Salivary gland performance in autoimmune diseases: review and meta-analysis

Immunolocalization patterns of histone-deacetylases in salivary glands of mice during postnatal development

OBJECTIVE

Histone-deacetylases (HDACs) are epigenetic modulators involved in the control of gene expression. No data are available on the expression or subcellular localization of HDACs in salivary glands. The present study aims to examine the subcellular distribution of HDACs in salivary glands during postnatal development.

DESIGN

The major salivary glands of C57/BL6 mice were separately removed at 10, 25, 30,60 and 90 days after birth. Hematoxylin-eosin (H&E) and immunohistochemical staining were performed for HDACs. Gene Expression of HDACs in C57BL/6. NOD-Aec1Aec2 mice salivary glands during the development of Sjögren's syndrome-like illness were also analyzed by using the gene expression datasets (GSE 15640).

RESULTS

In the mice salivary gland, HDACs were found to have different localization patterns at various stages of development (10, 25, 30, 60, and 90 days). Apart from HDAC6, ductal cells of salivary glands were the primary sites for HDAC localization. HDAC2, 8, 5, 10 and 11 were expressed at high levels in the salivary gland after birth while HDAC6 showed no expression during postnatal development. This suggests that these HDAC subtypes may have different roles in salivary gland function. In the context of Sjögren's syndrome-like illness, HDAC 2, 8 and 10 showed low expression while HDAC1, 6,5,3 and 11 had relatively high expression in the salivary gland.

CONCLUSIONS

This study has provided an important reference for understanding the spatiotemporal-specific expression of HDACs in the salivary gland. These results offer new clues for the experimenters and hold promise for developing innovative therapeutic strategies for salivary gland-related diseases.

Saliva: a challenging human fluid to diagnose brain disorders with a focus on Alzheimer's disease

Biomarkers are molecules of biological processes that help in both the diagnosis of human diseases and in follow-up assessments of therapeutic responses. Biomarkers can be measured in many human fluids, such as blood, cerebrospinal fluid, urine, and saliva. The -omics methods (genomics, RNomics, proteomics, and metabolomics) are useful at measuring thousands of markers in a small volume. Saliva is a human fluid that is easily accessible, without any ethical concerns. Yet, saliva remains unexplored in regard to many human disease biomarkers. In this review, we will give an overview on saliva and how it can be influenced by exogenous factors. As we focus on the potential use of saliva as a diagnostic tool in brain disorders (especially Alzheimer's disease), we will cover how saliva is linked to the brain. We will discuss that saliva is a heterogeneous human fluid, yet useful for the discovery of biomarkers in human disorders. However, a procedure and consensus that is controlled, validated, and standardized for the collection and processing of saliva is required, followed by a highly sensitive diagnostic approach.

Ultrasound abnormalities of the major salivary glands in Egyptian patients with systemic sclerosis

INTRODUCTION/OBJECTIVES

systemic sclerosis (SSc) is an autoimmune disorder with multiple organs destruction. This study aimed to identify the ultrasonographic changes of major salivary glands in Egyptian scleroderma patients and to detect their association to different disease manifestations.

METHODS

Forty-seven SSc patients and 43 apparent healthy volunteers were enrolled. Demographics, inflammatory markers, and autoimmune status were recorded. Ultrasound evaluation of salivary glands was performed. Salivary gland changes' associations were statistically examined with SSc susceptibility and disease manifestations.

RESULTS

Thirty-one SSc patients exhibited glandular pathology (p < 0.0001), compared to controls. Of these abnormalities, SSc patients showed a total parotid gray scale of 2, total submandibular gray scale of 2, total glandular gray scale of 4, and total glandular Doppler signal of 1 at p < 0.0001, compared to the control group. Patients with SSc and glandular pathology had a higher prevalence of arthritis (p = 0.029) and ESR (p = 0.002) than those with normal glandular ultrasound. Significant associations were reported between gray scale ultrasound (GSUS) of total parotid (odds ratio "OR" = 0.4), total submandibular (OR = 0.36), and total glandular (OR = 0.53) with susceptibility to SSc at p < 0.0001. Total glandular GSUS (p = 0.039) and total submandibular power Doppler (p = 0.044) correlated with the SSc duration. Total parotid GSUS (p = 0.008) and total glandular GSUS (p < 0.0001) correlated with Schirmer's test.

CONCLUSIONS

Major salivary glands are affected in SSc. Hence, scanning these glands with ultrasound is an additive tool besides the current practice. Key Points • Major salivary gland changes, observed by ultrasonography, are new findings in Egyptian SSc patients. • Ultrasound changes of major salivary glands are associated with inflammatory markers and clinical manifestations of SSc. • Scleroderma ultrasonography scans of the main salivary glands could be added to the routine work.

Unstimulated whole salivary flow in Sjögren's Syndrome: systematic literature review and meta-analysis

BACKGROUND

Sjögren's Syndrome compromises the exocrine function, producing xerostomia and xerophthalmia. It can appear as an isolated condition or associated with other autoimmune diseases (polyautoimmunity). The Unstimulated Salivary Flow rate (UWSF) is used to quantify saliva production. There is no objective evidence to differentiate the values in patients with Sjögren's versus healthy people or patients with non-Sjögren's sicca. The objective of the present review was to evaluate the UWSF in patients with Sjögren's syndrome in comparison to controls (healthy and non-Sjögren's sicca patients).

METHODS

A systematic literature review was carried out (PRISMA guidelines). Analytical observational studies of cases and controls, cross-sectional studies, cohort studies and randomized clinical trials (including healthy controls) were considered. The Medline/OVID, Lilacs, Embase, and Cochrane/OVID databases were consulted. MeSH, DeCS, keywords, and Boolean operators were used. The meta-analysis (RevMan 5.2) was done through the random-effects model [mean difference (MD)]. Level and quality of evidence were evaluated by the Oxford Center Levels of Evidence and Joanna Brigs list respectively.

RESULTS

Thirty-two articles were included (20 were case-control studies, 6 were cross-sectional, 2 prospective cohort, 2 retrospective cohort, and 2 studies were abstracts) and 28 were meta-analyzed. The unstimulated whole salivary flow rate in the Sjögren's group was lower than in controls (healthy and patients with non-Sjögren Sicca syndrome) (MD-0.18 ml/min; 95% CI, - 0.24 to - 0.13; chi²-P-value < 0.00001). Heterogeneity was 97% and there was publication bias (funnel plot). The level of evidence was mostly 3 or 4. The quality of evidence was met (97% of items valued).

CONCLUSION

For the first time, the unstimulated whole salivary flow rate is found to be lower in patients with Sjögren's syndrome compared to controls (healthy and non-SS sicca) through a meta-analysis.

TRIAL REGISTRATION

PROSPERO CRD42020211325 .

Salivary Metabolomics of Total Body Irradiated Nonhuman Primates Reveals Long-Term Normal Tissue Responses to Radiation

PURPOSE

To identify metabolomic biomarkers of acute radiation exposure in saliva that show time-dependent changes.

METHODS AND MATERIALS

Nonhuman primates were exposed to 4 Gy of total body irradiation with γ-rays. Saliva was collected from 7 animals twice before and at days 1, 3, 5, 7, 15, 21, 28, and 60 after irradiation. Profiling was conducted with liquid chromatography time-of-flight mass spectrometry. Multivariate data analysis and potential biomarker identification was conducted through random Forests and the software MetaboAnalyst. Candidate biomarkers were validated through tandem mass spectrometry, and receiver operating characteristic curves were constructed to show the diagnostic ability of the signature over time.

RESULTS

Untargeted metabolomic analysis revealed significant and persistent effects up to the 60 days evaluated in this study. Biomarkers spanning primarily amino acids and nucleotides were identified, with a significant number showing long-term responses. Fifteen biomarkers showed high statistical significance in the first week after irradiation and 16 at >7 days after irradiation (false discovery rate-adjusted P < .05). The combination of the biomarkers in a single biosignature was able to accurately show the diagnostic ability of the signature in a binary classifier system with receiver operating characteristic curves.

CONCLUSIONS

Radiation can alter the metabolome in saliva, and metabolomics could effectively be used to monitor radiation responses, as a biodosimetry method, in the event of a radiological incident. Saliva metabolomics also has potential relevance in a clinical setting.