Fructose prevents the development of hyperglycaemia in WBN/Kob diabetic fatty rats via maintaining high insulin levels.

Fructose is considered to negatively affect type 2 diabetes mellitus (T2DM); however, there are contradictory reports. The present study aimed to elucidate the effects of fructose-rich diet (FRD) on glucose metabolism of Wistar Bonn Kobori (WBN/Kob) fatty diabetic (WBKDF) rats, a spontaneous T2DM model, and Wistar rats. Wistar Bonn Kobori fatty diabetic and Wistar rats were fed either FRD or standard diet (STD) for 4 weeks. The food intake, body weight, plasma glucose and insulin were measured weekly. After the 4-week challenge, rats were subjected to an intravenous glucose tolerance test (IVGTT). The liver and pancreas were used for histological analysis. The 4-week challenge of FRD in Wistar rats did not cause hyperglycaemia, but increased insulin resistance (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR]). Feeding WBKDF rats with a FRD accelerated obesity, but prevented the onset of severe hyperglycaemia via maintaining high plasma insulin levels. Homeostatic Model Assessment for Insulin Resistance in WBKDF rats was not changed by FRD feeding. Intravenous glucose tolerance test revealed that FRD feeding in Wistar rats did not affect glucose tolerance, but slightly increased the plasma insulin level. In contrast, FRD feeding in WBKDF rats significantly reduced the glucose tolerance, but insulin response was not improved. Fructose-rich diet feeding did not alter the ß cell area in Wistar rats, but significantly increased it in WBKDF rats. In conclusion, FRD caused insulin resistance in Wistar rats, suggesting that fructose overconsumption is a risk factor for T2DM, whereas FRD inhibited severe hyperglycaemia by maintaining high insulin levels in WBKDF rats. Fructose may be a beneficial sugar for T2DM patients with severe obesity-induced insulin resistance.

Roles of Porphyromonas gulae proteases in bacterial and host cell biology.

Porphyromonas gulae, an animal-derived periodontal pathogen, expresses several virulence factors, including fimbria, lipopolysaccharide (LPS) and proteases. We previously reported that its invasive efficiency was dependent on fimbriae types. In addition, P. gulae LPS increased inflammatory responses via toll-like receptors. The present study was conducted to investigate the involvement of P. gulae proteases in bacterial and host cell biology. Porphyromonas gulae strains showed an ability to agglutinate mouse erythrocytes and also demonstrated co-aggregation with Actinomyces viscosus, while the protease inhibitors antipain, PMSF, TLCK and leupeptin diminished P. gulae proteolytic activity, resulting in inhibition of haemagglutination and co-aggregation with A. viscosus. In addition, specific proteinase inhibitors were found to reduce bacterial cell growth. Porphyromonas gulae inhibited Ca9-22 cell proliferation in a multiplicity of infection- and time-dependent manner. Additionally, P. gulae-induced decreases in cell contact and adhesion-related proteins were accompanied by a marked change in cell morphology from well spread to rounded. In contrast, inhibition of protease activity prevented degradation of proteins, such as E-cadherin, ß-catenin and focal adhesion kinase, and also blocked inhibition of cell proliferation. Together, these results indicate suppression of the amount of human proteins, such as γ-globulin, fibrinogen and fibronectin, by P. gulae proteases, suggesting that a novel protease complex contributes to bacterial virulence.

Porphyromonas gulae lipopolysaccharide elicits inflammatory responses through toll-like receptor 2 and 4 in human gingivalis epithelial cells.

Porphyromonas gulae, a Gram-negative black-pigmented anaerobe, has been associated with periodontal disease in companion animals and its virulence has been attributed to various factors, including lipopolysaccharide (LPS), protease and fimbriae. Toll-like receptors (TLRs) recognise pathogen-associated molecular patterns, such as peptidoglycan, lipids, lipoproteins, nucleic acid and LPS. Following P. gulae infection, some inflammatory responses are dependent on both TLR2 and TLR4. In addition, a recent clinical study revealed that acute and persistent inflammatory responses enhance the expressions of TLR2 and TLR4 in the oral cavity. In this study, we investigated the interaction between P. gulae LPS and human gingivalis epithelial cells (Ca9-22 cells). P. gulae LPS was found to increase TLR2 and TLR4 mRNA expressions and protein productions, and enhanced inflammatory responses, such as COX2 , TNF-ɑ, IL-6 and IL-8. Stimulated Ca9-22 cells exhibited phosphorylation of ERK1/2 and p38, and their inhibitors diminished inflammatory responses, while knockdown of the TLR2 and/or TLR4 genes with small interfering RNA (siRNA) prevented inflammatory responses. Moreover, p38 and ERK1/2 phosphorylation was decreased in TLR2 and TLR4 gene knockdown cells. These findings suggest that P. gulae LPS activates p38 and ERK1/2 via TLR2 and TLR4, leading to inflammatory responses in human gingival epithelial cells.

Author Correction: Inhibition of Porphyromonas gulae and periodontal disease in dogs by a combination of clindamycin and interferon alpha.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effects of liraglutide on metabolic syndrome in WBN/Kob diabetic fatty rats supplemented with a high-fat diet.

BACKGROUND: Liraglutide, a GLP-1 receptor agonist, has recently been used to treat metabolic syndrome (MS) because of its anti-diabetic and anti-obesity effects. We have previously shown that Wistar Bonn Kobori diabetic and fatty (WBN/Kob-Lepr fa , WBKDF) rats fed a high-fat diet (HFD) developed MS including marked obesity, hyperglycemia, and dyslipidemia. To obtain further information on WBKDF-HFD rats as a severe MS model, we performed a pharmacological investigation into the anti-MS effects of liraglutide in this model. METHODS: Seven-week-old male WBKDF-HFD rats were allocated to three groups (N = 8 in each group): a vehicle group, a low-dose liraglutide group, and a high-dose liraglutide group. They received subcutaneous injections of either saline or liraglutide at doses of 75 or 300 µg/kg body weight once daily for 4 weeks. RESULTS: Results showed that liraglutide treatment reduced body weight gain and food intake in a dose-dependent manner. The marked hyperglycemia and the glucose tolerance were also significantly ameliorated in the liraglutide-treated groups. Moreover, liraglutide also reduced the plasma triglyceride concentration and liver fat accumulation. CONCLUSIONS: The present study demonstrated that liraglutide could significantly alleviate MS in WBKDF-HFD rats, and the reaction to liraglutide is similar to human patients with MS. WBKDF-HFD rats are therefore considered to be a useful model for research on severe human MS.

Inhibition of Porphyromonas gulae and periodontal disease in dogs by a combination of clindamycin and interferon alpha.

Porphyromonas gulae is a major periodontal pathogen in dogs, which can be transmitted to their owners. A major virulence factor of P. gulae consists of a 41-kDa filamentous appendage (FimA) on the cell surface, which is classified into three genotypes: A, B, and C. Thus far, inhibition of periodontal disease in dogs remains difficult. The present study assessed the inhibitory effects of a combination of clindamycin and interferon alpha (IFN-α) formulation against P. gulae and periodontal disease. Growth of P. gulae was significantly inhibited by clindamycin; this inhibition had a greater effect on type C P. gulae than on type A and B isolates. In contrast, the IFN-α formulation inhibited the expression of IL-1ß and COX-2 elicited by type A and B isolates, but not that elicited by type C isolates. Furthermore, periodontal recovery was promoted by the administration of both clindamycin and IFN-α formulation to dogs undergoing periodontal treatment; moreover, this combined treatment reduced the number of FimA genotypes in oral specimens from treated dogs. These results suggest that a combination of clindamycin and IFN-α formulation inhibit P. gulae virulence and thus may be effective for the prevention of periodontal disease induced by P. gulae.

Adhesion and invasion of gingival epithelial cells by Porphyromonas gulae.

Porphyromonas gulae, an animal periodontal pathogen, possess fimbriae classified into three genotypes (A-C) based on the diversity of fimA genes encoding FimA. Accumulating evidence suggests that P. gulae strains with type C fimbriae are more virulent as compared to those with other types. The ability of these organisms to adhere to and invade gingival epithelial cells has yet to be examined. P. gulae showed the greatest levels of adhesion and invasion at a multiplicity of infection of 100 for 90 min. P. gulae type C and some type B strains invaded gingival epithelial cells at significantly greater levels than the other strains, at the same level of efficiency as P. gingivalis with type II fimbriae. Adhesion and invasion of gingival epithelial cells by P. gulae were inhibited by cytochalasin D and sodium azide, indicating the requirements of actin polymerization and energy metabolism for those activities. Invasion within gingival epithelial cells was blocked by staurosporine, whereas those inhibitors showed little effects on adhesion, while nocodazole and cycloheximide had negligible effects on either adhesion or invasion. P. gulae proteases were found to be essential for adhesion and invasion of gingival epithelial cells, while its DNA and RNA, and protein synthesis were unnecessary for those activities. Additionally, α5ß1 integrin antibodies significantly inhibited adhesion and invasion by P. gulae. This is the first report to characterize P. gulae adhesion and invasion of human gingival epithelial cells.

Identification and molecular characterization of Porphyromonas gulae fimA types among cat isolates.

Porphyromonas gulae, a Gram-negative black-pigmented anaerobe, is one of several major periodontal pathogens of animals. P. gulae isolates from dogs have been classified into three genotypes based on a 41-kDa filamentous appendage (FimA) on the cell surface, which is closely related to virulence in periodontal disease. However, other specific bacterial virulence factors contributing to the aggravation of periodontal disease in cats remain elusive. In the present study, we assessed FimA diversity in P. gulae isolates from cats and examined whether this diversity influenced periodontal condition. The putative amino acid sequences of FimA from 15 P. gulae isolates from 13 cats were classified into three genotypes (types A, B, and C), which showed 95-100% identity and similarity to the fimA types in dogs. The type C isolate showed greater adhesion and invasion properties in periodontal ligament fibroblasts as well as stronger inhibition of scratch closure of the cells compared with type A and B isolates. Next, a PCR-based method for identification of fimA genotype was developed and used to analyze 99 oral swab specimens from cats. High fimA type A detection rates were observed regardless of the periodontal condition, whereas types B and C were frequently detected from subjects with moderate and severe periodontitis, respectively. These results suggest that P. gulae isolates from cats can be classified into three types based on fimA genotype, which may be closely related to virulence in periodontitis.

Plasma 2-hydroxyglutarate, a promising prognostic biomarker candidate for skeletal muscle injury in Fischer 344 rats.

Previously, we have demonstrated the potential of plasma 2-hydroxyglutarate (2HG) as an easily detectable biomarker for skeletal muscle injury in rats. Here, we examined whether plasma 2HG was superior to conventional skeletal muscle damage biomarkers, including aspartate aminotransferase (AST), creatine kinase (CK), and skeletal muscle-type CK isoenzyme (CK-MM) levels, in rats. Skeletal muscle injury was induced in 4- or 9-week-old male Fischer 344 rats by cerivastatin (CER) or tetramethyl-p-phenylenediamine (TMPD) administration. Plasma 2HG levels were measured on days 4, 8, and 11 (CER group) and at 6 and 24 hr post-administration (TMPD group). Plasma AST, CK, and CK-MM activities and histopathological changes in the rectus femoris muscle were evaluated at the study endpoints. In the CER group, AST, CK, and CK-MM increased in 4- and 9-week-old rats, whereas increases in CK (4- and 9-week-old rats) and CK-MM (4-week-old rats) were not obvious in the TMPD group. In both 4- and 9-week-old rats, plasma 2HG increased on day 8 and at 24 hr post-administration in the CER and TMPD groups, respectively. Histopathological analysis revealed myofiber vacuolation and necrosis in both groups. The histopathological damage to the rectus femoris muscle was more severe in the CER than in the TMPD group. Increased plasma 2HG was associated with CER- and TMPD-induced skeletal muscle injuries in rats and was not affected by age differences or repeated blood collection. The results suggest that plasma 2HG is superior to CK and CK-MM as a biomarker for mild skeletal muscle injury.

Characteristics of WBN/Kob diabetic fatty rats supplemented with a fructose-rich diet as a metabolic syndrome model: response to a GLP-1 receptor agonist.

The incidence of metabolic syndrome is rapidly increasing worldwide, and adequate animal models are crucial for studies on its pathogenesis and therapy. In the search of an adequate experimental model to simulate human metabolic syndrome, the present study was performed to examine the pharmacological response of WBN/Kob-Leprfa (WBKDF) rats supplemented with a fructose-rich diet (FRD) to liraglutide, a GLP-1 receptor agonist. Male WBKDF rats fed FRD at 7 weeks of age were divided into 3 groups, and administered liraglutide (75, 300 µg/kg subcutaneously) or saline (control group), once daily for 4 weeks. All rats in the control group became overweight, and developed hyperglycemia, hypertension and dyslipidemia as they aged. The rats given liraglutide exhibited a dose-dependent reduction in body weight, visceral fat content and food intake compared with control rats. In addition, liraglutide suppressed the development of hyperglycemia, hypertension and dyslipidemia. An intravenous glucose tolerance test revealed that liraglutide improved glucose tolerance, insulin secretion and insulin resistance. On histological examination, decreased hepatic fatty degeneration was observed in the liraglutide groups. The present study demonstrated that liraglutide protected against obesity, hyperglycemia, hypertension, dyslipidemia, and hepatic steatosis in WBKDF rats fed FRD, suggesting that WBKDF rats fed FRD may be a useful model to investigate the etiology of human metabolic syndrome.

High-Salt Intake Ameliorates Hyperglycemia and Insulin Resistance in WBN/Kob-Leprfa/fa Rats: A New Model of Type 2 Diabetes Mellitus.

High-salt intake is a major risk factor for developing hypertension in type 2 diabetes mellitus, but its effects on glucose homeostasis are controversial. We previously found that high-salt intake induces severe hypertension in WBN/Kob diabetic fatty (WBKDF) rats. In the present study, we examined the effects of a high-salt intake on glucose homeostasis in WBKDF rats. Male WBKDF rats and age-matched Wistar rats at 6 weeks of age were each divided into two groups and fed either a normal-sodium (NS, 0.26%) diet or high-sodium (HS, 8%) diet for 7 weeks. Systolic blood pressure and urine volume were increased in WBKDF-HS and Wistar-HS. Body weight gain and food consumption were comparable between NS and HS in both strains. Plasma and urine glucose levels were significantly increased in WBKDF-NS but not in WBKDF-HS. HOMA-IR in WBKDF-HS was significantly lower compared with that in WBKDF-NS. The high plasma adiponectin level in WBKDF-NS compared with that in Wistar-NS was further enhanced in WBKDF-HS. Glycogen deposits and fat droplets in the livers of WBKDF-HS were reduced compared with those of WBKDF-NS. The present study demonstrated that HS intake ameliorated hyperglycemia and insulin resistance in WBKDF rats, which may be due to increased plasma levels of adiponectin.

Plasma 2-hydroxyglutarate and hexanoylcarnitine levels are potential biomarkers for skeletal muscle toxicity in male Fischer 344 rats.

To identify new candidate biomarkers for skeletal muscle toxicity, an unbiased metabolomic analysis was performed in rats treated with two distinct myotoxicants, cerivastatin (CER) and tetramethyl-p-phenylenediamine (TMPD). Skeletal muscle toxicity was induced in male Fischer 344 rats by administering CER or TMPD and monitored using established endpoints, such as increased plasma creatine kinase (CK) activity and histopathology, and a metabolomic analysis of skeletal muscle and plasma samples. Plasma CK levels in CER-treated rats were markedly elevated at Day 11; however, those in TMPD-treated rats showed a statistically significant decrease at 24 hr after dosing. Light microscopy revealed that vacuolated or necrotic fibers were evident in all CER-treated rats on Day 11, and slightly vacuolated fibers were observed in TMPD-treated rats at 6 and 24 hr after dosing. Metabolomic analysis of the rectus femoris indicated increases in 2-hydroxyglutarate (2HG) in CER-treated rats and hexanoylcarnitine in CER- and TMPD-treated rats. There were also increases in plasma 2HG in CER-treated rats on Days 8 and 11 and in TMPD-treated rats at 24 hr after dosing and increases in plasma hexanoylcarnitine in CER-treated rats on Day 11 and in TMPD-treated rats at 6 and 24 hr after dosing. These experiments demonstrated the potential of plasma 2HG and hexanoylcarnitine as specific and easily detectable biomarkers for skeletal muscle toxicity in rats and demonstrated the value of metabolomics for biomarker detection and identification in toxicological studies.

Effects of high-fat diet and fructose-rich diet on obesity, dyslipidemia and hyperglycemia in the WBN/Kob-Leprfa rat, a new model of type 2 diabetes mellitus.

Obesity and type 2 diabetes mellitus (T2DM) are occurring at epidemic-like rates, and these epidemics appear to have emerged largely from changes in daily diet. In the present study, we compared effects of high-fat diet (HFD) and fructose-rich diet (FRD) in WBN/Kob-Leprfa (WBKDF) rats that spontaneously develop obesity, dyslipidemia and T2DM. After a 4-week feeding of each diet, WBKDF-HFD and WBKDF-FRD rats exhibited aggravated obesity and dyslipidemia compared with WBKDF rats fed standard diet (STD). In contrast, hyperglycemia developed in WBKDF-STD rats was significantly inhibited in WBKDF-FRD rats, but not in WBKDF-HFD rats. The present study demonstrated that the 4-week feeding of HFD and FRD caused diet-induced obesity with a distinct phenotype in the glucose metabolism in WBKDF rats.

Effects of high-sodium intake on systemic blood pressure and vascular responses in spontaneously diabetic WBN/Kob-Leprfa/fa rats.

The prevalence of type 2 diabetes mellitus (T2DM) and hypertension has markedly increased worldwide. The purpose of the present study was to examine the effects of a high-salt intake on the systolic blood pressure (SBP) and vascular responses in WBN/Kob-Leprfa/fa (WBKDF) rats, a new spontaneous animal model of T2DM. Male WBKDF rats and age-matched Wistar rats at 6 weeks of age were each divided into two groups and fed either a normal-sodium (NS, 0.26%) diet or high-sodium (HS, 8%) diet for 14 weeks: (i) Wistar rats on NS diet (Wistar-NS); (ii) Wistar rats on HS diet (Wistar-HS); (iii) WBKDF rats on NS diet (WBKDF-NS); (iv) WBKDF rats on HS diets (WBKDF-HS). Neither WBKDF-NS nor Wistar-NS rats showed significant changes in SBP throughout the experiment, but both WBKDF-HS and Wistar-HS exhibited significant elevation of SBP, which was more prominent (P<.01) in WBKDF-HS than in Wistar-HS. Phenylephrine-induced contractions of isolated thoracic aortic rings were significantly (P<.01) enhanced in WBKDF-HS and Wistar-HS compared with the respective strain of rats on the NS diet. In contrast, acetylcholine- and nitroprusside-induced relaxation were significantly (P<.01) diminished in both WBKDF-HS and Wistar-HS, and these HS diet-induced changes were more profound (P<.01) in WBKDF rats than in Wistar rats. Significantly (P<.05) higher plasma concentrations of 8-iso-prostaglandin F2α and sodium ions were observed in WBKDF-HS than in Wistar-HS. The current study demonstrated that WBKDF-HS rats developed salt-sensitive hypertension associated with vascular dysfunction. The WBKDF rat may be a useful model for investigating the etiology of hypertension with T2DM.

Short communication: Distribution of Porphyromonas gulae fimA genotypes in oral specimens from dogs with mitral regurgitation.

Porphyromonas gulae, a suspected pathogen for periodontal disease in dogs, possesses approximately 41-kDa fimbriae (FimA) that are encoded by the fimA gene. In the present study, the association of fimA genotypes with mitral regurgitation (MR) was investigated. Twenty-five dogs diagnosed with MR (age range 6-13 years old, average 10.8 years) and 32 healthy dogs (8-15 years old, average 10.8 years) were selected at the participating clinics in a consecutive manner during the same time period. Oral swab specimens were collected from the dogs and bacterial DNA was extracted, then polymerase chain reaction analysis was performed using primers specific for each fimA genotype, with the dominant genotype determined. The rate for genotype C dominant specimens was 48.0% in the MR group, which was significantly higher than that in the control group (18.8%) (P <0.05). These results suggest that P. gulae fimA genotype C is associated with MR.

Prophylactic effects of the glucagon-like Peptide-1 analog liraglutide on hyperglycemia in a rat model of type 2 diabetes mellitus associated with chronic pancreatitis and obesity.

The objective of this study was to investigate the effects of liraglutide, an analog of human glucagon-like peptide 1 (GLP1), on WBN/Kob-Lepr(fa) (fa/fa) rats, which spontaneously develop type 2 diabetes mellitus with pancreatic disorder and obesity. Male fa/fa rats (age, 7 wk) were allocated into 4 groups and received liraglutide (37.5, 75, 150 µg/kg SC) or saline (control group) once daily for 4 wk. All rats in the control group became overweight and developed hyperglycemia as they aged. Although the rats given liraglutide showed a dose-dependent reduction in food intake, no significant effects on body weight or fat content occurred. In the liraglutide groups, the development of hyperglycemia was suppressed, even as plasma insulin concentrations increased in a dose-dependent manner. Intravenous glucose tolerance testing of the liraglutide-treated rats confirmed improvement of glucose tolerance and enhanced insulin secretion. Histologic examination revealed increased numbers of pancreatic ß-cell type islet cells and increased proliferation of epithelial cells of the small ducts in the liraglutide-treated groups. Although our study did not reveal a significant decrease in obesity after liraglutide administration, the results suggest a marked antidiabetic effect characterized by increased insulin secretion in fa/fa rats with pancreatic disorders.

Role of insulin resistance in the pathogenesis and development of type 2 diabetes in WBN/Kob-Lepr(fa) rats.

WBN/Kob-Lepr(fa) (fa/fa) rats have been identified as a new animal model of type 2 diabetes (T2DM), as they are characterized by impaired pancreatic insulin secretion and severe insulin resistance. Our previous study demonstrated impaired insulin secretion and its involvement in hyperglycemia in fa/fa rats. The present study was aimed at elucidating the role of insulin resistance in the development and progression of diabetes in these animals. Troglitazone (TGZ) was used as an insulin sensitizer. Insulin resistance and insulin secretory capacity were measured by a homeostasis model assessment of insulin resistance and the area under the blood concentration-time curve for plasma insulin levels after intravenous glucose tolerance testing, respectively. The fa/fa rats exhibited marked insulin resistance between 5 and 11 weeks of age, compared with age-matched Wistar rats. The insulin secretory capacity of fa/fa rats was higher than that of Wistar rats at 5 weeks of age, but decreased by 50% between 9 and 11 weeks of age. The fa/fa rats were fed a standard diet, with or without 0.2% w/w TGZ, for 4 weeks. Treatment with TGZ significantly improved insulin resistance, hyperglycemia and hypertriglyceridemia in both prophylactic and therapeutic study groups. These results suggest that insulin resistance is markedly involved in the development and progression of T2DM in fa/fa rats.

Shortened blood coagulation times in genetically obese rats and diet-induced obese mice.

The aim of this study was to investigate blood coagulation times in genetically obese rats and diet-induced obese (DIO) mice in order to clarify the relationship between visceral obesity and blood coagulation. WBN/Kob-Lepr(fa) (fa/fa) rats, a genetically obese model, exhibited a significantly shorter activated partial thromboplastin time (aPTT) and prothrombin time (PT) than age-matched Wistar rats. C57BL/6J mice fed a high-fat diet (60%), a DIO model, exhibited significantly shorter aPTT, PT and thrombin time than lean mice fed a standard diet. Higher body weight, visceral fat weight and insulin resistance were also shared by fa/fa rats and DIO mice. These results suggest that visceral obesity is related to accelerated blood coagulation in addition to disrupted metabolism of glucose and lipids.

Correlation of age with distribution of periodontitis-related bacteria in Japanese dogs.

We analyzed the distribution of 11 periodontitis-related bacterial species in dental plaque collected from 176 Japanese dogs divided into young (less than 2 years of age), middle-aged (2-7 years of age) and elderly (more than 8 years of age) groups using a polymerase chain reaction method. Clinical examination revealed that no dogs in the young group were affected by periodontitis, whereas the rates for gingivitis and periodontitis were high in the middle-aged and elderly groups. In addition, the total numbers of bacterial species in the middle-aged and elderly groups were significantly greater than in the young group. Our findings suggest that age is an important factor associated with the distribution of periodontitis-related bacteria and periodontal conditions in dogs.

Distribution and molecular characterization of Porphyromonas gulae carrying a new fimA genotype.

Porphyromonas gulae is a gram-negative black-pigmented anaerobe which is known to be a pathogen for periodontitis in dogs. Approximately 41kDa filamentous appendages on the cell surface (FimA) encoded by the fimA gene are regarded as important factors associated with periodontitis. The fimA genotype was classified into two major types and strains in type B were shown to be more virulent than those in type A. In the present study, we characterized a strain with a novel fimA genotype and designated it as type C. The putative amino acid sequence was shown to be similar to the genotype IV fimA of Porphyromonas gingivalis, a major pathogen of human periodontitis. Analyses using an oral squamous cell carcinoma cell line derived from tongue primary lesions revealed that the type C strain inhibited proliferation and scratch closure more than genotype A and B strains. In addition, experiments using a mouse abscess model demonstrated that the type C strain could induce much higher systemic inflammation when compared with strains of the other genotypes. Furthermore, molecular analyses of oral swab specimens collected from dogs demonstrated that the detection frequencies of P. gulae and the genotype C in the periodontitis group were significantly higher than those in the periodontally healthy group. These results suggest that FimA of P. gulae is diverse with the virulence of genotype C strains the highest and that molecular identification of genotype C P. gulae could be a possible useful marker for identifying dogs at high risk of developing periodontitis.