RESUMO
Leukocyte trafficking shows strong diurnal rhythmicity and is tightly regulated by circadian rhythms. As we age, leukocyte trafficking becomes dysregulated, contributing to the increased systemic, low-grade, chronic inflammation observed in older adults. Ageing is also associated with diminished circadian outputs and a dysregulation of the circadian rhythm. Despite this, there is little evidence to show the direct impact of age-associated dampening of circadian rhythms on the dysregulation of leukocyte trafficking. Here, we review the core mammalian circadian clock machinery and discuss the changes that occur in this biological system in ageing. In particular, we focus on the changes that occur to leukocyte trafficking rhythmicity with increasing age and consider how this impacts inflammation and the development of immune-mediated inflammatory disorders (IMIDs). We aim to encourage future ageing biology research to include a circadian approach in order to fully elucidate whether age-related circadian changes occur as a by-product of healthy ageing, or if they play a significant role in the development of IMIDs.
Assuntos
Envelhecimento/imunologia , Quimiotaxia de Leucócito/imunologia , Ritmo Circadiano/imunologia , Inflamação/imunologia , Animais , HumanosRESUMO
Fish oil supplementation is of great medical and public interest with epidemiological evidence of health benefits in humans, in particular by conferring protection against heart diseases. Its anti-inflammatory properties have also been reported. Initial results from short-lived mouse strains showed that fish oil can increase lifespan, affecting pathways like inflammation and oxidation thought to be involved in the regulation of aging. Could fish oil and its omega-3 fatty acids act as geroprotectors? Probably not. A new study by Strong et al. challenges the role for fish oil supplementation in aging. Using a large cohort of genetically heterogeneous mice in three sites, part of the Interventions Testing Program of the NIA, Strong et al. show that fish oil supplementation at either low or high dosages has no effect on the lifespan of male or female mice. Although it is still possible that fish oil supplementation has health benefits for specific age-related diseases, it does not appear to slow aging or have longevity benefits.
Assuntos
Óleos de Peixe , Longevidade , Animais , Antioxidantes , Suplementos Nutricionais , Feminino , Inibidores de Glicosídeo Hidrolases , Humanos , Masculino , Camundongos , Fator 2 Relacionado a NF-E2RESUMO
The National Institute on Aging Interventions Testing Program (ITP) evaluates agents hypothesized to increase healthy lifespan in genetically heterogeneous mice. Each compound is tested in parallel at three sites, and all results are published. We report the effects of lifelong treatment of mice with four agents not previously tested: Protandim, fish oil, ursodeoxycholic acid (UDCA) and metformin - the latter with and without rapamycin, and two drugs previously examined: 17-α-estradiol and nordihydroguaiaretic acid (NDGA), at doses greater and less than used previously. 17-α-estradiol at a threefold higher dose robustly extended both median and maximal lifespan, but still only in males. The male-specific extension of median lifespan by NDGA was replicated at the original dose, and using doses threefold lower and higher. The effects of NDGA were dose dependent and male specific but without an effect on maximal lifespan. Protandim, a mixture of botanical extracts that activate Nrf2, extended median lifespan in males only. Metformin alone, at a dose of 0.1% in the diet, did not significantly extend lifespan. Metformin (0.1%) combined with rapamycin (14 ppm) robustly extended lifespan, suggestive of an added benefit, based on historical comparison with earlier studies of rapamycin given alone. The α-glucosidase inhibitor, acarbose, at a concentration previously tested (1000 ppm), significantly increased median longevity in males and 90th percentile lifespan in both sexes, even when treatment was started at 16 months. Neither fish oil nor UDCA extended lifespan. These results underscore the reproducibility of ITP longevity studies and illustrate the importance of identifying optimal doses in lifespan studies.
Assuntos
Antioxidantes/farmacologia , Estradiol/farmacologia , Inibidores de Glicosídeo Hidrolases/farmacologia , Longevidade/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/metabolismo , alfa-Glucosidases/metabolismo , Acarbose/farmacologia , Animais , Medicamentos de Ervas Chinesas/farmacologia , Óleos de Peixe/farmacologia , Força da Mão , Masculino , Masoprocol/farmacologia , Metformina/farmacologia , Camundongos , Teste de Desempenho do Rota-Rod , Sirolimo/farmacologia , Análise de Sobrevida , Ácido Ursodesoxicólico/farmacologiaRESUMO
Diseases of failed inflammation resolution are common and largely incurable. Therapeutic induction of inflammation resolution is an attractive strategy to bring about healing without increasing susceptibility to infection. However, therapeutic targeting of inflammation resolution has been hampered by a lack of understanding of the underlying molecular controls. To address this drug development challenge, we developed an in vivo screen for proresolution therapeutics in a transgenic zebrafish model. Inflammation induced by sterile tissue injury was assessed for accelerated resolution in the presence of a library of known compounds. Of the molecules with proresolution activity, tanshinone IIA, derived from a Chinese medicinal herb, potently induced inflammation resolution in vivo both by induction of neutrophil apoptosis and by promoting reverse migration of neutrophils. Tanshinone IIA blocked proinflammatory signals in vivo, and its effects are conserved in human neutrophils, supporting a potential role in treating human inflammation and providing compelling evidence of the translational potential of this screening strategy.
Assuntos
Abietanos/farmacologia , Anti-Inflamatórios/farmacologia , Movimento Celular/efeitos dos fármacos , Ensaios de Triagem em Larga Escala , Inflamação/tratamento farmacológico , Infiltração de Neutrófilos/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Peixe-Zebra , Animais , Animais Geneticamente Modificados , Apoptose/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Proteínas de Fluorescência Verde/biossíntese , Proteínas de Fluorescência Verde/genética , Humanos , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Larva , Neutrófilos/imunologia , Neutrófilos/metabolismo , Neutrófilos/patologia , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Pesquisa Translacional Biomédica , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Peixe-Zebra/imunologia , Peixe-Zebra/metabolismoRESUMO
The (n-3) PUFA, DHA, is widely thought to posses the ability to modulate the inflammatory response. However, its modes of interaction with inflammatory cells are poorly understood. In particular, there are limited data on the interactions of DHA with vascular endothelium, the cells that regulate the traffic of leukocytes from the blood into inflamed tissue. Using human umbilical vein endothelial cells (EC) cultured in a flow-based adhesion assay and activated with TNFα, we tested whether supplementing human umbilical vein EC with physiologically achievable concentrations of DHA would inhibit the recruitment of flowing neutrophils. DHA caused a dose-dependent reduction in neutrophil recruitment to the EC surface, although cells that became adherent were activated and could migrate across the human umbilical vein EC monolayer normally. Using EPA as an alternative supplement had no effect on the levels of neutrophil adhesion in this assay. Analysis of adhesion receptor expression by qPCR demonstrated that DHA did not alter the transcriptional activity of human umbilical vein EC. However, DHA did significantly reduce E-selectin expression at the human umbilical vein EC surface without altering the total cellular pool of this adhesion receptor. Thus, we have identified a novel mechanism by which DHA alters the trafficking of leukocytes during inflammation and demonstrate that this involves disruption of intracellular transport mechanisms used to present adhesion molecules on the surface of cytokine-stimulated EC.
Assuntos
Adesão Celular/efeitos dos fármacos , Adesão Celular/fisiologia , Ácidos Docosa-Hexaenoicos/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/imunologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/fisiologia , Células Cultivadas , Selectina E/genética , Células Endoteliais/fisiologia , Expressão Gênica/efeitos dos fármacos , Humanos , Técnicas In Vitro , Inflamação/prevenção & controle , Molécula 1 de Adesão Intercelular/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Inflammation is a physiological response to tissue trauma or infection, but leukocytes, which are the effector cells of the inflammatory process, have powerful tissue remodelling capabilities. Thus, to ensure their precise localisation, passage of leukocytes from the blood into inflamed tissue is tightly regulated. Recruitment of blood borne neutrophils to the tissue stroma occurs during early inflammation. In this process, peptide agonists of the chemokine family are assumed to provide a chemotactic stimulus capable of supporting the migration of neutrophils across vascular endothelial cells, through the basement membrane of the vessel wall, and out into the tissue stroma. Here, we show that, although an initial chemokine stimulus is essential for the recruitment of flowing neutrophils by endothelial cells stimulated with the inflammatory cytokine tumour necrosis factor-alpha, transit of the endothelial monolayer is regulated by an additional and downstream stimulus. This signal is supplied by the metabolism of the omega-6-polyunsaturated fatty acid (n-6-PUFA), arachidonic acid, into the eicosanoid prostaglandin-D(2) (PGD(2)) by cyclooxygenase (COX) enzymes. This new step in the neutrophil recruitment process was revealed when the dietary n-3-PUFA, eicosapentaenoic acid (EPA), was utilised as an alternative substrate for COX enzymes, leading to the generation of PGD(3). This alternative series eicosanoid inhibited the migration of neutrophils across endothelial cells by antagonising the PGD(2) receptor. Here, we describe a new step in the neutrophil recruitment process that relies upon a lipid-mediated signal to regulate the migration of neutrophils across endothelial cells. PGD(2) signalling is subordinate to the chemokine-mediated activation of neutrophils, but without the sequential delivery of this signal, neutrophils fail to penetrate the endothelial cell monolayer. Importantly, the ability of the dietary n-3-PUFA, EPA, to inhibit this process not only revealed an unsuspected level of regulation in the migration of inflammatory leukocytes, it also contributes to our understanding of the interactions of this bioactive lipid with the inflammatory system. Moreover, it indicates the potential for novel therapeutics that target the inflammatory system with greater affinity and/or specificity than supplementing the diet with n-3-PUFAs.
Assuntos
Ácidos Graxos Ômega-3/metabolismo , Inflamação/fisiopatologia , Infiltração de Neutrófilos/fisiologia , Adesão Celular , Células Cultivadas , Quimiocina CCL2/genética , Quimiocina CXCL1/genética , Quimiocina CXCL2/genética , Cromatografia Líquida , Inibidores de Ciclo-Oxigenase , Selectina E/metabolismo , Ácido Eicosapentaenoico/metabolismo , Células Endoteliais/metabolismo , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Regulação da Expressão Gênica , Humanos , Inflamação/metabolismo , Molécula 1 de Adesão Intercelular/genética , Nitrobenzenos/metabolismo , Fosfolipídeos/química , Fosfolipídeos/metabolismo , Reação em Cadeia da Polimerase , Prostaglandina-Endoperóxido Sintases/metabolismo , Pirazóis/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sulfonamidas/metabolismo , Espectrometria de Massas em Tandem , Fator de Necrose Tumoral alfa/metabolismo , Molécula 1 de Adesão de Célula Vascular/metabolismoRESUMO
BACKGROUND AND AIMS: CD44 and its splice variants can be expressed on all leukocytes, conferring adhesive properties and enhancing cellular recruitment to the endothelium during inflammation. CD44 expression is increased in inflammatory conditions such as rheumatoid arthritis and CD44 variant 3 (CD44v3) expression may be associated with inflammation. We have examined CD44 and CD44v3 expression on peripheral blood monocytes from patients with peripheral arterial disease (PAD) and healthy controls. We have also examined the effect of fish oil supplementation on these markers. METHODS AND RESULTS: CD44 and CD44v3 were assessed at baseline and following dietary supplementation with fish oil for 12 weeks in both PAD and control groups. Monocytes from PAD patients had higher CD44 expression than those from controls (median intensity fluorescence (MIF): 480+/-278 vs 336+/-251 (mean+/-SD); p<0.001). Following 12 weeks' dietary supplementation with fish oil, CD44 expression was reduced in PAD patients (MIF: 480+/-278 vs 427+/-262; p=0.05) but not in controls (336+/-251 vs 355+/-280; ns). Monocyte CD44v3 expression was lower in cultured monocytes from PAD patients compared to those from controls (0.15+/-0.15 vs 0.22+/-0.14 OD units; p<0.02). This was increased in the PAD group following fish oil supplementation (0.15+/-0.14 to 0.27+/-0.23 OD units; p<0.001). CONCLUSION: Monocyte CD44 and CD44v3 expression are altered in arterial disease but are returned towards levels seen in control subjects by dietary fish oil supplementation.
Assuntos
Suplementos Nutricionais , Ácidos Docosa-Hexaenoicos/administração & dosagem , Ácido Eicosapentaenoico/administração & dosagem , Receptores de Hialuronatos/sangue , Monócitos/efeitos dos fármacos , Doenças Vasculares Periféricas/tratamento farmacológico , Administração Oral , Idoso , Idoso de 80 Anos ou mais , Cápsulas , Células Cultivadas , Combinação de Medicamentos , Humanos , Masculino , Pessoa de Meia-Idade , Monócitos/imunologia , Doenças Vasculares Periféricas/imunologia , Isoformas de Proteínas , Resultado do TratamentoRESUMO
Monocytes/macrophages are key orchestrators of inflammation and are involved in the pathogenesis of chronic inflammatory disorders, including atherosclerosis. (n-3) Fatty acids, found in fish oil, have been shown to have protective effects in such disorders. To investigate possible modes of action, we used a monocyte:endothelial cell (EC) coculture model to investigate the pro-inflammatory potential of monocytes. Monocytes were isolated from the blood of donors with peripheral arterial disease (PAD) or control donors, before and after a 12-wk supplementation of their diet with fish oil. The monocytes were cultured with human umbilical vein EC (HUVEC) for 24 h, after which the ability of the HUVEC to recruit flowing neutrophils was tested. Monocytes from either group of donors stimulated the EC to support the adhesion and migration of neutrophils. Fish oil supplementation reduced the potency of monocytes from normal subjects, but not those from patients with PAD, to induce recruitment. Concurrent medication may have acted as a complicating factor. On subgroup analysis, only those free of medication showed a significant effect of fish oil. Responses before or after supplementation were not closely linked to patterns of secretion of cytokines by cultured monocytes, tested in parallel monocultures. These results suggest that fish oil can modulate the ability of monocytes to stimulate EC and that this might contribute to their protective effects against chronic inflammatory disorders. Benefits, however, may depend on existing medical status and on other treatments being received.
Assuntos
Óleos de Peixe/farmacologia , Inflamação/metabolismo , Monócitos/efeitos dos fármacos , Proteínas Aviárias/metabolismo , Estudos de Casos e Controles , Adesão Celular , Células Cultivadas , Citocinas/metabolismo , Suplementos Nutricionais , Células Endoteliais/fisiologia , Humanos , Masculino , Monócitos/fisiologia , Neutrófilos/fisiologia , Doenças Vasculares Periféricas/metabolismo , Doenças Vasculares Periféricas/patologia , Fosfolipídeos/sangueRESUMO
Peripheral arterial disease (PAD) is an atherosclerotic disease. Evidence suggests that atherosclerosis is an inflammatory condition and long chain n-3 fatty acids, found in oily fish and fish oils, have been shown to reduce inflammation. Genetic and lifestyle factors such as body mass index (BMI) also influence inflammation. In this study we have examined the effect of fish oil in patients with claudication secondary to PAD. Fish oil supplementation, providing 1g EPA and 0.7 g DHA per day for 12 weeks, increased walking distance on a treadmill set at 3.2 km/h with a 7% incline. Walking distance to first pain increased from 76.2+/-8.5 m before fish oil to 140.6+/-25.5 m after fish oil (mean+/-SEM, p=0.004) and total distance walked increased from 160.0+/-21.5 m before fish oil to 242.1+/-34.5 m after fish oil (p=0.002). Fish oil supplementation also improved ankle brachial pressure index (ABPI) from 0.599+/-0.017 before fish oil to 0.776+/-0.030 after fish oil (p<0.001). The increase in walking distance was dependent on both BMI and genotype for single nucleotide polymorphisms in the genes encoding the pro-inflammatory cytokines tumour necrosis factor-alpha and interleukin (IL)-1beta and the anti-inflammatory cytokine IL-10 (detected using amplification refractory mutation system polymerase chain reaction). Neither BMI nor any of the genotypes examined affected the ability of fish oil to increase ABPI. The mechanisms by which fish oil affects walking distance and ABPI do not appear to be the same.