Could mucin 16 and colony-stimulating factor 2-receptor beta possible graft versus host disease biomarkers? Medical hypotheses

Perspectives on oral chronic graft-versus-host disease from immunobiology to morbid diagnoses

Chronic Graft-versus-Host Disease (cGVHD) is a major long-term complication, associated with morbidity and mortality in patients following allogenic hematopoietic cell transplantation (HCT) for immune hematopoietic disorders. The mouth is one of the most frequently affected organs after HCT (45-83%) and oral cGVHD, which may appear as the first visible sign. Manifestations present with mucosal lichenoid lesions, salivary gland dysfunction and limited oral aperture. Diagnosis of oral cGVHD severity is based on mucosal lesions with symptoms of sensitivity and pain and reduced oral intake. However, diagnostic difficulties arise due to subjective definitions and low specificity to cover the spectrum of oral cGVHD. In recent years there have been significant improvements in our understanding of the underlying oral cGVHD disease mechanisms. Drawing upon the current knowledge on the pathophysiology and biological phases of oral cGVHD, we address oral mucosa lichenoid and Sjogren's Syndrome-like sicca syndromes. We consider the response of alloreactive T-cells and macrophages to recipient tissues to drive the pathophysiological reactions and biological phases of acute inflammation (phase 1), chronic inflammation and dysregulated immunity (phase 2), and subsequent aberrant fibrotic healing (phase 3), which in time may be associated with an increased malignant transformation rate. When formulating treatment strategies, the pathophysiological spectrum of cGVHD is patient dependent and not every patient may progress chronologically through the biological stages. As such there remains a need to address and clarify personalized diagnostics and management to improve treatment descriptions. Within this review, we highlight the current state of the art knowledge on oral cGVHD pathophysiology and biological phases. We address knowledge gaps of oral cGVHD, with a view to facilitate clinical management and improve research quality on lichenoid biology and morbid forms of oral cGVHD.

Grading of minor salivary gland immuno-histopathology post-allogenic hematopoietic cell transplantation

The oral cavity commonly displays mucosal lichenoid lesions and salivary gland dysfunction, which are considered different chronic Graft-versus-Host Disease (cGVHD) pathophysiology's. However, diagnostics of salivary gland (sg-)cGVHD are limited. The objectives of the current study are to evaluate the minor salivary gland (MSG) histo-immunopathological profiles post allogenic hematopoietic cell transplantation based on sg-cGVHD criteria. Design: Histopathology was characterized according to two published grading strategies. Firstly, the National Institute of Health (NIH) assessed peri-ductal/acinar infiltration, exocytosis, damage, and fibrosis, and a points-based grading scheme was established (0-16 points, Grade (G) 0 to IV). Second, a modified Sjögren's Syndrome focus-score with parenchymal damage was also adapted, (0-10 points, Score 0 to 2). 146 MSG biopsies from 79 patients were compared, using the histopathological specific criteria for sg-cGVHD pathology. Quantitative immunohistochemistry for T-cells (CD4, CD8), B-cells (CD19, CD20), monocytic cells (CD68) and dendritic cells (CD1a) were also assessed. Results: The large-scale cohort validated the use of both grading schemes. GIII-GIV and score 2 signified a histopathological diagnosis of "likely" sg-cGVHD. Immunopathological severity was associated with increased T-cells (CD4 and CD8) and monocytic (CD68) infiltrate, with minimal involvement of B-cells (CD19 and CD20), and Langerhans cells (CD1a). Conclusions: Both schemes were verified as being suitable for histological grading to improve assessment and diagnosis of sg-cGVHD. The NIH cGVHD grading appears to be more beneficial for research purposes, including final diagnostics of "no/inactive", "possible" or "likely" cGVHD. The study highlights the intricacies of sg-cGVHD pathology; and the need for standardized assessment to improve patient management associated to sg-cGVHD.

Salivary ZG16B expression loss follows exocrine gland dysfunction related to oral chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) targets include the oral mucosa and salivary glands after allogeneic hematopoietic stem cell transplant (HSCT). Without incisional biopsy, no diagnostic test exists to confirm oral cGVHD. Consequently, therapy is often withheld until severe manifestations develop. This proteomic study examined saliva and human salivary gland for a biomarker profile at first onset of oral cGVHD prior to initiation of topical steroid therapy. Whole saliva collected at onset of biopsy-proven oral GVHD was assessed using liquid chromatography-coupled tandem mass spectrometry with identification of 569 proteins, of which 77 significantly changed in abundance. ZG16B, a secretory lectin protein, was reduced 2-fold in oral cGVHD saliva (p <0.05), and significantly decreased in salivary gland secretory cells affected by cGVHD. Single-cell RNA-seq analysis of healthy MSG localized ZG16B expression to two discrete acinar cell populations. Reduced ZG16B expression may indicate specific cGVHD activity and possibly general salivary gland dysfunction.

Salivary Changes before and after Hematopoietic Stem Cell Transplantation: A Systematic Review

Severe oral problems, including oral mucositis (OM) and xerostomia, often occur after conditioning therapy for hematopoietic stem cell transplantation (HSCT). Saliva plays a major role in protecting the oral mucosa and teeth. Alterations in salivary flow rate or salivary components resulting in decreased salivary defence mechanisms may affect oral/mucosal health and may influence the severity of OM. A systematic review was conducted to assess the current scientific knowledge on changes in salivary function and composition before and after HSCT. All English or Dutch articles examining salivary flow rate or salivary components before and after HSCT were included after title/abstract selection by 2 independent reviewers (weighted κ = .91). After quality assessment and exclusion of all research groups with both children age <14 years and adults, 33 articles were included for data analysis. Overall, the salivary flow rate was decreased at several days and months after HSCT. Although several salivary components were studied, most components were examined in only 1 or 2 studies with different patient populations or at different time points after HSCT. At 7 days after HSCT, albumin and proinflammatory cytokines were increased, whereas secretory IgA and components of the salivary antioxidant system were decreased. Secretory IgA levels were still reduced at 1 month after HSCT but returned to pre-HSCT values at 6 months after HSCT. Lactoferrin, secretory leukocyte protease inhibitor, and β₂-microglobulin levels were increased at 6 months after HSCT. Our findings show that changes in saliva reflect an inflammatory response occurring immediately after HSCT, followed by evidence of increased salivary antimicrobial defense mechanisms by 6 months after HSCT.

Salivary proteomics in lichen planus: A relationship with pathogenesis?

OBJECTIVES

Oral lichen planus is a chronic, T-cell-mediated, inflammatory disease that affects the oral cavity. The oral lichen planus pathogenesis is still unclear, however, the main evidence is that the mechanisms of activation of different T lymphocyte pathway induce apoptosis with an increase in Th1 and Th17 subtypes cells, triggered by the release of cytokines. This study analysed saliva proteomics to identify protein markers that might be involved in the pathogenesis and development of the disease.

MATERIAL AND METHODS

Proteins differentially expressed by oral lichen planus and healthy controls were screened using mass spectrometry; the proteins found in oral lichen planus were subjected to bioinformatics analysis, including gene ontology and string networks analysis. The multiplex analysis validation allowed the correlation between the proteins identified and the involved cytokines in Th17 response.

RESULTS

One hundred and eight proteins were identified in oral lichen planus, of which 17 proteins showed a high interaction between them and indicated an association with the disease. Expression of these proteins was correlated with the triggering of cytokines, more specifically the Th17 cells.

CONCLUSION

Proteins, such as S100A8, S100A9, haptoglobin, can trigger cytokines and might be associated with a pathological function and antioxidant activities in oral lichen planus.