[Morphology of the thymus and the specific features of its cellular composition in experimental acute and chronic ulcerative colitis].

Abstract

OBJECTIVE:

To investigate morphological changes in the thymus, the subpopulation composition of lymphocytes and its non-lymphoid cells in dextran-induced experimental acute ulcerative colitis and in different periods of chronic ulcerative colitis.

MATERIAL AND METHODS:

Acute and chronic ulcerative colitis was simulated in C57BL/6 mice, by replacing drinking water with a 1% aqueous dextran sulfate sodium solution. Thymic changes were morphometrically assessed; the number and absolute area of thymic corpuscles and epithelial cells were calculated; and the subpopulation composition of lymphocytes and thymic stromal cells was determined using flow cytofluorimetry; the Kruskal-Wallis test and the Mann-Whitney test were used to compare the groups.

RESULTS:

In acute catarrhal and ulcerative colitis, there was acute accidental thymic involution with devastation of the cortical substance and with a decline in its volume fraction, with an increase in the levels of cells dying through the mechanism of apoptosis, and with a decrease in the absolute number of lymphocytes, T-helper cells, cytotoxic T-cells, regulatory T-lymphocytes, B-lymphocytes, and dendritic cells, with a rise in the index of the area of thymic corpuscles and in the content of late-phase corpuscles among them, and with the appearance of thymic corpuscles as cyst-like cavities. In chronic ulcerative colitis, the cortex was expanded and the area of thymic corpuscles and the count of medullary epithelial cells increased. The cyst-like thymic corpuscles formed clusters, the count of dendritic cells increased in early-stage chronic ulcerative colitis, but the levels of macrophages decreased in both periods of its development.

CONCLUSION:

There is acute accidental involution and thymic hyperplasia with an increase in medullary epithelial cells and thymic corpuscles consisting of cytokeratin 19+ in the epithelial cells in experimental acute and chronic ulcerative colitis, respectively. The more pronounced epithelial cell response found in end-stage experimental chronic ulcerative colitis reflects the enhanced differentiation of regulatory T-lymphocytes and the larger number of which is observed in peripheral blood and in the focus of inflammation in patients with ulcerative colitis, according to the literature.

• Authors: E A Postovalova, O V Makarova, A M Kosyreva, L P Michailova
• Journal: Arkhiv patologii (Arkh Patol) Vol. 81 Issue 5 Pg. 53-63 ( 2019) ISSN: 0004-1955 [Print] Russia (Federation)
• Vernacular Title: Morfologiia timusa i osobennosti ego kletochnogo sostava pri éksperimental'nom ostrom i khronicheskom iazvennom kolite.
• PMID: 31626205 (Publication Type: Journal Article)

Chemical References

• Dextran Sulfate

Topics

• Animals
• Colitis, Ulcerative (chemically induced, pathology)
• Dextran Sulfate
• Lymphocytes (cytology)
• Mice
• Mice, Inbred C57BL
• Thymus Gland (cytology, pathology)