Multiple external root resorptions in a patient with Stage IV, Grade C periodontitis and autoimmune diseases: A case report

BACKGROUND

Pathological root resorption affects permanent teeth and is usually triggered by infectious-inflammatory stimuli and/or dental trauma. Periodontitis and traumatic occlusion have been reported as possible causative factors of root resorptions, whilst the impact of systemic diseases is less well understood. This case highlights the need for consideration of multiple risk factors, especially when presenting in combination.

METHODS AND RESULTS

A 62-year-old South Asian female presented with unstable Stage IV Grade C periodontitis, poor oral hygiene and multiple autoimmune conditions including oral lichen planus. Clinical and radiographic examination revealed multiple advanced apical and external root resorptions of the patient's molars associated with periapical bone loss, despite of a minimally restored dental status.

CONCLUSION

A likely etiology of this patient's multiple root resorptions is the presence of unstable periodontitis with periodontal-endodontic lesions, exacerbated by a dysbalanced immune response to infectious agents. Appropriate monitoring and managing of such patients can prevent or limit the pathological process of inflammatory root resorption.

KEY POINTS

Why is this case new information? This is the first report documenting advanced multiple external inflammatory root resorptions in a periodontitis patient with oral and systemic co-morbidities. What are the keys to successful management of this case? Early diagnosis, prevention and intervention to limit periodontal inflammation, endodontic infection and occlusal trauma. What are the primary limitations to success in this case? Late diagnosis of multiple root resorptions, palliative periodontal treatment due to poor oral hygiene compliance, and poorly controlled systemic inflammation favoring the persistence of a dysregulated immune response to the oral microbiota.

Quorum Sensing in Oral Biofilms: Influence on Host Cells

Quorum sensing molecules (QSMs) in the oral cavity regulate biofilm formation, the acquisition of iron, stress responses, and the expression of virulence factors. However, knowledge of the direct QSM-host interactions in the oral environment is limited, although their understanding could provide greater insight into the cross-kingdom communication occurring during oral disease development. This review aims to explore the literature on oral QSM-host interactions and to highlight areas of advancement in this field. The studies included in this review encompass an array of cell types and oral QSMs, with particular emphasis on immune cells and their relationship to periodontal diseases. It can be inferred from the current literature that QSMs are utilised by host cells to detect bacterial presence and, in the majority of cases, elicit an immune response towards the environmental QSMs. This may provide a base to target QSMs as a novel treatment of oral diseases. However, N-acyl homoserine lactone (AHL) detection methods remain an area for development, through which a greater understanding of the influence of oral QSMs on host cells could be achieved.

The role of the host-Neutrophil biology

Neutrophilic polymorphonuclear leukocytes (neutrophils) are myeloid cells packed with lysosomal granules (hence also called granulocytes) that contain a formidable antimicrobial arsenal. They are terminally differentiated cells that play a critical role in acute and chronic inflammation, as well as in the resolution of inflammation and wound healing. Neutrophils express a dense array of surface receptors for multiple ligands, ranging from integrins to support their egress from bone marrow into the circulation and from the circulation into tissues, to cytokine/chemokine receptors that drive their navigation to the site of infection or tissue damage and also prime them for a second stimulus, to pattern recognition receptors and immunoglobulin receptors to facilitate the destruction and removal of infective agents or debridement of damaged tissues. When afferent neutrophil signals are proportionate and coordinated they will phagocytose opsonized and unopsonized bacteria, activating the nicotinamide adenine dinucleotide phosphate oxidase (respiratory burst) to generate reactive oxygen species, which augment the proteolytic destruction of microbes secured within the phagosome. A highly orchestrated process of apoptosis follows, forming membrane-bound substructures that are removed by macrophages. Neutrophils are capable of various other forms of programmed cell death, such as NETosis and pyroptotic cell death, as well as nonprogrammed cell death by necrosis. In recent years, research has revealed that neutrophils are capable of far more subtle cell-cell interactions than previously thought possible. This includes synthesis of various inflammatory mediators and also myeloid cell training within bone marrow, where epigenetic and metabolic signals associated with returning neutrophils that undergo reverse egress from tissues into the vasculature and back to bone marrow program a hyperreactive subset of neutrophils during myelopoiesis that are capable of hypersensitive reactions to microbial aggressors. These characteristics are evident in various neutrophil subsets/subpopulations, creating broad heterogeneity in the behavior and biological repertoire of these seemingly schizophrenic immune cells. Moreover, neutrophils are critical effector cells of adaptive and innate immunity, binding to opsonized bacteria and destroying them by extracellular and intracellular methods. The former creates substantial collateral host tissue damage, as they are less specific than T-cytotoxic cell-killing mechanisms, and in conditions such as peri-implantitis, where plasma cells and neutrophils dominate the immune infiltrate, bone and tissue destruction are rapid and appear relentless. Finally, the role of neutrophils as conduits for periodontal-systemic disease connections and for oxidative damage to act as a causal link between the two has only recently been realized. In this chapter, we attempt to expand on these issues, emphasizing the contributions of European scientists throughout a detailed appraisal of the benefits and side effects of neutrophilic inflammation and immune function.

Functional responses of neutrophils to Fusobacterium nucleatum subspecies

Introduction

Fusobacterium nucleatum is an opportunistic oral pathogen with five subspecies: animalis, fusiforme, nucleatum, polymorphumandvincentii. These play an important role in biofilms associated with chronic gum disease (periodontitis). Neutrophils form the first line of defence against these and other oral pathogens, employing a multitude of anti-microbial strategies, which, alongside bacterial killing, also cause collateral host-tissue damage. The immunogenic properties of F. nucleatum subspecies are poorly understood. The purpose of this study was to investigate specific neutrophil responses to all F. nucleatum subspecies.

Methods

AllF. nucleatumsubspecieswere grown planktonically overnight and inactivated using 10% neutral buffered formalin. Peripheral blood neutrophils (PBN) and neutrophil-like cells (differentiated from HL-60 cells) were challenged with inactivated bacteria (MOI 100) and production of reactive oxygen species (ROS) was quantified by Luminol/Iso-luminol enhanced chemiluminescence assays. Release of neutrophil extracellular traps (NETs) was quantified fluorescently using Sytox-green. Additionally, phagocytosis of fluorescently labelled F. nucleatum subspecies was analysed in both cell groups by flow cytometry.

Results

In addition to differences in ROS generation by PBN and neutrophil-like cells in response to individual F. nucleatum subspecies, variations in the amount of extracellular DNA extruded during NETosis was evident. Moreover, distinct levels of phagocytic activity of both cell types will be shown.

Conclusion

F. nucleatum pathogenicity has been reported in oral as well as systemic diseases (colorectal cancer, cardiovascular disease). Understanding subspecies-specific effects of F. nucleatum on neutrophils will enhance our knowledge of the interactions between this bacterium and the host immune response and may help to identify new therapeutic targets.

Fusobacterium nucleatum Subspecies Differ in Biofilm Forming Ability in vitro

Development of dysbiosis in complex multispecies bacterial biofilms forming on teeth, known as dental plaque, is one of the factors causing periodontitis. Fusobacterium nucleatum (F. nucleatum) is recognised as a key microorganism in subgingival dental plaque, and is linked to periodontitis as well as colorectal cancer and systemic diseases. Five subspecies of F. nucleatum have been identified: animalis, fusiforme, nucleatum, polymorphum, and vincentii. Differential integration of subspecies into multispecies biofilm models has been reported, however, biofilm forming ability of individual F. nucleatum subspecies is largely unknown. The aim of this study was to determine the single-subspecies biofilm forming abilities of F. nucleatum ATCC type strains. Static single subspecies F. nucleatum biofilms were grown anaerobically for 3 days on untreated or surface-modified (sandblasting, artificial saliva, fibronectin, gelatin, or poly-L-lysine coating) plastic and glass coverslips. Biofilm mass was quantified using crystal violet (CV) staining. Biofilm architecture and thickness were analysed by scanning electron microscopy and confocal laser scanning microscopy. Bioinformatic analysis was performed to identify orthologues of known adhesion proteins in F. nucleatum subspecies. Surface type and treatment significantly influenced single-subspecies biofilm formation. Biofilm formation was overall highest on poly-L-lysine coated surfaces and sandblasted glass surfaces. Biofilm thickness and stability, as well as architecture, varied amongst the subspecies. Interestingly, F. nucleatum ssp. polymorphum did not form a detectable, continuous layer of biofilm on any of the tested substrates. Consistent with limited biofilm forming ability in vitro, F. nucleatum ssp. polymorphum showed the least conservation of the adhesion proteins CmpA and Fap2 in silico. Here, we show that biofilm formation by F. nucleatum in vitro is subspecies- and substrate-specific. Additionally, F. nucleatum ssp. polymorphum does not appear to form stable single-subspecies continuous layers of biofilm in vitro. Understanding the differences in F. nucleatum single-subspecies biofilm formation may shed light on multi-species biofilm formation mechanisms and may reveal new virulence factors as novel therapeutic targets for prevention and treatment of F. nucleatum-mediated infections and diseases.

COVID-19: Seroprevalence and Vaccine Responses in UK Dental Care Professionals

Dental care professionals (DCPs) are thought to be at enhanced risk of occupational exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, robust data to support this from large-scale seroepidemiological studies are lacking. We report a longitudinal seroprevalence analysis of antibodies to SARS-CoV-2 spike glycoprotein, with baseline sampling prior to large-scale practice reopening in July 2020 and follow-up postimplementation of new public health guidance on infection prevention control (IPC) and enhanced personal protective equipment (PPE). In total, 1,507 West Midlands DCPs were recruited into this study in June 2020. Baseline seroprevalence was determined using a combined IgGAM enzyme-linked immunosorbent assay and the cohort followed longitudinally for 6 mo until January/February 2021 through the second wave of the coronavirus disease 2019 pandemic in the United Kingdom and vaccination commencement. Baseline seroprevalence was 16.3%, compared to estimates in the regional population of 6% to 7%. Seropositivity was retained in over 70% of participants at 3- and 6-mo follow-up and conferred a 75% reduced risk of infection. Nonwhite ethnicity and living in areas of greater deprivation were associated with increased baseline seroprevalence. During follow-up, no polymerase chain reaction-proven infections occurred in individuals with a baseline anti-SARS-CoV-2 IgG level greater than 147.6 IU/ml with respect to the World Health Organization international standard 20-136. After vaccination, antibody responses were more rapid and of higher magnitude in those individuals who were seropositive at baseline. Natural infection with SARS-CoV-2 prior to enhanced PPE was significantly higher in DCPs than the regional population. Natural infection leads to a serological response that remains detectable in over 70% of individuals 6 mo after initial sampling and 9 mo from the peak of the first wave of the pandemic. This response is associated with protection from future infection. Even if serological responses wane, a single dose of the Pfizer-BioNTech 162b vaccine is associated with an antibody response indicative of immunological memory.

Regenerative surgical treatment of furcation defects: A systematic review and Bayesian network meta-analysis of randomized clinical trials

AIMS

To investigate the clinical performance of regenerative periodontal surgery in the treatment of furcation defects versus open flap debridement (OFD) and to compare different regenerative modalities.

MATERIAL AND METHODS

A systematic search was conducted to identify RCTs evaluating regenerative surgical treatment of furcations with a minimum of 12-month follow-up. Three authors independently reviewed, selected and extracted data from the search conducted and assessed risk of bias. Primary outcomes were tooth loss, furcation improvement (closure/conversion) (FImp), gain of horizontal bone level (HBL) and attachment level (HCAL). Secondary outcomes were gain in vertical attachment level (VCAL), probing pocket depth (PPD) reduction, PROMs and adverse events. Data were summarized into Bayesian standard and network meta-analysis in order to estimate direct and indirect treatment effects and to establish a ranking of treatments.

RESULTS

The search identified 19 articles, reporting on 20 RCTs (19 on class II, 1 on class III furcations) with a total of 575 patients/787 defects. Tooth loss was not reported. Furcation closure ranged between 0% and 60% (10 trials), and class I conversion from 29% to 100% (six trials). Regenerative techniques were superior to OFD for FImp (OR = 20.9; 90% CrI = 5.81, 69.41), HCAL gain (1.6 mm), VCAL gain (1.3 mm) and PPD reduction (1.3 mm). Bone replacement grafts (BRG) resulted in the highest probability (Pr = 61%) of being the best treatment for HBL gain. Non-resorbable membranes + BRG ranked as the best treatment for VCAL gain (Pr = 75%) and PPD reduction (Pr = 56%).

CONCLUSIONS

Regenerative surgery of class II furcations is superior to OFD. FImp (furcation closure or class I conversion) can be expected for the majority of defects. Treatment modalities involving BRG are associated with higher performance.

Systemic disease or periodontal disease? Distinguishing causes of gingival inflammation: a guide for dental practitioners. Part 2: cancer related, infective, and other causes of gingival pathology

Periodontitis and gingivitis are highly prevalent inflammatory diseases of the oral cavity, and typically are characterised by the presence of dental plaque. However, other causes of oral inflammation exist, which can resemble plaque-induced gingivitis and periodontitis, and may thus first be seen by a dental practitioner. This paper aims to provide dentists with an understanding of the manifestations of systemic diseases to the periodontium and highlights anamnestic and clinical clues important for distinguishing between plaque-induced and non plaque-induced lesions. In the first part of this series immune-mediated and hereditary conditions as causes of gingival lesions were discussed; this second part highlights cancer-related gingival lesions as well as those caused by specific pathogens, medication or malnutrition. A clear clinical, epidemiological and visual overview of the different conditions is provided. Early diagnosis of non plaque-related causes of gingival lesions can be vital for affected patients. Therefore, dental practitioners should be aware of the various manifestations of systemic diseases to the periodontium.

Neutrophil Subsets in Periodontal Health and Disease: A Mini Review

Neutrophils are amongst the most abundant immune cells within the periodontal tissues and oral cavity. As innate immune cells, they are first line defenders at the tooth-mucosa interface, and can perform an array of different functions. With regard to these, it has been observed over many years that neutrophils are highly heterogeneous in their behavior. Therefore, it has been speculated that neutrophils, similarly to other leukocytes, exist in distinct subsets. Several studies have investigated different markers of neutrophils in oral health and disease in recent years in order to define potential cell subsets and their specific tasks. This research was inspired by recent advancements in other fields of medicine in this field. The aim of this review is to give an overview of the current evidence regarding the existence and presence of neutrophil subsets and their possible functions, specifically in the context of periodontitis, gingivitis, and periodontal health.

Oral Neutrophils Characterized: Chemotactic, Phagocytic, and Neutrophil Extracellular Trap (NET) Formation Properties

Maintenance of oral health is in part managed by the immune-surveillance and antimicrobial functions of polymorphonuclear leukocytes (PMNs), which migrate from the circulatory system through the oral mucosal tissues as oral PMNs (oPMNs). In any microorganism-rich ecosystem, such as the oral cavity, PMNs migrate toward various exogenous chemoattractants, phagocytose bacteria, and produce neutrophil extracellular traps (NETs) to immobilize and eliminate pathogens. PMNs obtained from the circulation through venipuncture (hereafter called cPMNs) have been widely studied using various functional assays. We aimed to study the potential of oPMNs in maintaining oral health and therefore compared their chemotactic and antimicrobial functions with cPMNs. To establish chemotactic, phagocytic, and NET forming capacities, oPMNs and cPMNs were isolated from healthy subjects without obvious oral inflammation. Directional chemotaxis toward the chemoattractant fMLP was analyzed using an Insall chamber and video microscopy. fMLP expression was assessed by flow cytometry. Phagocytosis was analyzed by flow cytometry, following PMN incubation with heat-inactivated FITC-labeled micro-organisms. Furthermore, agar plate-based killing assays were performed with Escherichia coli (Ec). NET formation by oPMNs and cPMNs was quantified fluorimetrically using SYTOX™ Green, following stimulation with either PMA or RPMI medium (unstimulated control). In contrast to cPMNs, the chemotactic responses of oPMNs to fMLP did not differ from controls (mean velocity ± SEM of cPMNs: 0.79 ± 0.24; of oPMNs; 0.10 ± 0.07 micrometer/min). The impaired directional movement toward fMLP by oPMNs was explained by significantly lower fMLP receptor expression. Increased adhesion and internalization of various micro-organisms by oPMNs was observed. oPMNs formed 13 times more NETs than stimulated cPMNs, in both unstimulated and stimulated conditions. Compared to cPMNs, oPMNs showed a limited ability for intracellular killing of Ec. In conclusion, oPMNs showed exhausted capacity for efficient chemotaxis toward fMLP which may be the result of migration through the oral tissues into the oral cavity, being a highly “hostile” ecosystem. Overall, oPMNs' behavior is consistent with hyperactivity and frustrated killing. Nevertheless, oPMNs most likely contribute to maintaining a balanced oral ecosystem, as their ability to internalize microbes in conjunction with their abundant NET production remains after entering the oral cavity.

Consequences of cathepsin C inactivation for membrane exposure of proteinase 3, the target antigen in autoimmune vasculitis

Membrane-bound proteinase 3 (PR3^m) is the main target antigen of anti-neutrophil cytoplasmic autoantibodies (ANCA) in granulomatosis with polyangiitis, a systemic small-vessel vasculitis. Binding of ANCA to PR3^m triggers neutrophil activation with the secretion of enzymatically active PR3 and related neutrophil serine proteases, thereby contributing to vascular damage. PR3 and related proteases are activated from pro-forms by the lysosomal cysteine protease cathepsin C (CatC) during neutrophil maturation. We hypothesized that pharmacological inhibition of CatC provides an effective measure to reduce PR3^m and therefore has implications as a novel therapeutic approach in granulomatosis with polyangiitis. We first studied neutrophilic PR3 from 24 patients with Papillon-Lefèvre syndrome (PLS), a genetic form of CatC deficiency. PLS neutrophil lysates showed a largely reduced but still detectable (0.5-4%) PR3 activity when compared with healthy control cells. Despite extremely low levels of cellular PR3, the amount of constitutive PR3^m expressed on the surface of quiescent neutrophils and the typical bimodal membrane distribution pattern were similar to what was observed in healthy neutrophils. However, following cell activation, there was no significant increase in the total amount of PR3^m on PLS neutrophils, whereas the total amount of PR3^m on healthy neutrophils was significantly increased. We then explored the effect of pharmacological CatC inhibition on PR3 stability in normal neutrophils using a potent cell-permeable CatC inhibitor and a CD34⁺ hematopoietic stem cell model. Human CD34⁺ hematopoietic stem cells were treated with the inhibitor during neutrophil differentiation over 10 days. We observed strong reductions in PR3^m, cellular PR3 protein, and proteolytic PR3 activity, whereas neutrophil differentiation was not compromised.

Assessment of the involvement of the macrophage migration inhibitory factor-glucocorticoid regulatory dyad in the expression of matrix metalloproteinase-2 during periodontitis

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and counter-regulator of endogenous glucocorticoids (GCs). It is implicated in acute and chronic inflammatory diseases. This study investigated the role of the MIF-GC regulatory dyad in the expression and release of matrix metalloproteinase-2 (MMP-2) during periodontitis, in vivo and in vitro. In a Mif-knockout (KO) mouse model of ligature-induced periodontitis, gingival tissues and blood were collected and analysed for levels of interleukin-6 (IL-6), MIF, MMP-2, and corticosterone. In addition, human gingival fibroblasts (HGFs) were tested for production of IL-6 and MMP-2 after stimulation with hydrocortisone (HC), MIF, tumour necrosis factor-alpha (TNF-α), or Fusobacterium nucleatum, a pathogen known to elicit immune responses during periodontitis. Wild-type (WT) mice showed a local and systemic increase of MIF levels during inflammation, which was confirmed by increased local IL-6 concentrations. Systemic GC levels were reduced in WT and Mif-KO mice during inflammation, with overall lower concentrations in Mif-KO mice. In vivo and in vitro, MMP-2 production was not dependent on MIF or inflammatory stimuli, but was inhibited by HC. Therefore, MIF does not appear to stimulate expression of MMP-2 in the gingival tissues, whereas GC upregulates MIF and downregulates MMP-2. Our findings further suggest that MIF may regulate systemic GC levels.

Modulation of neutrophil chemotaxis by Aggregatibacter actinomycetemcomitans leukotoxin

Objective: Aggressive periodontitis (AgP) is frequently associated with the presence of Aggregatibacter actinomycetemcomitans, a Gram-negative pathogen, which expresses leukotoxin (Ltx) as a virulence factor. Ltx is known to disturb neutrophil function and to activate these cells. This study was aimed at investigating the ability of Ltx to alter the chemotactic behaviour of neutrophils, the most abundant leukocyte in periodontitis.

Methods: Neutrophils from healthy blood donors were isolated and stimulated or primed with low concentrations of Ltx (1, 5 and 10 ng/mL). Neutrophil migration in response to Ltx gradients and to the biofilm-derived chemotactic agent fMLP after Ltx-priming was monitored by real-time video microscopy using an Insall chamber.

Results: Although Ltx alone enhanced neutrophil movement at all concentrations, low directional accuracy was observed compared to the positive control (fMLP). Ltx priming led to directional movement towards fMLP with significantly enhanced speed. In case of 10 ng/mL Ltx, however, this chemotactic response towards fMLP appeared to be delayed.

Conclusion: The results indicate that Ltx induces non-directional neutrophil movement, whilst enhancing migration towards fMLP. Clincially, this may lead to the presence of a higher number of activated neutrophils in the periodontal tissues, potentially causing more pronounced host tissue damage.

Long-term release of antibiotics by carbon nanotube-coated titanium alloy surfaces diminish biofilm formation by Staphylococcus epidermidis

Bacterial biofilms cause a considerable amount of prosthetic joint infections every year, resulting in morbidity and expensive revision surgery. To address this problem, surface modifications of implant materials such as carbon nanotube (CNT) coatings have been investigated in the past years. CNTs are biologically compatible and can be utilized as drug delivery systems. In this study, multi-walled carbon nanotube (MWCNT) coated TiAl6V4 titanium alloy discs were fabricated and impregnated with Rifampicin, and tested for their ability to prevent biofilm formation over a period of ten days. Agar plate-based assays were employed to assess the antimicrobial activity of these surfaces against Staphylococcus epidermidis. It was shown that vertically aligned MWCNTs were more stable against attrition on rough surfaces than on polished TiAl6V4 surfaces. Discs with coated surfaces caused a significant inhibition of biofilm formation for up to five days. Therefore, MWCNT-modified surfaces may be effective against pathogenic biofilm formation on endoprostheses.

Effects of Aggregatibacter actinomycetemcomitans leukotoxin on neutrophil migration and extracellular trap formation

Background

Aggressive periodontitis is associated with the presence of Aggregatibacter actinomycetemcomitans, a leukotoxin (Ltx)-producing periodontal pathogen. Ltx has the ability to lyse white blood cells including neutrophils.

Objectives

This study was aimed at investigating the interactions between neutrophils and Ltx with regard to the chemotactic properties of Ltx and the release of neutrophil extracellular traps (NETs).

Methods

Neutrophils from healthy blood donors were isolated and incubated for 30 min and 3 h with increasing concentrations of Ltx (1, 10, and 100 ng/mL) as well as with A. actinomycetemcomitans strains (NCTC 9710 and HK 1651) producing different levels of Ltx. Formation of NETs and cell lysis were assessed by microscopy, fluorescence-based assays, and measurement of released lactate dehydrogenase. Neutrophil migration in response to different Ltx gradients was monitored by real-time video microscopy, and image analysis was performed using ImageJ software.

Results

Although Ltx (10 and 100 ng/mL) and the leukotoxic A. actinomycetemcomitans strain HK 1651 lysed some neutrophils, other cells were still capable of performing NETosis in a concentration-dependent manner. Low doses of Ltx and the weakly leukotoxic strain NCTC 9710 did not lead to neutrophil lysis, but did induce some NETosis. Furthermore, all three concentrations of Ltx enhanced random neutrophil movement; however, low directional accuracy was observed compared with the positive control (fMLP).

Conclusions

The results indicate that Ltx acts both as a neutrophil activator and also causes cell death. In addition, Ltx directly induces NETosis in neutrophils prior to cell lysis. In future studies, the underlying pathways involved in Ltx-meditated neutrophil activation and NETosis need to be investigated further.

Soluble RANKL Cleaved from Activated Lymphocytes by TNF-α-Converting Enzyme Contributes to Osteoclastogenesis in Periodontitis

Host immune responses play a key role in promoting bone resorption in periodontitis via receptor activator of NF-κB ligand (RANKL)-dependent osteoclastogenesis. Both membrane-bound RANKL (mRANKL) expressed on lymphocytes and soluble RANKL (sRANKL) are found in periodontal lesions. However, the underlying mechanism and cellular source of sRANKL release and its biological role in periodontitis are unclear. TNF-α-converting enzyme (TACE) is reported to cleave the following: 1) precursor TNF-α with release of mature, soluble TNF-α and 2) mRANKL with release of sRANKL. Both soluble TNF-α and sRANKL are found in the periodontitis lesion, leading to the hypothesis that TACE expressed on lymphocytes is engaged in RANKL shedding and that the resulting sRANKL induces osteoclastogenesis. In the current study, upon stimulating PBLs with mitogens in vitro, RANKL expression, sRANKL secretion, and TACE expression were all upregulated. Among the four putative mRANKL sheddases examined in neutralization assays, TACE was the only functional sheddase able to cleave mRANKL expressed on PBL. Moreover, PBL culture supernatant stimulated with mitogens in the presence of anti-TACE Ab or anti-RANKL Ab showed a marked reduction of osteoclastogenesis from osteoclast precursors, indicating that TACE-mediated sRANKL may possess sufficient osteoclastogenic activity. According to double-color confocal microscopy, B cells expressed a more pronounced level of RANKL and TACE expression than T cells or monocytes in periodontally diseased gingiva. Conditioned medium of patients' gingival lymphocyte culture increased in vitro osteoclastogenic activity, which was suppressed by the addition of anti-TACE Ab and anti-RANKL Ab. Therefore, TACE-mediated cleavage of sRANKL from activated lymphocytes, especially B cells, can promote osteoclastogenesis in periodontitis.

Oral inflammation and bacteremia: implications for chronic and acute systemic diseases involving major organs

Gingivitis and periodontitis are both highly prevalent gum diseases characterized by an accumulation of a polymicrobial biofilm (dental plaque) around teeth and inflammation in adjacent soft tissues. During dental procedures, even tooth brushing, these bacteria and their components, such as endotoxin, can easily disseminate into the systemic circulation through minor or major gingival injuries. Particularly in immuno-compromised subjects or patients with preexisting pathologic conditions, bacteremia may lead to bacterial infection of distant organs, which may cause immunological reactions. Oral bacteria and endotoxins have been found in sepsis, infective endocarditis, lung infection, liver disease and many other potentially lethal disorders. This article presents a review of the possible pathologic consequences of bacteremia originating in the oral cavity and points out the most commonly affected organs as well as preventive and treatment measures. At the present time, plaque control by subjects and/or dental professionals is one of the most effective means to prevent the onset and progression of oral bacteremia-induced systemic diseases.

Dynamic interactions of neutrophils and biofilms

BACKGROUND

The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms.

OBJECTIVE/DESIGN

In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed.

RESULTS/CONCLUSION

Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

[Patient education for self-management of oral anticoagulation - situation in Hesse]

AIM

Oral anticoagulation (OAC) has been shown to be highly effective in preventing thromboembolic complications. Self-management can enable patients with a long-term indication for OAC to be actively involved in the therapy, but in Germany the implementation of self-management is linked to mandatory training. To illustrate significant structural disparities between education centres in Hesse, all such centres were identified and a list generated, specifying the differences.

METHOD

Using our own questionnaire, we interviewed all known patient education centres in Hesse between January and July 2012, and conducted a descriptive analysis of their structural features.

RESULTS

There were 44 datasets for statistical interpretation. We distinguished between centres with ASA certification (n=19) and centres without (n=25). On average, certified centres provide 6 h of training (range 2-9) compared to 5.5 h (range 1-12) in uncertified centers. Certified centres hold more group sessions per year (on average 17 vs. 8) and more individual training sessions (on average 10 vs. 5). Certified centres train 10-365 patients per year and uncertified centers between 5 and 77. Certified centres offer retraining more frequently (84% vs. 40%) and more often conclude the training with a written test (74% vs. 44%). Only 9 centres provide materials for patients with a migration background.

CONCLUSION

The results show that in Hesse, severe structural discrepancies exist in training programmes for self-management of OAC, and it can be assumed that patients participating in trainings in different Hessian education centres face very differing conditions. To improve the quality of the trainings and to ensure patients have similar levels of knowledge, it is imperative that centres be regularly inspected with the help of proven quality indicators.

[Measurement of tissue-shift for head neck rotation]

BACKGROUND

During neck surgery the head of the patient is located in such a position that the neck-tissue is deformed compared to the normal head-position. The consideration of this tissue deformation of the neck during head rotation is the first step to using preoperative image data for medical navigation.

MATERIAL AND METHODS

The tissue shift was measured and analyzed based on MRT-image data of a subject group of 5 patients.

RESULTS

The big vessels, lying contralateral to the rotation, demonstrated a larger shift than those vessels, lying ipsilateral. The shift was nonlinear to the head rotation and the shift of the V. jugularis interna was less pronounced than the shift of the A. carotis communis even though they both run in the same adventitia. In the cranial neck section, the movement of the tissue was larger than in the caudal neck section.

CONCLUSION

The knowledge about tissue shifts in different head positions should promote intraoperative, minimally invasive procedures. The expectation is that such examinations facilitate the navigation in neck surgery with online calculation of tissue shifts.

The antimicrobial activity of the appetite peptide hormone ghrelin

The present study examined the antimicrobial activity of the peptide ghrelin. Both major forms of ghrelin, acylated ghrelin (AG) and desacylated ghrelin (DAG), demonstrated the same degree of bactericidal activity against Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), while bactericidal effects against Gram-positive Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) were minimal or absent, respectively. To elucidate the bactericidal mechanism of AG and DAG against bacteria, we monitored the effect of the cationic peptides on the zeta potential of E. coli. Our results show that AG and DAG similarly quenched the negative surface charge of E. coli, suggesting that ghrelin-mediated bactericidal effects are influenced by charge-dependent binding and not by acyl modification. Like most cationic antimicrobial peptides (CAMPs), we also found that the antibacterial activity of AG was attenuated in physiological NaCl concentration (150mM). Nonetheless, these findings indicate that both AG and DAG can act as CAMPs against Gram-negative bacteria.

Aspirin reduces the incidence of second eye NAION: a retrospective study

The objective of this study was to determine if aspirin reduces the incidence of second eye involvement after nonarteritic anterior ischemic optic neuropathy (NAION) in one eye. Records were reviewed of 131 patients who sustained unilateral NAION. Of these, the 33 patients who sustained second eye NAION were compared to those followed for a minimum of 2 years without sustaining a second eye NAION (67). Thirty-one of the 131 patients were excluded because of inadequate follow-up. Except for diabetes (relative risk [RR] 1.43, p = 0.05), the incidence of second eye NAION was independent of gender, age, cup/disk, hypertension, anemia, and migraine. The degree of visual acuity or field dysfunction in the first eye correlated poorly with the acuity (r = 0.28) and field (r = 0.33) loss in the second eye. Aspirin (65-1,300 mg) taken two or more times per week decreased the incidence (17.5% vs. 53.5%) and relative risk (RR = 0.44, p = 0.0002) of second eye AION regardless of the usual risk factors. Even after eliminating those patients who had bilateral disease when first referred, ASA still reduced the incidence of second eye involvement (35% vs. 13%, RR = 0.74, p = 0.01). Aspirin may be an effective means of reducing second eye NAION.

Iodoaminopotentidine and related compounds: a new class of ligands with high affinity and selectivity for the histamine H2 receptor

The synthesis and biological evaluation of a new class of histamine H2 antagonists with N-cyano-N'-[omega-[3-(1-piperidinylmethyl)phenoxy] alkyl]guanidine partial structure are described as part of an extensive research program to find model compounds for the development of new radioligands with high H2 affinity and specific activity. High receptor affinity is achieved by an additional (substituted) aromatic ring, which is connected with the third guanidine N by a carbon chain spacer and an amine, carboxamide, ester, or sulfonamide link ("polar group"). In functional studies for H2 antagonistic activity and other pharmacological actions [e.g. H1 antihistaminic, antimuscarinic, antiadrenergic (alpha 1, beta 1), 5-HT2 blocking activity] in the isolated guinea pig atrium and ileum and rat aorta and tail artery, the compounds proved to be highly potent and selective histamine H2 receptor antagonists. The H2 antagonistic activity is mainly depending on the length of both the N'-alkyl chain (chain A) and the N"-spacer (chain B). Compounds with a C3 chain A and a C2 chain B are most potent in the preferred group of substances, i.e., the carboxamide series. A wide variety of substituents at the aromatic ring is tolerated, among them iodine, amino, and azido groups. These compounds are up to 32 times more potent than cimetidine in the isolated guinea pig right atrium. The replacement of the carboxamide by an ester group (44c) is well tolerated, while replacement of the cyanoguanidine by an urea group results in nearly 100-fold decrease in activity (46c,e). The iodinated benzamides are among the most potent H2 antagonists known so far. The [125I]-labeled form of 31f ([125I]iodoaminopotentidine, [125I]-N-[2-(4-amino-3-iodobenzamido) ethyl]-N'-cyano-N"-[3-[3-(1-piperidinylmethyl) phenoxy]propyl]guanidine) and its photolabile analogue 31h ([125I]iodoazidopotentidine, [125I]-N-[2-(4-azido-3- iodobenzamido)ethyl]-N'-cyano-N"-[3-[3-(1-piperidinyl-methyl)pheno xy] propyl]guanidine) proved to be useful probes for reversible and irreversible labeling of the histamine H2 receptor. Radioligand binding studies in guinea pig cerebral membranes revealed considerably higher H2 receptor affinity for 31f (pKi = 9.15), 31h (pKi = 8.58), and some analogues than functional experiments (guinea pig atrium), presumably reflecting an easier access to the H2 receptors in membranes.

Reversible and irreversible labelling of H1- and H2 -receptors using novel [125I] probes

We have recently designed the first 125I-labelled probes specific for the histamine H1 and H2 receptors. These reversible and irreversible antagonists are among the most potent H1 and H2 ligands and have enabled investigations into the biochemical and pharmacological properties of these two receptors. In various brain animal species, the ligand binding peptide of the H1 and H2 receptors, as determined by photoaffinity labeling, resides within 56-59 kDa peptides. In contrast, in guinea pig heart, the ligand binding domain of the H1 receptor is characterized by a higher molecular weight (68 kDa), suggesting the presence of an isoform of this protein, clearly differentiable by this biochemical property but not by its pharmacology. The reversible 125I-probes allowed us to extend the pharmacology of these receptors in several biological preparations and in human brain, and to establish their interaction with G-proteins. A detailed mapping of H1 and, for the first time, of H2 receptors, has been achieved in guinea pig brain, establishing their presence in almost all brain areas. These experiments show that there is no correlation between the density of H2 receptor and the activity of adenylate cyclase sensitive to histamine suggesting a molecular heterogeneity of this receptor.

Reversible and irreversible labeling and autoradiographic localization of the cerebral histamine H2 receptor using [125I]iodinated probes

Iodoaminopotentidine (I-APT)--i.e., N-[2-(4-amino-3-iodobenzamido)ethyl]-N'-cyano-N''-(3-[3- (1-piperidinylmethyl)phenoxy]propyl)guanidine--represents one of the most potent H2-receptor antagonists known so far. In membranes of guinea pig brain 125I-APT bound reversibly, selectively, and with high affinity (Kd = 0.3 nM) to a homogeneous population of sites unambiguously identified as H2 receptors by inhibition studies conducted with a large panel of antagonists. 125I-APT binding was also inhibited by histamine, and the effect was modulated by a guanyl nucleotide, which is consistent with the association of the H2 receptor with a guanine nucleotide binding regulatory protein. The low nonspecific binding of 125I-APT generated high contrast autoradiographic pictures in brain sections and established the precise distribution of H2 receptors. Their highly heterogeneous distribution and laminated pattern in some areas--e.g., cerebral and hippocampal cortices--suggest their major association with neuronal elements. These localizations were more consistent than those of H1 receptors with the distribution of histaminergic projections, indicating that H2 receptors mediate a larger number of postsynaptic actions of histamine--e.g., in striatum. Colocalizations of H1 and H2 receptors in some areas account for their known synergistic interactions in cAMP formation induced by histamine. The distribution of 125I-APT binding sites did not strictly parallel that of the H2-receptor-linked adenylate cyclase activity, which may reflect heterogeneity among H2 receptors. After UV irradiation and SDS/PAGE analysis, [125I]iodoazidopotentidine (125I-AZPT), a photoaffinity probe derived from 125I-APT, was covalently incorporated in several peptides, among which the labeling of two peptides of 59 and 32 kDa was prevented by H2 antagonists, suggesting that they correspond to H2-receptor binding peptides or proteolysis products of the latter. These probes should be useful for sensitive radioassays, localization, purification, and molecular studies of the H2 receptor, which were previously impracticable.

Conceptual framework shifts in immunogenetics. II. Some notes on the Ag system

Two Caucasian population materials totalling 530 individuals and 3,180 typing results are analyzed with regard to various combinations of the Ag(x, y, a1, d, c, g) factors. Superficially, both materials appear well aligned to each other and the contemporary (simple-complex) framework. However, when the same set of data are structuralized within a new (complex-simple) framework, the typing results for 12 of 362 or 3.3% of the Swiss and no less than 19 of 168 or 11.3% of the English samples are not compatible with the new framework specifying that the various anti-Ag reagents can be arranged in two 'inclusion groups'--the anti-Ag (y greater than d greater than c) and the anti-Ag (g greater than a1 greater than x) series.

Conceptual framework shifts in immunogenetics. I. A new look at cis AB antigens in the ABO system

The so-called 'cis AB' blood group is accounted for by proposing that 'normal' anti-A and anti-B reagents are cross-reacting with partially overlapping reaction ranges. Hence, they are labelled anti-AX and anti-BX, respectively. Some consequences of a complex-simple model where 'cis AB' is accordingly produced by a simple (mono-factorial) antigen X (produced a simple gene X at the ABO-locus) are briefly explored.

Towards a unified theory for immunogenetic systems. Some selected properties of ABC- and AB-D reaction patterns generated by S3 and T3 universes

The principles of a radically new unified theory and a unified but fundamentally theory-invariant classification system are described and exemplified for immunogenetic systems. The classification system permits a differentiation of immunogenetic systems into 15 qualitatively distinct classes with quantitative subsets when tested against two reagents. It can easily be expanded into a n-reagent taxonomy. The theory logically explains a set of selected and previously more or less "unexplainable" properties and their (even more unexplainable and probably previously unnoticed) associations in two main classes of immunogenetic systems, the ABC- and AB-D systems. The associated properties discussed are the presence (+) or absence (-) of: 1. antithetical alleles; 2. dosage effects; 3. inherited "strong" and "weak" antigens; 4. "silent" or "amorphous" genes. In ABC- systems, properties 1 and 2 are present while 3 and 4 are absent or extremely rare (i.e. 1+2+3-4-). In AB-D systems, properties 1 and 2 are absent while 3 and 4 are present (i.e. 1-2-3+4+). Through the design of hypothetical immunogenetic universes (HIU), these property associations are shown to be produced by the contemporary (simple-complex) framework-dependent transformations of experimental observables/matrix facts and not by any corresponding associated properties present in the input HIU in themselves.

Towards a unified theory for immunogenetic systems. I. Probing the serologic field--a meta-serologic approach

A serologic field (SEF) is produced by the in vitro studies of antibody-antigen interactions and usually includes serologic information processing (SIF). SIF can be regarded as the process whereby essentially "meaningless" raw data or experimental observables emanating from an input reality are structuralized and hence falsified into a "meaningful" pattern, Gestalt or output image. According to this "black box model", different "fact categories" (FC) can be identified in SEF. Traditional serology generally confounds its FC whereby fact category mistakes (FCM) are produced. Some FCM are structurally similar to the description of "mice" as four-letter animals or as a four-legged word--i.e. facts about "thing-properties" (animals, legs) are confounded with facts about "language-properties" (letters, words). In SEF, antibody and antigen molecules (thing-properties) are similarly endowed with "empty symbols" (language-properties). Due to such FCM, radically new meanings are assigned to experimental observables if the serologic language and/or theory is changed. The present meta-serologic approach consists of the design of a meta-serologic symbol language (SL-2) which includes the contemporary (simple-complex) conceptual framework (language and theory) as a limiting case. Consequently, some truly radical and revolutionary Gestalt switches will be generated when a specified SEF is mapped onto SL-2.