RESUMO
BACKGROUND: Skin health declines with age and this is partially attributed to immunosenescence. Mast cells (MCs) are innate immune cells that coordinate tissue immune responses integral to skin homeostasis and disease. OBJECTIVES: To understand how MCs contribute to human skin ageing, we investigated how intrinsic ageing impacts MC phenotype and MC relationships with other immune cells and skin structures. METHODS: In photoprotected skin biopsies from young (≤ 30 years) and aged (≥ 75 years) individuals, immunostaining and spatial morphometry were performed to identify changes in MC phenotype, number, distribution and interaction with the vasculature and nerve fibres. Quantitative polymerase chain reaction was used to measure changes in gene expression related to immune cell activity and neuropeptide signalling. RESULTS: Skin MCs, macrophages and CD8+ T cells increased in number in intrinsically aged vs. young skin by 40%, 44% and 90%, respectively (P < 0·05), while CD4+ T cells and neutrophils were unchanged. In aged skin, MCs were more numerous in the papillary dermis and showed a reduced incidence of degranulation (50% lower than in young, P < 0·01), a conserved tryptase-chymase phenotype and coexpression of granzyme B. In aged skin, MCs increased their association with macrophages (~ 48% vs. ~27%, P < 0·05) and nerve fibres (~29% vs. 16%, P < 0·001), while reducing their interactions with blood vessels (~34% vs. 45%, P < 0·001). Additionally, we observed modulation of gene expression of vasoactive intestinal peptide (VIP; increased) and substance P (decreased) with age; this was associated with an increased frequency of VIP+ nerve fibres (around three times higher in aged skin, P < 0·05), which were strongly associated with MCs (~19% in aged vs. 8% in young, P < 0·05). CONCLUSIONS: In photoprotected skin we observed an accumulation of MCs with increasing age. These MCs have both altered functionality and distribution within the skin, which supports a role for these cells in altered tissue homeostasis during ageing.
Assuntos
Comunicação Celular/imunologia , Macrófagos/imunologia , Mastócitos/imunologia , Envelhecimento da Pele/imunologia , Pele/citologia , Adulto , Idoso , Biópsia , Linfócitos T CD8-Positivos , Contagem de Células , Perfilação da Expressão Gênica , Humanos , Fibras Nervosas/imunologia , Fibras Nervosas/metabolismo , Pele/imunologia , Pele/patologia , Peptídeo Intestinal Vasoativo/metabolismoRESUMO
Oculodentodigital syndrome (ODD) is a rare, usually autosomal-dominant disorder that is characterized by developmental abnormalities of the face, eyes, teeth, and limbs. The most common clinical findings include a long, narrow nose, short palpebral fissures, type III syndactyly, and dental abnormalities including generalized microdontia and enamel hypoplasia. Recently, it has been shown that mutations in the gene GJA1, which encodes the gap junction protein connexin 43, underlie oculodentodigital syndrome. Gap junction communication between adjacent cells is known to be vital during embryogenesis and subsequently for normal tissue homeostasis. Here, we report 8 missense mutations in the coding region of GJA1, 6 of which have not been described previously, in ten unrelated families diagnosed with ODD. In addition, immunofluorescence analyses of a developmental series of mouse embryos and adult tissue demonstrates a strong correlation between the sites of connexin 43 expression and the clinical phenotype displayed by individuals affected by ODD.
Assuntos
Conexina 43/genética , Anormalidades Craniofaciais/genética , Mutação de Sentido Incorreto , Sindactilia/genética , Anormalidades Dentárias/genética , Animais , Análise Mutacional de DNA , Desenvolvimento Embrionário/genética , Anormalidades do Olho/genética , Feminino , Humanos , Masculino , Camundongos , Odontogênese/genética , SíndromeAssuntos
DNA Mitocondrial/genética , Gastroenteropatias/genética , Gastroenteropatias/fisiopatologia , Doenças Mitocondriais/genética , Doenças Mitocondriais/fisiopatologia , Mutação Puntual/genética , Adenina/metabolismo , Adulto , Sequência de Bases/genética , Análise Mutacional de DNA , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Metabolismo Energético/genética , Evolução Fatal , Feminino , Gastroenteropatias/metabolismo , Motilidade Gastrointestinal/genética , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/patologia , Trato Gastrointestinal/fisiopatologia , Marcadores Genéticos/genética , Predisposição Genética para Doença/genética , Testes Genéticos , Guanina/metabolismo , Humanos , Síndrome MELAS/genética , Síndrome MELAS/fisiopatologia , Pessoa de Meia-Idade , Mitocôndrias/genética , Mitocôndrias/metabolismo , Doenças Mitocondriais/metabolismo , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologiaRESUMO
Mitochondrial DNA (mtDNA) disease is a common cause of myopathy and the presence of histochemically demonstrated cytochrome c oxidase (COX) deficiency is an extremely useful diagnostic feature. However, there is currently no quantitative information regarding the variability of COX deficiency within or between muscles. This study addresses this issue by studying a number of skeletal muscle samples obtained at post-mortem from three patients with mitochondrial disease due to established mitochondrial DNA defects. COX deficient muscle fibres were enumerated in sections of these muscles and analysed according to patient, individual muscle, position within a particular muscle and sample size. Descriptive statistics were generated followed by an analysis of variance (ANOVA) to assess the effect of these parameters on the mean percentage of COX deficient fibres. We observed statistically significant variation in the percentage of COX deficient fibres within individual muscles from each patient for samples sizes of between 100 and 400 fibres. Our results have implications for the way in which biopsies of skeletal muscle are used for the assessment of disease severity, progression and response to treatment.
Assuntos
Deficiência de Citocromo-c Oxidase/complicações , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Miopatias Mitocondriais/enzimologia , Miopatias Mitocondriais/etiologia , Músculo Esquelético/enzimologia , Adulto , Análise de Variância , Southern Blotting/métodos , Deficiência de Citocromo-c Oxidase/patologia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Histocitoquímica/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodosRESUMO
AIM: To study the normal distributions of mitochondria and voltage gated Na+ channels in the human optic nerve head in order to gain insight into the potential mechanisms of optic nerve dysfunction seen in the inherited optic neuropathies. METHODS: Five fresh frozen human optic nerves were studied. Longitudinally orientated, serial cryosections of optic nerve head were cut for mitochondrial enzyme histochemistry and immunolabelling for cytochrome c oxidase (COX) subunits and voltage gated Na+ channel subtypes (Na(v) 1.1, 1.2, 1.3, and 1.6). RESULTS: A high density of voltage gated Na+ channels (subtypes Na(v) 1.1, 1.3, and 1.6) in the unmyelinated, prelaminar, and laminar optic nerve was found. This distribution co-localised both with areas of high COX activity and strong immunolabelling for COX subunits I and IV. CONCLUSIONS: Increased numbers of mitochondria in the prelaminar optic nerve have previously been interpreted as indicating a mechanical hold up of axoplasmic flow at the lamina cribrosa. These results suggest that this increased mitochondrial density serves the higher energy requirements for electrical conduction in unmyelinated axons in the prelaminar and laminar optic nerve and is not a reflection of any mechanical restriction. This could explain why optic neuropathies typically occur in primary inherited mitochondrial diseases such as Leber's hereditary optic neuropathy, myoclonic epilepsy with ragged red fibres (MERRF), and Leigh's syndrome. Secondary mitochondrial dysfunction has also been reported in dominant optic atrophy, Friedreich's ataxia, tobacco alcohol amblyopia, Cuban epidemic optic neuropathy, and chloramphenicol optic neuropathy. These diseases are rare but these findings challenge the traditional theories of optic nerve structure and function and may suggest an alternative approach to the study of commoner optic neuropathies such as glaucoma.
Assuntos
Mitocôndrias/metabolismo , Condução Nervosa/fisiologia , Disco Óptico/metabolismo , Canais de Sódio/metabolismo , Adulto , Idoso , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Humanos , Técnicas Imunoenzimáticas , Ativação do Canal Iônico/fisiologia , Masculino , Pessoa de Meia-Idade , Fibras Nervosas Amielínicas/fisiologia , Disco Óptico/fisiologiaRESUMO
PURPOSE: To evaluate somatic mitochondrial (mt)DNA mutations in the macula during ageing. METHODS: Ten 30-microm cryostat sections from the macula (foveal and perifoveal regions) and peripheral retina of 14 donors (aged 14-94 years) were cut for cytochrome c oxidase cytochemistry. The photoreceptor layer was microdissected and DNA extracted for 4977-bp mtDNA (mtDNA(4977)) quantification using PCR. Dual cytochemistry for cytochrome c oxidase and succinate dehydrogenase allowed the detection of cytochrome c oxidase-deficient cones. RESULTS: Findings showed a progressive accumulation of mtDNA(4977) from ages 14 to 94 years. From ages 14 to 60 years there was an increase from 0.006% to 0.25%, and from ages 60 to 94 years there was a steeper increase from 0.25% to 5.39%. Counts of cones in the dual-reacted preparations showed more cytochrome c oxidase-deficient cones in the foveal region than elsewhere. CONCLUSIONS: The results show that mitochondrial DNA deletions and cytochrome c oxidase-deficient cones accumulate in the ageing retina, particularly in the foveal region. These defects may contribute to the changes in macular function observed in ageing and age-related maculopathy.
Assuntos
Envelhecimento/genética , Deficiência de Citocromo-c Oxidase/metabolismo , DNA Mitocondrial/genética , Degeneração Macular/genética , Mitocôndrias/genética , Mutação , Células Fotorreceptoras Retinianas Cones/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Contagem de Células , Análise Mutacional de DNA , Eletroforese em Gel de Ágar , Feminino , Deleção de Genes , Humanos , Degeneração Macular/enzimologia , Masculino , Pessoa de Meia-Idade , Mitocôndrias/metabolismoRESUMO
In adult paraplegic subjects one tibialis anterior muscle received daily electrical stimulation for 4 weeks at twice the motor threshold to determine changes of morphological and histochemical profiles (this paper) and of contractile properties (preceding paper). Bilateral biopsies, obtained 4 weeks before, and immediately after, electrical stimulation, were studied for fibre type proportions, fibre diameters, oxidative capacity, microvasculature and histopathology. Before stimulation the biopsies showed disuse with increased type 2 fibre proportions and decreased oxidative capacity (succinate dehydrogenase (SDH) activity). The effects of two stimulus patterns were compared. Following stimulation SDH activity increased significantly in all stimulated muscles. Inconsistent changes occurred in fibre type proportions, fibre diameters, capillary density and capillary/fibre ratios. Both stimulus patterns evoked similar results. In five/seven subjects subsarcolemmal vacuolation was observed. Electrical stimulation for 4 weeks at only twice motor threshold improves oxidative capacity, but different stimulus parameters are probably needed for significant fibre type conversion.