Breaking the Gingival Barrier in Periodontitis

The break of the epithelial barrier of gingiva has been a subject of minor interest, albeit playing a key role in periodontal pathology, transitory bacteraemia, and subsequent systemic lowgrade inflammation (LGI). The significance of mechanically induced bacterial translocation in gingiva (e.g., via mastication and teeth brushing) has been disregarded despite the accumulated knowledge of mechanical force effects on tight junctions (TJs) and subsequent pathology in other epithelial tissues. Transitory bacteraemia is observed as a rule in gingival inflammation, but is rarely observed in clinically healthy gingiva. This implies that TJs of inflamed gingiva deteriorate, e.g., via a surplus of lipopolysaccharide (LPS), bacterial proteases, toxins, Oncostatin M (OSM), and neutrophil proteases. The inflammation-deteriorated gingival TJs rupture when exposed to physiological mechanical forces. This rupture is characterised by bacteraemia during and briefly after mastication and teeth brushing, i.e., it appears to be a dynamic process of short duration, endowed with quick repair mechanisms. In this review, we consider the bacterial, immune, and mechanical factors responsible for the increased permeability and break of the epithelial barrier of inflamed gingiva and the subsequent translocation of both viable bacteria and bacterial LPS during physiological mechanical forces, such as mastication and teeth brushing

Effect of hormone replacement therapy on bone formation quality and mineralization regulation mechanisms in early postmenopausal women

Post-menopausal osteoporosis is characterized by a negative imbalance between bone formation and bone resorption resulting in a net bone loss, increasing the risk of fracture. One of the earliest interventions to protect against this was hormonal replacement therapy (HRT). Bone strength depends on both the amount and quality of bone, the latter including compositional / material and structural properties. Bone compositional / material properties are greatly dependent on both patient-, and tissue-age. Raman spectroscopy is an analytical tool ideally suited for the determination of bone compositional / material properties as a function of tissue age as it is capable of analyzing areas ~1 × 1 μm2 in tetracycline labeled bone forming areas. Using such analysis of humeri from an ovariectomized primate animal model, we reported that loss of estrogen results in alteration in the mineralization regulation mechanisms by osteoid organic matrix attributes at actively forming bone surfaces. In the present work, we used Raman microspectroscopic techniques to compare osteoid and youngest mineralized tissue composition, as well as relationships between osteoid organic matrix quality and quality attributes of the earliest mineralized tissue in paired iliac crest biopsies obtained from early postmenopausal women before and after two years of HRT therapy. Significant correlations between osteoid proteoglycans, sulfated proteoglycans, pyridinoline, and earliest mineralized tissue mineral content were observed, suggesting that in addition to changes in bone turnover rates, HRT affects the osteoid composition, mineralization regulation mechanisms, and potentially fibrillogenesis

Effects of Three Years Treatment With Once-Yearly Zoledronic Acid on the Kinetics of Bone Matrix Maturation in Osteoporotic Patients

ABSTRACT: INTRODUCTION: Yearly 5-mg infusions of Zolendronic acid (ZOL) for 3 years have shown pronounced antifracture efficacy. The purpose of the present study was to test whether ZOL affects the kinetics of forming bone material properties maturation. METHODS: Iliac crest biopsies obtained during the HORIZON-PFT clinical trial were analysed by Raman microspectroscopy in the area of actively bone forming surfaces as a function of tissue age (ZOL = 23, placebo (PLC) = 47)) in trabecular and osteonal bone, to determine ZOL’s effect on bone material quality indices (mineral / matrix, relative proteoglycan content, mineral crystallinity) maturation kinetics. RESULTS: Mineral / matrix ratio increased in both groups as a function of tissue age, at both osteonal and trabecular bone forming surfaces, ZOL exhibiting the greatest increase in the trabecular surfaces only. The relative proteoglycan content showed a dependency on tissue age in both trabecular and osteonal surfaces, with the ZOL receiving patients exhibiting significantly lower values in the tissue age 8-22 days in the trabecular surfaces. Mineral crystallinity (both crystallite length and thickness) showed a dependence on tissue age, with ZOL-treated patients exhibiting lower crystallite length compared to PLC only in the 8-22 day old tissue at trabecular surfaces, while crystal thickness was lower in the 1-5 day old tissue at both osteonal and trabecular surfaces. CONCLUSIONS: The results of the present study suggest that once-yearly administration of intravenous ZOL for 3 years in humans does not exert any deleterious effects on the evolution of intrinsic bone material properties at actively forming osteonal and trabecular surfaces, while it may have a beneficial effect on the progression of the mineral to matrix ratio and mineral maturity / crystallinity bone quality indices

Correction: Advanced Glycation Endproducts and Bone Material Properties in Type 1 Diabetic Mice.

[This corrects the article DOI: 10.1371/journal.pone.0154700.]

Homozygosity for CREB3L1 premature stop codon in first case of recessive osteogenesis imperfecta associated with OASIS-deficiency to survive infancy

Background Mutations of the endoplasmic reticulum (ER) stress transducer OASIS (encoded by CREB3L1), cause severe recessive osteogenesis imperfecta (OI) not compatible with surviving the neonatal period, as has been shown in two unrelated families through a whole gene deletion vs. a qualitative alteration of OASIS Heterozygous carriers in the described families have exhibited a mild phenotype. OASIS is a transcription factor highly expressed in osteoblasts, and OASIS(-/-) mice exhibit severe osteopenia and spontaneous fractures. Here, we expand the clinical spectrum by a detailed phenotypic characterization of the first case of OASIS-associated OI surviving the neonatal period, with heterozygous family members being unaffected. Methods: All OI-associated genes were sequenced. Primary human osteoblast-like cell (hOB) and fibroblast (FB) cultures were obtained for qPCR, and steady-state collagen biochemistry. FB, hOB and skin biopsies were ultrastructurally analyzed. Bone was analyzed by |mu CT, histomorphometry, quantitative backscattered electron imaging (qBEI), and Raman microspectroscopy. Results: The proband, a boy with severe OI, had blue sclera and tooth agenesis A homozygous CREB3L1 stop codon mutation was detected by sequencing, while several family members were heterozygotes Markedly low levels of CREB3L1 mRNA were confirmed by qPCR in hOBs (16%) and FB (21%), however, collagen I levels were only reduced in hOBs (5-10%) Electron microscopy of hOBs showed pronounced alterations, with numerous myelin figures and diminished RER vs. normal ultrastructure of FB. Bone histomorphometry and qBEI were similar to collagen I OI, with low trabecular thickness and mineral apposition rate, and increased bone matrix mineralization. Raman microspectroscopy revealed low level of glycosaminoglycans. Clinical response to lifelong bisphosphonate treatment was as expected in severe OI with steadily increasing bone mineral density, but despite this the boy suffered repeated childhood fractures. Conclusions: Deficiency of OASIS can cause severe OI compatible with surviving the neonatal period A marked decrease of collagen type I transcription was noted in bone tissue, but not in skin, and ultrastructure of hOBs was pathological. Results also suggested OASIS involvement in glycosaminoglycan secretion in bone

Matrix Properties by Raman Spectroscopy in femoral bones.

<p>Raman microspectroscopic measurement showed a decrease in mineral/matrix ratio [v₂PO₄/Amide III] (panel A) and in relative lipids content [lipids/Amide III] (panel B) in diabetic OVE26 mice (n = 6) as compared to wildtype FVB mice (n = 6). Mineral maturity/crystallinity [FWHH V₁PO₄] did not differ (panel C) in diabetic OVE26 mice. In contrast, relative pyridinoline content was increased in diabetic OVE26 mice (panel D), while there was no difference in relative proteoglycan content [PG/ Amide III] (panel E). The mean value is indicated by the grey diamond; the median by the horizontal line; the 25% and 75% by the boxes and the 95% confidence interval by the bars.</p

Mechanical indices in the femoral bones of wildtype and diabetic mice.

<p>Fracture toughness testing demonstrated decreased initiation (panel A) and propagation (panel B) toughness in diabetic OVE26 (n = 6) vs wildtype FVB (n = 6) mice. Reference point indentation showed increased IDI (indentation distance increase; panel C) and a tendency toward increased TID (total indentation distance; panel D). The mean value is indicated by the grey diamond; the median by the horizontal line; the 25% and 75% by the boxes and the 95% confidence interval by the bars.</p

Analysis of different standard references by Raman microspectroscopy to confirm the Raman marker bands for pentosidine (PEN) and carboxymethyl-lysine (CML).

<p>The Raman measurements and spectra treatments were as described in Materials and Methods. The bone Raman spectra was obtained from the periosteal surface of a heathy and diabetic mouse. The Raman marker bands for PEN (~1495 cm^-1) and CML (~1150 cm^-1) are highlighted. The purified collagen Raman spectra from a human bone was kindly provided by Dr. Robins and the proteoglycan and lysine references were purchased from Sigma Aldrich. Both AGEs references (PEN and CML) were purchased from PolyPeptide Laboratories France SAS.</p