Nuclear parameters and chromatin remodeling in epithelial cells and lymphocytes from the palpebral conjunctiva of dogs with keratoconjunctivitis sicca.

OBJECTIVE: To study parameters related to nuclear morphology and chromatin remodeling in epithelial cells and lymphocytes from the inferior palpebral conjunctiva of dogs with and without keratoconjunctivitis sicca (KCS). ANIMALS STUDIED: Thirty-two dogs (64 eyes) were included in the study. Based on the tear production measured by Schirmer tear test 1, the dogs were distributed into control and KCS groups. PROCEDURES: Epithelial cells and lymphocytes were collected by conjunctival brush cytology, fixed on glass slides, and subjected to the Feulgen reaction, a topochemical method specific for DNA/chromatin. Feulgen-stained cells were studied by microscopy and video image analysis to establish nuclear size (area and perimeter) and shape (relative nuclear roundness factor = RNRF), DNA content (ploidy), and compaction and texture of chromatin. RESULTS: Conjunctival samples in the KCS group showed infiltration of inflammatory and immune cells. Micronuclei, snake-like chromatin, aberrant chromosomes, and goblet cells were not detected. Compared with the controls, cells on the conjunctival surface of dogs with KCS showed altered nuclei. Conjunctival epithelial cells were more affected by KCS (changes in nuclear size, shape, DNA content, and chromatin compaction) than lymphocytes (changes in chromatin compaction, only). Significant chromatin decompaction was observed in both conjunctival epithelial cells and lymphocytes. CONCLUSIONS: Our results show that KCS promotes chromatin remodeling in epithelial cells and lymphocytes on the conjunctival surface of dogs. The changes described in this study are different from those reported for conjunctival cell nuclei of human KCS patients.

A supramolecular look at microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny.

Various approaches have been taken to improve our knowledge of the microenvironmental regulation of limbal epithelial stem cells. Researchers have extensively investigated the roles of growth factors, survival factors, cytokines, enzymes, and permeable molecules secreted by the limbal cells. However, recent evidence suggests that stem cell fate (i.e., self-renewal or differentiation) can also be influenced by biophysical and mechanical cues related to the supramolecular organization and the liquid crystalline (mesophase) nature of the stromal extracellular matrix. These cues can be sensed by stem cells and transduced into intracellular biochemical and functional responses, a process known as mechanotransduction. The objective of this review is to offer perspectives on the supramolecular microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny.

A supramolecular look at microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny / Uma visão supramolecular sobre a regulação microambiental de células tronco epiteliais limbais e a diferenciação de sua progênie

ABSTRACT Various approaches have been taken to improve our knowledge of the microenvironmental regulation of limbal epithelial stem cells. Researchers have extensively investigated the roles of growth factors, survival factors, cytokines, enzymes, and permeable molecules secreted by the limbal cells. However, recent evidence suggests that stem cell fate (i.e., self-renewal or differentiation) can also be influenced by biophysical and mechanical cues related to the supramolecular organization and the liquid crystalline (mesophase) nature of the stromal extracellular matrix. These cues can be sensed by stem cells and transduced into intracellular biochemical and functional responses, a process known as mechanotransduction. The objective of this review is to offer perspectives on the supramolecular microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny.

RESUMO Muitas abordagens têm sido utilizadas para ampliar entendimentos sobre a regulação microambiental das células tronco epiteliais limbais. Neste contexto, pesquisadores têm exaustivamente investigado a participação de fatores de crescimento, fatores de sobrevida, citocinas, enzimas e moléculas permeáveis secretadas pelas células limbais. Entretanto, evidências recentes sugerem que o destino (ie. autorrenovação ou recrutamento para a via de diferenciação) das células tronco também sofre influência de estímulos biofísicos ou mecânicos relacionados à organização supramolecular e à natureza liquido-cristalina (mesofases) da matriz extracelular estromal. Esses estímulos podem ser percebidos e traduzidos pelas células tronco em sinais bioquímicos que geram respostas funcionais, através de um processo designado de mecanotransdução. Objetiva-se, com a presente revisão, oferecer ao leitor perspectivas supramoleculares sobre a regulação microambiental das células tronco epiteliais limbais e a diferenciação de sua progênie.

Polymorphisms in GABRB3 and oral clefting in the Brazilian population.

The aim of this study was to evaluate the influence of the γ-aminobutyric acid receptor type A ß-3 subunit (GABRB3) polymorphisms in patients with nonsyndromic cleft lip and/or palate (NSCL/P). We carried out a structured case-control analysis of three GABRB3 polymorphisms (rs4477673, rs6576618, and rs981778) in 229 patients with nonsyndromic cleft lip with or without cleft palate (CL±P) and in 314 unaffected controls from Brazil. The polymorphisms were genotyped by the TaqMan 5'-exonuclease allelic discrimination assay, and each sample was independently typed for 40 biallelic short insertion/deletion markers (INDELs) to characterize the genomic ancestry. The genotype distributions of the three polymorphisms were as expected by the Hardy-Weinberg equilibrium test. After adjustment to ancestry contribution, the minor A allele of rs981778 was associated with NSCL/P, but significant results did not persist after Bonferroni correction for multiple tests. Similarly, the haplotype analysis revealed that the CCA haplotype (C allele of rs4477673, C allele of rs6576618, and A allele of rs981778) was correlated with NSCL/P, but this association did not remain statistically significant after Bonferroni correction. With a weak association, our data do not support the hypothesis that the GABRB3 variants are a cause of NSCL/P, but further studies are warranted.