A mouse model linking viral hepatitis and salivary gland dysfunction

DMA, a Small Molecule, Increases Median Survival and Reduces Radiation-Induced Xerostomia via the Activation of the ERK1/2 Pathway in Oral Squamous Cell Carcinoma

Survival, recurrence, and xerostomia are considerable problems in the treatment of oral squamous carcinoma patients. In this study, we investigated the role of DMA (5-(4-methylpiperazin-1-yl)-2-[2′-(3,4-dimethoxyphenyl)5″benzimidazoyl]benzimidazole) as a salivary gland cytoprotectant in a patient-derived xenograft mouse model. A significant increase in saliva secretion was observed in the DMA-treated xenograft compared to radiation alone. Repeated doses of DMA with a high dose of radiation showed a synergistic effect on mice survival and reduced tumor growth. The mean survival rate of tumor-bearing mice was significantly enhanced. The increased number of Ki-67-stained cells in the spleen, intestine, and lungs compared to the tumor suggests DMA ablates the tumor but protects other organs. The expression of aquaporin-5 was restored in tumor-bearing mice injected with DMA before irradiation. The reduced expression of αvβ3 integrin and CD44 in DMA alone and DMA with radiation-treated mice suggests a reduced migration of cells and stemness of cancer cells. DMA along with radiation treatment results in the activation of the Ras/Raf/MEK/ERK pathway in the tumor, leading to apoptosis through caspase upregulation. In conclusion, DMA has strong potential for use as an adjuvant in radiotherapy in OSCC patients.

Salivary Histatin 5 Level in Women with Vaginal Candidiasis

Histatins (Hsts) are considered a prominent member of antimicrobial peptides rich in histidine, bearing antifungal activity against Candida species. Hst5 is the most effective among them. Although Hst5 is not found in the cervicovaginal fluid, it has been detected in the human serum. Saliva acts as a mirror, reflecting the cause and effect relationship between several diseases. We aimed to show the salivary Hst5 levels with vaginal candidiasis. Women in the reproductive age group (18-50 years) were enrolled in the study. Patients and controls were classified based on the presence or absence of vaginal discharge suggestive of candidiasis, respectively. Vaginal and salivary samples were collected from all the women. Vaginal samples were cultured for the growth of Candida species. Salivary samples were tested by protein electrophoresis to detect Hst5 levels, and the results were compared between the two groups. A total of 80 women were included in this study. The mean age of women in vaginal candidiasis and control groups was 34.25 ± 8.06 and 36.83 ± 7.29 years, respectively. Candida species were isolated from the vaginal samples of the patient group (34 C. albicans, 6 non-Candida albicans) but not from the control group. Hst5 levels in the patient and control group were found to be 0.0571 ± 0.003 ng/mL and 0.0641 ± 0,0031 ng/mL, respectively. Hst5 levels were found to be significantly lower in the vaginal candidiasis group (p=0.001). We conclude that decreased salivary Hst5 levels in women are associated with vaginal candidiasis. Candida infection is a cause or result of lower salivary Hst5 levels, and it may be an important finding for the etiopathogenesis, diagnosis, and treatment of the disease, but further analysis is needed.

Protective MCMV immunity by vaccination of the salivary gland via Wharton's duct: replication-deficient recombinant adenovirus expressing individual MCMV genes elicits protection similar to that of MCMV

Salivary glands, a major component of the mucosal immune system, confer antigen-specific immunity to mucosally acquired pathogens. We investigated whether a physiological route of inoculation and a subunit vaccine approach elicited MCMV-specific and protective immunity. Mice were inoculated by retrograde perfusion of the submandibular salivary glands via Wharton's duct with tcMCMV or MCMV proteins focused to the salivary gland via replication-deficient adenovirus expressing individual MCMV genes (gB, gH, IE1; controls: saline and replication deficient adenovirus without MCMV inserts). Mice were evaluated for MCMV-specific antibodies, T-cell responses, germinal center formation, and protection against a lethal MCMV challenge. Retrograde perfusion with tcMCMV or adenovirus expressed MCMV proteins induced a 2- to 6-fold increase in systemic and mucosal MCMV-specific antibodies, a 3- to 6-fold increase in GC marker expression, and protection against a lethal systemic challenge, as evidenced by up to 80% increased survival, decreased splenic pathology, and decreased viral titers from 10(6) pfu to undetectable levels. Thus, a focused salivary gland immunization via a physiological route with a protein antigen induced systemic and mucosal protective immune responses. Therefore, salivary gland immunization can serve as an alternative mucosal route for administering vaccines, which is directly applicable for use in humans.

Is IL-17 an accomplice contributing to salivary gland damage during CMV infection?

Aim: This study aimed to explore the potential role of IL-17 in the pathological damage to the salivary gland during CMV infection. Materials & methods: For all studies, 4-week-old female BALB/c mice were used. Mouse embryo fibroblast cells were isolated from embryos of pregnant mice. The Smith murine CMV (MCMV) strain was propagated and obtained from homogenates of the salivary glands. BALB/c mice were randomly divided into two groups. Mice in one group were infected with Smith MCMV to establish disseminated infection; mice in the other group were controls. Four mice of each group were randomly chosen to be harvested on days 3, 7, 14 and 28. Viral titers in salivary gland tissues were determined using a standard plaque assay; IL-17+ T cells in the spleen were analyzed by flow cytometry; the expressions of IL-17 and IL-17 receptor (IL-17R) mRNA was measured by reverse transcription PCR; and the pathology of the salivary glands in infected mice were assessed by hematoxylin and eosin staining. Results: The viral titers in salivary gland tissues, which were much higher than those of other organs, elevated on day 7 and peaked on day 14, then gradually declined on day 28. The percentages of CD4+IL-17+ T cells were increased in MCMV-infected mice compared with controls, with the main increase of CD4+IL-17+ T cells being Th17 cells (p < 0.05). In salivary gland tissues, the expression of IL-17 and IL-17R mRNA increased significantly and achieved the highest level on day 14, which was significantly higher than that of the controls (p < 0.05). Compared with controls, serious inflammatory cellular infiltrates in the salivary glands were present on day 7 after MCMV infection, and on day 14, many of the cellular infiltrate became larger and coalesced with neighboring foci. We found that IL-17 and IL-17R were enriched in the salivary glands when the tissues were mainly injured. Conclusion: The results illustrated that the inflammatory factors, IL-17 and IL-17R, possibly contributed to the process of viral infection and played a part in inducing pathological damage of the salivary gland.

Salivary gland hypofunction induced by activation of innate immunity is dependent on type I interferon signaling

BACKGROUND

Activation of innate immunity through polyinosinic:polycytidylic acid [poly(I:C)] causes acute salivary gland hypofunction. As a major consequence of poly(I:C) treatment is type I interferon (IFN) production, this study was undertaken to investigate their role in salivary gland dysfunction.

METHODS

Different strains of mice deficient in either interferon alpha receptor (IFNAR1(-/-)) or IL-6(-/-), or IL-10(-/-), or EBI3(-/-) were treated with poly(I:C). Salivary gland function was determined by measuring pilocarpine-induced saliva volume. Gene expression levels were measured by real-time PCR. Ca(2+) mobilization studies were performed using ex-vivo acinar cells.

RESULTS

A single injection of poly(I:C) rapidly induced salivary gland hypofunction in wild-type B6 mice (41% drop in saliva volumes compared to PBS-treated mice). In contrast, the loss of function in poly(I:C)-treated IFNAR(-/-) mice was only 9.6%. Gene expression analysis showed reduced levels of Il-6, Il-10, and Il-27 in submandibular glands of poly(I:C)-treated IFNAR(-/-) mice. While salivary gland dysfunction in poly(I:C)-treated IL-10(-/-) and EBI3(-/-) mice was comparable to wild-type mice, the IL-6(-/-) mice were more resistant, with only a 21% drop in function. Pilocarpine-induced Ca(2+) flux was significantly suppressed in acinar cells obtained from poly(I:C)-treated wild-type mice.

CONCLUSIONS

Our data demonstrate that a combined action of type I IFNs and IL-6 contributes toward salivary gland hypofunction. This happens through interference with Ca(2+) mobilization within acinar cells. Thus, in acute viral infections and diseases like Sjögren's syndrome, elevated levels of type I IFNs and IL-6 can directly affect glandular function.

Natural killer cells regulate murine cytomegalovirus-induced sialadenitis and salivary gland disease

The transmission of herpesviruses depends on viral shedding at mucosal surfaces. The salivary gland represents a major site of persistent viral replication for many viruses, including cytomegalovirus. We established a mouse model of salivary gland dysfunction after acute viral infection and investigated the cellular requirements for the loss of secretion. Murine cytomegalovirus (MCMV) infection severely impaired saliva secretion independently of salivary gland virus levels. Lymphocytes or circulating monocytes/macrophages were not required for secretory dysfunction. Dysfunction occurred before glandular inflammation, suggesting that a soluble mediator initiated the disruption of acinar cell function. Despite genetic differences in innate resistance to MCMV, NK cells protected the host against acinar atrophy and the loss of secretions under conditions of an exceedingly low virus inoculum. NK cells also modulated the type of glandular inflammation after infection, as they prevented an influx of Siglec-F(+) polymorphonuclear leukocytes (PMNs). Therefore, beyond their recognized role in controlling MCMV replication, NK cells preserve organ integrity and function and regulate the innate inflammatory response within the gland.

Small molecule inhibitors of the host cell COX/AREG/EGFR/ERK pathway attenuate cytomegalovirus-induced pathogenesis

As with other herpesviruses, human cytomegalovirus (hCMV) has the ability to establish lifelong persistence and latent infection following primary exposure, salivary glands (SMGs) being the primary site of both. In the immunocompromised patient, hCMV is a common cause of opportunistic infections, and subsequent morbidity and mortality. Elucidating the molecular pathogenesis of CMV-induced disease is critical to the development of more effective and safer drug therapies. In the present study, we used a novel mouse postnatal SMG organ culture model of mCMV-induced dysplasia to investigate a candidate signaling network suggested by our prior studies (COX-2/AREG/EGFR/ERK). The objective was to employ small molecule inhibitors to target several key steps in the autocrine loop, and in this way ameliorate pathology. Our results indicate that upregulation of ERK phosphorylation is necessary for initial mCMV-induced pathogenesis, and that ErbB receptor family phosphorylation and downstream signaling are highly relevant targets for drug discovery.

Salivary glands act as mucosal inductive sites via the formation of ectopic germinal centers after site-restricted MCMV infection

We investigated the hypothesis that salivary gland inoculation stimulates formation of ectopic germinal centers (GCs), transforming the gland into a mucosal inductive site. Intraglandular infection of mice with murine cytomegalovirus (MCMV; control: UV-inactivated MCMV) induces salivary gland ectopic follicles comprising cognate interactions between CD4(+) and B220(+) lymphocytes, IgM(+) and isotype-switched IgG(+) and IgA(+) B cells, antigen presenting cells, and follicular dendritic cells. B cells coexpressed the GC markers GCT (57%) and GL7 (52%), and bound the lectin peanut agglutinin. Lymphoid follicles were characterized by a 2- to 3-fold increase in mRNA for CXCL13 (lymphoid neogenesis), syndecan-1 (plasma cells), Blimp-1 (plasma cell development/differentiation), and a 2- to 6-fold increase for activation-induced cytidine deaminase, PAX5, and the nonexcised rearranged DNA of an IgA class-switch event, supporting somatic hypermutation and class-switch recombination within the salivary follicles. Intraglandular inoculation also provided protection against a systemic MCMV challenge, as evidenced by decreased viral titers (10(5) plaque-forming units to undetectable), and restoration of normal salivary flow rates from a 6-fold decrease. Therefore, these features suggest that the salivary gland participates in oral mucosal immunity via generation of ectopic GCs, which function as ectopic mucosal inductive sites.

Toll-like Receptor3-mediated Induction of Chemokines in Salivary Epithelial Cells

Toll-like receptors (TLRs) functionally expressed in salivary epithelial cells, but their roles remain elusive. Among TLRs family, TLR3 is activated by dsRNA, a byproduct of viral infection. The aim of this study was to investigate the role of TLR3 in the inflammatory immune responses using HSG cells. Reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR and ELISA were performed to identify expression of TLRs and TLR3-mediated chemokine inductions. The chemotaxis assay of activated T lymphocytes was also performed. Treatment of HSG cells with polyinosinic: polycytidylic acid (poly(I:C)) significantly increased interferon-γ-inducible protein 10 (IP-10), interferoninducible T-cell α chemoattractant (I-TAC), and regulated on activation, normal T-cells expressed and secreted (RANTES) gene expressions in a concentration-dependent manner. Anti-TLR3 antibody blocked the increases of IP-10 and I-TAC genes. Poly(I:C)-induced increases of IP-10 and I-TAC were also confirmed at protein levels from cell lysates, but their release into extracellular medium was detected only in IP-10. We found that the culture media from HSG cells stimulated with poly(I:C) significantly increases T lymphocyte migration. Our results suggest that TLR3 plays an important role in chemokine induction, particularly IP-10, in salivary epithelial cells.