Acinar autolysis and mucous extravasation in human sublingual glands: a microscopic postmortem study

Extracellular matrix turnover in salivary gland disorders and regenerative therapies: Obstacles and opportunities

Salivary gland (SG) extracellular matrix (ECM) has a major influence on tissue development, homeostasis, and tissue regeneration after injury. During aging, disease, and physical insult, normal remodeling of the SG microenvironment (i.e. ECM) becomes dysregulated, leading to alterations in matrix composition which disrupt tissue architecture/structure, alter cell activity, and negatively impact gland function. Matrix metalloproteinases (MMPs) are a large and diverse family of metalloendopeptidases which play a major role in matrix degradation and are intimately involved in regulating development and cell function; dysregulation of these enzymes leads to the production of a fibrotic matrix. In the SG this altered fibrotic ECM (or cell microenvironment) negatively impacts normal cell function and the effectiveness of gene and stem cell therapies which serve as a foundation for many SG regenerative therapies. For this reason, prospective regenerative strategies should prioritize the maintenance and/or restoration of a healthy SG ECM. Mesenchymal stem cells (MSCs) have great potential for mitigating damage to the SG microenvironment by ameliorating inflammation, reducing fibrosis, and repairing the damaged milieu of extracellular regulatory cues, including the matrix. This review addresses our current understanding of the impact of aging and disease on the SG microenvironment and suggests critical deficiencies and opportunities in ECM-targeted therapeutic interventions.

The Potential of Light Microscopic Features of the Oral Mucosa in Predicting Post-mortem Interval

Objectives

The post-mortem interval (PMI) refers to the amount of time elapsed between death and discovery of the body. This study aimed to evaluate light microscopic cellular changes in the oral mucosa and identify the potential of this method for predicting PMI.

Methods

This prospective study was conducted between July 2016 and January 2018 at the Institute of Dental Sciences, Siksha ‘O’ Anusandhan University, Bhubaneswar, India. A total of 150 post-mortem (including 75 gingival and 75 buccal mucosa samples) and 40 ante-mortem (including 20 gingival and 20 buccal mucosa samples) tissue samples were compared using haematoxylin and eosin, periodic acid-Schiff (PAS) and van Gieson stains. Microscopic changes in the epithelium and connective tissue were categorised according to PMI stage as early (<12.5 hours since death), intermediate (12.5–20.5 hours since death) or late (>20.5 hours since death).

Results

Most epithelial cellular changes occurred early, except for arc-shaped nuclei and epithelial shredding which were intermediate and late changes, respectively. However, microscopic changes in the connective tissue were only observable at ≥12.5 hours. There was a progressive decrease in intensity in van Gieson stains and an increase in intensity in PAS stains as PMI increased. Several microscopic features were found to be significant predictors of PMI including epithelial homogenisation, cytoplasmic vacuolation, nuclear degeneration, arc-shaped nuclei, chromatin clumping, red blood cell clumping and lysis, melanin incontinency, myofibril degeneration, salivary gland acini degeneration and epithelial connective tissue separation (P <0.050 each).

Conclusion

These findings indicate that microscopic evaluation of the oral mucosa may be helpful for PMI prediction.

Differential immunohistochemical expression of type I collagen and matrix metalloproteinase 2 among major salivary glands of young and geriatric mice

Objective

This study aimed to demonstrate the immunohistochemical changes associated with MMP-2 and type 1 collagen separately for the first time in the major salivary glands (the parotid, submaxillary, and sublingual glands) that occur with aging in mice.

Material and Methods

Fourteen Balb/c white mice (50-80 g) were used in this study. The animals were divided into two equal groups. Group I consisted of young animals (2-month-old) (n=7) and Group II consisted of older animals (18-month-old) (n=7). After routine histological follow-ups, Hematoxylin-eosin (H&E), Masson’s Trichrome staining and immunohistochemical staining was performed for type I collagen and MMP-2.

Results

We observed that there were age-related decreases in the number of acinar cells, increase in eosinophilic zymogen granules in cells, collagen accumulation in fibrotic areas and dilatation in interlobular ducts. Also, while type I collagen and MMP-2 immunoreactivity were moderate in the salivary glands of the young mice, they were high in the salivary glands of the old mice (p=0.001). In the H-score assessment, MMP-2 immunoreactivity was lower at a significant level in young mice than in old mice (p=0.001).

Conclusions

This study showed that anatomical, physiological and morphological abnormalities occur in all three major salivary glands as a natural consequence of aging.

Comparison of volume and attenuation of the spleen between postmortem and antemortem computed tomography

OBJECTIVES

The purpose of this study is to compare the postmortem changes in computed tomography (CT) findings between normal spleen, splenic infarct, and splenic tumor infiltration.

METHODS

The institutional review board approved this study, and informed consent was obtained from the next of kin. We studied 63 consecutive subjects who underwent antemortem CT, postmortem CT, and autopsy between February 2012 and December 2013. Postmortem CT was performed within 1678 min after death and was followed by pathological studies. The subjects were divided into three groups based on the pathological findings: normal, splenic infarct, and splenic tumor infiltration. The volume and attenuation of the spleen were compared between antemortem and postmortem CT using paired t tests. Gender, age, time elapsed since death, and the causes of death were examined as potential confounding factors of the postmortem changes in volume and attenuation.

RESULTS

In all groups, the spleen decreased in volume and attenuation increased on postmortem CT compared with antemortem CT. The postmortem changes in spleen volume and attenuation were not significantly associated with sex, age, time elapsed since death, or causes of death.

CONCLUSIONS

Spleen volume decreased and attenuation increased on postmortem CT compared with antemortem CT in subjects with a normal spleen, splenic infarct, or splenic tumor infiltration. These results should caution us against underestimating the significance of splenomegaly on postmortem CT, misinterpreting reduced splenic volume as the presence of hypovolemic or distributive shock in the subject while alive, and confusing postmortem splenic hyperattenuation with diseases characterized by this finding.