Porphyromonas gingivalis and the pathogenesis of rheumatoid arthritis: analysis of various compartments including the synovial tissue

Introduction

We evaluated the presence of Porphyromonas gingivalis (Pg) DNA in the synovial tissue through synovial biopsy and in other compartments of rheumatoid arthritis (RA) patients in comparison with patients affected by other arthritides. Possible links with clinical, immunologic and genetic features were assessed.

Methods

Peripheral blood (PB), sub-gingival dental plaque, synovial fluid (SF) and synovial tissue samples were collected from 69 patients with active knee arthritis (32 with RA and 37 with other arthritides, of which 14 had undifferentiated peripheral inflammatory arthritis - UPIA). Demographic, clinical, laboratory and immunological data were recorded. The presence of Pg DNA was evaluated through PCR. The HLA-DR haplotype was assessed for 45 patients with RA and UPIA.

Results

No differences arose in the positivity for Pg DNA in the sub-gingival plaque, PB and SF samples between RA and the cohort of other arthritides. Full PB samples showed a higher positivity for Pg DNA than plasma samples (11.8% vs. 1.5%, P = 0.04). Patients with RA showed a higher positivity for Pg DNA in the synovial tissue compared to controls (33.3% vs. 5.9%, P <0.01). UPIA and RA patients carrying the HLA DRB1*04 allele showed a higher positivity for Pg DNA in the synovial tissue compared to patients negative for the allele (57.1% vs. 16.7%, P = 0.04). RA patients positive for Pg DNA in the sub-gingival plaque had a lower disease duration and a higher peripheral blood leucocyte and neutrophil count. The presence of Pg DNA did not influence disease activity, disease disability or positivity for autoantibodies.

Conclusions

The presence of Pg DNA in the synovial tissue of RA patients suggests a pathogenic role of the bacterium. The higher positivity of Pg DNA in full peripheral blood and synovial tissue samples compared to plasma and synovial fluid suggests a possible intracellular localization of Pg, in particular in patients positive for HLA-DR4.     

Mapping the twin‐arginine protein translocation network of Bacillus subtilis

Bacteria employ twin‐arginine translocation (Tat) pathways for the transport of folded proteins to extracytoplasmic destinations. In recent years, most studies on bacterial Tat pathways addressed the membrane‐bound TatA(B)C subunits of the Tat translocase, and the specific interactions between this translocase and its substrate proteins. In contrast, relatively few studies investigated possible coactors in the TatA(B)C‐dependent protein translocation process. The present studies were aimed at identifying interaction partners of the Tat pathway of Bacillus subtilis, which is a paradigm for studies on protein secretion by Gram‐positive bacteria. Specifically, 36 interaction partners of the TatA and TatC subunits were identified by rigorous application of the yeast two‐hybrid (Y2H) approach. Our Y2H analyses revealed that the three TatA isoforms of B. subtilis can form homo‐ and heterodimers. Subsequently, the secretion of the Tat substrates YwbN and PhoD was tested in mutant strains lacking genes for the TatAC interaction partners identified in our genome‐wide Y2H screens. Our results show that the cell wall‐bound protease WprA is important for YwbN secretion, and that the HemAT and CsbC proteins are required for PhoD secretion under phosphate starvation conditions. Taken together, our findings imply that the Bacillus Tat pathway is embedded in an intricate protein–protein interaction network.     

Proteome of Human Stem Cells from Periodontal Ligament and Dental Pulp

Background

Many adult tissues contain a population of stem cells with the ability to regenerate structures similar to the microenvironments from which they are derived in vivo and represent a promising therapy for the regeneration of complex tissues in the clinical disorder. Human adult stem cells (SCs) including bone marrow stem cells (BMSCs), dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) have been characterized for their high proliferative potential, expression of characteristic SC-associated markers and for the plasticity to differentiate in different lineage in vitro.

Methodology/Principal Findings

The aim of this study is to define the molecular features of stem cells from oral tissue by comparing the proteomic profiles obtained with 2-DE followed by MALDI-TOF/TOF of ex-vivo cultured human PDLSCs, DPSCs and BMSCs. Our results showed qualitative similarities in the proteome profiles among the SCs examined including some significant quantitative differences. To enrich the knowledge of oral SCs proteome we performed an analysis in narrow range pH 4–7 and 6–9, and we found that DPSCs vs PDLSCs express differentially regulated proteins that are potentially related to growth, regulation and genesis of neuronal cells, suggesting that SCs derived from oral tissue source populations may possess the potential ability of neuronal differentiation which is very consistent with their neural crest origin.

Conclusion/Significance

This study identifies some differentially expressed proteins by using comparative analysis between DPSCs and PDLSCs and BMSCs and suggests that stem cells from oral tissue could have a different cell lineage potency compared to BMSCs.     

Tissue transglutaminase: a new target to reverse cancer drug resistance

Cancer resistance mechanisms, which result from intrinsic genetic alterations of tumor cells or acquired genetic and epigenetic changes, limit the long-lasting benefits of anti-cancer treatments. Tissue transglutaminase (TG2) has emerged as a putative gene involved in tumor cell drug resistance and evasion of apoptosis. Although some reports have indicated that TG2 can suppress tumor growth and enhance the growth inhibitory effects of anti-tumor agents, several studies have presented both pro-survival and anti-apoptotic roles for TG2 in malignant cells. Increased TG2 expression has been found in several tumors, where it was considered a potential negative prognostic marker, and it is often associated with advanced stages of disease, metastatic spread and drug resistance. TG2 mediates drug resistance through the activation of survival pathways and the inhibition of apoptosis, but also by regulating extracellular matrix (ECM) formation, the epithelial-to-mesenchymal transition (EMT) or autophagy. Because TG2 knockdown or inhibition of TG2 enzymatic activity may reverse drug resistance and sensitize cancer cells to drug-induced apoptosis, many small molecules capable of blocking TG2 have recently been developed. Additional insight into the multifunctional nature of TG2 as well as translational studies concerning the correlation between TG2 expression, function or location and cancer behavior will aid in translating these findings into new therapeutic approaches for cancer patients.     

Morphological adaptation to water uptake and transport in the poikilohydric moss Tortula ruralis

Abstract

In this paper different water-holding and transport adaptations to face the uneven and intermittent distribution of water in the ectohydric moss Tortula ruralis are referred to.

The external conduction of water is operated by different and efficient systems (spaces between adjacent shoots, between leaves, leaves and stems, leaves and rhizoids, life form, etc.) which facilitate absorption and transport of solutions.

Also epi-organ capillary systems (bases and revoluted margin of leaves, a groove, a close network of capillary channels determined by the papillae), intra-organ capillary systems (hyalocysts) and certain amount of internal conduction (conducting parenchyma, stereoma) co-operante to absorb and distribute water to the whole gametophyte.

In addition, some adaptations to xerophytism and heliophytism (life form, disposition of phylloids, hair-points) are discussed.     

Granule-derived granzyme B mediates the vulnerability of human neurons to T cell-induced neurotoxicity

Multiple sclerosis (MS) is considered an autoimmune disease of the CNS and is characterized by inflammatory cells infiltrating the CNS and inducing demyelination, axonal loss, and neuronal death. Recent evidence strongly suggests that axonal and neuronal degeneration underlie the progression of permanent disability in MS. In this study, we report that human neurons are selectively susceptible to the serine-protease granzyme B (GrB) isolated from cytotoxic T cell granules. In vitro, purified human GrB induced neuronal death to the same extent as the whole activated T cell population. On the contrary, activated T cells isolated from GrB knockout mice failed to induce neuronal injury. We found that following internalization through various parts of neurons, GrB accumulated in the neuronal soma. Within the cell body, GrB diffused out of endosomes possibly through a perforin-independent mechanism and induced subsequent activation of caspases and cleavage of α-tubulin. Inhibition of caspase-3, a well-known substrate for GrB, significantly reduced GrB-mediated neurotoxicity. We demonstrated that treatment of neurons with mannose-6-phosphate prevented GrB entry and inhibited GrB-mediated neuronal death, suggesting mannose-6-phosphate receptor-dependent endocytosis. Together, our data unveil a novel mechanism by which GrB induces selective neuronal injury and suggest potential new targets for the treatment of inflammatory-mediated neurodegeneration in diseases such as MS.     

The potential antioxidant activity of 2,3-dihydroselenophene, a prototype drug of 4-aryl-2,3-dihydroselenophenes

Here we present our results in palladium cross-coupling reaction of aryl boronic acids with 4-iodo-2,3-dihydroselenophene derivatives. The cross-coupled products were obtained in satisfactory yields. A dehydrogenation of 4,5-diphenyl-2,3-dihydroselenophene was activated by DDQ and the 2,3-diarylselenophene was obtained in good yield. Regarding the antioxidant activity, the selenophene derivative 3a was effective in counteracting lipid and protein oxidation as well as scavenging ABTS radical. The findings of the present study indicate that 3a is a prototype for future drug development programs to treat disorders mediated by reactive oxygen species.     

A G613A missense in the Hutchinson’s progeria lamin A/C gene causes a lone,autosomal dominant atrioventricular block

Background

LMNA/C mutations have been linked to the premature aging syndrome Hutchinson’s progeria, dilated cardiomyopathy 1A, skeletal myopathies (such as the autosomal dominant variant of Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy), Charcot-Marie-Tooth disorder type 2B1, mandibuloacral dysplasia, autosomal dominant partial lipodystrophy, and axonal neuropathy. Atrioventricular block (AVB) can be associated with several cardiac disorders and it can also be a highly heritable, primitive disease.One of the most common pathologies associated with AVB is dilated cardiomyopathy (DCM), which is characterized by cardiac dilatation and reduced systolic function. In this case, onset has been correlated with several mutations in genes essential for the proper maturation of cardiomyocytes, such as the gene for lamin A/C. However, no clear genotype–phenotype relationship has been reported to date between LMNA/C mutations and cardiomyopathies.

Results

DNA and medical histories were collected from (n?=?11) members of different generations of one family, the proband of which was implanted with a pacemaker for lone, type II AVB. Exome sequencing analysis was performed on three relatives with AVB, and the mutations therein identified validated in a further three AVB-affected family members.In the initial three AVB family members, we identified 10 shared nonsynonymous single-nucleotide variations with a rare or unreported allele frequency in the 1000 Genomes Project database. Follow-up genetic screening in the additional three affected relatives disclosed a correlation between the lone AVB phenotype and the single-nucleotide polymorphism rs56816490, which generates an E317K change in lamin A/C. Although this mutation has already been described by others in a DCM-affected proband with familiarity for AVB and sudden death, the absence of DCM in our large, AVB-affected family is indicative of genotype–phenotype correlation between rs56816490 and a familial, autosomal dominant form of lone AVB.

Conclusions

Screening for G613A in LMNA/C in patients with lone AVB and their relatives might prevent sudden death in families affected by AVB but without familiarity for DCM. Lone AVB is an age-related disease caused by mutations in LMN A/C gene rather than a complication of DCM.