Age-related changes in beta-adrenoceptors of lymphocytes

Age-related changes of standardized uptake values in the blood pool and liver: a decade-long retrospective study of the outcomes of 2,526 subjects

Background

Background activity on fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is often used as a reference to assess a patient's response to tumor treatment. To produce a suitable background activity reference, we examined the variations in standardized uptake values (SUVs) in the blood pool and liver of a large multi-aged population.

Methods

A total of 2,526 subjects underwent ¹⁸F-FDG PET/CT examinations and were divided into 12 age groups. Pearson's partial correlation and multivariate regression analyses were performed to assess the associations between individual factors and SUVs of the blood pool and liver and to identify the factor that most influenced the SUVs. The mean SUVs across the age groups were also determined.

Results

Positive correlations were found between individual factors and SUVs. Age appeared to be the most important predictor of SUVs and was significantly associated with the blood pool SUV_max (ß=0.466, P=0.000), blood pool SUV_mean (ß=0.393, P=0.000), liver SUV_max (ß=0.347, P=0.000), and liver SUV_mean (ß=0.354, P=0.000). Blood pool and liver SUVs rose rapidly until the age of 20 and then showed a slow upward trend without reaching a plateau.

Conclusions

Age is an important factor that influences variations in the blood pool and liver SUVs. Our study clarified this understanding of age-related variations in SUVs and provided a normal range of blood pool and liver SUVs that may aid clinicians in evaluating tumors with greater accuracy.

Neural regulation of cancer: from mechanobiology to inflammation

Despite recent progress in cancer research, the exact nature of malignant transformation and its progression is still not fully understood. Particularly metastasis, which accounts for most cancer death, is a very complex process, and new treatment strategies require a more comprehensive understanding of underlying regulatory mechanisms. Recently, the sympathetic nervous system (SNS) has been implicated in cancer progression and beta-blockers have been identified as a novel strategy to limit metastasis. This review discusses evidence that SNS signaling regulates metastasis by modulating the physical characteristics of tumor cells, tumor-associated immune cells and the extracellular matrix (ECM). Altered mechanotype is an emerging hallmark of cancer cells that is linked to invasive phenotype and treatment resistance. Mechanotype also influences crosstalk between tumor cells and their environment, and may thus have a critical role in cancer progression. First, we discuss how neural signaling regulates metastasis and how SNS signaling regulates both biochemical and mechanical properties of tumor cells, immune cells and the ECM. We then review our current knowledge of the mechanobiology of cancer with a focus on metastasis. Next, we discuss links between SNS activity and tumor-associated inflammation, the mechanical properties of immune cells, and how the physical properties of the ECM regulate cancer and metastasis. Finally, we discuss the potential for clinical translation of our knowledge of cancer mechanobiology to improve diagnosis and treatment.

beta(2)-Adrenergic receptor-dependent sexual dimorphism for murine leukocyte migration

In wild-type FVB mice, leukocyte recruitment to lipopolysaccharide was sexually dimorphic, with a greater number of leukocytes recruited in females. In male beta(2)-adrenergic receptor knock out mice (bred on a congenic FVB background) the number of leukocytes recruited was increased approximately 4-fold, while in females there was no change, eliminating sexual dimorphism in leukocyte migration. While there were significantly fewer recruited CD62L(+) and CD11a(+) leukocytes in wild-type males, only in male beta-adrenergic receptor knock out mice was there an increase in the number of recruited CD11a(+) leukocytes, again eliminating sexual dimorphism. Thus, leukocyte migration and CD11a(+) adhesion molecule expression in male, but not in female, leukocytes is beta-adrenergic receptor-dependent. Our findings provide support for a role of beta(2)-adrenergic receptor mechanisms in the inflammatory response, and suggest that beta(2)-adrenergic receptor on male leukocytes contributes to sexual dimorphism in the effect of stress on inflammatory diseases.

Age-related changes in hepatic and splenic insulin receptors and serum insulin and glucose levels in inbred mice

Inbred mice of strains A/J, DBA/1J, and SJL/J were housed and aged in our animal colony, and parameters of carbohydrate metabolism were assessed at various ages. The patterns of age-related change were both organ- and strain-specific. Age-related changes in two of the strains were associated with relative carbohydrate intolerance. Common to all three strains was a biphasic pattern of change in hepatic insulin receptor number, with a decrease in early life and a return to earlier levels late in life. In both A/J and DBA/1J mice, there was a sharp increase in serum insulin level (twofold to 9.7-fold) that corresponded to the decrease in hepatic insulin receptors and was associated with hyperglycemia; no significant change in serum insulin or glucose levels was seen in SJL/J mice, despite a similar biphasic pattern in hepatic insulin receptor concentration. Age-related changes in splenic insulin receptors resembled changes in the liver in A/J and SJL/J mice, ie, there were synchronous biphasic age-related patterns. This was not the case in the spleens of DBA/1J mice, in which we did not observe age-related changes. There was no change in insulin receptor affinity with age, nor was there any difference in affinity between tissues or mouse strains. The pattern of change in hepatic insulin receptors and serum insulin levels was more complex than has been previously recognized. We do not know the mechanisms responsible for this complex pattern, but it must involve at least two discrete age-related events.(ABSTRACT TRUNCATED AT 250 WORDS)

Alloimmunization-induced changes in beta-adrenoceptor expression and cAMP on B lymphocytes

In this report we have examined the effect of alloimmunization on beta-adrenergic expression in lymphocytes. We have observed a variation in the number of beta-adrenoceptors (Bmax) according to the degree of immunization without modifications in their affinity (Kd). This phenomenon was accompanied with parallel variations of intracellular cAMP levels. A decrease in Bmax values was observed during the first and second immunizations. Then the Bmax began to increase, exceeding control values up to the fourth and fifth immunizations, and remaining constant at the sixth immunizations. Only B cell-enriched populations showed variation in Bmax values of beta-adrenoceptors with alloimmunization. In contrast, the Bmax values of T cell-enriched populations did not change. Kd values were similar in all cell types tested. The number of binding sites was not dependent on the animal's age. Modifications in cAMP levels of B cell-enriched populations were correlated with changes in beta-adrenoceptor expression. These results suggest that beta-adrenoceptor expression and cAMP intracellular levels in B cell-enriched populations vary with the number of alloimmunizations. In addition, the antibody synthesis induced by allogenic stimulus was inversely proportional to the number of beta-adrenoceptors expressed on B cells. Perhaps these findings are evidence of a control mechanism that regulates antibody synthesis during the immune response.

Developmental change in the second half of life--strategies for modification of selected compartments of aging

Age-related changes of different individuals multicentric and polymorphic. We have approached this problem of age-related changes by examining (1) membrane densities of receptors of various ligands in different organs, and (2) changes in different classes of T cells and of antibody response. Three strategies have been developed to modify progression of age-related changes to different extents in different compartments in which age-related changes occur. The first is based on administration of hormones, the second on administration of purine analogues and the third on administration of diets which differ in fatty acid content. Details of this last approach are reviewed in this paper. Lifespan of different species is a component of the evolution of each species. The variables which are decisive in the evolutionary processes which affect lifespans of different species are not necessarily variables which play a decisive role in the different health span of different individuals of the same species. For each individual of a given species, relative health span represents variations within the limits of the evolved lifespan of the species and depends on alleles of many different genes.

Variations in age-related decline in striatal D2-dopamine receptors in a variety of mouse strains

To determine the importance of inheritance on the age-associated decline in D2-dopamine receptor number, the binding of [3H]spiperone to mouse striatal membranes was measured in animals ranging from 7 to 104 weeks of age from 5 murine strains (C57BL/6J, C3/HeJ, A/J, SJL/J and DBA/1J). In young mice, receptor number (Bmax) was influenced by genetic background such that C57BL/6J less than SJL/J less than A/J = DBA/1J = C3H/HeJ. A 50-60% decline in Bmax with age was found in all strains except for C57BL/6J. Bmax in the C57BL/6J mice were lower than in the other strains of young animals (7-15 weeks) but remained relatively constant throughout life (measured up to 104 weeks of age). Furthermore, the maximal decline in receptor number was observed relatively early in life (16-30 weeks) and remained constant thereafter. Neither age nor genetic background influenced ligand affinity (Kd). Thus the results of this study suggest that the maximal decline in Bmax for the dopamine receptor occurs before the second half of life and that the magnitude of this decline is polymorphic.

Polymorphism of age-related changes in stimulatory capacity of murine dendritic cells

All through life, regulatory and executive components of the immune system undergo changes, differing in rate and extent, dependent on the genetic background. We have, here, examined age-dependent changes in stimulatory capacity of dendritic cells (DC) in allogeneic mixed leukocyte reaction (MLR). DC of mice of five strains showed very little change as they aged. DC from mice of two other strains showed a significant age-related decrease of stimulatory activity and those of one strain showed an increase. The capacity of DC to stimulate syngeneic MLR was examined in three strains, as a function of age, and was found to decrease in one and to slightly increase in two. The underlying cause for this extensive polymorphism remains to be determined. We could not find supporting evidence for the view that the observed changes were related to changes in Ia density on dendritic cells.