Synthesis and propagation of complement C3 by microglia/monocytes in the aging retina

INTRODUCTION Complement activation is thought to contribute to the pathogenesis of age-related macular degeneration (AMD), which may be mediated in part by para-inflammatory processes. We aimed to investigate the expression and localization of C3, a crucial component of the complement system, in the retina during the course of aging. METHODS SD rats were born and reared in low-light conditions, and euthanized at post-natal (P) days 100, 450, or 750. Expression of C3, IBA1, and Ccl- and Cxcl- chemokines was assessed by qPCR, and in situ hybridization. Thickness of the ONL was assessed in retinal sections as a measure of photoreceptor loss, and counts were made of C3-expressing monocytes. RESULTS C3 expression increased significantly at P750, and correlated with thinning of the ONL, at P750, and up-regulation of GFAP. In situ hybridization showed that C3 was expressed by microglia/monocytes, mainly from within the retinal vasculature, and occasionally the ONL. The number of C3-expressing microglia increased significantly by P750, and coincided spatiotemporally with thinning of the ONL, and up-regulation of Ccl- and Cxcl- chemokines. CONCLUSIONS Our data suggest that recruited microglia/monocytes contribute to activation of complement in the aging retina, through local expression of C3 mRNA. C3 expression coincides with age-related thinning of the ONL at P750, although it is unclear whether the C3-expressing monocytes are a cause or consequence. These findings provide evidence of activation of complement during natural aging, and may have relevance to cellular events underling the pathogenesis of age-related retinal diseases.Funding provided by Australian Research Council Centres of Excellence Program Grant (CE0561903)

670-nm light treatment reduces complement propagation following retinal degeneration

AIM: Complement activation is associated with the pathogenesis of age-related macular degeneration (AMD). We aimed to investigate whether 670-nm light treatment reduces the propagation of complement in a light-induced model of atrophic AMD. METHODS: Sprague–Dawley (SD) rats were pretreated with 9 J/cm(2) 670-nm light for 3 minutes daily over 5 days; other animals were sham treated. Animals were exposed to white light (1,000 lux) for 24 h, after which animals were kept in dim light (5 lux) for 7 days. Expression of complement genes was assessed by quantitative polymerase chain reaction (qPCR), and immunohistochemistry. Counts were made of C3-expressing monocytes/microglia using in situ hybridization. Photoreceptor death was also assessed using outer nuclear layer (ONL) thickness measurements, and oxidative stress using immunohistochemistry for 4-hydroxynonenal (4-HNE). RESULTS: Following light damage, retinas pretreated with 670-nm light had reduced immunoreactivity for the oxidative damage maker 4-HNE in the ONL and outer segments, compared to controls. In conjunction, there was significant reduction in retinal expression of complement genes C1s, C2, C3, C4b, C3aR1, and C5r1 following 670 nm treatment. In situ hybridization, coupled with immunoreactivity for the marker ionized calcium binding adaptor molecule 1 (IBA1), revealed that C3 is expressed by infiltrating microglia/monocytes in subretinal space following light damage, which were significantly reduced in number after 670 nm treatment. Additionally, immunohistochemistry for C3 revealed a decrease in C3 deposition in the ONL following 670 nm treatment. CONCLUSIONS: Our data indicate that 670-nm light pretreatment reduces lipid peroxidation and complement propagation in the degenerating retina. These findings have relevance to the cellular events of complement activation underling the pathogenesis of AMD, and highlight the potential of 670-nm light as a non-invasive anti-inflammatory therapy

Manifestações neurológicas na intoxicação de lactentes pela associação dimeticona e homatropina: relato de 6 casos Neurological manifestations in the intoxication of infants by dimethicone plus homatropine: report of 6 cases

OBJETIVO: alertar que o uso da associação dimeticona/homatropina (Espasmo Luftal®) em recém-nascidos e lactentes de até dois meses, pode causar episódios disfuncionais transitórios extrapiramidais. MÉTODO: relato de 6 casos de crianças com menos de 2 meses, em uso diário da associação dimeticona/homatropina, que apresentaram sintomas agudos caracterizados por crises repetidas de curta duração com desvio tônico da cabeça para trás (opistótono), desvio do olhos para cima com olhar fixo e expressão de terror, postura mantida em hipertonia extensora dos 4 membros e emissão de choro e/ou sons guturais. RESULTADOS: os sintomas extrapiramidais desapareceram (e não retornaram) após a suspensão da associação dimeticona/homatropina. Não foram constatadas anormalidades no exame neurológico, eletrencefalograma e provas sanguíneas. CONCLUSÕES: a associação dimeticona/homatropina pode determinar em crianças com menos de 2 meses, quadro disfuncional dos gânglios da base. É importante diferenciá-lo das crises epilépticas generalizadas, a fim de se evitar a utilização, errônea, de drogas antiepilépticas.<br>OBJECTIVE: to alert that use of dimethicone plus homatropine in infants up to two months, may cause episodes of transitory extrapyramidal disturbances. METHOD: report 6 infants up to two months old, in daily use of dimethicone plus homatropine, that presented typical symptoms of the basal ganglia dysfunction, characterized by repeated crisis of short duration with tonic back shift of the head (opisthotonos), deviation of the eyes upward with looking fixed and terror expression, maintained in extending hipertonia posture of the 4 members and cry and/or guttural sounds emission. RESULTS: the extrapyramidal symptoms disappeared (and did not return) after interruption of dimethicone plus homatropine. Abnormalities were not verified in neurological examination, EEG and blood tests. CONCLUSIONS: the associated dimethicone/homatropine can produce in infants with less than 2 months, basal ganglia disturbances. The differentiation of these symptoms with the widespread epileptic crisis is essential, in order to avoid the erroneous use of antiepileptic drugs