Abstract：
In this study, we investigated the effects of the artificial photoperiods that mimic summer (16L:8D; 16 h Light: 8 h Dark) and winter (8L:16D) solstices, equinoxes (12L:12D), and the artificial 24-h light regimen (24L:0D) on the leukocyte populations and the T helper and regulatory type responses on rainbow trout (Oncorhynchus mykiss). Using flow cytometry analysis, we found that photoperiod induces changes in head kidney leukocyte subsets. The lymphoid subset increased in the 16L:8D summer solstice regime. The analysis using antibodies against B and T cells showed the increase of CD4-1+ T lymphocytes and other unidentified lymphoid cells, with no changes in the B cells. To investigate the modulatory influence of the photoperiod on the fish T cell response, we quantified in the head kidney the transcript levels of genes involved in the Th1 type response (t-bet, ifn-ƴ, il-12p35, il-12p40c), Th2 type response (gata3, il-4/13a), Th17 response (ror-ƴt, il-17a/f), T regulatory response (foxp3α, il-10a, tgf-β1), and the T cell growth factor il-2. The results showed that the seasonal photoperiod alone has a limited influence on the expression of these genes, as the only difference was observed in il-14/13a and il-10a transcripts of fish kept on the 16L:8D regimen. In addition, the 24L:0D treatment used in aquaculture produces a reduction of il-14/13a and il-17a/f. We also evaluated the effect of photoperiod in the presence of an antigenic stimulus. Thus, in fish immunized with the recombinant viral protein 1 (rVP1) of infectious pancreatic necrosis virus (IPNV), the photoperiod had a striking influence on the type of adaptive immune response. Each photoperiod fosters a unique immune signature of antigenic response. A classical type 1 response is observed in fish subjected to the 16L:8D photoperiod. In contrast, fish in the 12L:12D photoperiod showed only the upregulation of il-12p40c. Furthermore, none of the cytokines were increased in fish maintained on the artificial 24L:0D regimen, and a decrease in the master transcription factors (t-bet, ror-ƴt, and foxp3α) was observed. Thus, fish on the 12L:12D and 24L:0D photoperiod appear hyporesponsive regarding the T cell response. Altogether, this study showed that photoperiods modify the magnitude and quality of the T-helper response in rainbow trout and thus impact essential mechanisms for the generation of immune memory and protection against microorganisms.
摘要：
在这项研究中,我们研究了模拟夏季（16L：8D）和冬季（8L：16D）的人工光周期的影响，春分（12L：12D），以及对白细胞种群的人工24小时光照方案（24L：0D）以及对虹鳟鱼（Oncorhynchusmykiss）的T辅助和调节型反应。使用流式细胞术分析，我们发现光周期诱导头肾白细胞亚群的变化。在16L：8D夏至制度下，淋巴亚群增加。使用针对B细胞和T细胞的抗体的分析显示CD4-1+T淋巴细胞和其他未识别的淋巴样细胞的增加,B细胞没有变化。为了研究光周期对鱼类T细胞反应的调节作用，我们在头肾中定量了参与Th1型反应的基因的转录水平(t-bet,ifn-，il-12p35,il-12p40c),Th2型反应（gata3，il-4/13a），Th17响应(错误-t，il-17a/f)，T调节反应(foxp3α，il-10a,tgf-β1)，和T细胞生长因子il-2。结果表明，仅季节性光周期对这些基因的表达影响有限，因为在16L：8D方案保存的鱼的il-14/13a和il-10a转录物中观察到唯一的差异。此外,水产养殖中使用的24L:0D处理产生IL-14/13a和IL-17a/f的减少。我们还评估了在抗原刺激存在下光周期的影响。因此，在用传染性胰腺坏死病毒（IPNV）的重组病毒蛋白1（rVP1）免疫的鱼中，光周期对适应性免疫应答的类型有显著影响。每个光周期促进抗原应答的独特免疫特征。在经历16D：8L光周期的鱼中观察到经典的1型反应。相比之下,12L：12D光周期中的鱼仅显示il-12p40c的上调。此外，在人工24L：0D方案下维持的鱼类中，细胞因子均未增加，和主转录因子的减少(t-bet，ror-t,和foxp3α)被观察到。因此，12L：12D和24L：0D光周期上的鱼对T细胞反应表现出反应不足。总之,这项研究表明，光周期改变了虹鳟鱼T辅助反应的大小和质量，从而影响了产生免疫记忆和针对微生物的保护的基本机制。
