Herpes Simplex Virus Type 1 Infection of Human Periodontal Ligament.

The periodontal ligament (PDL) is a complex connective tissue that connects the tooth root to the dental alveolar bone and plays crucial mechanical roles. PDL also exhibits regenerative roles and regulatory functions to maintain periodontium integrity and homeostasis. While PDL exposure to oral microbial pathogens is common, virtually nothing is known regarding viral infections of PDL. In particular, human herpes simplex virus type 1 (HSV-1) persistently infects the oral cavity through infections of the oral epithelium, connective tissue and neurons. While the oral spread of HSV-1 is generally asymptomatic, this virus has also been implicated in various oral pathologies. In this study, using a primary cell model derived from PDL (PDL cells), and whole surgical fragments of PDL, we provide evidence supporting the efficient infection of PDL by HSV-1 and the promotion of cytopathic effects. Infection of PDL by HSV-1 was also associated with an acute innate inflammatory response, as illustrated by the production of antiviral interferons and pro-inflammatory cytokines. Furthermore, this inflammatory response to HSV-1 was exacerbated in the presence of bacterial-derived products, such as peptidoglycans. This work therefore highlights the ability of HSV-1 to infect mesenchymal cells from PDL, suggesting that PDL may serve as a viral reservoir for the periodontal spread of HSV-1. Moreover, this raises questions about HSV-1 oral pathogenesis, as HSV-1-associated cytopathic and inflammatory effects may contribute to profound alterations of PDL integrity and functioning.

Heterogeneous NLRP3 inflammasome signature in circulating myeloid cells as a biomarker of COVID-19 severity.

Dysregulated immune response is the key factor leading to unfavorable coronavirus disease 2019 (COVID-19) outcome. Depending on the pathogen-associated molecular pattern, the NLRP3 inflammasome can play a crucial role during innate immunity activation. To date, studies describing the NLRP3 response during severe acute respiratory syndrome coronavirus 2 infection in patients are lacking. We prospectively monitored caspase-1 activation levels in peripheral myeloid cells from healthy donors and patients with mild to critical COVID-19. The caspase-1 activation potential in response to NLRP3 inflammasome stimulation was opposed between nonclassical monocytes and CD66b+CD16dim granulocytes in severe and critical COVID-19 patients. Unexpectedly, the CD66b+CD16dim granulocytes had decreased nigericin-triggered caspase-1 activation potential associated with an increased percentage of NLRP3 inflammasome impaired immature neutrophils and a loss of eosinophils in the blood. In patients who recovered from COVID-19, nigericin-triggered caspase-1 activation potential in CD66b+CD16dim cells was restored and the proportion of immature neutrophils was similar to control. Here, we reveal that NLRP3 inflammasome activation potential differs among myeloid cells and could be used as a biomarker of a COVID-19 patient's evolution. This assay could be a useful tool to predict patient outcome. This trial was registered at www.clinicaltrials.gov as #NCT04385017.

Problematic molecular diagnosis of HSV-1 infection due to a single nucleotide polymorphism in the US7 gene.

BACKGROUND: HSV-1 infection is very common worldwide and can be associated with severe medical conditions such as encephalitis and neonatal herpes. Current diagnosis relies heavily on molecular assays targeting the viral genome. One of the pitfalls of these assays is genetic variability, as viral polymorphisms located in the target region can impair the detection of HSV-1. OBJECTIVES: The aim of this study was to determine if genetic diversity of HSV-1 could account for equivocal assay results we obtained during routine diagnosis of HSV-1 in a genital specimen with the HSV-1 HSV-2 VZV R-gene® assay. STUDY DESIGN: The presence of HSV-1 in the genital swab studied was assessed using the HSV-1 HSV-2 VZV R-gene® qPCR assay and viral culture. Genetic variability of the patient's HSV-1 isolate was determined using molecular cloning, sequencing and comparison of the sequence of the isolate with those of previously published strains. RESULTS: We identified an HSV-1 isolate carrying a novel single-nucleotide polymorphism (SNP) located in the US7 gene from a genital swab. This SNP resulted in a missense substitution in the gI protein. It was responsible for the generation of an altered amplification curve when the genital specimen was checked for HSV-1 presence with the Argene HSV-1 HSV-2 VZV R-gene® assay, preventing unequivocal determination of the HSV-1 status of the sample analyzed. CONCLUSIONS: This study raises awareness of the risk of misdiagnosis of HSV-1 infections when "single-target" molecular assays are employed.

Quantification of HPV16 E6/E7 mRNA Spliced Isoforms Viral Load as a Novel Diagnostic Tool for Improving Cervical Cancer Screening.

High-risk human papillomaviruses (HPVs) have been identified as the main contributors to cervical cancer. Despite various diagnostic tools available, including the predominant Papanicolaou test (Pap test), technical limitations affect the efficiency of cervical cancer screening. The aim of this study was to evaluate the diagnostic performance of spliced HPV16 E6/E7 mRNA viral loads (VL) for grade 2 or higher cervical intraepithelial neoplasia diagnosis. A new dedicated (quantitative reverse transcription polymerase chain reaction) qRT-PCR assay was developed, allowing selective quantification of several HPV16 E6/E7 mRNA: Full length (FL) with or without all or selected spliced forms (total E6/E7 mRNA corresponding to SP + E6^E7 mRNA (T), + spliced E6/E7 mRNA containing intact E7 ORF (SP), and E6/E7 mRNA containing disrupted E6 and E7 ORFs calculated by the following subtraction T-SP (E6^E7)). Twenty HPV16 DNA and mRNA positive uterine cervical smears representative of all cytological and histological stages of severity were tested. We have shown that all E6/E7 mRNA isoforms expression levels were significantly increased in high grade cervical lesions. Statistical analysis demonstrated that the SP-E6/E7 VL assay exhibited: (i) The best diagnostic performance for identification of both cervical intraepithelial neoplasia (CIN)2+ (90% (56⁻100) sensitivity and specificity) and CIN3+ (100% (72⁻100) sensitivity and 79% (49⁻95) specificity) lesions; (ii) a greater sensitivity compared to the Pap test for CIN2+ lesions detection (80% (44⁻97)); (iii) a predictive value of the histological grade of cervical lesions in 67% of atypical squamous cells of unknown significance (ASC-US) and 100% of low-grade (LSIL) patients. Overall, these results highlight the value of SP-E6/E7 mRNA VL as an innovative tool for improving cervical cancer screening.

CD1c-Related DCs that Express CD207/Langerin, but Are Distinguishable from Langerhans Cells, Are Consistently Present in Human Tonsils.

Several subsets of dendritic cells (DCs) are present in the oropharyngeal tonsillar tissues and are thought to behave as major actors in development and regulation of immunity by acting as a first line of recognition for airborne and alimentary antigens. We previously discovered in human adult tonsils infected with Epstein-Barr virus (EBV), a subset of DCs that expressed langerin/CD207, a lectin usually recognized as a hallmark of epidermal Langerhans cells (LCs). In the present study, we analyzed the content of several child and adult tonsils in order to characterize in more detail the phenotype of these tonsillar CD207-expressing DCs (tCD207 DCs) and to compare it with that of other human DC subsets. We showed that all the human tonsils studied (n = 12) contained significant proportions of tCD207 DCs among tonsillar cells expressing HLA-DR. Moreover, the presence of tCD207 DCs in tonsils from young children free of EBV infection indicated that these cells could be established early in the tonsil independently of EBV infection. We also showed that tCD207 DCs, that were found mainly located within the tonsillar lymphoid stroma, were distinguishable from LCs by the level of expression of CD1a and EpCAM, and also from human inflammatory DCs by the lack of CD1a, CD206, and CD14 expression. Detailed analysis of cell surface DC markers showed that tCD207 DCs were unrelated to CD141(+) DCs or macrophages, but defined a subtype of tonsillar DCs closely related to myeloid resident CD1c DCs. Since it was established that blood CD1c myeloid DCs exhibit plasticity and are capable of expressing CD207 notably in the presence of inflammatory cytokines, it is tempting to speculate that CD207(+) CD1c(+) DCs may play a specific immune role.

EBV infection is common in gingival epithelial cells of the periodontium and worsens during chronic periodontitis.

An amplifying role for oral epithelial cells (ECs) in Epstein-Barr Virus (EBV) infection has been postulated to explain oral viral shedding. However, while lytic or latent EBV infections of oro/nasopharyngeal ECs are commonly detected under pathological conditions, detection of EBV-infected ECs in healthy conditions is very rare. In this study, a simple non-surgical tissue sampling procedure was used to investigate EBV infection in the periodontal epithelium that surrounds and attaches teeth to the gingiva. Surprisingly, we observed that the gingival ECs of the periodontium (pECs) are commonly infected with EBV and may serve as an important oral reservoir of latently EBV-infected cells. We also found that the basal level of epithelial EBV-infection is significantly increased in chronic periodontitis, a common inflammatory disease that undermines the integrity of tooth-supporting tissues. Moreover, the level of EBV infection was found to correlate with disease severity. In inflamed tissues, EBV-infected pECs appear to be prone to apoptosis and to produce larger amounts of CCL20, a pivotal inflammatory chemokine that controls tissue infiltration by immune cells. Our discovery that the periodontal epithelium is a major site of latent EBV infection sheds a new light on EBV persistence in healthy carriers and on the role of this ubiquitous virus in periodontitis. Moreover, the identification of this easily accessible site of latent infection may encourage new approaches to investigate and monitor other EBV-associated disorders.

Specific infiltration of langerin-positive dendritic cells in EBV-infected tonsil, Hodgkin lymphoma and nasopharyngeal carcinoma.

We report here the existence of a novel subset of langerin (CD207)-positive, immature dendritic cells (DCs) (CD83(neg) ) abundantly infiltrating Epstein Barr virus (EBV)-infected areas in tonsil, Hodgkin lymphoma and nasopharyngeal carcinoma. These CD207(+) DCs differ from conventional epidermal Langerhans cells in their lack of CD1a and CCR6 and their unusual tissue localization. CD207(+) DC infiltration strongly correlates with EBV infection because it was neither detected in EBV negative specimens nor in tissues infected with other human viruses. These immature DCs might represent good candidates for induction of the EBV-specific immune response.

Focal adhesion kinase is not required for Src-induced formation of invadopodia in KM12C colon cancer cells and can interfere with their assembly.

Overexpression of active Src induces invadopodia formation and associated matrix degradation in KM12C colon cancer cells. FAK is present with active Src at sites of matrix-degrading activity (invadopodia), specifically residing in rings surrounding the cortactin-containing invadopodia cores. Since FAK is a key effector protein in many aspects of Src function, we addressed whether FAK is necessary for Src-induced invadopodia formation and matrix degradation in KM12C colon cancer cells. We found that efficient knockdown of FAK expression by siRNA had no effect on invadopodia formation or matrix degradation. However, overexpression of FAK could actually suppress invadopodia formation and matrix degradation. FAK phosphorylation on the putative auto-phosphorylation tyrosine 397 and the Src-specific sites are all required for overexpressed FAK to inhibit invadopodia formation, while the kinase activity of exogenous FAK is apparently not required. These data imply that kinase activities other than FAK auto-phosphorylation may contribute to the phosphorylation of FAK tyrosine 397 in some contexts to promote an activity of FAK that can counteract invadopodia formation. Further work is required to determine how the strength of signalling through FAK suppresses invadopodia, but we propose that FAK controls the balance of adhesion types in cells, and that this is one of the determinants of whether a cancer cell can make stable matrix-degrading invadopodia.

Silencing of hSlo potassium channels in human osteosarcoma cells promotes tumorigenesis.

Potassium channels, the most diverse superfamily of ion channels, have recently emerged as regulators of carcinogenesis, thus introducing possible new therapeutic strategies in the fight against cancer. In particular, the large conductance Ca(2+)-activated K(+) channels, often referred to as BK channels, are at the crossroads of several tumor-associated processes such as cell proliferation, survival, secretion and migration. Despite the high BK channel expression in osteosarcoma (OS), their function has not yet been investigated in this malignant bone pathology. Here, using stable RNA interference to reduce the expression of hSlo, the human pore-forming alpha-subunit of the BK channel, in human Cal72 OS cells, we show that BK channels play a functional role in carcinogenesis. Our results reveal for the first time that BK channels exhibit antitumoral properties in OS in vivo and affect the tumor microenvironment through the modulation of both chemokine expression and leukocyte infiltration.

Soluble fractalkine prevents monocyte chemoattractant protein-1-induced monocyte migration via inhibition of stress-activated protein kinase 2/p38 and matrix metalloproteinase activities.

In this study, we address the question of the cross-talk between two chemokines that are cosecreted during inflammation, namely monocyte chemoattractant protein-1 (MCP-1) and soluble fractalkine (s-FKN), toward monocyte migration. We found that s-FKN fails to induce MonoMac6 cell migration per se. Interestingly, this chemokine antagonizes transendothelial migration and chemotaxis of MonoMac6 cells and freshly isolated human monocytes induced by MCP-1, indicating a direct effect of s-FKN on monocytic cells. In this study, we found that stress-activated protein kinase (SAPK)1/c-Jun N-terminal kinase 1 and SAPK2/p38 are involved in the control of MCP-1-induced MonoMac6 cell migration. We demonstrated that s-FKN abrogates the MCP-1-induced SAPK2/p38 activation as well as the upstream Pyk2 activity. Furthermore, we observed that s-FKN also inhibits the activity of a major matrix metalloproteinase (MMP), namely MMP-2. Taken collectively, our results indicate that the s-FKN antagonizes the chemoattractant effect of MCP-1 on monocytes, likely by inhibiting crucial signaling pathways, like SAPK2/p38 and MMP-2 activities.