A Single Amino Acid Substitution within the Paramyxovirus Sendai Virus Nucleoprotein Is a Critical Determinant for Production of Interferon-Beta-Inducing Copyback-Type Defective Interfering Genomes.

One of the first defenses against infecting pathogens is the innate immune system activated by cellular recognition of pathogen-associated molecular patterns (PAMPs). Although virus-derived RNA species, especially copyback (cb)-type defective interfering (DI) genomes, have been shown to serve as real PAMPs, which strongly induce interferon-beta (IFN-ß) during mononegavirus infection, the mechanisms underlying DI generation remain unclear. Here, for the first time, we identified a single amino acid substitution causing production of cbDI genomes by successful isolation of two distinct types of viral clones with cbDI-producing and cbDI-nonproducing phenotypes from the stock Sendai virus (SeV) strain Cantell, which has been widely used in a number of studies on antiviral innate immunity as a representative IFN-ß-inducing virus. IFN-ß induction was totally dependent on the presence of a significant amount of cbDI genome-containing viral particles (DI particles) in the viral stock, but not on deficiency of the IFN-antagonistic viral accessory proteins C and V. Comparison of the isolates indicated that a single amino acid substitution found within the N protein of the cbDI-producing clone was enough to cause the emergence of DI genomes. The mutated N protein of the cbDI-producing clone resulted in a lower density of nucleocapsids than that of the DI-nonproducing clone, probably causing both production of the DI genomes and their formation of a stem-loop structure, which serves as an ideal ligand for RIG-I. These results suggested that the integrity of mononegaviral nucleocapsids might be a critical factor in avoiding the undesirable recognition of infection by host cells.IMPORTANCE The type I interferon (IFN) system is a pivotal defense against infecting RNA viruses that is activated by sensing viral RNA species. RIG-I is a major sensor for infection with most mononegaviruses, and copyback (cb)-type defective interfering (DI) genomes have been shown to serve as strong RIG-I ligands in real infections. However, the mechanism underlying production of cbDI genomes remains unclear, although DI genomes emerge as the result of an error during viral replication with high doses of viruses. Sendai virus has been extensively studied and is unique in that its interaction with innate immunity reveals opposing characteristics, such as high-level IFN-ß induction and strong inhibition of type I IFN pathways. Our findings provide novel insights into the mechanism of production of mononegaviral cbDI genomes, as well as virus-host interactions during innate immunity.

Periodontal condition in Japanese coronary heart disease patients: A comparison between coronary and non-coronary heart diseases.

OBJECTIVE: The aim of this clinical trial was to assess the relationship between periodontal bacterial burden and coronary heart disease (CHD) in Japanese population. BACKGROUND: Many epidemiological reports suggest that periodontitis is a risk factor for CHD; however, the influence of each periodontal bacterium and periodontal condition in Japanese CHD patients is unclear. METHODS: We studied 897 patients with cardiovascular diseases in Tokyo Medical and Dental University Hospital from May 2012 to August 2015. The subjects were divided into six groups according to age and the existence of CHD (46-60 years with CHD (n = 56): Group YC, 61-70 years with CHD (n = 106): Group MC, over 70 years with CHD (n = 177): Group EC, 46-60 years without CHD (n = 152): Group YN, 61-70 years without CHD (n = 216): Group MN, and over 70 years without CHD (n = 190): Group EN). RESULTS: We found that the patients in Groups MC and EC had deeper periodontal pocket compared to the patients in Group YN (P < 0.05), although there was no statistical difference of pocket depth between Group YC and Groups MC and EC. Many subjects in Group EC had high anti-Porphyromonas gingivalis and anti-Prevotella intermedia antibodies in comparison to Group EN (P < 0.05). The CHD patients generally had worse oral condition than the non-CHD patients. Elderly with CHD had a higher level of serum anti-Porphyromonas gingivalis antibody and anti-Prevotella intermedia antibody than those without CHD. CONCLUSION: Increased periodontal infection was found in Japanese CHD patients compared to non-CHD patients.

Increased Oral Porphyromonas gingivalis Prevalence in Cardiovascular Patients with Uncontrolled Diabetes Mellitus.

The aim of this study was to determine the correlation between periodontopathic bacteria and diabetes mellitus (DM) status in cardiovascular disease (CVD) subjects.DM is associated with the progression of periodontitis. Several epidemiological studies have suggested that periodontitis may be a risk factor for CVD. However, no study has compared the periodontal condition between well-controlled and poorly-controlled DM patients with CVD.The subjects were well-controlled (n = 73) or poorly-controlled (n = 39) DM patients with CVD. Blood examinations and dental clinical measurements, including number of teeth, probing pocket depth, bleeding on probing (BOP), and clinical attachment level (CAL) were performed. Periodontopathic bacterial existence was evaluated.Worsened CAL and BOP rate were detected in the uncontrolled DM group compared to the controlled group. We found increased salivary Porphyromonas gingivalis counts in the uncontrolled DM group compared to well-controlled DM subjects.Specific periodontopathic bacterial infection may affect DM condition in CVD patients.

Detrimental effects of specific Periodontopathic bacterial infection on tachyarrhythmia compared to Bradyarrhythmia.

BACKGROUND: Tachyarrhythmia (TA) and bradyarrhythmia (BA) are cardiac rhythm disorders that result in the decline of quality of life. While patients with periodontitis are at a high risk of cardiovascular disease (CVD), little causal information between TA and BA has been provided to date. To assess the relationship, periodontal bacterial infection in patients with TA or BA was evaluated. METHODS: The subjects were patients with TA (n = 98) or BA (n = 40) who attended Tokyo Medical and Dental University hospital. Periodontal and blood examinations were performed. Periodontopathic bacterial existence in saliva was evaluated. RESULTS: We found that specific periodontopathic bacteria, Porphyromonas gingivalis and Prevotella intermedia, were highly detected in saliva from TA patients compared to BA subjects. The rates of hypertension and dyslipidemia were comparable between the two groups. CONCLUSION: Specific periodontal bacterial infection might affect TA progression.

Periodontitis deteriorates peripheral arterial disease in Japanese population via enhanced systemic inflammation.

Peripheral arterial disease (PAD) is a common manifestation of arterial stenosis of the extremity that reduces arterial flow. While patients with periodontitis are at a high risk of PAD, little causal information has been provided to date. To clarify the relationship, we conducted this cross-sectional study. The oral condition of patients with or without PAD, who attended Tokyo Medical and Dental University Hospital, was evaluated. Blood examinations and dental clinical measurements, including number of teeth, probing pocket depth (PPD), bleeding on probing (BOP) and clinical attachment level (CAL) were performed. Chi-square test was performed to compare gender, smoker rate, prevalence of DM, hypertension and dyslipidemia and edentulous rate. Wilcoxon test was used to compare bacterial counts and anti-bacterial antibodies and Student's t test was used to compare the other numerical values. The subjects were patients with (n = 34) or without (n = 956) PAD. We revealed that the PAD patients had more missing teeth (17.5 ± 11.0), a higher rate of edentulism (18%), and higher serum inflammatory factor levels than non-PAD patients (10.9 ± 8.7, 5%, respectively). On the other hand, there was no significant difference between hypertension, dyslipidemia, smoking status, HbA1c, bacterial antibody titers, and bacterial counts between the groups. In conclusion, we clarified that PAD patients had decreased tooth number and worsened oral and periodontal condition with enhanced systemic inflammation.

Sendai virus C proteins regulate viral genome and antigenome synthesis to dictate the negative genome polarity.

The order Mononegavirales comprises a large number of nonsegmented negative-strand RNA viruses (NNSVs). How the genome polarity is determined is a central issue in RNA virus biology. Using a prototypic species, vesicular stomatitis virus (VSV), it has been established that the negative polarity of the viral genome is defined solely by different strengths of the cis-acting replication promoters located at the 3' ends of the genome and antigenome, resulting in the predominance of the genome over the antigenome. This VSV paradigm has long been applied for the Mononegavirales in general without concrete proof. We now found that another prototypic species, Sendai virus (SeV), undergoes a marked shift from the early antigenome-dominant to the late genome-dominant phase during the course of infection. This shift appeared to be governed primarily by the expression of the accessory C protein, because no such shift occurred in a recombinant SeV with the C gene deleted, and antigenomes were dominant throughout infection, generating antigenome-dominant and noninfectious progeny virions. Therefore, we proposed for the first time a trans-regulatory mechanism, the SeV paradigm, to dictate the genome polarity of an NNSV. A series of promoter-swapped SeV recombinants suggested the importance of the primary as well as secondary structures of the promoters in this trans-regulation.

Arl6IP1 has the ability to shape the mammalian ER membrane in a reticulon-like fashion.

The ER (endoplasmic reticulum) consists of the nuclear envelope and a peripheral network of membrane sheets and tubules. Two classes of the evolutionarily conserved ER membrane proteins, reticulons and REEPs (receptor expression-enhancing proteins)/DP1 (deleted in polyposis locus 1)/Yop1 (YIP 1 partner), shape high-curvature ER tubules. In mammals, four members of the reticulon family and six members of the REEP family have been identified so far. In the present paper we report that Arl6IP1(ADP-ribosylation factor-like 6 interacting protein 1), an anti-apoptotic protein specific to multicellular organisms, is a potential player in shaping the ER tubules in mammalian cells. Arl6IP1, which does not share an overall primary sequence homology with reticulons, harbours reticulon-like short hairpin transmembrane domains and binds to atlastin, a GTPase that mediates the formation of the tubular ER network. Overexpression of Arl6IP1 induced extensive tubular structures of the ER and excluded a luminal protein. Furthermore, overexpression of Arl6IP1 stabilized the ER tubules, allowing the cells to maintain the ER tubules even in the absence of microtubules. Arl6IP1 constricted liposomes into tubules. The short hairpin structures of the transmembrane domains were required for the membrane-shaping activity of Arl6IP1. The results of the present study indicate that Arl6IP1 has the ability to shape high-curvature ER tubules in a reticulon-like fashion.

Inhibition of interferon regulatory factor 3 activation by paramyxovirus V protein.

The V protein of Sendai virus (SeV) suppresses innate immunity, resulting in enhancement of viral growth in mouse lungs and viral pathogenicity. The innate immunity restricted by the V protein is induced through activation of interferon regulatory factor 3 (IRF3). The V protein has been shown to interact with melanoma differentiation-associated gene 5 (MDA5) and to inhibit beta interferon production. In the present study, we infected MDA5-knockout mice with V-deficient SeV and found that MDA5 was largely unrelated to the innate immunity that the V protein suppresses in vivo. We therefore investigated the target of the SeV V protein. We previously reported interaction of the V protein with IRF3. Here we extended the observation and showed that the V protein appeared to inhibit translocation of IRF3 into the nucleus. We also found that the V protein inhibited IRF3 activation when induced by a constitutive active form of IRF3. The V proteins of measles virus and Newcastle disease virus inhibited IRF3 transcriptional activation, as did the V protein of SeV, while the V proteins of mumps virus and Nipah virus did not, and inhibition by these proteins correlated with interaction of each V protein with IRF3. These results indicate that IRF3 is important as an alternative target of paramyxovirus V proteins.

Comparison of perfusion-metabolism mismatch in 99mTc-MIBI and 123I-BMIPP scintigraphy with cardiac magnetic resonance in patients with dilated cardiomyopathy.

BACKGROUND: Cardiac magnetic resonance (CMR) imaging is an established method of detecting myocardial fibrosis related to prognosis in patients with dilated cardiomyopathy (DCM). Recent studies have found that (99m)Tc-methoxy-isobutyl-isonitrile (MIBI) and (123)I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP) dual single-photon-emission computerized tomography (MIBI-BMIPP dual SPECT) can detect perfusion-metabolism mismatches. We compared MIBI-BMIPP dual SPECT with CMR findings and assessed their prognostic abilities to determine the significance of abnormal metabolism in patients with DCM. METHODS AND RESULTS: Fifty inpatients with DCM (age 58 ± 12 y; 14 female) were assessed with the use of MIBI-BMIPP dual SPECT and CMR. Perfusion-metabolism mismatches were identified mainly at the left ventricular free wall, whereas late gadolinium enhancement (LGE) was evident mostly at the septal wall. During a median follow-up of 33 months, 9 patients developed cardiac events including death, heart failure, and fatal arrhythmia. Event-free survival rates were significantly lower for patients with LGE plus a mismatch than with other abnormalities (P = .001). Among clinical and imaging variables, LGE plus a mismatch was significantly associated with cardiac events (hazard ratio 7.9, 95% confidence interval 1.8-35.6; P = .007). CONCLUSIONS: Coexisting LGE and a perfusion-metabolism mismatch accurately predict future cardiac events in patients with DCM.

Crystal Structure of the cis-Dimer of Nectin-1: implications for the architecture of cell-cell junctions.

In multicellular organisms, cells are interconnected by cell adhesion molecules. Nectins are immunoglobulin (Ig)-like cell adhesion molecules that mediate homotypic and heterotypic cell-cell adhesion, playing key roles in tissue organization. To mediate cell-cell adhesion, nectin molecules dimerize in cis on the surface of the same cell, followed by trans-dimerization of the cis-dimers between the neighboring cells. Previous cell biological studies deduced that the first Ig-like domain of nectin and the second Ig-like domain are involved in trans-dimerization and cis-dimerization, respectively. However, to understand better the steps involved in nectin adhesion, the structural basis for the dimerization of nectin must be determined. In this study, we determined the first crystal structure of the entire extracellular region of nectin-1. In the crystal, nectin-1 formed a V-shaped homophilic dimer through the first Ig-like domain. Structure-based site-directed mutagenesis of the first Ig-like domain identified four essential residues that are involved in the homophilic dimerization. Upon mutating the four residues, nectin-1 significantly decreased cis-dimerization on the surface of cultured cells and abolished the homophilic and heterophilic adhesion activities. These results indicate that, in contrast with the previous notion, our structure represents a cis-dimer. Thus, our findings clearly reveal the structural basis for the cis-dimerization of nectins through the first Ig-like domains.

Disruption of atherosclerotic neointima seven years after bare metal stent deployment.

A 58-year-old male with a history of prior myocardial infarction, hypertension, and dyslipidemia was admitted due to deteriorating exertional angina. A bare metal stent (Multilink plus™, GUIDANT Corporation, Santa Clara, CA, USA) had been implanted into the proximal left anterior descending artery because of ST-elevation myocardial infarction 7 years earlier. Optical coherence tomography (OCT) showed a disruption of the atherosclerotic neointima overlying the stent. Intravascular imaging studies and pathological studies have shown that neointima within a bare-metal stent often transform into atherosclerotic tissue during an extended period of time. In the current report, OCT demonstrated that a disruption of the atherosclerotic neointima has the potential to cause the development of unstable clinical features. OCT examinations therefore help to understand the pathogenesis of acute coronary syndrome after stent implantation.

Inhibition of virus-like particle release of Sendai virus and Nipah virus, but not that of mumps virus, by tetherin/CD317/BST-2.

Tetherin (also known as BST-2 or CD317) has recently been identified as a potent IFN-induced anti-viral protein that inhibits the release of diverse enveloped virus particles from infected cells. The anti-viral activity of tetherin on a number of enveloped viruses, including retroviruses, filoviruses and arenaviruses, has been examined. Here, we show that tetherin is also capable of blocking the release of virus-like particles (VLPs) driven by the matrix protein of Sendai virus. Together with inhibition of Nipah virus VLP release by tetherin, these results indicate that paramyxoviruses are to be added to the list of viruses that are susceptible to tetherin inhibition. Tetherin co-localized with Nipah virus matrix proteins and accumulated in cells, indicating that it is present at, or recruited to, sites of particle assembly. It should be noted, however, that tetherin was not effective against the release of paramyxovirus mumps VLPs, indicating that certain enveloped viruses may not be sensitive to tetherin activity.

Analysis of interaction of Sendai virus V protein and melanoma differentiation-associated gene 5.

Sendai virus (SeV), a pneumotropic virus of rodents, has an accessory protein, V, and the V protein has been shown to interact with MDA5, inhibiting IRF3 activation and interferon-ß production. In the present study, interaction of the V protein with various IRF3-activating proteins including MDA5 was investigated in a co-immunoprecipitation assay. We also investigated interaction of mutant V proteins from SeVs of low pathogenicity with MDA5. The V protein interacted with at least retinoic acid inducible gene I, inhibitor of κB kinase epsilon and IRF3 other than MDA5. However, only MDA5 interacted with the V protein dependently on the C-terminal V unique (Vu) region, inhibiting IRF3 reporter activation. The Vu region has been shown to be important for viral pathogenicity. We thus focused on interaction of the V protein with MDA5. Point mutations in the Vu region destabilized the V protein or abolished the interaction with MDA5 when the V protein was stable. The V-R320G protein was highly stable and interacted with MDA5, but did not inhibit activation of IRF3 induced by MDA5. Viral pathogenicity of SeV is related to the inhibitory effect of the V protein on MDA5, but is not always related to the binding of V protein with MDA5.

Ebola vaccine-induced protection in nonhuman primates correlates with antibody specificity and Fc-mediated effects.

Although substantial progress has been made with Ebola virus (EBOV) vaccine measures, the immune correlates of vaccine-mediated protection remain uncertain. Here, five mucosal vaccine vectors based on human and avian paramyxoviruses provided nonhuman primates with varying degrees of protection, despite expressing the same EBOV glycoprotein (GP) immunogen. Each vaccine produced antibody responses that differed in Fc-mediated functions and isotype composition, as well as in magnitude and coverage toward GP and its conformational and linear epitopes. Differences in the degree of protection and comprehensive characterization of the response afforded the opportunity to identify which features and functions were elevated in survivors and could therefore serve as vaccine correlates of protection. Pairwise network correlation analysis of 139 immune- and vaccine-related parameters was performed to demonstrate relationships with survival. Total GP-specific antibodies, as measured by biolayer interferometry, but not neutralizing IgG or IgA titers, correlated with survival. Fc-mediated functions and the amount of receptor binding domain antibodies were associated with improved survival outcomes, alluding to the protective mechanisms of these vaccines. Therefore, functional qualities of the antibody response, particularly Fc-mediated effects and GP specificity, rather than simply magnitude of the response, appear central to vaccine-induced protection against EBOV. The heterogeneity of the response profile between the vaccines indicates that each vaccine likely exhibits its own protective signature and the requirements for an efficacious EBOV vaccine are complex.

Antitumor activity of an oncolytic measles virus against canine urinary bladder transitional cell carcinoma cells.

The prognosis of canine transitional cell carcinoma (TCC) of urinary bladder is generally poor because it is difficult to diagnose at early stages and conventional therapies, such as surgical resection and/or chemotherapy, are often not curative treatments. Based on our previous report that recombinant measles virus (rMV-SLAMblind) therapy could be a new treatment for canine mammary tumor, the applicability of rMV-SLAMblind in canine urinary bladder TCC was examined in this study. A canine TCC cell line was established from a TCC patient dog by transplanting a piece of the tumor mass into an immunodeficient mouse and then isolating the primary TCC cells from the grown tumor mass. The primary cultured cells, named TCC-NU1, express nectin-4, a receptor for rMV-SLAMblind infection. The rMV-SLAMblind infected TCC-NU1 cells, and dose-dependently showed cell cytotoxicity. Moreover, intratumoral administration of rMV-SLAMblind in a xenograft model bearing TCC-NU1 cells significantly suppressed the tumor growth reducing the endpoint mass of tumors in treated mice compared to control mice. These results suggest that virotherapy with rMV-SLAMblind be a new candidate therapy for canine TCC.

Novel avian paramyxovirus-based vaccine vectors expressing the Ebola virus glycoprotein elicit mucosal and humoral immune responses in guinea pigs.

Paramyxovirus vaccine vectors based on human parainfluenza virus type 3 (HPIV-3) and Newcastle disease virus (NDV) have been previously evaluated against Ebola virus (EBOV) challenge. Although both the viral vectored vaccines efficiently induce protective immunity, some concerns remain to be solved. Since HPIV-3 is a common human pathogen, the human population has pre-existing immunity to HPIV-3, which may restrict the replication of the vaccine vector. For NDV, mesogenic (intermediate virulent) strain used in previous studies is currently classified as a Select Agent in the United States, thus making it unsuitable to be used as a vaccine vector. To overcome these concerns, we have developed a modified NDV vector based on a mesogenic NDV strain, in which the ectodomains of envelope glycoproteins were replaced with the corresponding ectodomains from avian paramyxovirus serotype 3 (APMV-3). The modified NDV vector was highly attenuated in chickens and was able to express the EBOV glycoprotein (GP) gene at high level. In addition, the recombinant APMV-3 was also evaluated as a vaccine vector to express the EBOV GP gene. Guinea pigs immunized with these two vector vaccines developed high levels of neutralizing GP-specific IgG and IgA antibodies.

Antibody Repertoires to the Same Ebola Vaccine Antigen Are Differentially Affected by Vaccine Vectors.

Comparative immune response profiling is important for selecting next-generation vaccines. We comprehensively evaluated the antibody responses from a panel of nine respiratory vaccines against Ebola virus (EBOV) derived from human and avian paramyxoviruses expressing EBOV glycoprotein (GP). Most vaccines were protective in guinea pigs but yielded antibody repertoires that differed in proportion targeting key antigenic regions, avidity, neutralizing antibody specificities, and linear epitope preferences. Competition studies with monoclonal antibodies from human survivors revealed that some epitopes in GP targeted for neutralization were vector dependent, while EBOV-neutralizing titers correlated with the response magnitude toward the receptor-binding domain and GP1/GP2 interface epitopes. While an immunogen determines the breadth of antibody response, distinct vaccine vectors can induce qualitatively different responses, affecting protective efficacy. These data suggest that immune correlates of vaccine protection cannot be generalized for all vaccines against the same pathogen, even if they use the exact same immunogen.

Japanese Cardiovascular Disease Patients with Diabetes Mellitus Suffer Increased Tooth Loss in Comparison to Those without Diabetes Mellitus -A Cross-sectional Study.

Objective Tooth loss is an irreversible condition that reflects the end-stage of oral diseases, including periodontitis. Although periodontitis is a major factor in the progression of diabetes mellitus (DM) and cardiovascular disease (CVD), no previous studies have compared tooth loss in CVD patients with and without DM. Methods The subjects included CVD patients with (n=94) and without (n=145) DM who attended Tokyo Medical and Dental University Hospital. Blood examinations and periodontal measurements were performed. Results The oral and periodontal examinations revealed that the numbers of missing teeth in the DM group were increased in comparison to the non-DM group. There was no significant difference between the groups with regard to the incidence of edentulism, the probing pocket depth, the clinical attachment level or the incidence of bleeding on probing. Conclusion We showed that the numbers of missing teeth among CVD patients with DM was significantly higher than that among CVD patients without DM.

Avian Paramyxovirus Type-3 as a Vaccine Vector: Identification of a Genome Location for High Level Expression of a Foreign Gene.

Avian paramyxovirus serotype 3 (APMV-3) causes infection in a wide variety of avian species, but it does not cause apparent diseases in chickens. On the contrary, APMV-1, also known as Newcastle disease virus (NDV), can cause severe disease in chickens. Currently, natural low virulence strains of NDV are used as live-attenuated vaccines throughout the world. NDV is also being evaluated as a vaccine vector against poultry pathogens. However, due to routine vaccination programs, chickens often possess pre-existing antibodies against NDV, which may cause the chickens to be less sensitive to recombinant NDV vaccines expressing antigens of other avian pathogens. Therefore, it may be possible for an APMV-3 vector vaccine to circumvent this issue. In this study, we determined the optimal insertion site in the genome of APMV-3 for high level expression of a foreign gene. We generated recombinant APMV-3 viruses expressing the green fluorescent protein (GFP) by inserting the GFP gene at five different intergenic regions in the genome. The levels of GFP transcription and translation were evaluated. Interestingly, the levels of GFP transcription and translation did not follow the 3'-to-5' attenuation mechanism of non-segmented, negative-sense RNA viruses. The insertion of GFP gene into the P-M gene junction resulted in higher level of expression of GFP than when the gene was inserted into the upstream N-P gene junction. Unlike NDV, insertion of GFP did not attenuate the growth efficiency of AMPV-3. Thus, APMV-3 could be a more useful vaccine vector for avian pathogens than NDV.

Toll-like receptor-2 has a critical role in periodontal pathogen-induced myocardial fibrosis in the pressure-overloaded murine hearts.

Recent studies have indicated that periodontopathic bacteria might accelerate the development of cardiac fibrosis. Porphyromonas gingivalis (P. gingivalis), a major periodontal bacterium, is mainly recognized by Toll-like receptor-2 (TLR-2). However, the role of TLR-2 in the acceleration of cardiac fibrosis via infections caused by periodontal bacteria has not yet been investigated. Here we investigated the role TLR-2 has in periodontal pathogen-induced cardiac fibrosis. TLR-2 knockout (KO) and wild type (WT) male C57BL/6 mice were subjected to a transverse aortic constriction (TAC) surgical procedure 2 weeks after chamber implantation. After the TAC operation, mice received injections once a week of P. gingivalis or vehicle into the chambers that were implanted in the back of mice. Fractional shortening (FS) was measured using echocardiography 1 week after the TAC surgical procedure. Four weeks after the TAC surgical procedure, blood and heart samples were collected. FS in the infected group of WT mice was significantly lower than in mice that received sham operations; however, FS in the uninfected group did not decrease in a similar manner to that in the infected group. Cardiac fibrosis was significantly enhanced in TAC-operated WT mice infected with P. gingivalis (n=14), whereas it was inhibited in TAC-operated TLR-2 KO mice infected with P. gingivalis (n=7). The level of matrix metalloproteinase-2 (MMP-2) mRNA was higher in WT mice infected with P. gingivalis compared with non-infected WT mice. However, the level of MMP-2 mRNA was significantly lower in TLR-2 KO mice compared with that in WT mice. In conclusion, TLR-2 had a critical role in the development of cardiac fibrosis under the conditions of pressure overload and periodontal pathogen infection.