Recognition of Neisseria meningitidis by the Long Pentraxin PTX3 and Its Role as an Endogenous Adjuvant

Long pentraxin 3 (PTX3) is a non-redundant component of the humoral arm of innate immunity. The present study was designed to investigate the interaction of PTX3 with Neisseria meningitidis. PTX3 bound acapsular meningococcus, Neisseria-derived outer membrane vesicles (OMV) and 3 selected meningococcal antigens (GNA0667, GNA1030 and GNA2091). PTX3-recognized microbial moieties are conserved structures which fulfil essential microbial functions. Ptx3-deficient mice had a lower antibody response in vaccination protocols with OMV and co-administration of PTX3 increased the antibody response, particularly in Ptx3-deficient mice. Administration of PTX3 reduced the bacterial load in infant rats challenged with Neisseria meningitidis. These results suggest that PTX3 recognizes a set of conserved structures from Neisseria meningitidis and acts as an amplifier/endogenous adjuvant of responses to this bacterium.     

Mutations in CSPP1 Cause Primary Cilia Abnormalities and Joubert Syndrome with or without Jeune Asphyxiating Thoracic Dystrophy

Joubert syndrome (JBTS) is a recessive ciliopathy in which a subset of affected individuals also have the skeletal dysplasia Jeune asphyxiating thoracic dystrophy (JATD). Here, we have identified biallelic truncating CSPP1 (centrosome and spindle pole associated protein 1) mutations in 19 JBTS-affected individuals, four of whom also have features of JATD. CSPP1 mutations explain ∼5% of JBTS in our cohort, and despite truncating mutations in all affected individuals, the range of phenotypic severity is broad. Morpholino knockdown of cspp1 in zebrafish caused phenotypes reported in other zebrafish models of JBTS (curved body shape, pronephric cysts, and cerebellar abnormalities) and reduced ciliary localization of Arl13b, further supporting loss of CSPP1 function as a cause of JBTS. Fibroblasts from affected individuals with CSPP1 mutations showed reduced numbers of primary cilia and/or short primary cilia, as well as reduced axonemal localization of ciliary proteins ARL13B and adenylyl cyclase III. In summary, CSPP1 mutations are a major cause of the Joubert-Jeune phenotype in humans; however, the mechanism by which these mutations lead to both JBTS and JATD remains unknown.     

PTX3 interacts with inter-alpha-trypsin inhibitor: implications for hyaluronan organization and cumulus oophorus expansion

Pentraxin 3 (PTX3) and heavy chains (HCs) of inter-alpha-trypsin inhibitor (IalphaI) are essential for hyaluronan (HA) organization within the extracellular matrix of the cumulus oophorus, which is critical for in vivo oocyte fertilization and female fertility. In this study, we examined the possibility that these molecules interact and cooperate in this function. We show that HCs and PTX3 colocalize in the cumulus matrix and coimmunoprecipitate from cumulus matrix extracts. Coimmunoprecipitation experiments and solid-phase binding assays performed with purified human IalphaI and recombinant PTX3 demonstrate that their interaction is direct and not mediated by other matrix components. PTX3 does not bind to IalphaI subcomponent bikunin and, accordingly, bikunin does not compete for the binding of PTX3 to IalphaI, indicating that PTX3 interacts with IalphaI subcomponent HC only. Recombinant PTX3-specific N-terminal region, but not the PTX3-pentraxin C-terminal domain, showed the same ability as full-length protein to bind to HCs and to enable HA organization and matrix formation by Ptx3(-/-) cumulus cell oocyte complexes cultured in vitro. Furthermore, a monoclonal antibody raised against PTX3 N terminus, which inhibits PTX3/IalphaI interaction, also prevents recombinant full-length PTX3 from restoring a normal phenotype to in vitro-cultured Ptx3(-/-) cumuli. These results indicate that PTX3 directly interacts with HCs of IalphaI and that such interaction is essential for organizing HA in the viscoelastic matrix of cumulus oophorus, highlighting a direct functional link between the two molecules.     

An unusual case of a basophilic variant of chronic myelogenous leukemia

The described basophilic variant of CML in blastic crisis was characterized by a distinct hyperhistaminemia, a moderate hypocoagulation and an insufficiently effective cytostatic therapy. Cell kinetic was characterized by a marked diminution of the whole marketing index (with H3-thymidine) of blasts and immature basophils with simultaneous prolongation of the generation time in comparison to myeloblasts at the chronic stage of the CML. Aneuploid cell clones prevailed in the bone-marrow.     

Cutting Edge: Regulator of G protein signaling-1 selectively regulates gut T cell trafficking and colitic potential

The RGS1 gene is associated with celiac disease, multiple sclerosis, and type I diabetes, which are all T cell-mediated pathologies, yet there is no reported analysis of regulator of G protein signaling (RGS)1 biology in human T cells. This study shows that RGS1 expression is substantially higher in T cells from human gut versus peripheral blood and that this can be exaggerated in intestinal inflammation. Elevated RGS1 levels profoundly reduce T cell migration to lymphoid-homing chemokines, whereas RGS1 depletion selectively enhances such chemotaxis in gut T cells and impairs their colitogenic potential. These findings provide a revised framework in which to view the linkage of RGS1 to inflammatory disease.     

Mapping of deletion and translocation breakpoints in 1q44 implicates the serine/threonine kinase AKT3 in postnatal microcephaly and agenesis of the corpus callosum

Deletions of chromosome 1q42-q44 have been reported in a variety of developmental abnormalities of the brain, including microcephaly (MIC) and agenesis of the corpus callosum (ACC). Here, we describe detailed mapping studies of patients with unbalanced structural rearrangements of distal 1q4. These define a 3.5-Mb critical region extending from RP11-80B9 to RP11-241M7 that we hypothesize contains one or more genes that lead to MIC and ACC when present in only one functional copy. Next, mapping of a balanced reciprocal t(1;13)(q44;q32) translocation in a patient with postnatal MIC and ACC demonstrated a breakpoint within this region that is situated 20 kb upstream of AKT3, a serine-threonine kinase. The murine orthologue Akt3 is required for the developmental regulation of normal brain size and callosal development. Whereas sequencing of AKT3 in a panel of 45 patients with ACC did not demonstrate any pathogenic variations, whole-mount in situ hybridization confirmed expression of Akt3 in the developing central nervous system during mouse embryogenesis. AKT3 represents an excellent candidate for developmental human MIC and ACC, and we suggest that haploinsufficiency causes both postnatal MIC and ACC.     

INDUCED APOSPORY IN THE LIVERWORT BLASIA PUSILLA

Immature sporophytes of Blasia pusilla L. collected in the field were excised from the protective gametophytic tissues and cultured on a slightly modified Knop's agar substrate in microphytotrons. Under the experimental conditions the setae elongated and after 33½ to 6 weeks many began to give rise to from 1 to 20 or more aposporous outgrowths. These subsequently developed into young gametophytes. The apices were then cut off, sterilized, and grown on glucose-mineral agar in aseptic culture. The resulting gametophytes were similar to haploid plants derived from spores in pattern and rate of growth, and in possession of rhizoids, ventral scales, lateral lobes, auricles, and stellate and discoid gemmae. They produced archegonia but no antheridia. The chromosome number of the aposporous plants was 18 in contrast to the normal haploid number of 9.     

Pentraxins in innate immunity: lessons from PTX3

The innate immune system constitutes the first line of defence against microorganisms and plays a primordial role in the activation and regulation of adaptive immunity. The innate immune system is composed of a cellular arm and a humoral arm. Components of the humoral arm include members of the complement cascade and soluble pattern recognition molecules (PRMs). These fluid-phase PRMs represent the functional ancestors of antibodies and play a crucial role in the discrimination between self, non-self and modified-self. Moreover, evidence has been presented that these soluble PRMs participate in the regulation of inflammatory responses and interact with the cellular arm of the innate immune system. Pentraxins consist of a set of multimeric soluble proteins and represent the prototypic components of humoral innate immunity. Based on the primary structure of the protomer, pentraxins are divided into two groups: short pentraxins and long pentraxins. The short pentraxins C-reactive protein and serum amyloid P-component are produced by the liver and represent the main acute phase proteins in human and mouse, respectively. The long pentraxin PTX3 is produced by innate immunity cells (e.g. PMN, macrophages, dendritic cells), interacts with several ligands and plays an essential role in innate immunity, tuning inflammation and matrix deposition. PTX3 provides a paradigm for the mode of action of humoral innate immunity.