Short-Term Effects of Y-27632, a Rho-Associated Protein Kinase Inhibitor, on Chromatin Supraorganization and DNA Amount in Epithelial Cells of the Rat Cornea and Limbus

Nuclear morphology, chromatin compaction, and epigenetic changes in lymphocytes of dogs infected with Ehrlichia canis

Canine monocytic ehrlichiosis (CME), induced by Ehrlichia canis, is an important infectious disease in dogs, characterized by various clinical signs and consequent immune dysfunction. This study aimed to characterize nuclear morphology, chromatin compaction, histone H3 acetylation, and DNA methylation in lymphocytes from dogs naturally infected with E. canis, compared with healthy controls. A total of 30 dogs were included in this study, comprising 15 healthy dogs and 15 dogs with confirmed E. canis infection, verified through polymerase chain reaction. Blood samples were collected from these dogs to isolate peripheral blood mononuclear cells. The isolated cells were prepared into smears and stained using the Feulgen reaction for subsequent analysis. These stained smears underwent video imaging analysis to assess nuclear morphology and chromatin parameters. Additionally, lymphocytes isolated from the PBMCs were analyzed to quantify global levels of histone H3 acetylation and DNA methylation. The results indicated significant increases in nuclear size and alterations in chromatin architecture in the lymphocytes of dogs with E. canis infection. A significant reduction in histone H3 acetylation was observed in this group, suggesting a potential mechanism of transcriptional repression. In contrast, no significant differences in DNA methylation were detected between the infected dogs and the healthy controls. In conclusion, our findings reveal distinct morphological and epigenetic alterations in lymphocytes associated with E. canis infection, thereby enhancing the understanding of the immune dysfunction observed in dogs with CME.

Hedgehog Signaling Pathway Regulates the Proliferation and Differentiation of Rat Meibomian Gland Epithelial Cells

Purpose

Meibomian glands play a vital role in maintaining ocular surface stability. This study aimed to investigate whether Hedgehog signaling is involved in the regulation of meibomian gland epithelial cells.

Methods

Rat meibomian glands epithelial cells (RMGECs) were isolated from ducts and ductules, and then were cultivated to passage two on Matrigel coated wells in meibomian gland epithelial cells medium (MGECM). Cells were switched from MGECM to differentiation medium (DM) or DM added 10 µg/mL azithromycin (DM + AZM) when reached 50% to 60% confluence. The effects of the Smoothened (Smo) agonist (Smo agonist [SAG]) and antagonist (by cyclopamine) on RMGECs were analyzed using quantitative RT-PCR, cell proliferation analysis, immunofluorescence staining, and Nile red staining.

Results

The Hedgehog receptor, Smo, and its downstream molecules, Glis, were expressed both in vivo and in vitro. Smo and Gli1 both decreased with the increase of differentiation in vitro. Smo antagonist, cyclopamine, reduced cell numbers, and the expression of Ki67 in MGECM, and promoted the expression of SREBP1 and lipid production in DM + AZM. Smo agonist, SAG, inhibited the expression of SREBP1 and lipid accumulation in DM + AZM but showed no significant effects on raising cell numbers and the expression of Ki67 in MGECM.

Conclusions

The Hedgehog signaling pathway appears to play important roles in RMGECs proliferation and differentiation. This may provide a potential therapeutic way to treat meibomian gland dysfunction (MGD).

Reduction in Histone H3 Acetylation and Chromatin Remodeling in Corneas of Alloxan-Induced Diabetic Rats

PURPOSE

To evaluate acetylation of histone H3, chromatin remodeling, nuclear size and shape, DNA ploidy, and distribution of nucleolus organizing regions (NORs) in corneal epithelial and stromal cells of diabetic and nondiabetic rats.

METHODS

Diabetes was induced by a single intraperitoneal injection of alloxan. All diabetic rats (n = 20) included in the study had 4 weeks of moderate-to-severe hyperglycemia (plasma glucose levels >400 mg/dL). Acetylated histone H3 levels were quantified in corneal tissue using a colorimetric assay. Chromatin remodeling, nuclear sizes (area/perimeter) and shapes (circularity), and DNA ploidies were evaluated from Feulgen-stained tissue sections using video image analysis. Distributions of NORs were studied in tissue sections impregnated with silver ions. Ophthalmic clinical parameters, including corneal sensitivity, were investigated. Twenty nondiabetic rats were used as controls.

RESULTS

Acetylation of histone H3 was reduced in the corneas of the diabetic rats. Nuclei in corneal epithelial cells of diabetic rats compacted chromatin, increased in size, modified their shapes, and elevated DNA ploidy. The only nuclear change observed in the corneal stromal cells of diabetic rats was chromatin decompaction. The size of the silver-stained NOR did not differ between the study samples. The corneal sensitivity in diabetic rats was 51.8% lower than that in nondiabetic rats.

CONCLUSIONS

The results of this study show that alloxan-induced diabetes altered the histone H3 acetylation pattern and compromised the chromatin supraorganization in corneal tissue/cells. Continued research is needed to understand the clinical and morphofunctional significance of changes in corneal cell nuclei of diabetic individuals.