Inflammatory cytokines and the nuclear vitamin D receptor are implicated in the pathophysiology of dental resorptive lesions in cats

Microspatial distribution of trace elements in feline dental hard tissues: early life exposure to essential and toxic elements

Introduction

Trace elements play a key role in dental tissue development, as dental hard tissues accumulate both essential and toxic trace elements during mineralization. Characterization of the spatial accumulation pattern of trace elements may provide insight into exposure to toxic elements over time and to the nature of disease processes affecting the hard dental tissues. Here, we present the first report of the use of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to map the microspatial distribution of multiple trace elements, essential and toxic, across feline dental hard tissues.

Methods

Eleven teeth were extracted from 8 cats. Nine teeth were from 7 cats diagnosed with idiopathic tooth resorption on intraoral radiographs prior to extraction. Two teeth were included from a cadaver that had no signs of tooth resorption on intraoral radiographs. The normal dental tissue was analyzed from each sample using LA-ICP-MS to map the microspatial distribution of essential and toxic trace elements across feline enamel, dentin, and cementum.

Results

Results showed a higher accumulation of barium and strontium in coronal dentin as compared to root dentin. The timing of the accumulation mirrors nursing timelines seen in teeth from human and non-human primates, consistent with barium and strontium being sourced from maternal milk. Results also showed a higher uptake of lead in the coronal dentin, suggesting this lead exposure was likely passed from mother to offspring.

Discussion

This work characterizes a baseline for elemental distribution in feline teeth linked to early life exposure to toxic elements such as lead and provides a framework for future studies investigating long-term environmental exposures to trace elements, essential and toxic, and their involvement in feline systemic and dental diseases.

Evaluation of Feline Permanent Canine Tooth Mineral Density Using Micro-Computed Tomography

The tooth is made up of three mineralized tissues, enamel, dentin, and cementum, which surround a non-mineralized tissue called the dental pulp. Micro-computed tomography (mCT) is an imaging technology based on X-rays that allows non-invasive visualization of objects at a microscopic scale, according to their radiopacity and in three dimensions (3D). Likewise, it allows the subsequent execution of morphological and quantitative analysis of the objects, such as, for example, the determination of the relative mineral density (MD). The present work aimed to describe the MD of feline teeth using mCT. The studied sample consisted of four European Shorthair cats, from which nine canine teeth were extracted per medical indication. These teeth were evaluated through dental radiography before and after their extraction. Using mCT and the CTAn software, the values of the relative mineral density of the root of each tooth and of specific segments corresponding to the coronal, middle, and apical thirds of the root were determined. Mean MD of root tissues was 1.374 ± 0040 g·cm−3, and of hard root, tissues was 1.402 ± 0.035 g·cm−3. Through mCT, it was possible to determine the mean MD values of feline canine teeth. The study of MD could become an ancillary method for the diagnosis and characterization of dental pathology.

Blood Parameters and Feline Tooth Resorption: A Retrospective Case Control Study from a Spanish University Hospital

Simple Summary

Tooth resorption (TR) is a progressive destruction of hard dental tissues, leading to dental fractures. Our aims were to describe the TR clinical presentation on data from a university veterinary hospital (September 2018–May 2019; Northeastern Spain), and to study several blood parameters (34) for ascertaining potential systemic effects associated with TR. Cases (29) had positive radiographic TR diagnosis and controls (58) showed healthy mouths when presented for elective surgery; orthopedic surgery or soft tissues procedures. Blood parameters significantly different for cases and controls were chosen for multiple regression analysis (correction factor: age). TR was detected in 130/870 teeth (14.9%). TR stage 4 and 5; and types 1 and 2 were the most frequent. The status of LLP1, LRP1, and LLM1could be considered as TR sentinels. A significant association was found between TR stage and TR type (p < 0.001). TR presence was significantly associated with high creatinine levels and low urea nitrogen/creatinine and albumin/globulin ratios. A positive association was found between TR index and globulin levels. When affected by TR, systemic implication related to infection/inflammation or even kidney damage could be present; therefore, special care in these aspects must be provided in feline clinics.

Abstract

Tooth resorption (TR; progressive destruction of hard dental tissues) varies in prevalence according to population, age, and country (29–66.1%). Our objective was twofold: describing the TR clinical presentation in Northeastern Spain, and studying 34 blood parameters to ascertain potential systemic effects associated with TR. Cases (29; presented from September 2018 to May 2019) and controls (58) were considered. Non-parametric tests were carried out to compare cases and controls for each blood parameter; those showing significant differences were chosen for multiple regression analysis (binomial logistic and hierarchical multiple regressions). In case TR was detected in 130/870 teeth (14.9%), TR stage and type were correlated (p < 0.001). Increasing CREA values (p = 0.034) and decreasing BUN/CREA and ALB/GLOB values were associated with TR presence (p = 0.029 and p = 0.03, respectively). Increasing GLOB was associated with increasing severity of TR (p < 0.01). Type 1 TR (highly related to inflammation and periodontal disease PD) was the most frequently observed type; the association of TR and inflammation biomarkers (ALB/GLOB, GLOB) are explained by this fact. The concomitant presence of PD and TR in old cats would cause TR association with kidney damage biomarkers (CREA, BUN/CREA). When affected by TR, special care in these aspects must be provided to cats.

Microbiome analysis of feline odontoclastic resorptive lesion (FORL) and feline oral health

Introduction

Feline odontoclastic resorptive lesion (FORL) is one of the most common and painful oral diseases of the cat. It is characterised by tooth resorption due to destructive activity of odontoclasts. FORL can result in tooth loss. While the aetiology of FORL is not clearly understood, it is thought to be multifactorial and bacteria are likely to play a major role.

Hypothesis

Dysbiosis of the normal feline oral microbiota leads to an alteration in commensal bacteria populations, which results in the development of FORL.

Aim

The purpose of the current study was to determine the composition of the microbiomes associated with feline oral health and FORL.

Methodology

Supragingival plaque was collected from 25 cats with a healthy oral cavity and 40 cats with FORL. DNA was extracted from each sample, the V4 region of the 16S rRNA gene amplified by polymerase chain reaction and amplicons sequenced. Diversity and species richness analyses were performed, principal component analysis was used to explore differences between the oral microbiomes of healthy cats and those with FORL, and linear discriminant analysis effect size was used to assess differences between the groups.

Results

The six most abundant bacterial genera identified were Bergeyella, Capnocytophaga, Lampropedia, Morexella, Porphyromonas and Treponema. Two-step cluster analysis of the data identified two FORL sub-groups (FORL-1, FORL-2). The FORL-2 sub-group was very similar to the healthy group, whilst the FORL-1 sub-group was clearly different from both the FORL-2 sub-group and the healthy groups. In this analysis, Capnocytophaga (P <0.001) and Lampropedia (P <0.01) were found at significantly lower levels and Porphyromonas at a slightly higher level in the FORL-1 sub-group compared to the healthy and FORL-2 sub-groups. Microbial diversity was found to be less in the FORL-1 sub-group than in the healthy group. Lampropedia sp., a phosphate-accumulating oral commensal species, was significantly lower in the FORL-1 sub-group.

Conclusion

The oral microbiota associated with the FORL-1 sub-group is distinct from that found in the healthy group and FORL-2 sub-group. Lampropedia species may influence the local calcium-phosphate ratio, which could be a factor in tooth and bone resorption observed in FORL.

Transcriptomic profiling of feline teeth highlights the role of matrix metalloproteinase 9 (MMP9) in tooth resorption

Tooth resorption (TR) in domestic cats is a common and painful disease characterised by the loss of mineralised tissues from the tooth. Due to its progressive nature and unclear aetiology the only treatment currently available is to extract affected teeth. To gain insight into TR pathogenesis, we characterised the transcriptomic changes involved in feline TR by sequencing RNA extracted from 14 teeth (7 with and 7 without signs of resorption) collected from 11 cats. A paired comparison of teeth from the same cat with and without signs of resorption identified 1,732 differentially expressed genes, many of which were characteristic of osteoclast activity and differentiation, in particular matrix metalloproteinase 9 (MMP9). MMP9 expression was confirmed by qPCR and immunocytochemistry of odontoclasts located in TR lesions. A hydroxamate-based MMP9 inhibitor reduced both osteoclast formation and resorption activity while siRNA targeting MMP9 also inhibited osteoclast differentiation although had little effect on resorption activity. Overall, these results suggest that increased MMP9 expression is involved in the progress of TR pathogenesis and that MMP9 may be a potential therapeutic target in feline TR.

A multidisciplinary study of pain in cats undergoing dental extractions: A prospective, blinded, clinical trial

This study aimed to evaluate pain scores, analgesic requirements, food intake and serum inflammatory cytokines in cats before and after clinically recommended dental treatment. Twenty-four cats were included in a prospective, blinded clinical trial. Cats were equally divided into minimal (minimal dental treatment) or severe (multiple dental extractions) oral disease groups. They were admitted (day 0) and underwent oral examination/radiographs/treatment under general anesthesia (day 1; acepromazine-hydromorphone-propofol-isoflurane-meloxicam-local anesthetic blocks). Serum inflammatory cytokines were measured on days 0 and 6. Pain was scored using the Glasgow composite measure pain scale-feline (CMPS-F). Rescue analgesia was administered with hydromorphone if CMPS-F ≥ 5/20. Dry and soft food intake (%) during 3 minutes and 2 hours, and daily soft food were calculated. The Cochran-Mantel-Haenszel and Chi-square tests, Spearman’s rank correlation and linear mixed models were used for statistical analysis (alpha = 0.05). Pain scores were significantly increased in cats with severe disease when compared with baseline (up to day 4) and minimal disease (all postoperative time points). Prevalence of rescue analgesia was significantly higher in severe (91.7%) than minimal disease (0%); analgesics were required up to day 3. Pain scores and frequency of rescue analgesia were significantly correlated with the number of tooth extractions, gingival and calculus index. Prevalence of rescue analgesia was significantly correlated with the number of missing teeth, teeth extractions and gingival index. Dry and soft food intake during 3 minutes, and dry food intake during 2 hours were significantly lower in the severe than minimal disease group throughout the study. Some cytokines differed between groups between day 0 and day 6 and were associated with the presence of tooth resorption and number of missing tooth and tooth fractures. Long-term analgesia is required after dental extractions in cats with severe oral disease. This condition reduces food intake and influences serum inflammatory cytokines.

Early Signs of Bone and Cartilage Changes Induced by Treadmill Exercise in Rats

This study aims to investigate the earliest alterations of bone and cartilage tissues as a result of different exercise protocols in the knee joint of Wistar rats. We hypothesize that pretraining to a continuous intense running protocol would protect the animals from cartilage degeneration. Three groups of animals were used: (i) an adaptive (pretraining) running group that ran for 8 weeks with gradually increasing velocity and time of running followed by a constant running program (6 weeks of 1.12 km/hour running per day); (ii) a non-adaptive running (constant running) group that initially rested for 8 weeks followed by 6 weeks of constant running; and (iii) a non-running (control) group. At weeks 8, 14, and 20 bone and cartilage were analyzed. Both running groups developed mild symptoms of cartilage irregularities, such as chondrocyte hypertrophy and cell clustering in different cartilage zones, in particular after the adaptive running protocol. As a result of physical training in the adaptive running exercise a dynamic response of bone was detected at week 8, where bone growth was enhanced. Conversely, the thickness of epiphyseal trabecular and subchondral bone (at week 14) was reduced due to the constant running in the period between 8 and 14 weeks. Finally, the intermediate differences between the two running groups disappeared after both groups had a resting period (from 14 to 20 weeks). The adaptive running group showed an increase in aggrecan gene expression and reduction of MMP2 expression after the initial 8 weeks running. Thus, the running exercise models in this study showed mild bone and cartilage/chondrocyte alterations that can be considered as early-stage osteoarthritis. The pretraining adaptive protocol before constant intense running did not protect from mild cartilage degeneration. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Risk assessment of feline tooth resorption: a Portuguese clinical case control study

Tooth resorption (TR) is one of the most common dental diseases in cats. Determination of risk factors has not yet been fully assessed and, to the best knowledge of the authors, this disease has never been studied in Portuguese cats. The objective of this case-control study was to determine type and distribution of TR lesions, evaluate risk factors, and establish relationships between variables in this disease. The study included data from 71 cats admitted for general anesthesia for various reasons. The cats were randomly selected. The inclusion criteria were availability of clinical history and owner permission. Cats with known oral disease were not excluded from the study. All cats received ultrasonic scaling and polishing of the teeth, a thorough oral examination, and full-mouth radiographs. A strong statistical relation was found between age and TR. The age group of 10 to 15-years showed an increased risk of 6.56 times for TR occurrence compared with the group 0 to 4-years of age. Presence of gingivitis in all index levels was related to an increased risk for TR. No relation was found between age or gingivitis index and lesion type. Mandibular third premolar and molar teeth were most commonly affected by TR, especially for type 1 lesions. Canine teeth were statistically more likely to have type 2 lesions. The trend for the canine teeth to be more affected with type 2 lesions needs further verification.

Increased vitamin D-driven signalling and expression of the vitamin D receptor, MSX2, and RANKL in tooth resorption in cats

Tooth resorption occurs in 20-75% of cats (Felis catus). The aetiology is not known, but vitamin D is suggested to be involved. Vitamin D acts through a nuclear receptor (VDR) and increases the expression of receptor activator of nuclear factor-kappaB ligand (rankl) and muscle segment homeobox 2 (msx2) genes. Mice lacking the muscle segment homeobox 2 (msx2) gene show decreased levels of rankl, suggesting an interaction among VDR, MSX2, and RANKL. Here, we investigated the expression of VDR, MSX2, and RANKL proteins, and the activity of the VDR-mediated signalling pathway (using the quantitative polymerase chain reaction on VDR target genes), in tooth resorption, and measured the serum levels of vitamin D metabolites in cats. Tooth resorption was categorized into either resorptive or reparative stages. In the resorptive stage, odontoclasts expressed MSX2 and RANKL (100% and 88%, respectively) and fibroblasts expressed VDR and MSX2 (both at 100%), whereas fibroblasts expressed RANKL in only 29% of the sites analysed. In the reparative stage, cementoblasts expressed VDR, MSX2, and RANKL, whereas fibroblasts expressed VDR and MSX2, but not RANKL. The vitamin D status did not differ between the groups, based on the serum levels of 25-hydroxycholecalciferol. However, increased expression of VDR protein, and the relative gene expression levels of 1alpha-hydroxylase and the VDR-target gene, 24-hydroxylase, indicated the involvement of an active vitamin D signalling in the pathophysiology of tooth resorption in cats.