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Open Access Publications from the University of California

Scholarly Works (6 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2017)

Periodontitis (PD) is characterized by bacterial infection and inflammation of supporting tissues of the teeth. If left untreated, PD can lead to tooth loss. PD affects ~47% of the U.S. population over 30 and, interestingly, twin studies have shown PD to be 50% heritable. While the host immunoinflammatory response and genetic background play a role in PD, few studies have mechanistically interrogated genetic targets to validate candidate genes associated with PD.

Objective: Identify genes that mediate Lipopolysaccharide (LPS)-induced periodontitis.

Methods: P. gingivalis (P.g.)-LPS was injected between maxillary molars in 104 strains of the Hybrid Mouse Diversity Panel (HMDP) 2x/week for 6 weeks. Following sacrifice, maxillae were scanned (microCT) and bone loss was quantitated. FaST-LMM was used to identify genetic loci associated to bone loss. Gene expression (microarray) and protein (histology) were further assessed in A/J and C57BL/6J. CX-C motif chemokine receptor 3 (CXCR3) knockout (KO) and wild-type (WT) mice were analyzed radiographically and histologically after LPS-injections. AMG-487, an in vivo CXCR3 inhibitor, was injected systemically and locally and maxillae were analyzed radiographically and histologically after LPS-injections to investigate the therapeutic potential of CXCR3 inhibition.

Results: 50% heritability and a strain-dependent 6-fold difference in LPS-induced bone loss were observed across the HMDP. Our FaST-LMM and RNA expression data identified Cxcl family members (inflammatory immune cell chemoattractants essential in immune responses) as associated with PD. Additionally, Cxcl10 protein, as well as, an increase in immune cells and pro-inflammatory cytokines were observed in C57BL/6J (high bone loss) and not in A/J (low bone loss) after LPS-injections. Most interestingly, deleting CXCR3 (Cxcl10 receptor), demonstrated ~50% reduction in bone loss and a decrease in osteoclasts after LPS-injections compared to WT mice. Furthermore, mice treated with AMG-487 systemically and locally resulted in ~50% reduction in bone loss and decreased osteoclasts after LPS-injections.

Conclusions: Using a genome-wide association approach, we have identified CXCR3 as a possible target for modulating the host response in PD susceptibility. Our future work will characterize the CXCR3 pathway and validate other candidate genes associated with LPS-induced bone loss with the ultimate goal to identify patients at high risk to PD.

    Cover page: Genome-Wide Association Study Identifies CXCR3 as a Partial Mediator of LPS-induced Periodontitis
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2023)
    OBJECTIVE: This study aimed to assess if Nigella sativa oil (NSO), a health supplement containing thymoquinone as a major component, can act as a protective agent in salivary gland stem cells following radiotherapy (RT) damage. METHODS: Forty, 10-week-old, male C3H/HeJ mice were randomized to four experimental groups: sham RT + H2O gavage (control) (N = 4); 15 Gy RT + H2O gavage (N = 12); sham RT + NSO gavage (N = 12); and 15 Gy RT + NSO gavage (N = 12). Weight changes, saliva production, and salivary gland histopathologic staining were recorded for each group over the course of the experiment. RESULTS: All mice in the sham RT + H2O gavage and sham RT + NSO gavage groups demonstrated 100% 60-day survival. RT + H2O compared to RT + NSO gavaged mice were significantly underweight by an average of 6.4 g (p < .001). Salivary output showed significant decline in RT + H2O gavaged mice at days 3 and 16, whereas salivary output in RT + NSO during these same time periods was comparable to the control. At day 60, all mice that survived recovered salivary function regardless of their treatment arm. Salivary specimens from the RT + NSO gavage group demonstrated early signs of recovery of Kr 5+ salivary gland stem cells in both submandibular and sublingual glands at day 16 with complete recovery by day 60, marked by strong histopathologic staining, whereas the RT + H2O gavage group did not recover as effectively. CONCLUSION: NSO may help preserve salivary function in mice treated with RT and may mitigate xerostomia by accelerating the recovery of salivary gland stem cells. LEVEL OF EVIDENCE: Not applicable.
      Cover page: Nigella sativa oil mitigates xerostomia and preserves salivary function in radiotherapy-treated mice.
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2022)

      Objectives

      This experimental study was carried out to investigate the effects of locally delivered nanoparticles (AMG-487 NP) containing a CXCR3 antagonist in inhibiting the progression of LPS-induced inflammation, osteoclastic activity, and bone resorption on a murine model.

      Materials and methods

      Thirty, 7-week-old C57BL/6 J male mice were used. Inflammatory bone loss was induced by Porphyromonas gingivalis-lipopolysaccharide (P.g.-LPS) injections between the first and second maxillary molars, bilaterally, twice a week for 6 weeks (n = 20). AMG-487 NP were incorporated into a liposome carrier and locally delivered on sites where P.g.-LPS was injected. Control mice (n = 10) were injected with vehicle only. Experimental groups included (1) control, (2) LPS, and (3) LPS + NP. At the end of 1 and 6 weeks, mice were euthanized, maxillae harvested, fixed, and stored for further analysis.

      Results

      Volumetric bone loss analysis revealed, at 1 week, an increase in bone loss in the LPS group (47.9%) compared to control (27.4%) and LPS + NP (27.8%) groups. H&E staining demonstrated reduced inflammatory infiltrate in the LPS + NP group compared to LPS group. At 6 weeks, volumetric bone loss increased in all groups; however, treatment with the CXCR3 antagonist (LPS + NP) significantly reduced bone loss compared to the LPS group. CXCR3 antagonist treatment significantly reduced osteoclast numbers when compared to LPS group at 1 and 6 weeks.

      Conclusions

      This study showed that local delivery of a CXCR antagonist, via nanoparticles, in a bone resorption model, induced by LPS injection, was effective in reducing inflammation, osteoclast numbers, and bone loss.

      Clinical relevance

      CXCR3 blockade can be regarded as a novel target for therapeutic intervention of bone loss. It can be a safe and convenient method for periodontitis treatment or prevention applicable in clinical practice.
        Cover page: Local delivery of a CXCR3 antagonist decreases the progression of bone resorption induced by LPS injection in a murine model
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2015)
        Dental implants are a widely used treatment option for tooth replacement. However, they are susceptible to inflammatory diseases such as peri-implant mucositis and peri-implantitis, which are highly prevalent and may lead to implant loss. Unfortunately, the understanding of the pathogenesis of peri-implant mucositis and peri-implantitis is fragmented and incomplete. Therefore, the availability of a reproducible animal model to study these inflammatory diseases would facilitate the dissection of their pathogenic mechanisms. The objective of this study is to propose a murine model of experimental peri-implant mucositis and peri-implantitis. Screw-shaped titanium implants were placed in the upper healed edentulous alveolar ridges of C57BL/6J mice 8 weeks after tooth extraction. Following 4 weeks of osseointegration, Porphyromonas gingivalis -lipolysaccharide (LPS) injections were delivered to the peri-implant soft tissues for 6 weeks. No-injections and vehicle injections were utilized as controls. Peri-implant mucositis and peri-implantitis were assessed clinically, radiographically (microcomputerized tomograph [CT]), and histologically following LPS-treatment. LPS-injections resulted in a significant increase in soft tissue edema around the head of the implants as compared to the control groups. Micro-CT analysis revealed significantly greater bone loss in the LPS-treated implants. Histological analysis of the specimens demonstrated that the LPS-group had increased soft tissue vascularity, which harbored a dense mixed inflammatory cell infiltrate, and the bone exhibited noticeable osteoclast activity. The induction of peri-implant mucositis and peri-implantitis in mice via localized delivery of bacterial LPS has been demonstrated. We anticipate that this model will contribute to the development of more effective preventive and therapeutic approaches for these 2 conditions.
          Cover page: A Murine Model of Lipopolysaccharide-Induced Peri-Implant Mucositis and Peri-Implantitis
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2019)
          Heart rate is under the precise control of the autonomic nervous system. However, the wiring of peripheral neural circuits that regulate heart rate is poorly understood. Here, we develop a clearing-imaging-analysis pipeline to visualize innervation of intact hearts in 3D and employed a multi-technique approach to map parasympathetic and sympathetic neural circuits that control heart rate in mice. We identify cholinergic neurons and noradrenergic neurons in an intrinsic cardiac ganglion and the stellate ganglia, respectively, that project to the sinoatrial node. We also report that the heart rate response to optogenetic versus electrical stimulation of the vagus nerve displays different temporal characteristics and that vagal afferents enhance parasympathetic and reduce sympathetic tone to the heart via central mechanisms. Our findings provide new insights into neural regulation of heart rate, and our methodology to study cardiac circuits can be readily used to interrogate neural control of other visceral organs.
            Cover page: Identification of peripheral neural circuits that regulate heart rate using optogenetic and viral vector strategiesCreative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2017)

            Aim

            To evaluate the effects of metformin (Met) on inflammation, oxidative stress, and bone loss in a rat model of ligature-induced periodontitis.

            Materials & methods

            Male albino Wistar rats were divided randomly into five groups of twenty-one rats each, and given the following treatments for 10 days: (1) no ligature + water, (2) ligature + water, (3) ligature + 50 mg/kg Met, (4) ligature + 100 mg/kg Met, and (5) ligature + 200 mg/kg Met. Water or Met was administered orally. Maxillae were fixed and scanned using Micro-computed Tomography (μCT) to quantitate linear and bone volume/tissue volume (BV/TV) volumetric bone loss. Histopathological characteristics were assessed through immunohistochemical staining for MMP-9, COX-2, the RANKL/RANK/OPG pathway, SOD-1, and GPx-1. Additionally, confocal microscopy was used to analyze osteocalcin fluorescence. UV-VIS analysis was used to examine the levels of malondialdehyde, glutathione, IL-1β and TNF-α from gingival tissues. Quantitative RT-PCR reaction was used to gene expression of AMPK, NF-κB (p65), and Hmgb1 from gingival tissues. Significance among groups were analysed using a one-way ANOVA. A p-value of p<0.05 indicated a significant difference.

            Results

            Treatment with 50 mg/kg Met significantly reduced concentrations of malondialdehyde, IL-1β, and TNF-α (p < 0.05). Additionally, weak staining was observed for COX-2, MMP-9, RANK, RANKL, SOD-1, and GPx-1 after 50 mg/kg Met. OPG and Osteocalcin showed strong staining in the same group. Radiographically, linear measurements showed a statistically significant reduction in bone loss after 50 mg/kg Met compared to the ligature and Met 200 mg/kg groups. The same pattern was observed volumetrically in BV/TV and decreased osteoclast number (p<0.05). RT-PCR showed increased AMPK expression and decreased expression of NF-κB (p65) and HMGB1 after 50 mg/kg Met.

            Conclusions

            Metformin, at a concentration of 50 mg/kg, decreases the inflammatory response, oxidative stress and bone loss in ligature-induced periodontitis in rats.
              Cover page: Effects of metformin on inflammation, oxidative stress, and bone loss in a rat model of periodontitis
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