The Long Pentraxin PTX3 Is an Endogenous Inhibitor of Hyperoxaluria-Related Nephrocalcinosis and Chronic Kidney Disease

The long pentraxin 3 (PTX3) exerts a variety of regulatory functions in acute and chronic tissue inflammation. In particular, PTX3 acts as an opsonin for a variety of pathogens and endogenous particles. We hypothesized that PTX3 would exhibit opsonin-like functions toward calcium oxalate crystals, too, and inhibit crystal growth. This process is fundamental in kidney stone disease as well as in hyperoxaluria-related nephrocalcinosis, the paradigmatic cause of chronic kidney disease (CKD) in children with primary hyperoxaluria type I due to genetic defects in oxalate metabolism. Direct effects of PTX3 on calcium oxalate crystals were investigated in chemico by adding recombinant PTX3 to supersaturated calcium and oxalate solutions. PTX3, but not isomolar concentrations of albumin, dose-dependently inhibited crystal growth. In vivo, the PTX3 protein was undetectable in tubular epithelial cells and urine of wild-type mice under physiological conditions. However, its levels increased within 3 weeks of feeding an oxalate-rich diet, an exposure inducing hyperoxaluria-related nephrocalcinosis and CKD in selected mouse strains (male and female C57BL/6N and male Balb/c mice) but not in others (male and female 129SV and CD-1, male and female Balb/c mice). Genetic ablation of ptx3 in nephrocalcinosis un-susceptible B6;129 mice was sufficient to raise the oxalate nephropathy phenotype observed in susceptible strains. We conclude that PTX3 is an endogenous inhibitor of calcium oxalate crystal growth. This mechanism limits hyperoxaluria-related nephrocalcinosis, e.g., in primary or secondary hyperoxaluria, and potentially also in the more prevalent kidney stone disease

Human Pentraxin 3 Binds to the Complement Regulator C4b-Binding Protein

The long pentraxin 3 (PTX3) is a soluble recognition molecule with multiple functions including innate immune defense against certain microbes and the clearance of apoptotic cells. PTX3 interacts with recognition molecules of the classical and lectin complement pathways and thus initiates complement activation. In addition, binding of PTX3 to the alternative complement pathway regulator factor H was shown. Here, we show that PTX3 binds to the classical and lectin pathway regulator C4b-binding protein (C4BP). A PTX3-binding site was identified within short consensus repeats 1–3 of the C4BP α-chain. PTX3 did not interfere with the cofactor activity of C4BP in the fluid phase and C4BP maintained its complement regulatory activity when bound to PTX3 on surfaces. While C4BP and factor H did not compete for PTX3 binding, the interaction of C4BP with PTX3 was inhibited by C1q and by L-ficolin. PTX3 bound to human fibroblast- and endothelial cell-derived extracellular matrices and recruited functionally active C4BP to these surfaces. Whereas PTX3 enhanced the activation of the classical/lectin pathway and caused enhanced C3 deposition on extracellular matrix, deposition of terminal pathway components and the generation of the inflammatory mediator C5a were not increased. Furthermore, PTX3 enhanced the binding of C4BP to late apoptotic cells, which resulted in an increased rate of inactivation of cell surface bound C4b and a reduction in the deposition of C5b-9. Thus, in addition to complement activators, PTX3 interacts with complement inhibitors including C4BP. This balanced interaction on extracellular matrix and on apoptotic cells may prevent excessive local complement activation that would otherwise lead to inflammation and host tissue damage

Genetic PTX3 deficiency and aspergillosis in stem-cell transplantation

BACKGROUND: The soluble pattern-recognition receptor known as long pentraxin 3 (PTX3) has a nonredundant role in antifungal immunity. The contribution of single-nucleotide polymorphisms (SNPs) in PTX3 to the development of invasive aspergillosis is unknown. METHODS: We screened an initial cohort of 268 patients undergoing hematopoietic stem-cell transplantation (HSCT) and their donors for PTX3 SNPs modifying the risk of invasive aspergillosis. The analysis was also performed in a multicenter study involving 107 patients with invasive aspergillosis and 223 matched controls. The functional consequences of PTX3 SNPs were investigated in vitro and in lung specimens from transplant recipients. RESULTS: Receipt of a transplant from a donor with a homozygous haplotype (h2/h2) in PTX3 was associated with an increased risk of infection, in both the discovery study (cumulative incidence, 37% vs. 15%; adjusted hazard ratio, 3.08; P=0.003) and the confirmation study (adjusted odds ratio, 2.78; P=0.03), as well as with defective expression of PTX3. Functionally, PTX3 deficiency in h2/h2 neutrophils, presumably due to messenger RNA instability, led to impaired phagocytosis and clearance of the fungus. CONCLUSIONS: Genetic deficiency of PTX3 affects the antifungal capacity of neutrophils and may contribute to the risk of invasive aspergillosis in patients treated (Funded by the European Society of Clinical Microbiology and Infectious Diseases and others) .with HSCT.Supported by grants from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) (to Dr. Carvalho); the German Ministry for Education and Science (03Z2JN21, to Dr. Kurzai); the European Commission (FP7-HEALTH-2009-260338, to Dr. Romani; FP7-HEALTH-2011-280873, to Dr. Mantovani), the European Research Council (ERC-2008-AdG-233417, to Dr. Mantovani; ERC-2011-AdG-293714, to Dr. Romani), Associazione Italiana per la Ricerca sul Cancro (99629, to Dr. Mantovani); and Fundacao para a Ciencia e Tecnologia, Portugal (SFRH/BPD/46292/2008, to Dr. Carvalho; SFRH/BD/65962/2009, to Dr. Cunha; and SFRH/BPD/70783/2010, to Dr. Almeida)

Medidas da transpiração em porta-enxertos de citros

Estudou-se a variação diurna da transpiração de quatro porta -enxertos de citros, durante 12 horas, em intervalos de 60 minutos, pelo método das pesagens. Verificou-se que não ocorreu diferenças estatísticas na marcha diária da transpiração, entre Poncirus trifoliata, Citrus aurantium (laranja Azeda), Citrus sinensis (laranja Caipira) e Citrus limonia (limão Cravo). O limoeiro Cravo mostrou, nas condições estudadas, área foliar superior à Poncirus, laranja Azeda e laranja Caipira. Observou-se ainda uma correlação positiva entre a área foliar e a transpiração dos quatro porta-enxertos de citros.Diurnal transpiration rates of four citrus rootstocks were measured during 12 hours separated by intervals of 60 minutes, through the weighing method. Plants of Poncirus trifoliata, Citrus aurantium, Citrus sinensis, and Citrus limonia do not present statistical differences in the daily march of transpiration. In the studied conditions C. limonia showed higher leaf area than P. trifoliata, C. aurantium, and C. sinensis. There was a positive correlation between leaf area and transpiration of the four citrus rootstodks

Chemical Linkage to Injected Tissues Is a Distinctive Property of Oxidized Avidin

We recently reported that the oxidized avidin, named AvidinOX®, resides for weeks within injected tissues as a consequence of the formation of Schiff's bases between its aldehyde groups and tissue protein amino groups. We also showed, in a mouse pre-clinical model, the usefulness of AvidinOX for the delivery of radiolabeled biotin to inoperable tumors. Taking into account that AvidinOX is the first oxidized glycoprotein known to chemically link to injected tissues, we tested in the mouse a panel of additional oxidized glycoproteins, with the aim of investigating the phenomenon. We produced oxidized ovalbumin and mannosylated streptavidin which share with avidin glycosylation pattern and tetrameric structure, respectively and found that neither of them linked significantly to cells in vitro nor to injected tissues in vivo, despite the presence of functional aldehyde groups. The study, extended to additional oxidized glycoproteins, showed that the in vivo chemical conjugation is a distinctive property of the oxidized avidin. Relevance of the high cationic charge of avidin into the stable linkage of AvidinOX to tissues is demonstrated as the oxidized acetylated avidin lost the property. Plasmon resonance on matrix proteins and cellular impedance analyses showed in vitro that avidin exhibits a peculiar interaction with proteins and cells that allows the formation of highly stable Schiff's bases, after oxidation

Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix

The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix

The retinoid agonist Tazarotene promotes angiogenesis and wound healing

Therapeutic angiogenesis is a major goal ofregenerative medicine, but no clinically approved small molecule exists that enhancesnew blood vessel formation. Here we show, using a phenotype-driven high-content imaging screen of an annotated chemical library of 1280 bioactive small molecules, that the retinoid agonist Tazarotene, enhances in vitroangiogenesis, promoting branching morphogenesis, and tubule remodeling. The pro-angiogenic phenotype is mediated by Retinoic Acid Receptor (RAR) but not Retinoic X Receptor(RXR) activation, and is characterized by secretion of the pro-angiogenic factors Hepatocyte Growth Factor (HGF), Vascular Endothelial Growth Factor (VEGFA), Plasminogen Activator, Urokinase (PLAU) and Placental Growth Factor (PGF), and reduced secretion of the antiangiogenic factor Pentraxin-3 (PTX3) from adjacent fibroblasts. In vivo, Tazarotene enhanced the growth of mature and functional microvessels in Matrigel implants and wound healing models, and increased blood flow. Notably, in ear punch wound healing model, Tazarotene promoted tissue repair characterized by rapid ear punch closure with normal-appearing skin containing new hair follicles, and maturing collagen fibers. Our study suggests that Tazarotene, an FDA-approved small molecule, could be potentially exploited for therapeutic applications in neovascularization and wound healing