Salivary hypofunction in patients with familial amyloidotic polyneuropathy

Current developments and opportunities of pluripotent stem cells-based therapies for salivary gland hypofunction

Salivary gland hypofunction (SGH) caused by systemic disease, drugs, aging, and radiotherapy for head and neck cancer can cause dry mouth, which increases the risk of disorders such as periodontitis, taste disorders, pain and burning sensations in the mouth, dental caries, and dramatically reduces the quality of life of patients. To date, the treatment of SGH is still aimed at relieving patients' clinical symptoms and improving their quality of life, and is not able to repair and regenerate the damaged salivary glands. Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and extended pluripotent stem cells (EPSCs), are an emerging source of cellular therapies that are capable of unlimited proliferation and differentiation into cells of all three germ layers. In recent years, the immunomodulatory and tissue regenerative effects of PSCs, their derived cells, and paracrine products of these cells have received increasing attention and have demonstrated promising therapeutic effects in some preclinical studies targeting SGH. This review outlined the etiologies and available treatments for SGH. The existing efficacy and potential role of PSCs, their derived cells and paracrine products of these cells for SGH are summarized, with a focus on PSC-derived salivary gland stem/progenitor cells (SGS/PCs) and PSC-derived mesenchymal stem cells (MSCs). In this Review, we provide a conceptual outline of our current understanding of PSCs-based therapy and its importance in SGH treatment, which may inform and serve the design of future studies.

Salivary gland development and disease

Mammalian salivary glands synthesize and secrete saliva via a vast interconnected network of epithelial tubes attached to secretory end units. The extensive morphogenesis required to establish this organ is dependent on interactions between multiple cell types (epithelial, mesenchymal, endothelial, and neuronal) and the engagement of a wide range of signaling pathways. Here we describe critical regulators of salivary gland development and discuss how mutations in these impact human organogenesis. In particular, we explore the genetic contribution of growth factor pathways, nerve-derived factors and extracellular matrix molecules to salivary gland formation in mice and humans.

Xerostomia in hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (AGel amyloidosis) is a rare, dominantly inherited systemic disease with worldwide distribution, caused by c.654G > A or c.654G > T gelsolin gene mutation. The disease mainly manifests with late-onset dystrophy of the cornea, laxity of the skin and dysfunction of the cranial nerves whereas the oral manifestations have remained less-studied. To examine if AGel amyloidosis also affects salivary gland function, we studied 27 patients. In a questionnaire, 89% of them reported oral dryness, and 74% oral and ocular dryness. Unstimulated (UWS) and stimulated whole salivary flow (SWS) rates were measured, and salivary proteins were analyzed in the patients and controls. Hyposalivation according to UWS was detected in 67% of the patients, while decreased SWS occurred in 63% of the patients and 19% of the controls (p = 0.001). The secretion rates of salivary total protein and IgA were significantly lower in patients than controls. Histopathological analyses of labial salivary gland biopsies showed deposition of gelsolin amyloid, atrophy and inflammation. This study showed that AGel amyloidosis belongs to the differential diagnostic choices to be kept in mind in the patients presenting with xerostomia, low secretion rates of salivary total protein and IgA and/or deposition of amyloid in the minor salivary glands. AGel amyloidosis patients should be advised for efficient dental care.

Xerostomia and salivary hypofunction in vulnerable elders: prevalence and etiology

OBJECTIVE

The goal of this article is to review existing research on the prevalence and etiology of dry mouth in the vulnerable elders and identify knowledge gaps.

STUDY DESIGN

Vulnerable elders (VE) are persons aged >65 years who have any or all of the following: limited mobility, limited resources, or complex health status. A systematic search was conducted of PubMed sources from 1989 to May 2010. Evidence was evaluated on the prevalence and etiology of xerostomia and salivary gland hypofunction (SGH) in VE.

RESULTS

The search identified 1,422 publications. The inclusion/exclusion criteria yielded 348 articles, 80 of which are cited herein.

CONCLUSIONS

Research has showed a high prevalence of xerostomia and SGH in VE. Common etiologies include medications, poor general health, female gender, and age. Gaps still exist in the evaluation of dry mouth in VE. Nonetheless, oral dryness will remain an important health issue as life expectancy increases.

Salivary dysfunction associated with systemic diseases: systematic review and clinical management recommendations

OBJECTIVES

The objective of this study was to identify systemic diseases associated with hyposalivation and xerostomia and develop evidence-based management recommendations for hyposalivation/xerostomia.

STUDY DESIGN

Literature searches covered the English language medical literature from 1966 to 2005. An evidence-based review process was applied to management studies published from 2002 to 2005.

RESULTS

Several systemic diseases were identified. From studies published 2002 to 2005, 15 were identified as high-quality studies and were used to support management recommendations: pilocarpine and cevimeline are recommended for treating hyposalivation and xerostomia in primary and secondary Sjögren's syndrome (SS). IFN-alpha lozenges may enhance saliva flow in primary SS patients. Anti-TNF-alpha agents, such as infliximab or etanercept, are not recommended to treat hyposalivation in SS. Dehydroepiandrosterone is not recommended to relieve hyposalivation or xerostomia in primary SS. There was not enough evidence to support any recommendations for the use of local stimulants, lubricants, and protectants for hyposalivation/xerostomia. However, professional judgment and patient preferences may support the use of a specific product for an individual patient.

CONCLUSIONS

These evidence-based management recommendations should guide the clinician's management decisions for patients with salivary dysfunction related to systemic disease. Future treatment strategies may include new formulations of existing drugs, e.g., local application of pilocarpine. Recent discoveries on gene expression and a better understanding of the etiopathogenesis of SS may open new treatment options in the future.