Antibody Formation in Hibernating Ground Squirrels (Citellus tridecemlineatus)

McKenna, John M.; Musacchia, X. J.

doi:10.3181/00379727-129-33408

Cited by 23 publications

(17 citation statements)

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“…This increase in bone marrow C3 mRNA is the opposite of a trend seen in hibernating golden-mantled ground squirrels, which showed a decrease in liver C3 mRNA (51). A decrease in plasma complement protein has not been consistently observed in hibernating bats or ground squirrels, but lower complement activity has been proposed as a mechanism for the decrease in T-cell stimulation of antibody production by B cells during hibernation (13,37,56,60,84). Cell-based reactions and blood flow will be slowed in torpor, limiting leukocytic exudation, and to compensate, the innate complementbased immune reaction may be enhanced.…”

Section: Discussionmentioning

confidence: 84%

Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels

Cooper

Sell

Fahrenkrog

et al. 2016

Physiological Genomics

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M. Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels. Physiol Genomics 48: 513-525, 2016. First published May 20, 2016 doi:10.1152/physiolgenomics.00120.2015.-Mammalian hibernators adapt to prolonged periods of immobility, hypometabolism, hypothermia, and oxidative stress, each capable of reducing bone marrow activity. In this study bone marrow transcriptomes were compared among thirteen-lined ground squirrels collected in July, winter torpor, and winter interbout arousal (IBA). The results were consistent with a suppression of acquired immune responses, and a shift to innate immune responses during hibernation through higher complement expression. Consistent with the increase in adipocytes found in bone marrow of hibernators, expression of genes associated with white adipose tissue are higher during hibernation. Genes that should strengthen the bone by increasing extracellular matrix were higher during hibernation, especially the collagen genes. Finally, expression of heat shock proteins were lower, and cold-response genes were higher, during hibernation. No differential expression of hematopoietic genes involved in erythrocyte or megakaryocyte production was observed. This global view of the changes in the bone marrow transcriptome over both short term (torpor vs. IBA) and long term (torpor vs. July) hypothermia can explain several observations made about circulating blood cells and the structure and strength of the bone during hibernation. erythrocyte; leukocyte; megakaryocyte; osteoblast; adipose BONE MARROW IS A COMPLEX ORGAN consisting of many different cell types and stem cell pools. These cells express both unique and common sets of genes and likely influence each other's activities. Hematopoietic stem cells can differentiate into lymphoid progenitor cells that produce natural killer cells and lymphocytes, or into myeloid progenitor cells that give rise to erythrocytes, the remaining leukocytes, and megakaryocytes. Megakaryocytes in turn shed anucleated platelets involved in blood clotting and inflammation. Bone marrow resident mesenchymal stem cells can differentiate to produce resident bone cells including osteoblasts, adipocytes, and chondrocytes (64). Osteoblasts can terminally differentiate into osteocytes and are involved in maintaining bone strength and extracellular matrix production. Bone marrow adipose composition is affected by age, diet, and disease states. Bone marrow may also contain skeletal muscle and hepatocyte stem cell pools. Because of the rapid rate of mitosis by multiple resident stem cell pools, bone marrow is sensitive to damage by radiation and chemotherapy, leaving patients immunocompromised and anemic (25). Bone mineral density and collagen are decreased by prolonged disuse such as bed rest or immobilization (45,86). Recent studies have also demonstrated an increase in neutrophils, natural killer cells, and lymphocytes and a decrease in monocytes in patients subjected to 60 days of bed rest (38). Finally, bone marrow adipocytes increase in ...

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Section: Discussionmentioning

confidence: 84%

Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels

Cooper

Sell

Fahrenkrog

et al. 2016

Physiological Genomics

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“…For example, antibody production is markedly diminished during the winter in thirteen-lined ground squirrels (Citrellus tridecemlineatus; McKenna & Musacchia, 1968), and typhus infections in flying squirrels (Glaucomys volans) peak in the autumn and early winter months (Sonenshine et al, 1978). In wild cotton rats (Sigmodon hispidus), complex seasonal changes in cell-mediated and humoral immune function occur, with a general pattern of greater thymus and spleen masses, along with enhanced antibody responses in winter (Lochmiller et al, 1994).…”

Section: Phenomenology Of Immunological Photoperiodismmentioning

confidence: 99%

Photoperiodic time measurement and seasonal immunological plasticity

Stevenson¹,

Prendergast²

2015

Frontiers in Neuroendocrinology

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Seasonal variations in immunity are common in nature, and changes in day length are sufficient to trigger enhancement and suppression of immune function in many vertebrates. Drawing primarily on data from Siberian hamsters, this review describes formal and physiological aspects of the neuroendocrine regulation of seasonal changes in mammalian immunity. Photoperiod regulates immunity in a trait-specific manner, and seasonal changes in gonadal hormone secretion and thyroid hormone signaling all participate in seasonal immunomodulation. Photoperiod-driven changes in the hamster reproductive and immune systems are associated with changes in iodothyronine deiodinase-mediated thyroid hormone signaling, but photoperiod exerts opposite effects on the epigenetic regulation of reproductive neuroendocrine and lymphoid tissues. Photoperiodic changes in immunocompetence may explain a proportion of the annual variance in disease incidence and severity in nature, and provide a useful framework to help understand brain-immune interactions.

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“…Expression of intercellular adhesion molecule-1 (ICAM-1) on rat microvascular endothelial cells is increased when exposed to plasma from hibernating 13-lined ground squirrels (Drew et al, 2001; Yasuma et al, 1997), suggesting that increased ICAM-1 expression may be responsible for margination or extravasation of leukocytes from the circulation (Yasuma et al, 1997). In addition, antibody production from leukocytes is drastically reduced during hibernation (Drew et al, 2001; McKenna and Musacchia, 1968; Sidky and Auerbach, 1968). In hibernating hamsters and ground squirrels, fat-soluble factors released from brown adipose tissue can act as immunosuppressants during hibernation (Atanassov et al, 1995; Drew et al, 2001; Sidky et al, 1969).…”

Section: Torpormentioning

confidence: 99%

Neuroprotection: Lessons from hibernators

Dave

Christian

Pérez-Pinzón

et al. 2012

Comparative Biochemistry and Physiology Part B: Biochemistry an

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Mammals that hibernate experience extreme metabolic states and body temperatures as they transition between euthermia, a state resembling typical warm blooded mammals, and prolonged torpor, a state of suspended animation where the brain receives as low as 10% of normal cerebral blood flow. Transitions into and out of torpor are more physiologically challenging than the extreme metabolic suppression and cold body temperatures of torpor per se. Mammals that hibernate show unprecedented capacities to tolerate cerebral ischemia, a decrease in blood flow to the brain caused by stroke, cardiac arrest or brain trauma. While cerebral ischemia often leads to death or disability in humans and most other mammals, hibernating mammals suffer no ill effects when blood flow to the brain is dramatically decreased during torpor or experimentally induced during euthermia. These animals, as adults, also display rapid and pronounced synaptic flexibility where synapses retract during torpor and rapidly re-emerge upon arousal. A variety of coordinated adaptations contribute to tolerance of cerebral ischemia in these animals. In this review we discuss adaptations in heterothermic mammals that may suggest novel therapeutic targets and strategies to protect the human brain against cerebral ischemic damage and neurodegenerative disease.

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Antibody Formation in Hibernating Ground Squirrels (Citellus tridecemlineatus)

Cited by 23 publications

References 0 publications

Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels

Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels

Photoperiodic time measurement and seasonal immunological plasticity

Neuroprotection: Lessons from hibernators

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