Antimicrobial and antibiofilm effects of abietic acid on cariogenic Streptococcus mutans.

Dental caries is a type of oral microbiome dysbiosis and biofilm infection that affects oral and systemic conditions. For healthy life expectancy, natural bacteriostatic products are ideal for daily and lifetime use as anti-oral infection agents. This study aimed to evaluate the inhibitory effects of abietic acid, a diterpene derived from pine rosin, on the in vitro growth of cariogenic bacterial species, Streptococcus mutans. The effective minimum inhibitory concentration of abietic acid was determined through observation of S. mutans growth, acidification, and biofilm formation. The inhibitory effects of abietic acid on the bacterial membrane were investigated through the use of in situ viability analysis and scanning electron microscopic analysis. Cytotoxicity of abietic acid was also examined in the context of several human cell lines using tetrazolium reduction assay. Abietic acid was found to inhibit key bacterial growth hallmarks such as colony forming ability, adenosine triphosphate activity (both planktonic and biofilm), acid production, and biofilm formation. Abietic acid was identified as bacteriostatic, and this compound caused minimal damage to the bacterial membrane. This action was different from that of povidone-iodine or cetylpyridinium chloride. Additionally, abietic acid was significantly less cytotoxic compared to povidone-iodine, and it exerted lower toxicity towards epithelial cells and fibroblasts compared to that against monocytic cells. These data suggest that abietic acid may prove useful as an antibacterial and antibiofilm agent for controlling S. mutans infection.

A novel hybrid adenoretroviral vector with more extensive E3 deletion extends transgene expression in submandibular glands.

Salivary glands are an attractive target for gene transfer. Salivary epithelial cells are considered to be highly differentiated and have low rates of cell division (~6 months), affording the opportunity to obtain relatively long-term transgene expression in the absence of genomic integration. Here, we report a novel modified hybrid adenoretroviral vector, which provides stable transgene expression in salivary epithelial cells in vivo for up to 6 months in the absence of genomic integration. This modified hybrid vector, Ad(ΔE1/3)LTR(2)EF1α-hEPO, encodes human erythropoietin (hEPO) and differs from a previously developed hybrid vector, AdLTR(2)EF1α-hEPO, by having more extensive E3 gene deletion. Following direct salivary gland gene transfer by retroductal cannulation, rats transduced with Ad(ΔE1/3)LTR(2)EF1α-hEPO had sustained, elevated serum hEPO levels and hematocrits for 6 months (length of experiment), as compared with ~2 months for animals administered the AdLTR(2)EF1α-hEPO vector. Immunohistochemistry demonstrated that this novel vector could transduce both acinar and ductal cells. Interestingly, the Ad(ΔE1/3)LTR(2)EF1α-hEPO vector evoked much weaker local (salivary gland) immune responses than seen after AdLTR(2)EF1α-hEPO vector delivery, which likely permits its significantly lengthened transgene expression in this tissue.

Extended transgene expression from a nonintegrating adenoviral vector containing retroviral elements.

We studied the effects of specific retroviral elements in a first-generation serotype 5 adenoviral (Ad5) vector, AdLTR(2)EF1alpha-hEPO. This vector contains 858 base pair (bp) [251-bp envelope sequence plus 607-bp long-terminal repeat (LTR)] from Moloney murine leukemia virus (MoMLV), upstream of the human elongation factor-1alpha (EF1alpha) promoter and human erythropoietin (hEPO) cDNA, with the LTR sequence downstream of the polyadenylation signal. We compared expression of AdLTR(2)EF1alpha-hEPO with corresponding expressions of two conventional Ad5 vectors, AdEF1alpha-hEPO and AdCMV-hEPO, in vivo in submandibular glands in rats. Both the conventional vectors yielded low serum hEPO levels by day 7, and little change in hematocrits. In contrast, after receiving AdLTR(2)EF1alpha-hEPO, the rats showed elevated hEPO levels and hematocrits for 1-3 months. In vitro studies showed that the integration efficiencies of all the vectors were similar (approximately 10(-3)). Approximately 0.1% of the vector genomes were present 1 year after delivery in the case of each of the three vectors, primarily as intact linear double-strand DNA. The unique results seen with AdLTR(2)EF1alpha-hEPO are partly because of LTR enhancer activity. However, other cis-acting activity, which is not immunomodulatory but nevertheless influences promoter methylation, appears to be involved. A vector such as AdLTR(2)EF1alpha-hEPO may prove useful in clinical applications in which extended, but not "permanent," transgene expression is desirable.

Appearance of multidrug-resistant opportunistic bacteria on the gingiva during leukemia treatment.

BACKGROUND: Dentists generally recognize the importance of periodontal treatment in patients with leukemia, with the most attention paid to preventing the development of odontogenic infection. For physicians, the worst type of infection is one caused by multidrug-resistant bacteria. Here, we report a patient with an abnormal increase in multidrug-resistant opportunistic bacteria in the gingiva during hematopoietic cell transplantation (HCT). METHODS: A 53-year-old woman receiving HCT for leukemia had an insufficient blood cell count for invasive periodontal treatment before HCT. Even brushing caused difficulties with hemostasis. Therefore, frequent pocket irrigation and local minocycline administration were performed. RESULTS: The multidrug-resistant opportunistic bacterium Stenotrophomonas maltophilia was detected first in phlegm 2 days before HCT, and it was detected in a gingival smear and a blood sample 7 and 11 days after HCT, respectively. The patient developed sepsis on day 11 and died 14 days after HCT. Frequent irrigation and local antibiotic application were ineffective against S. maltophilia on the gingiva. Inflammatory gingiva without scaling and root planing showed bleeding tendency, and this interfered with the eradication of this bacterium. CONCLUSIONS: The gingiva in patients undergoing leukemia treatment acts as sites of proliferation and reservoirs for multidrug-resistant opportunistic bacteria. Severe systemic infection by multidrug-resistant bacteria in such patients with leukemia also may involve the gingiva. To prevent abnormal increases in such bacteria on the gingiva, scaling and/or root planing before chemotherapy, which reduces bleeding on brushing during the neutropenic period caused by chemotherapy, may contribute to infection control in such patients, although it was impossible in this case.

Adeno-associated virus serotype 2-mediated gene transfer to the parotid glands of nonhuman primates.

Salivary glands (SGs) are promising gene transfer targets with potential clinical applicability. Previous experiments in rodents using recombinant serotype 2 adeno-associated viral (rAAV2) vectors have demonstrated relatively stable transgene-encoded protein levels after SG gene transfer. In the present study, we examine direct SG administration of rAAV2 vectors encoding rhesus macaque erythropoietin (RhEPO) to the parotid glands of nonhuman primates using two different doses (n = 3 per group; 1 x 10(10) or 3 x 10(11) particles/gland, respectively). Gene transfer had no negative effects on general macaque physiology (e.g., weight, complete blood count, and serum chemistry). Macaques were euthanized 6 months after vector administration and complete necropsy and pathology assessments were performed, revealing no vector-related pathological lesions in any of the examined organs. In the high-dose group, RhEPO expression increased quickly (i.e., by week 1) and levels remained relatively stable both in serum and saliva until the end of the study. Serum-to-saliva ratios of RhEPO revealed secretion of the transgene product into the bloodstream, but not to the extent previously observed in mice. Furthermore, the kinetic results were not predicted by those observed in murine SGs. With respect to viral biodistribution, at necropsy vector was found overwhelmingly in the targeted parotid gland ( approximately 100 times more than levels in other tissues, most of which were similar to tissue levels in nontreated animals). We conclude that administration of modest doses of rAAV2 vectors to SGs for therapeutic purposes can be accomplished without significant or permanent injury to the targeted gland or to distant organs of nonhuman primates.

Toxicity and biodistribution of a first-generation recombinant adenoviral vector, encoding aquaporin-1, after retroductal delivery to a single rat submandibular gland.

Before conducting a phase 1/2 clinical trial of a serotype 5 adenovirus encoding human aquaporin-1 (AdhAQP1) for the treatment of radiation-damaged salivary glands, we have conducted a detailed toxicity and biodistribution study in adult rats. AdhAQP1 (2x108-2x1011 particles) was delivered to a single submandibular gland by retroductal cannulation. Administration of this vector resulted in no animal mortality or morbidities, and no adverse signs of clinical toxicity. In addition, over the 92-day time course of the study, with both male and female rats, there were no consistent treatment-related changes in serum indicators of hepatic, renal, and cardiac functions. Importantly, we also observed no vector-associated effects on either water consumption by, or hematocrit levels in, study animals. However, three suggestive mild gender-related response differences were seen. Female, but not male, rats exhibited small reductions in food consumption (10-15%) and body weight gain (5-10%), and evidence of persistent inflammation, after vector treatment. These were vector, but not dose, related. Three days after delivery of 2x1011 particles of AdhAQP1, vector was detected primarily in the targeted gland; 9 of 10 samples from the targeted gland were positive, whereas only 5 of 90 nonoral samples were positive. There was no evidence of the generation of replication-competent adenovirus in saliva or blood samples. In aggregate, these findings show that localized delivery of AdhAQP1 to salivary glands appears to occur without significant toxicity.

Effect of serotype 5 adenoviral and serotype 2 adeno- associated viral vector-mediated gene transfer to salivary glands on the composition of saliva.

Key to the development of a useful clinical therapy is the minimization of side effects. Routine safety testing, however, does not provide information about the physiological status of many potentially useful gene transfer target sites. In this study, we evaluated the longitudinal effects of intrasalivary duct delivery of recombinant serotype 5 adenoviral (rAd5; 10(9)-10(10) particles/gland in rats) and recombinant serotype 2 adeno-associated viral (rAAV2; 10(8)-10(9) particles/gland in mice) vectors on salivary composition. Both vectors led to modest, transient alterations in several salivary components that thereafter returned to normal. The changes suggested two initial specific consequences of rAd5 and rAAV2 vector administration: (1) a modest breach of the mucosal barrier in the targeted glands, indicated by elevations in salivary albumin, total protein, and Na+ levels, and (2) an innate host response, indicated by transient elevations in either salivary lactoferrin and IgA levels (rAd5) or mucin (rAAV2). These studies are consistent with the notion that administration of modest doses of rAd5 and rAAV2 vectors to salivary glands for a therapeutic purpose can be accomplished without severe or permanent injury to the target tissue, or compromise to its essential exocrine physiological function.

Salivary gland gene therapy.

Salivary glands have proven to be unusual but valuable target sites for multiple clinical gene transfer applications. Access to salivary glands for gene transfer is easy. Multiple studies in animal models have yielded proofs of concept for novel treatments for damaged salivary glands following therapeutic irraditation, in Sjögren's syndrome, and for gene therapeutics systemically by way of the blood-stream and locally in the oral cavity and upper gastrointestinal tract.

Periodontal treatment in severe aplastic anemia.

BACKGROUND: Aplastic anemia (AA) is a rare hematologic disease characterized by hypo-cellular bone marrow. The clinical features include fatigue, increased bruising, and gingival bleeding caused by anemia, leukopenia, and thrombocytopenia. A patient with AA is at high risk for infection because of leukopenia. The risk of systemic infection is especially high in AA patients with severe local infections, including periodontitis. Accordingly, periodontal treatment should include antibiotic prophylaxis to reduce the risk of systemic infection. However, treatment of periodontitis in the AA patient is significantly complicated by the bleeding disorder. We present a case report of the successful periodontal treatment of an AA patient with spontaneous gingival bleeding. METHODS: The patient was closely monitored for platelet and neutrophil counts before every treatment. The patient's platelet count was always under 10,000/microl. Therefore, it was necessary to increase platelet counts to over 25,000/microl by transfusion, after which subgingival scaling with anesthesia was performed. When the neutrophil count was less than 2,000/microl, local minocycline chemotherapy was applied to the pockets. Periodontal infection was monitored by detection of bacterial DNA and measurement of serum immunoglobulin (Ig) G titer against periodontal bacteria. RESULTS: Following the physical and chemical treatment, the gingival appearance improved dramatically and the spontaneous gingival bleeding disappeared. Moreover, the IgG titer against periodontal bacteria decreased to normal range and specific periodontal pathogens were no longer detectable in the tested pockets. CONCLUSION: We believe that the treatment strategy in the present report provides new sight into treatment planning for severely medically compromised patients.

Transcriptional regulation of beta-defensin-2 by lipopolysaccharide in cultured human cervical carcinoma (HeLa) cells.

Human beta-defensin-2 (hBD-2) is an antimicrobial peptide with a broad spectrum of antimicrobial activity against bacteria, yeast and fungi. Here, we analyzed the transcriptional regulation of hBD-2 in cultured human cervical carcinoma (HeLa) cells with or without lipopolysaccharide (LPS). DNA from position -329 to -39 in the hBD-2 promoter region contained the consensus binding sites for transcription factors, one site for nuclear factor for IL-6 expression (NF-IL6) and two sites for nuclear factor-(kappa)B (NF-(kappa)B). Reporter gene assays for promoter activity revealed that the region had the highest level of responsiveness to LPS. Furthermore, mutations in both of the NF-(kappa)B binding sites caused a significant reduction of the responsiveness to LPS, whereas mutation in the NF-IL6 binding site resulted in an elevation of the basal promoter activity. Electrophoretic mobility shift assays demonstrated that LPS induced the binding of HeLa nuclear factors to 60-bp probe containing the two NF-(kappa)B binding sites, suggesting that the sites were essential for the binding. Our results suggest that the two NF-(kappa)B binding sites contribute to LPS-mediated hBD-2 transcription while the NF-IL6 binding site represses LPS-independent hBD-2 transcription in the HeLa cells.

Antibacterial activity of synthetic human B defensin-2 against periodontal bacteria.

The oral epithelium is continuously exposed to a variety of microbial challenges that can cause infectious diseases such as periodontal disease. Human B Defensin-2 (hBD-2) is a cationic antimicrobial peptide with low molecular weight, which is inducible from oral epithelial cells upon either bacterial infection or stimulation with inflammatory cytokines. This peptide has a broad antimicrobial spectrum that includes gram-positive bacteria, gram-negative bacteria, and fungi. Therefore, it is thought that hBD-2 plays an important role as one of natural immunities to bacterial infection. However, its activity is inhibited by body fluids such as serum. The aim of this study was to assess the antibacterial activity of synthetic hBD-2 against oral bacteria in the presence of saliva or serum. The antibacterial activity of synthetic hBD-2 was tested against Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Streptococcus mutans, and Escherichia coli. Antibacterial broth assay and diffusion assay were performed in vitro. The antibacterial activity of hBD-2 was approximately equal to that of minocycline at equimolar concentrations. Furthermore, the activity of hBD-2 remained at 60% in the presence of 80% saliva, whereas no activity remained in the presence of 20% serum. Our results suggest the possibility that synthetic hBD-2 could be useful to prevent infection by periodontal bacteria.