exhibited no such binding and inhibitory effect. Furthermore, mCRP was able to inhibit properdindirected C3 and C5b-9 deposition on viable PTECs. The inhibitory ability of mCRP was not unique for viable cells but also demonstrated for binding to necrotic Jurkat cells, a target for properdin binding and complement activation. In summary, mCRP is an inhibitor of properdin in both binding to necrotic cells and viable renal cells, regulating complement activation on the cell surface. We propose that mCRP limits amplification of tissue injury by controlling properdin-directed complement activation by damaged tissue and cells. [ABSTRACT FROM AUTHOR]

Properdin (P) stabilizes the alternative pathway (AP) convertases, being the only known positive regulator of the complement system. In addition, P is a pattern recognition molecule able to initiate directly the AP on non-self surfaces. Although P deficiencies have long been known to be associated with Neisseria infections and P is often found deposited at sites of AP activation and tissue injury, the potential role of P in the pathogenesis of complement dysregulation-associated disorders has not been studied extensively. Serum P levels were measured in 49 patients with histological and clinical evidence of C3 glomerulopathy (C3G). Patients were divided into two groups according to the presence or absence of C3 nephritic factor (C3NeF), an autoantibody that stabilizes the AP C3 convertase. The presence of this autoantibody results in a significant reduction in circulating C3 ( P < 0·001) and C5 levels ( P < 0·05), but does not alter factor B, P and sC5b-9 levels. Interestingly, in our cohort, serum P levels were low in 17 of the 32 C3NeF-negative patients. This group exhibited significant reduction of C3 ( P < 0·001) and C5 ( P < 0·001) and increase of sC5b-9 ( P < 0·001) plasma levels compared to the control group. Also, P consumption was correlated significantly with C3 ( r = 0·798, P = 0·0001), C5 ( r = 0·806, P < 0·0001), sC5b-9 ( r = −0·683, P = 0·043) and a higher degree of proteinuria ( r = −0·862, P = 0·013). These results illustrate further the heterogeneity among C3G patients and suggest that P serum levels could be a reliable clinical biomarker to identify patients with underlying surface AP C5 convertase dysregulation. [ABSTRACT FROM AUTHOR]

Citrobacter rodentium is an attaching and effacing mouse pathogen that models enteropathogenic and enterohemorrhagic Escherichia coli in humans. The complement system is an important innate defense mechanism; however, only scant information is available about the role of complement proteins during enteric infections. In this study, we examined the impact of the lack of properdin, a positive regulator of complement, in C. rodentium-induced colitis. Following infection, properdin knockout (PKO) mice had increased diarrhea and exacerbated inflammation combined with defective epithelial cell-derived IL-6 and greater numbers of colonizing bacteria. The defect in the mucosal response was reversed by administering exogenous properdin to PKO mice. Then, using in vitro and in vivo approaches, we show that the mechanism behind the exacerbated inflammation of PKO mice is due to a failure to increase local C5a levels. We show that C5a directly stimulates IL-6 production from colonic epithelial cells and that inhibiting C5a in infected wild-type mice resulted in defective epithelial IL-6 production and exacerbated inflammation. These outcomes position properdin early in the response to an infectious challenge in the colon, leading to complement activation and C5a, which in turn provides protection through IL-6 expression by the epithelium. Our results unveil a previously unappreciated mechanism of intestinal homeostasis involving complement, C5a, and IL-6 during bacteria-triggered epithelial injury. [ABSTRACT FROM AUTHOR]

Lipoproteins can induce complement activation resulting in opsonization and binding of these complexes to complement receptors. We investigated the binding of opsonized native LDL and acetylated LDL (acLDL) to the complement receptor 1 (CR1). Binding of complement factors C3b, IgM, C1q, mannose-binding lectin (MBL), and properdin to LDL and acLDL were investigated by ELISA. Subsequent binding of opsonized LDL and acLDL to CR1 on CR1-transfected Chinese Hamster Ovarian cells (CHO-CR1) was tested by flow cytometry. Both native LDL and acLDL induced complement activation with subsequent C3b opsonization upon incubation with normal human serum. Opsonized LDL and acLDL bound to CR1. Binding to CHO-CR1 was reduced by EDTA, whereas MgEGTA only reduced the binding of opsonized LDL, but not of acLDL suggesting involvement of the alternative pathway in the binding of acLDL to CR1. In vitro incubations showed that LDL bound C1q, whereas acLDL bound to C1q, IgM, and properdin. MBL did neither bind to LDL nor to acLDL. The relevance of these findings was demonstrated by the fact that ex vivo up-regulation of CR1 on leukocytes was accompanied by a concomitant increased binding of apolipoprotein B-containing lipoproteins to leukocytes without changes in LDL-receptor expression. In conclusion, CR1 is able to bind opsonized native LDL and acLDL. Binding of LDL to CR1 is mediated via the classical pathway, whereas binding of acLDL is mediated via both the classical and alternative pathways. Binding of lipoproteins to CR1 may be of clinical relevance due to the ubiquitous cellular distribution of CR1. [ABSTRACT FROM AUTHOR]

Se estudiaron 39 enfermos con mieloma múltiple (12 IgA y 27 IgG) en diferentes estadios de la enfermedad: 9 en estadios I + II y 30 en el estadio III, y en diferentes fases clínicas: 17 en fase activa precoz, 7 en fase estable, 8 en recaída y 7 en fase refractaria. Se evaluó la actividad hemolítica de la vía clásica, de la vía alterna y del factor B del complemento. Se cuantificaron los componentes C3 y C4 y se determinó la presencia de inmunocomplejos circulantes. Se comprobó una disminución significativa de la actividad hemolítica de la vía alterna (p= 0,0002), de la actividad hemolítica del factor B (p= 0,00001) y de los niveles séricos de C3 (p= 0,00001). Estas alteraciones se mantuvieron independientemente del tipo de paraproteína, estadio y fase clínica de los pacientes estudiados39 patients with multiple myeloma (12 IgA and 27 IgG) in different stages of the diseases were studied. 9 were in stages I + II and 30 in stage III. As regards the clinical phases, 17 were in active early phase, 7 in steady phase, 8 in relapse and 7 in refractory phase. The hemolytic activity of the classical pathway, of the alternative pathway and of the complement factor B was evaluated. Components C3 and C4 were quantitated and the presence of circulating immune complexes was determined. A significant reduction of the hemolytic activity of the alternative pathway (p=0.0002), of the hemolytic activity of factor B (p=0.00001), and of the serum levels of C3 (p=0.00001) was proved. These alterations occurred regardless of the type of paraprotein and of the stage and cinical phase of the studied patients

Background Urinary (U)-complement components have been detected in patients with proteinuric renal diseases, and complement activation via the alternative pathway (AP) is believed to play a role in renal tubular damage. The present study aimed to examine the regulation of complement AP activation in patients with renal tubular damage by focusing on the balance between properdin (P) and factor H (fH). Methods In the in vivo studies, U concentrations of P, fH and membrane attack complex (MAC) were measured in patients with renal diseases using an enzyme-linked immunosorbent assay (ELISA), and their relationships with the clinical data were evaluated. In the in vitro studies, human proximal tubular epithelial cells (PTECs) were incubated with normal human serum (NHS), P-depleted serum (PDS), purified P and/or fH. Changes in cell morphology and phenotype were assessed by microscopy, real-time polymerase chain reaction (PCR), immunostaining and a cell viability assay. Results The U-P, fH and MAC concentrations were significantly higher in patients with renal disease than in normal controls and correlated with the U-protein and tubular damage markers. Furthermore, multivariate analysis revealed a relationship between P levels and tubular damage markers. There were no significant changes in morphology and mRNA expression in the AP components (P, fH, fB, C3, C5 and C9) after the addition of up to 25% NHS. Dosedependent depositions of P or fH were observed after the addition of P or fH on PTECs. Depositions of P were not inhibited by fH in a mixture of a fixed concentration of P and a variable concentration of fH, and vice versa. Preincubation with the fixed concentration of P before the addition of NHS or PDS increased the depositions of P, C3 and MAC compared with incubation with intact NHS or intact PDS only; the depositions of C3 and MAC showed a serum-dependent trend. Preincubation with P before NHS addition significantly suppressed cell viability without causing morphological changes. Conclusions In the pathogenesis of renal tubular damage, P can directly bind to PTECs and may accelerate AP activation by surpassing fH regulation. [ABSTRACT FROM AUTHOR]

Modern medicine has established three central antimicrobial therapeutic concepts: vaccination, antibiotics, and, recently, the use of active immunotherapy to enhance the immune response toward specific pathogens. The efficacy of vaccination and antibiotics is limited by the emergence of new pathogen strains and the increased incidence of antibiotic resistance. To date, immunotherapy development has focused mainly on cytokines. Here we report the successful therapeutic application of a complement component, a recombinant form of properdin (Pn), with significantly higher activity than native properdin, which promotes complement activation via the alternative pathway, affording protection against N. menigitidis and S. pneumoniae. In a mouse model of infection, we challenged C57BL/6 WT mice with N. menigitidis B-MC58 6 h after i.p. administration of Pn (100 ug/mouse) or buffer alone. Twelve hours later, all control mice showed clear symptoms of infectious disease while the Pn treated group looked healthy. After 16 hours, all control mice developed sepsis and had to be culled, while only 10% of Pn treated mice presented with sepsis and recoverable levels of live Meningococci. In a parallel experiment, mice were challenged intranasally with a lethal dose of S. pneumoniae D39. Mice that received a single i.p. dose of Pn at the time of infection showed no signs of bacteremia at 12 h postinfection and had prolonged survival times compared with the saline-treated control group (P < 0.0001). Our findings show a significant therapeutic benefit of Pn administration and suggest that its antimicrobial activity could open new avenues for fighting infections caused by multidrug-resistant neisserial or streptococcal strains. [ABSTRACT FROM AUTHOR]

Abstract: Properdin, an upregulator of the alternative complement pathway, has been thoroughly studied in the mammalian species, but its research in the lower vertebrates such as fish is rather limited. Additionally, information regarding the structure–activity relationship of properdin remains rather fragmentary. In this report, we showed that zebrafish properdin gene zfp was abundantly expressed in the liver of adult fish, while it was primarily expressed in the brain, neural plate, developing lens, and neutrophil in the early embryos/larvae. Recombinant TSR modules of zfP were demonstrated to be able to bind to C3b, LPS, LTA and both gram-negative and positive bacteria. Moreover, TSR5 of zfP was able to enhance the phagocytosis of microbes by macrophages. These results together support the notion that properdin is a pattern recognition molecule capable of identifying non-self antigens/structures, and indicate that TSR5 plays a central role in the capacity of properdin to promote phagocytosis. It is also suggested that properdin is associated with the pattern formation and immune defense of early developing embryos/larvae. [Copyright &y& Elsevier]

Abstract: Aberrant complement activation is known to exacerbate the pathology in a spectrum of degenerative diseases of aging. We previously reported that aurin tricarboxylic acid (ATA) is an orally effective agent which prevents formation of the membrane attack complex of complement. It inhibits C9 attachment to tissue bound C5b678 and thus prevents bystander lysis of host cells. In this study, we investigated the effects of ATA on the alternative complement pathway. We found that ATA prevented cleavage of the tissue bound properdin-C3b-Factor B complex into the active C3 convertase enzyme properdin-C3b-Factor Bb. This inhibition was reversed by adding Factor D to the serum. Using enzyme-linked immunosorbent type assays, we established that ATA binds directly to Factor D and C9 but not to properdin or other complement proteins. We conclude that ATA, by inhibiting at two stages of the alternative pathway, might be a particularly effective therapeutic agent in conditions such as macular degeneration, paroxysmal nocturnal hemoglobinemia, and rheumatoid arthritis, in which activation of the alternative complement pathway initiates self damage. [Copyright &y& Elsevier]

Properdin and factor H are two key regulatory proteins having opposite functions in the alternative complement pathway. Properdin up-regulates the alternative pathway by stabilizing the C3bBb complex, whereas factor H downregulates the pathway by promoting proteolytic degradation of C3b. While factor H is mainly produced in the liver, there are several extrahepatic sources. In addition to the liver, factor H is also synthesized in fetal tubuli, keratinocytes, skin fibroblasts, ocular tissue, adipose tissue, brain, lungs, heart, spleen, pancreas, kidney, muscle, and placenta. Neutrophils are the major source of properdin, and it is also produced by monocytes, T cells and bone marrow progenitor cell line. Properdin is released by neutrophils from intracellular stores following stimulation by N-formyl-methionine-leucine-phenylalanine (fMLP) and tumor necrosis factor alpha (TNF-α). The HEP G2 cells derived from human liver has been found to produce functional properdin. Endothelial cells also produce properdin when induced by shear stress, thus is a physiological source for plasma properdin. The diverse range of extrahepatic sites for synthesis of these two complement regulators suggests the importance and need for local availability of the proteins. Here, we discuss the significance of the local synthesis of properdin and factor H. This assumes greater importance in view of recently identified unexpected and novel roles of properdin and factor H that are potentially independent of their involvement in complement regulation. [ABSTRACT FROM AUTHOR]

Studies in animal models suggest that complement activation is crucial in the pathogenesis of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). Here we investigate the circulating complement activation profile of 66 patients with active stage AAV compared to that of 54 patients with AAV in remission. Plasma levels of C3a, C5a, soluble C5b-9, and Bb, all determined by enzyme-linked immunosorbent assay, were significantly higher in active stage than in remission of AAV, while plasma levels of properdin were significantly lower in the former than the latter disease stage. There was no significant difference in the plasma levels of C4d between active stage and remission. The plasma level of Bb in patients with active AAV significantly correlated with the proportion of total and cellular crescents in the renal biopsy, the erythrocyte sedimentation rate, and the Birmingham Vasculitis Activity Scores. Thus, systemic activation of complement by the alternative pathway takes place in human AAV. Circulating Bb might be a useful biomarker in assessing disease activity of AAV. [ABSTRACT FROM AUTHOR]

Properdin, the only positive regulatory protein of the complement system, acts as both a stabilizer of the alternative pathway convertases and as a selective pattern recognition molecule of certain microorganisms and host cells (i.e. apoptotic/necrotic cells) by serving as a platform for de novo C3b,Bb assembly. Properdin, a highly positively charged protein, normally exists as cyclic dimers (P2), trimers (P3), and tetramers (P4) of head-to-tail associations of monomeric 53kDa subunits. While most complement proteins are produced mainly in the liver, properdin is synthesized primarily by various cell types including neutrophils, monocytes, primary T cells, and shear-stressed endothelial cells resulting in properdin serum levels of 4-25 μg/ml. Multiple inflammatory agonists stimulate the release of properdin from stimulated leukocytes into the cellular microenvironment. Concentrated, focused increases in properdin levels may lead to stabilization and initiation of alternative pathway convertases, thus greatly amplifying the complement response to a local stimulus. This review highlights current knowledge related to these properties and discusses the implications of properdin production in a pro-inflammatory microenvironment. [ABSTRACT FROM AUTHOR]

Human complement factor B (BF) is an essential component of the alternate complement pathway and therefore important in innate immune and autoimmune responses. The BF gene is located in the central region of major histocompatibility complex (MHC) and is known to encode more than 30 protein variants that can be resolved by isoelectric focusing and gel electrophoresis. There are three BF alleles – BF*S, BF*FB and BF*FA – that differ in codon 7 at nucleotide positions 94 and 95. These alleles have CGG, TGG or CAG triplets at their codon 7, respectively, that code for Arg, Trp or Gln residues. We have developed a novel polymerase chain reaction using sequence-specific primers-based allotyping assay that can identify nucleotide substitutions in codon 7 in all the three BF alleles. The assay was validated by sequencing and amplified fragment length polymorphism. Using this SSP assay, we report the BF alleles located on the multiple human leukocyte antigen (HLA)-DR3 haplotypes that are unique in the Indian population and are associated with autoimmunity. The common type 1 diabetes (T1D)-favoring Caucasian haplotype HLA-A1-B8-DR3 (ancestral haplotype AH8.1) carries BF*S. However, in the North Indian T1D patients, the most common haplotype is HLA-A26-B8-DR3 (AH8.2) and this carried BF*FB. Because of its association with AH8.2, the BF*FB was overrepresented in the patients (51.03%) compared with healthy controls (32.7%, OR = 2.148, 95% CI = 1.34–3.44, P = 0.002). Similar studies on allotyping BF alleles in different haplotypes in various populations could have important implications in understanding mechanisms of MHC haplotypic diversifications and disease associations and designing future therapeutic approaches. [ABSTRACT FROM AUTHOR]

C3 and Bf alleles were examined in the general population, in 67 patients with biopsy-confirmed mesangial IgA nephropathy and 81 patients with other types of glomerulonephritis, from the Heidelberg and Leiden renal programmes respectively.In both populations, a significant excess of homozygous phenotype C3FF (3.4% in controls; 10.4% in IgA nephropathy) and a deficit of C3FS heterozygous phenotype (35.8% in controls; 19.4% in IgA nephropathy) were observed in patients with IgA nephropathy, but not in other types of glomerulonephritis. No difference of C3 gene frequencies was found. C3FF was associated with an adverse clinical outcome (a higher prevalence of renal failure and hypertension).A significant excess of Bf-F gene frequency was noted (0.20 in controls; 0.33 in IgA nephropathy). In addition, an excess of phenotype BfFF was found (none in controls; 10.4% in IgA nephropathy). BfFF homozygotes also carried a higher risk of an adverse outcome (renal failure and hypertension).The data suggest a role for genetically coded (presumably) immunological factors in the genesis and course of IgA nephropathy. [ABSTRACT FROM PUBLISHER]

HLA and Bf genotypes have been determined in 75 Type 1 (insulin-dependent) diabetic probands ascertained from two family studies. The Bf associations were similar in those families with two affected children compared with those families with one affected child. The strong association of B18 with the rare allele BfF1 was confirmed but, with rare exception, the gene encoding for BfF1 only occurred on chromosomes coding for both B18 and CW5. These findings are similar to the strong allelic association between these specificities found more frequently in Southern Europe and Spain, but no HLA-A locus association was found in the present study. All HLA-B 8 positive subjects and 15 out of 16 BW62 positive probands possessed BfS. In contrast to other reports, we could not find any evidence to support the idea that BfF1 is associated with a younger age of onset of diabetes. It is concluded that there is no specific susceptibility gene for Type 1 diabetes linked to the Bf locus and that the Bf associations can be explained purely on the basis of the known allelic association, or linkage disequilibrium, within the HLA system. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift für Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift für Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this issue of the Journal of Heart and Lung Transplantation , Marrón-Liñares et al report the results of an interesting study in which they evaluated 51 genes associated with the complement pathway in a small number of heart recipients to explore their relationship with antibody-mediated rejection (AMR). Next-generation sequencing was used in 46 heart transplant recipients (23 with AMR and 23 without AMR). The authors identified a significant association of 2 single-nucleotide polymorphisms with the absence or presence of AMR, respectively, p.Gly54Asp-MBL2 in the mannose-binding lectin (MBL) 2 gene and p.Asn428(p=)-CFP in the alternative complement factor properdin (CFP) gene. This article is a new contribution to the heart transplant literature. It suggests that complement single-nucleotide polymorphisms may influence circulating levels of selected proteins of both the lectin pathway and alternative complement pathways, thus potentially determining which patients will develop AMR. [ABSTRACT FROM AUTHOR]

Genetic polymorphism of plasma properdin factor B (BF) was detected in domestic rabbit, Oryctolagus cuniculus , by means of isoelectric focusing and immunoblotting. The analysis of 298 individuals, corresponding to one French and two Portuguese populations, revealed the existence of six alleles, of which BF*A, B and C were common alleles, and D, F and G were rare ones. [ABSTRACT FROM AUTHOR]

The properdin factor B(Bf) variant F1 was found in 20% of 70 black patients with Type 1 (insulindependent) diabetes compared with 7.3% of 165 control subjects, yielding a significant relative risk of 3.1. In addition, the BfF allele was negatively associated with Type 1 diabetes among blacks, resulting in a relative risk of 0.4. The data suggest that Type 1 diabetes in black Americans may be partially due to admixture of Caucasoid genes. [ABSTRACT FROM AUTHOR]

The 54 kDa protein properdin, also known as factor P (FP), plays a major role in the complement system through the stabilization of the alternative pathway convertases. FP circulates in the blood as cyclic dimers, trimers and tetramers, and this heterogeneity challenges detailed structural insight into the mechanism of convertase stabilization by FP. Here, the generation of an intact FP monomer and a variant monomer with the third thrombospondin repeat liberated is described. Both FP monomers were excised from recombinant full‐length FP containing internal cleavage sites for TEV protease. These FP monomers could be crystallized, and complete data sets extending to 2.8 Å resolution for the intact FP monomer and to 3.5 Å resolution for the truncated variant were collected. The principle of specific monomer excision and domain removal by the insertion of a protease cleavage site may be broadly applicable to structural studies of oligomeric, flexible and modular proteins. A heterogeneous distribution of oligomers complicated the structure determination of the complement regulator properdin. Using TEV protease excision from recombinant oligomers, two types of properdin monomers could be crystallized. [ABSTRACT FROM AUTHOR]

The article presents research showing the significance of recombinant properdin in protecting mice against Neisseria meningitides and Streptococcus pneumoniae infection.