Cleavage of IgG1 in gingival crevicular fluid is associated with the presence of Porphyromonas gingivalis

BACKGROUND AND OBJECTIVES

Immunoglobulin (Ig) G1 plays an important role in the adaptive immune response. Kgp, a lysine-specific cysteine protease from Porphyromonas gingivalis, specifically hydrolyses IgG1 heavy chains. The purpose of this study was to examine whether cleavage of IgG1 occurs in gingival crevicular fluid (GCF) in vivo, and whether there is any association with the presence of Porphyromonas gingivalis and other periodontopathogens.

MATERIAL AND METHODS

GCF was obtained from nine patients with aggressive periodontitis, nine with chronic periodontitis and five periodontally healthy individuals. The bacterial loads of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Prevotella intermedia and Tannerella forsythia were analysed by real-time polymerase chain reaction, and the presence and cleavage of IgG1 and IgG2 were determined using Western blotting. Kgp levels were measured by ELISA.

RESULTS

Cleaved IgG1 was identified in the GCF from 67% of patients with aggressive periodontitis and in 44% of patients with chronic periodontitis. By contrast, no cleaved IgG1 was detectable in healthy controls. No degradation of IgG2 was detected in any of the samples, regardless of health status. Porphyromonas gingivalis was found in high numbers in all samples in which cleavage of IgG1 was detected (P < 0.001 compared with samples with no IgG cleavage). Furthermore, high numbers of Tannerella forsythia and Prevotella intermedia were also present in these samples. The level of Kgp in the GCF correlated with the load of Porphyromonas gingivalis (r = 0.425, P < 0.01). The presence of Kgp (range 0.07-10.98 ng/mL) was associated with proteolytic fragments of IgG1 (P < 0.001). However, cleaved IgG1 was also detected in samples with no detectable Kgp.

CONCLUSION

In patients with periodontitis, cleavage of IgG1 occurs in vivo and may suppress antibody-dependent antibacterial activity in subgingival biofilms especially those colonized by Porphyromonas gingivalis.

t⁴ workshop report. Nanotoxicology: "the end of the beginning" - signs on the roadmap to a strategy for assuring the safe application and use of nanomaterials

In October 2010, a group of experts met as part of the transatlantic think tank for toxicology (t4) to exchange ideas about the current status and future of safety testing of nanomaterials. At present, there is no widely accepted path forward to assure appropriate and effective hazard identification for engineered nanomaterials. The group discussed needs for characterization of nanomaterials and identified testing protocols that incorporate the use of innovative alternative whole models such as zebrafish or C. elegans, as well as in vitro or alternative methods to examine specific functional pathways and modes of action. The group proposed elements of a potential testing scheme for nanomaterials that works towards an integrated testing strategy, incorporating the goals of the NRC report Toxicity Testing in the 21st Century: A Vision and a Strategy by focusing on pathways of toxic response, and utilizing an evidence-based strategy for developing the knowledge base for safety assessment. Finally, the group recommended that a reliable, open, curated database be developed that interfaces with existing databases to enable sharing of information.

Nanomaterial cell interactions: are current in vitro tests reliable?

New properties of engineered nanomaterials raise great expectations for industrial, scientific as well as medical applications. At the same time concerns among consumers regarding the safety aspects of this new technology emerge. Furthermore, among the multitude of published studies, a considerable number do not reveal reliable data. Thus, standardized, validated, reliable, robust, reproducible and intelligent testing strategies are urgently needed that address nanomaterial toxicity. This article discusses the reliability of currently used in vitro toxicity assays. It covers major problems, pitfalls and challenges of assay performance and validation. We recommend a series of different controls to improve the experimental quality and, thus, also the reliability and reproducibility of current in vitro systems. These recommendations consequently applied in the future will increase the safe and sustainable use of nanotechnology.

The middle radioulnar joint and triarticular forearm complex

The forearm is composed of the radial and ulnar shafts, which are linked by the interosseous membrane and intercalated between the elbow and wrist. The radius and ulna are connected by three joints, the proximal, middle, and distal radioulnar joints. The forearm ensures pronation/supination and longitudinal load transfer. The biomechanical and clinical relevance of the proximal and distal radioulnar joints is well established. In contrast, the middle radioulnar joint was considered relatively unimportant until studies published in the last decade showed that it fulfils crucial biomechanical functions and is of considerable clinical significance. We believe the conventional concept in which the forearm is viewed as part of either the elbow or the wrist is outdated and that a more relevant concept describes the forearm as a triarticular complex that functions as a full-fledged entity. In this concept, the three forearm radioulnar joints (proximal, middle, distal) work together to provide stability, mobility and load transfer. Here, we will argue for the relevance of the triarticular complex concept based on published data about forearm biomechanics and pathological conditions.

C60 fullerene: a powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays

Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C(60) is still controversially discussed. The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C(60) fullerene in comparison to water stirred C(60) fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract. We could demonstrate that water-soluble side products which were formed in THF nC(60) suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo.

Postmenopausal hormone therapy and regional brain volumes: the WHIMS-MRI Study

OBJECTIVES

To determine whether menopausal hormone therapy (HT) affects regional brain volumes, including hippocampal and frontal regions.

METHODS

Brain MRI scans were obtained in a subset of 1,403 women aged 71-89 years who participated in the Women's Health Initiative Memory Study (WHIMS). WHIMS was an ancillary study to the Women's Health Initiative, which consisted of two randomized, placebo-controlled trials: 0.625 mg conjugated equine estrogens (CEE) with or without 2.5 mg medroxyprogesterone acetate (MPA) in one daily tablet. Scans were performed, on average, 3.0 years post-trial for the CEE + MPA trial and 1.4 years post-trial for the CEE-Alone trial; average on-trial follow-up intervals were 4.0 years for CEE + MPA and 5.6 years for CEE-Alone. Total brain, ventricular, hippocampal, and frontal lobe volumes, adjusted for age, clinic site, estimated intracranial volume, and dementia risk factors, were the main outcome variables.

RESULTS

Compared with placebo, covariate-adjusted mean frontal lobe volume was 2.37 cm(3) lower among women assigned to HT (p = 0.004), mean hippocampal volume was slightly (0.10 cm(3)) lower (p = 0.05), and differences in total brain volume approached significance (p = 0.07). Results were similar for CEE + MPA and CEE-Alone. HT-associated reductions in hippocampal volumes were greatest in women with the lowest baseline Modified Mini-Mental State Examination scores (scores <90).

CONCLUSIONS

Conjugated equine estrogens with or without MPA are associated with greater brain atrophy among women aged 65 years and older; however, the adverse effects are most evident in women experiencing cognitive deficits before initiating hormone therapy.

Canonical Wnt signaling transiently stimulates proliferation and enhances neurogenesis in neonatal neural progenitor cultures

Canonical Wnt signaling triggers the formation of heterodimeric transcription factor complexes consisting of beta-catenin and T cell factors, and thereby controls the execution of specific genetic programs. During the expansion and neurogenic phases of embryonic neural development canonical Wnt signaling initially controls proliferation of neural progenitor cells, and later neuronal differentiation. Whether Wnt growth factors affect neural progenitor cells postnatally is not known. Therefore, we have analyzed the impact of Wnt signaling on neural progenitors isolated from cerebral cortices of newborn mice. Expression profiling of pathway components revealed that these cells are fully equipped to respond to Wnt signals. However, Wnt pathway activation affected only a subset of neonatal progenitors and elicited a limited increase in proliferation and neuronal differentiation in distinct subsets of cells. Moreover, Wnt pathway activation only transiently stimulated S-phase entry but did not support long-term proliferation of progenitor cultures. The dampened nature of the Wnt response correlates with the predominant expression of inhibitory pathway components and the rapid actuation of negative feedback mechanisms. Interestingly, in differentiating cell cultures activation of canonical Wnt signaling reduced Hes1 and Hes5 expression suggesting that during postnatal neural development, Wnt/beta-catenin signaling enhances neurogenesis from progenitor cells by interfering with Notch pathway activity.

Risk factors for venous thromboembolic events in cancer patients

BACKGROUND

Cancer patients of the Department of Internal Medicine (Cancer Research) of the Essen University Medical School (Tumor Clinics), Germany, were examined and questioned with the aim of identifying those who run a high risk of deep vein thrombosis (DVT).

PATIENTS AND METHODS

Between September 2002 and April 2003, cancer therapy and DVT risk factors of 507 cancer patients (53% males, 47% females, mean age 56+/-12 years) were documented. During a mean follow-up of 8+/-5 months, 60 patients (12%) suffered from new venous thromboembolic events (VTE): 28 at the lower limb, 25 at the upper limb and 13 pulmonary embolisms.

RESULTS

The following factors were considered as predictive for an increased VTE risk: inpatient treatment (P<0.0001), prior DVT in medical history (P=0.0275), DVT in family (P=0.0598), chemotherapy (P=0.0080), fever (P=0.0093) and CRP (P<0.001). After combining factors in one variable (number of factors) the predicted VTE risk increased with the number of factors in both outpatients (OR 1.85, 95% CI 1.18-2.88, P=0.0071) and inpatients (OR 2.34, 95% CI 1.63-3.36, P<or=0.0001). In the absence of all these factors the predicted VTE risk was 2.3%, increasing to 72% if all were present.

CONCLUSIONS

In cancer patients the risk of VTE steadily increases with the number of risk factors, and identification of patients at high risk is possible.

Inhibition of human immunodeficiency virus-1 (HIV-1) by beta-chemokine analogues in mononuclear cells from HIV-1-infected patients with active tuberculosis

Tuberculosis (TB) enhances human immunodeficiency virus-1 (HIV-1) activity in patients with dual HIV-1/TB infection. Therapies that control augmentations of HIV-1 activity at sites of Mycobacterium tuberculosis (MTB) infection may be useful in inhibition of viral expansion. Regulated upon activation, normal T-cell expressed and secreted (RANTES) analogues (AOP and NNY) are potent in inhibiting the entry of primary HIV-1 isolates into host mononuclear cells. These analogues were used to inhibit MTB-induced HIV-1 entry in blood monunuclear cells (PBMC) from patients with pulmonary TB, and pleural fluid mononuclear cells (PFMC) from patients with pleural TB. PBMC or PFMC were cultured with and without MTB in presence and absence of RANTES analogues. HIV-1 strong stop DNA was assessed by real-time polymerase chain reaction (PCR) as a measure of infection. CCR5 mRNA was assessed by real-time reverse transcription (RT)-PCR and by immunostaining and FACS analysis. HIV-1 infection was induced by MTB in vitro in PBMC from the majority (14 of 20) of HIV-1/TB subjects, and new infection was inhibited by AOP- or NNY-RANTES. HIV-1 infection was also inhibited by these reagents in MTB-induced PFMC from three of three patients with pleural TB. Expression of CCR5 mRNA was significantly induced by MTB in PBMC from patients with pulmonary TB. Further, expression of CCR5 was higher in PFMC compared to PBMC from patients with pleural TB. Also, CCR5 was fourfold higher on CD14(+) pleural mononuclear cells than on CD4(+) lymphocytes. Blocking new HIV-1 infection of mononuclear cells may be useful in control of HIV-1 during dual HIV-1/TB infection.