Seasonal changes in immune function 5. Photoperiod, melatonin, and immunity 6. Energetics and immune function 7. Hormonal influence on immune function 8.
Clinical significance of seasonal patterns of immune function and disease References Index. View via Publisher. Save to Library. Create Alert. Share This Paper. They wanted to see if there were seasonal changes in the types of white cells in the blood. Finally, they looked at gene expression in fat tissue samples taken from women from the UK. They did this to see whether only cells in the immune system showed variation in gene expression with the seasons.
Some genes were more active in the summer and others in winter. Again, some genes were more active in the summer and others in the winter. The genes included one encoding protein, which controls the production of anti-inflammatory proteins and was found to be more active in the summer months. Other genes involved in promoting inflammation were more active in the winter.
Seasonal genes from the samples of Icelandic people did not show the same pattern. The numbers of different types of white blood cells from the UK samples also showed seasonal variation. Lymphocytes, which mostly fight viral infections, were highest in October and lowest in March. Eosinophils, which have many immune functions, including allergic reactions, were highest in the summer. There were also seasonal patterns in the numbers of different types of white blood cell from people in The Gambia, but these were different from those in the UK. All white cell types increased during the rainy season.
The researchers say their results indicate gene expression and the composition of blood varies with seasons and geographical locations. They say the increased gene expression of inflammatory proteins in the European winter may help explain why some autoimmune conditions are more likely to start in the winter, such as type 1 diabetes.
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This research found seasonal variations in gene expression in one type of white blood cell. Some genes became more active in the summer months, while others became more active in the winter. For example, one gene involved in the body's anti-inflammation response was increased during the summer, while some involved in inflammation were increased in the winter.
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The researchers also found seasonal variation in the numbers of each type of white cell. These patterns were different in samples taken from people in the UK, compared with people from The Gambia. Activation of the immune system is energy demanding and although efficient for combating infections, the induction of fever occurs at a high metabolic cost Lochmiller and Deerenberg, The amount of energy consumed during immune activation has not yet been determined in cod, but it is well known that resistance to, recovery from, and coping with stressors can be energy intensive for fish Schreck and Tort, A protracted immune response will consume more energy.
It may also lead to excessive tissue damage initiating energy demanding cellular repair processes.
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As important as mounting an immune response toward foreign organisms is the subsequent control and down-regulation of cascading inflammatory events and return to homeostasis. Production of a larger immune response than necessary is perhaps the most obvious sort of tolerance failure in infections Ayres and Schneider, Interestingly, the peak of gene expression between weeks 2 and 3 pi correlated well with the deaths observed in the infected, high temperature group.
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Due to rapid tissue decomposition, samples for evaluation of immune gene expression were not collected from the deceased fish. However, based on the fact that no live B. When evaluating host protection against infection it is often difficult to disentangle disease tolerance from resistance to infection.
However, an overall assessment of host homeostasis and direct quantification of parameters that estimate tissue function plotted against host pathogen load may reveal variations in disease tolerance Soares et al. These observations suggest that a reduced disease tolerance occurred in the warm water group.
Seasonal immunity: Activity of thousands of genes differs from winter to summer -- ScienceDaily
In addition to modulating the immune response, the environmental temperature will also affect other physiological processes in fish. Transcriptome analysis of liver in rainbow trout subjected to heat stress revealed that several pathways, including those for protein metabolism and energy metabolism, as well as immunity, were influenced Li et al. As pointed out by Hanna et al.
Metabolic rate was not investigated in the present study, but serum chemistry analysis showed that temperature affected the homeostasis of different electrolytes, in particular potassium. The reported values should therefore solely be compared to the control samples in our study, which were treated similarly.
Hypokalemia may be due to loss of potassium through the kidneys in mammals, but infectious diseases are also supposed to be a major cause in fish Mayer and Donnelly, Temperature, but not infection, was correlated with hypokalemia in our material. Electrolyte imbalance can have detrimental effects on the cardiovascular system with hypertension and ventricular arrhythmias as the most severe aftermath Weiner and Wingo, Cortisol has several established physiological roles in osmoregulation, metabolism, growth, stress, and immune function in teleosts McCormick, The mineral corticoid aldosterone is the primary regulator of salt and water balance in mammals.
In the absence of aldosterone, cortisol has an important osmoregulatory function in fish. It is not known whether changes in the serum potassium concentration can affect cortisol levels, but it is tempting to hypothesize that these two factors are interdependent. However, our study does not support any conclusions and the connection between osmoregulation, low potassium levels and cortisol in cod needs to be further investigated.
Growth is also affected by temperature. None of the cod reached sexual maturity during the study period, but in the natural environment this would be a factor to consider when evaluating multiple synchronous energy demanding processes. In their natural environment, animals usually have limited access to nutritional resources. Constraints created by the amount of energy allocated to fuel the immune response may create trade-offs between immune function and other fitness-related traits like growth, reproduction and thermoregulation Lochmiller and Deerenberg, Resistance responses can be expensive in terms of energy expenditure and profound changes in energy distribution occur upon infection.
Disruption of these changes can also reduce tolerance if not enough energy is left for repair processes Schneider and Ayres, Infection did not have any significant impact on growth rate in our study, indicating that the increased growth observed in cod kept at the highest temperature was not impeded by the activated immune response.
The results presented herein highlight the importance of timely balanced immune responses.
Our study is the first to describe death following concomitant temperature stress and infection despite efficient clearance of an opportunistic bacterial infection. In addition to diseases caused by pathogenic microbes, health and well-being of fish may also be hampered by non-pathogenic microbes. We show here that immune activation at increased water temperature, close to the thermal limit of the species, resulted in an efficient immune response toward an opportunistic pathogen; however, the combined amount of energy spent on resistance and tolerance, growth and physiological homeostasis may have contributed to increased mortality.
The North Sea cod stock has been in poor condition for the last decades, experiencing drastic population declines most probably due to overfishing Sobel, ; ICES, ; Engelhard et al. Although registered improvements, nine smaller coastal stocks are still listed as vulnerable MCS, Sustainable management of Atlantic cod in the future requires our awareness of potentially additive, synergistic or antagonistic health effects induced by environmental stress. Unsuccessful adaptation to chronic stressors can result in allostatic overload and mortality Sneddon et al. In light of current and predicted climate change, it is of utmost importance to increase our knowledge on how temperature stress affects the energetic cost of immune activation in ectotherms and how disease resistance and tolerance are influenced by unfavorable physical environmental conditions.
The authors declare that all the data supporting the findings of this study are available within the article and its Supplementary Information files and from the corresponding author upon reasonable request. AL wrote the paper. KS and RR wrote sections of the manuscript. All authors provided critical evaluation of the manuscript, read and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Breines and E. The publication charges for this article have been funded by a grant from the publication fund of UiT - The Arctic University of Norway. Ayres, J. Tolerance of infections. Baumann, K.
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