Pathogen-accelerated atherosclerosis occurs early after exposure and can be prevented via immunization

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact [email protected] (M.S.D.)--Boston University Goldman School of Dental Medicine, 2004 (Periodontology and Oral Biology).Includes bibliography (leaves 41-54).Accumulating evidence suggests that specific infectious agents such as Porphyromonas gingivalis may accelerate atherosclerosis in both human and animal studies. However, several recent clinical studies to define the early events associated with pathogen-accelerated atherosclerosis have reported negative results on progression of atherosclerosis following treatment of patients with antibiotics. Their results suggest that infection may contribute to early atherosclerosis which might be associated with chronic inflammation and atherosclerosis at an early stage. In this study, apolipoprotein E-deficient (ApoE[-/-]mice were either challenged with P. gingivalis or an invasive-impaired P. gingivalis fimbriae-deficient mutant (FimA-) or immunized with a heat-killed P. gingivalis preparation prior to oral challenge with P. gingivalis and the inflammatory response and atheroma deposition in the aorta were characterized. Animals were sacrificed 24-hours or 6-weeks after the final bacterial challenge. Serum analysis of all groups of mice (unchallenged, challenged with P. gingivalis, challenged with fimA- mutant and immunized and challenged with P. gingivalis) revealed no differences in interleukin-6 or serum amyloid A between groups. At both time points as evidenced by oil red O staining and immunohistochemistry, mice infected with P. gingivalis but not mice challenged with fimA­ mutant or immunized and challenged mice presented with increased atheroma formation, evidence of macrophage infiltration, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and Toll-like receptor-2 and -4 in aortic arch tissue. We conclude that invasive P. gingivalis infection accelerates atherosclerosis very early after exposure to this organism likely through a mechanism involving up-regulation of innate immune markers. Furthermore, immunization prior to bacterial challenge presents early inflammatory events and acceleration of atherosclerosis

Entering, Linked with the Sphinx: Lysophosphatidic Acids Everywhere, All at Once, in the Oral System and Cancer

Oral health is crucial to overall health, and periodontal disease (PDD) is a chronic inflammatory disease. Over the past decade, PDD has been recognized as a significant contributor to systemic inflammation. Here, we relate our seminal work defining the role of lysophosphatidic acid (LPA) and its receptors (LPARs) in the oral system with findings and parallels relevant to cancer. We discuss the largely unexplored fine-tuning potential of LPA species for biological control of complex immune responses and suggest approaches for the areas where we believe more research should be undertaken to advance our understanding of signaling at the level of the cellular microenvironment in biological processes where LPA is a key player so we can better treat diseases such as PDD, cancer, and emerging diseases

Upregulation of miR-30d in Persistent AF

Background: Atrial fibrillation (AF) begets AF in part due to atrial remodeling, the molecular mechanisms of which have not been completely elucidated. This study was conducted to identify microRNA(s) responsible for electrical remodeling in AF. Methods and Results: The expression profiles of 1205 microRNAs, in cardiomyocytes from patients with persistent AF and from age-, gender-, and cardiac function-matched control patients with normal sinus rhythm, were examined by use of a microRNA microarray platform. Thirty-nine microRNAs differentially expressed in AF patients’ atria were identified, including miR-30d, as a candidate responsible for ion channel remodeling by in silico analysis. MiR-30d was significantly upregulated in cardiomyocytes from AF patients, whereas the mRNA and protein levels of CACNA1C/ Cav1.2 and KCNJ3/Kir3.1, postulated targets of miR-30d, were markedly reduced. KCNJ3/Kir3.1 expression was downregulated by transfection of the miR-30 precursor, concomitant with a reduction of the acetylcholine-sensitive inward-rectifier K+ current (IK.ACh). KCNJ3/Kir3.1 (but not CACNA1C/Cav1.2) expression was enhanced by the knockdown of miR-30d. The Ca2+ ionophore, A23187, induced a dose-dependent upregulation of miR-30d, followed by the suppression of KCNJ3 mRNA expression. Blockade of protein kinase C signaling blunted the [Ca2+]i-dependent downregulation of Kir3.1 via miR-30d. Conclusions: The downward remodeling of IK.ACh is attributed, at least in part, to deranged Ca2+ handling, leading to the upregulation of miR-30d in human AF, revealing a novel post-transcriptional regulation of IK.ACh

Demonstration of the hepatocyte growth factor signaling pathway in the in vitro neuritogenic activity of chondroitin sulfate from ray fish cartilage

Chondroitin sulfate (CS) was isolated from ray fish cartilage, an industrial waste, after protease digestion, and its structure and neurite outgrowth-promoting (NOP) activity were analyzed to investigate a potential application to nerve regeneration. A disaccharide analysis using chondroitinase ABC revealed that the major unit in the CS preparation was GlcUA-GalNAc(6-O-sulfate) (63%), where GlcUA and GalNAc represent D-glucuronic acid and N-acetyl-D-galactosamine, respectively. Small proportions of other disaccharide units, GlcUA-GalNAc(4-O-sulfate) (25%), GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate) (7%), and GlcUA-GalNAc (5%), were also detected. The average molecular mass of CS was estimated to be 142 kDa by gel-filtration chromatography. The prepration showed NOP activity in vitro, which was eliminated by digestion with chondroitinase ABC, suggesting that a polymeric structure is required for the activity. Antibodies against hepatocyte growth factor (HGF) and its receptor c-Met suppressed the NOP activity, suggesting the involvement of the HGF signaling pathway in the in vitro NOP activity of the CS preparation. Since the specific binding of HGF to the CS preparation was also demonstrated by surface plasmon resonance spectroscopy, the CS chains were fractionated using an HGF-immobilized column into unbound and bound fractions accounting for 44 and 56% of the total yield, respectively. The latter contained a higher proportion of the GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate) unit, and showed greater NOP activity than the former, indicating that the HGF-binding domain contains GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate) and is involved in the NOP activity. CS from ray cartilage may have potential pharmaceutical applications

Single Nucleotide Variants of the Human TIM-1 IgV Domain with Reduced Ability to Promote Viral Entry into Cells

Human T-cell immunoglobulin mucin 1 (hTIM-1) is known to promote cellular entry of enveloped viruses. Previous studies suggested that the polymorphisms of hTIM-1 affected its function. Here, we analyzed single nucleotide variants (SNVs) of hTIM-1 to determine their ability to promote cellular entry of viruses using pseudotyped vesicular stomatitis Indiana virus (VSIV). We obtained hTIM-1 sequences from a public database (Ensembl genome browser) and identified 35 missense SNVs in 3 loops of the hTIM-1 immunoglobulin variable (IgV) domain, which had been reported to interact with the Ebola virus glycoprotein (GP) and phosphatidylserine (PS) in the viral envelope. HEK293T cells transiently expressing wildtype hTIM-1 or its SNV mutants were infected with VSIVs pseudotyped with filovirus or arenavirus GPs, and their infectivities were compared. Eleven of the thirty-five SNV substitutions reduced the efficiency of hTIM-1-mediated entry of pseudotyped VSIVs. These SNV substitutions were found not only around the PS-binding pocket but also in other regions of the molecule. Taken together, our findings suggest that some SNVs of the hTIM-1 IgV domain have impaired ability to interact with PS and/or viral GPs in the viral envelope, which may affect the hTIM-1 function to promote viral entry into cells

Pathogen-Accelerated Atherosclerosis Occurs Early after Exposure and Can Be Prevented via Immunization

Here we report on early inflammatory events associated with Porphyromonas gingivalis-accelerated atherosclerosis in apolipoprotein E knockout (ApoE(−/−)) mice. Animals challenged with P. gingivalis presented with increased macrophage infiltration, innate immune marker expression, and atheroma without elevated systemic inflammatory mediators. This early local inflammatory response was prevented in mice immunized with P. gingivalis. We conclude that localized up-regulation of innate immune markers early after infection, rather than systemic inflammation, contributes to pathogen-accelerated atherosclerosis

Molecular Mechanisms Underlying the Cellular Entry and Host Range Restriction of Lujo Virus

Like other human-pathogenic arenaviruses, Lujo virus (LUJV) is a causative agent of viral hemorrhagic fever in humans. LUJV infects humans with high mortality rates, but the susceptibilities of other animal species and the molecular determinants of its host specificity remain unknown. We found that mouse-and hamster-derived cell lines (NIH 3T3 and BHK, respectively) were less susceptible to a replication-incompetent recombinant vesicular stomatitis virus (Indiana) pseudotyped with the LUJV glycoprotein (GP) (VSVDG*-LUJV/GP) than were human-derived cell lines (HEK293T and Huh7). To determine the cellular factors involved in the differential susceptibilities between the human and mouse cell lines, we focused on the CD63 molecule, which is required for pH-activated GP-mediated membrane fusion during LUJV entry into host cells. The exogenous introduction of human CD63, but not mouse or hamster CD63, into BHK cells significantly increased susceptibility to VSVDG*-LUJV/GP. Using chimeric human mouse CD63 proteins, we found that the amino acid residues at positions 141 to 150 in the large extracellular loop (LEL) region of CD63 were important for the cellular entry of VSVDG*-LUJV/GP. By site-directed mutagenesis, we further determined that a phenylalanine at position 143 in human CD63 was the key residue for efficient membrane fusion and VSVDG*-LUJV/GP infection. Our data suggest that the interaction of LUJV GP with the LEL region of CD63 is essential for cell susceptibility to LUJV, thus providing new insights into the molecular mechanisms underlying the cellular entry of LUJV and the host range restriction of this virus. IMPORTANCE Lujo virus (LUJV) infects humans with high mortality rates, but the host range of LUJV remains unknown. We found that rodent-derived cell lines were less susceptible to LUJV infection than were human-derived cell lines, and the differential susceptibilities were determined by the difference of CD63, the intercellular receptor of LUJV. We further identified an amino acid residue on human CD63 important for efficient LUJV infection. These results suggest that the interaction between LUJV glycoprotein and CD63 is one of the important factors determining the host range of LUJV. Our findings on the CD63-regulated susceptibilities of the cell lines to LUJV infection provide important information for the development of anti-LUJV drugs as well as the identification of natural hosts of LUJV. Importantly, our data support a concept explaining the molecular mechanism underlying viral tropisms controlled by endosomal receptors

Lysophosphatidic acid (LPA) 18:1 transcriptional regulation of primary human gingival fibroblasts

The pleiotropic, bioactive lipid lysophosphatidic acid [(LPA), 1-acyl-sn-glycerol-3-phosphate] exerts critical regulatory actions in physiology and pathophysiology in many systems. It is present in normal bodily fluids, and is elevated in pathology (1). In vivo, “LPA” exists as distinct molecular species, each having a single fatty acid of varying chain length and degree of unsaturation covalently attached to the glycerol backbone via an acyl, alkyl, or alkenyl link. These species differ in affinities for the individual LPA receptors [(LPARs), LPA1-6] and coupling to G proteins (2). However, LPA 18:1 has been and continues to be the most commonly utilized species in reported studies. The actions of “LPA” remain poorly defined in oral biology and pathophysiology. Our laboratory has addressed this knowledge gap by studying in vitro the actions of the major human salivary LPA species [18:1, 18:0, and 16:0 (3)] in human oral cells (4–7). This includes gingival fibroblasts (GF), which our flow cytometry data from multiple donors found that they express LPA1-5 (6). We have also reported that these species are ten-fold elevated to pharmacologic levels in the saliva and gingival crevicular fluid obtained from patients with moderate–severe periodontitis (8). As the potential of LPA to regulate transcriptional activity had not been examined in the oral system, this study used whole human genome microarray analysis to test the hypothesis that LPA 18:1-treated human GF would show significant changes in gene transcripts relevant to their biology, wound-healing, and inflammatory responses. LPA 18:1 was found to significantly regulate a large, complex set of genes critical to GF biology in these categories and to periodontal disease. The raw data has been deposited at NCBI's GEO database as record GSE57496

Human ACE2 Genetic Polymorphism Affecting SARS-CoV and SARS-CoV-2 Entry into Cells

Severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2 have a single envelope glycoprotein (S protein) that binds to human angiotensin-converting enzyme 2 (ACE2) on the host cell membrane. Previous mutational scanning studies have suggested that some substitutions corresponding to single nucleotide variants (SNVs) in human ACE2 affect the binding affinity to the receptor binding domain (RBD) of the SARS-CoV-2 S protein. However, the importance of these substitutions in actual virus infection is still unclear. In this study, we investigated the effects of the reported ACE2 SNV substitutions on the entry of SARS-CoV and SARS-CoV-2 into cells, using vesicular stomatitis Indiana virus (VSIV) pseudotyped with S proteins of these coronaviruses (CoVs). HEK293T cells transfected with plasmids expressing ACE2 having each SNV substitution were infected with the pseudotyped VSIVs and relative infectivities were determined compared to the cells expressing wild-type ACE2. We found that some of the SNV substitutions positively or negatively affected the infectivities of the pseudotyped viruses. Particularly, the H505R substitution significantly enhanced the infection with the pseudotyped VSIVs, including those having the substitutions found in the S protein RBD of SARS-CoV-2 variants of concern. Our findings suggest that human ACE2 SNVs may potentially affect cell susceptibilities to SARS-CoV and SARS-CoV-2. IMPORTANCE SARS-CoV and SARS-CoV-2 are known to cause severe pneumonia in humans. The S protein of these CoVs binds to the ACE2 molecule on the plasma membrane and mediates virus entry into cells. The interaction between the S protein and ACE2 is thought to be important for host susceptibility to these CoVs. Although previous studies suggested that some SNV substitutions in ACE2 might affect the binding to the S protein, it remains elusive whether these SNV substitutions actually alter the efficiency of the entry of SARS CoVs into cells. We analyzed the impact of the ACE2 SNVs on the cellular entry of SARS CoVs using pseudotyped VSIVs having the S protein on the viral surface. We found that some of the SNV substitutions positively or negatively affected the infectivities of the viruses. Our data support the notion that genetic polymorphisms of ACE2 may potentially influence cell susceptibilities to SARS CoVs. SARS-CoV and SARS-CoV-2 are known to cause severe pneumonia in humans. The S protein of these CoVs binds to the ACE2 molecule on the plasma membrane and mediates virus entry into cells