Improvement of Redox State and Functions of Immune Cells as Well as of Behavioral Response in Aged Mice After Two-Week Supplementation of Fermented Milk with Probiotics.

The homeostatic systems, such as the nervous and immune systems, show deterioration in aging as a consequence of the age-related oxidative-inflammatory stress establishment. The supplementation with fermented milk containing probiotic bacteria could be a good nutritional strategy to improve homeostatic system functions in aged individuals through the modulation of their redox state. The aim of the present study was to evaluate the effect of 2-week supplementation with a commercial fermented milk containing yogurt species (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus), and the probiotic Lactobacillus casei DN-114001 on behavior, redox state, and immune cell functions of aged mice as well as on their life span. Aged female ICR-CD1 mice were supplemented with fermented milk containing these probiotics for 2 weeks. After this period, a variety of behavioral tests were performed and several parameters of redox state and function of peritoneal leukocytes were analyzed. The results showed that the 2-week supplementation of fermented milk containing probiotics improved behavior (such as muscular vigor, exploratory activity, and anxiety-like behavior) as well as the redox state and functions of peritoneal immune cells in aged mice. In conclusion, the present study shows that the supplementation with fermented milk containing probiotics for a short period of time could be a good nutritional strategy to promote healthy aging.

Comparison of cell mechanical measurements provided by Atomic Force Microscopy (AFM) and Micropipette Aspiration (MPA).

A comparative analysis of T-lymphocyte mechanical data obtained from Micropipette Aspiration (MPA) and Atomic Force Microscopy (AFM) is presented. Results obtained by fitting the experimental data to simple Hertz and Theret models led to non-Gaussian distributions and significantly different values of the elastic moduli obtained by both techniques. The use of more refined models, taking into account the finite size of cells (simplified double contact and Zhou models) reduces the differences in the values calculated for the elastic moduli. Several possible sources for the discrepancy between the techniques are considered. The analysis suggests that the local nature of AFM measurements compared with the more general character of MPA measurements probably contributed to the differences observed.

Oxidative-Inflammatory Stress in Immune Cells from Adult Mice with Premature Aging.

Oxidative and inflammatory stresses are closely related processes, which contribute to age-associated impairments that affect the regulatory systems such as the immune system and its immunosenescence. Therefore, the aim of this work was to confirm whether an oxidative/inflammatory stress occurs in immune cells from adult mice with premature aging, similar to that shown in leukocytes from chronologically old animals, and if this results in immunosenescence. Several oxidants/antioxidants and inflammatory/anti-inflammatory cytokines were analyzed in peritoneal leukocytes from adult female CD1 mice in two models of premature aging-(a) prematurely aging mice (PAM) and (b) mice with the deletion of a single allele (hemi-zygotic: HZ) of the tyrosine hydroxylase (th) gene (TH-HZ), together with cells from chronologically old animals. Several immune function parameters were also studied in peritoneal phagocytes and lymphocytes. The same oxidants and antioxidants were also analyzed in spleen and thymus leukocytes. The results showed that the immune cells of PAM and TH-HZ mice presented lower values of antioxidant defenses and higher values of oxidants/pro-inflammatory cytokines than cells from corresponding controls, and similar to those in cells from old animals. Moreover, premature immunosenescence in peritoneal leukocytes from both PAM and TH-HZ mice was also observed. In conclusion, adult PAM and TH-HZ mice showed oxidative stress in their immune cells, which would explain their immunosenescence.

Social environment improves immune function and redox state in several organs from prematurely aging female mice and increases their lifespan.

Aging is associated with a chronic oxidative stress (increase of oxidants and decrease of antioxidants), which contributes to immunosenescence and therefore shorter longevity. Nevertheless, a positive social network has been related to the adequate maintenance of health and deceleration of aging. Adult prematurely aging mice (PAM) are characterized by their inadequate stress response to a T-maze, showing premature immunosenescence and oxidative stress establishment. These impairments contribute to shorter life spans in comparison to exceptional non-PAM (ENPAM). However, it is not known whether these characteristics of PAM could be prevented by a positive cohabitation. Therefore, the aim of the present work was to determine if the premature immunosenescence and oxidative stress shown by PAM could be avoided by the cohabitation with ENPAM, increasing their life span. Female CD1 PAM and ENPAM were divided into three experimental groups: PAM controls, ENPAM controls and a social environment experimental group, containing in the same cage ENPAM and PAM (proportion 5/2, respectively). After 2 months, mice were sacrificed and spleen, thymus, liver and heart removed. Later, several immune functions as well as oxidative stress parameters were assessed in spleen and thymus leukocytes. Also, several oxidative stress parameters were analyzed in liver and heart. The results showed that PAM, after co-housing with ENPAM, had improved immune functions and redox balance in spleen and thymus leukocytes. This improvement of redox state was also observed in liver and heart. Furthermore, all these positive effects seem to be related to the increased life span of PAM.

Improvements in Behavior and Immune Function and Increased Life Span of Old Mice Cohabiting With Adult Animals.

The social environment can affect the regulatory systems, and cohabitation with sick subjects is a negative factor for the nervous and immune systems, compromising the life span. Nevertheless, the possible beneficial effects of a positive social environment on nervous and immune functions and longevity have not yet been studied. The aim of this study was to analyze several behavioral and immune function parameters and life span in old mice after their cohabitation with adult animals. Old and adult ICR-CD1 female mice were divided into three experimental groups: adult controls, old controls, and a social environment experimental group. The latter contained two old mice with five adult mice. After 2 months in these conditions, mice were submitted to a behavioral battery of tests to analyze their sensorimotor abilities, anxiety-like behaviors, and exploratory capacities. Peritoneal leukocytes were then collected, and several immune functions as well as oxidative and inflammatory stress parameters were assessed. The animals were maintained in the same conditions until natural death occurred. The results showed that old animals, after cohabitation with adult mice, presented an improvement of behavioral capacities, immune functions, and a lower oxidative and inflammatory stress. Consequently, they exhibited a higher life span.

Role of macrophages in age-related oxidative stress and lipofuscin accumulation in mice.

The age-related changes in the immune functions (immunosenescence) may be mediated by an increase of oxidative stress and damage affecting leukocytes. Although the "oxidation-inflammation" theory of aging proposes that phagocytes are the main immune cells contributing to "oxi-inflamm-aging", this idea has not been corroborated. The aim of this work was to characterize the age-related changes in several parameters of oxidative stress and immune function, as well as in lipofuscin accumulation ("a hallmark of aging"), in both total peritoneal leukocyte population and isolated peritoneal macrophages. Adult, mature, old and long-lived mice (7, 13, 18 and 30 months of age, respectively) were used. The xanthine oxidase (XO) activity-expression, basal levels of superoxide anion and ROS, catalase activity, oxidized (GSSG) and reduced (GSH) glutathione content and lipofuscin levels, as well as both phagocytosis and digestion capacity were evaluated. The results showed an age-related increase of oxidative stress and lipofuscin accumulation in murine peritoneal leukocytes, but especially in macrophages. Macrophages from old mice showed lower antioxidant defenses (catalase activity and GSH levels), higher oxidizing compounds (XO activity/expression and superoxide, ROS and GSSG levels) and lipofuscin levels, together with an impaired macrophage functions, in comparison to adults. In contrast, long-lived mice showed in their peritoneal leukocytes, and especially in macrophages, a well-preserved redox state and maintenance of their immune functions, all which could account for their high longevity. Interestingly, macrophages showed higher XO activity and lipofuscin accumulation than lymphocytes in all the ages analyzed. Our results support that macrophages play a central role in the chronic oxidative stress associated with aging, and the fact that phagocytes are key cells contributing to immunosenescence and "oxi-inflamm-aging". Moreover, the determination of oxidative stress and immune function parameters, together with the lipofuscin quantification, in macrophages, can be used as useful markers of the rate of aging and longevity.

Inmunosenescencia prematura en ratones con una deficiencia en la síntesis de catecolaminas. Efecto del ambiente social / Premature immunosenescence in catecholamines syntesis deficient mice. Effect of social environment

Introducción. La salud depende del buen funcionamiento de los sistemas homeostáticos (el nervioso, endocrino e inmunitario) y de la adecuada comunicación entre ellos. Se ha comprobado que el estado funcional y redox del sistema inmunitario es un excelente marcador de salud, y que una inmunosenescencia prematura supone una menor esperanza de vida. Dado que las catecolaminas modulan la funcionalidad de las células inmunitarias, la alteración en su síntesis podría contribuir a esa inmunosenescencia. Entre las estrategias que se pueden utilizar para controlarla está el ambiente social. Objetivo. Comprobar si una haploinsuficiencia de la tirosina hidroxilasa (TH), enzima limitante de la síntesis de catecolaminas, generaría una inmunosenescencia prematura, y si es posible la modulación de esta por el ambiente social. Material y métodos. Se usaron ratones machos ICR-CD1 adultos (9±1 meses) hemizigotos (HZ) para la tirosina hidroxilasa (TH-HZ) y controles (WT), que fueron distribuidos en cuatro subgrupos: WT>50% (en la jaula, la proporción de WT fue mayor al 50%), WT<50%, TH-HZ<50% y TH-HZ>50%. En leucocitos peritoneales se valoró la fagocitosis, quimiotaxis y linfoproliferación en presencia de lipopolisacárido. También, la actividad de las enzimas antioxidantes glutatión reductasa y glutatión peroxidasa, y el cociente glutatión oxidado/glutatión reducido. Resultados. Los TH-HZ>50% presentaron, en leucocitos, una funcionalidad y estado redox deteriorados respecto a WT>50 y similar a ratones viejos. Sin embargo, los TH-HZ<50% mostraron valores similares a los WT<50%. Conclusión. Una haploinsuficiencia de la enzima TH provoca una inmunosenescencia prematura, la cual puede ser compensada por la convivencia con un número apropiado de animales WT (AU)

Introduction. Healthy state depends on the appropriate function of the homeostatic systems (nervous, endocrine and immune systems) and the correct communication between them. The functional and redox state of the immune system is an excellent marker of health, and animals with premature immunosenescence show a shorter lifespan. Since catecholamines modulate the function of immune cells, the alteration in their synthesis could provoke immunosenescence. The social environment could be a strategy for modulating this immunosenescence. Aim. To determine if an haploinsufficiency of tyrosine hydroxylase (TH), the limiting enzyme of synthesis of catecholamines, may produce a premature immunosenescence and if this immunosenescence could be modulated by the social environment. Materials and methods. Adult (9±1 months) male ICR-CD1 mice with deletion of a single allele (hemi-zygotic: HZ) of the tyrosine hydroxylase enzyme (TH-HZ) and wild-type (WT) mice were used. Animals were housed in four subgroups: WT>50% (in the cage, the proportion of WT mice was higher than 50% in relation to TH-HZ), WT<50%, TH-HZ<50% and TH-HZ>50%. Peritoneal leukocytes were collected and phagocytosis, chemotaxis and proliferation of lymphocytes in the presence of lipopolysaccharide were analyzed. Glutathione reductase and glutathione peroxidase activities as well as oxidized/reduced glutathione ratio were studied. Results. TH-HZ>50% mice showed a deteriorated function and redox state in leukocytes respect to WT>50% and similar to old mice. However, TH-HZ<50% animals had similar values to those found in WT<50% mice. Conclusion. The haploinsufficiency of TH generates premature immunosenescence, which appears to be compensated by living together with an appropriate number of WT animals (AU)

Improved Measurement of Elastic Properties of Cells by Micropipette Aspiration and Its Application to Lymphocytes.

Mechanical deformability of cells is an important property for their function and development, as well as a useful marker of cell state. The classical technique of micropipette aspiration allows single-cell studies and we provide here a method to measure the two basic mechanical parameters, elastic modulus and Poisson's ratio. The proposed method, developed from finite-element analysis of micropipette aspiration experiments, may be implemented in future technologies for the automated measurement of mechanical properties of cells, based on the micropipette aspiration technique or on the cell transit through flow constrictions. We applied this method to measure the elastic parameters of lymphocytes, in which the mechanical properties depend on their activation state. Additionally, we discuss in this work the accuracy of previous models to estimate the elastic modulus of cells, in particular the analytical model by Theret et al., widely used in the field. We show the necessity of using an improved model, taking into account the finite size of the cells, to obtain new insights that may remain hidden otherwise.

[Premature immunosenescence in catecholamines syntesis deficient mice. Effect of social environment]. / Inmunosenescencia prematura en ratones con una deficiencia en la síntesis de catecolaminas. Efecto del ambiente social.

INTRODUCTION: Healthy state depends on the appropriate function of the homeostatic systems (nervous, endocrine and immune systems) and the correct communication between them. The functional and redox state of the immune system is an excellent marker of health, and animals with premature immunosenescence show a shorter lifespan. Since catecholamines modulate the function of immune cells, the alteration in their synthesis could provoke immunosenescence. The social environment could be a strategy for modulating this immunosenescence. AIM: To determine if an haploinsufficiency of tyrosine hydroxylase (TH), the limiting enzyme of synthesis of catecholamines, may produce a premature immunosenescence and if this immunosenescence could be modulated by the social environment. MATERIALS AND METHODS: Adult (9±1 months) male ICR-CD1 mice with deletion of a single allele (hemi-zygotic: HZ) of the tyrosine hydroxylase enzyme (TH-HZ) and wild-type (WT) mice were used. Animals were housed in four subgroups: WT>50% (in the cage, the proportion of WT mice was higher than 50% in relation to TH-HZ), WT<50%, TH-HZ<50% and TH-HZ>50%. Peritoneal leukocytes were collected and phagocytosis, chemotaxis and proliferation of lymphocytes in the presence of lipopolysaccharide were analyzed. Glutathione reductase and glutathione peroxidase activities as well as oxidized/reduced glutathione ratio were studied. RESULTS: TH-HZ>50% mice showed a deteriorated function and redox state in leukocytes respect to WT>50% and similar to old mice. However, TH-HZ<50% animals had similar values to those found in WT<50% mice. CONCLUSION: The haploinsufficiency of TH generates premature immunosenescence, which appears to be compensated by living together with an appropriate number of WT animals.

Immune function parameters as markers of biological age and predictors of longevity.

Chronological age is not a good indicator of how each individual ages and thus how to maintain good health. Due to the long lifespan in humans and the consequent difficulty of carrying out longitudinal studies, finding valid biomarkers of the biological age has been a challenge both for research and clinical studies. The aim was to identify and validate several immune cell function parameters as markers of biological age. Adult, mature, elderly and long-lived human volunteers were used. The chemotaxis, phagocytosis, natural killer activity and lymphoproliferation in neutrophils and lymphocytes of peripheral blood were analyzed. The same functions were measured in peritoneal immune cells from mice, at the corresponding ages (adult, mature, old and long lived) in a longitudinal study. The results showed that the evolution of these functions was similar in humans and mice, with a decrease in old subjects. However, the long-lived individuals maintained values similar to those in adults. In addition, the values of these functions in adult prematurely aging mice were similar to those in chronologically old animals, and they died before their non-prematurely aging mice counterparts. Thus, the parameters studied are good markers of the rate of aging, allowing the determination of biological age.

Topographical and mechanical characterization of living eukaryotic cells on opaque substrates: development of a general procedure and its application to the study of non-adherent lymphocytes.

The mechanical behavior of living murine T-lymphocytes was assessed by atomic force microscopy (AFM). A robust experimental procedure was developed to overcome some features of lymphocytes, in particular their spherical shape and non-adherent character. The procedure included the immobilization of the lymphocytes on amine-functionalized substrates, the use of hydrodynamic effects on the deflection of the AFM cantilever to monitor the approaching, and the use of the jumping mode for obtaining the images. Indentation curves were analyzed according to Hertz's model for contact mechanics. The calculated values of the elastic modulus are consistent both when considering the results obtained from a single lymphocyte and when comparing the curves recorded from cells of different specimens.

Function and redox state of peritoneal leukocytes as preclinical and prodromic markers in a longitudinal study of triple-transgenic mice for Alzheimer's disease.

The aging process involves the impairment of the immune system (immunosenescence), based on the imbalance of the redox status, as occurs in neurodegenerative diseases such as Alzheimer's disease (AD). Since in AD there is a systemic disorder, we aimed to assess longitudinally, from before the onset until the complete establishment of AD, cell populations, several functions, and oxidative stress parameters in peritoneal leukocytes of triple transgenic mice for AD (3xTgAD). These animals mimic the human AD pathophysiology. The results indicate a premature immunosenescence in 3xTgAD at 4 months of age, when the immunoreactivity against intracellular amyloid-ß fibrils appears. Thus, decreases in functions such as chemotaxis, phagocytosis, and lymphoproliferation, as well as a lower reduced glutathione content and higher xanthine oxidase activity, appear in leukocytes. Moreover, NK percentage and cytotoxic activity, CD25+ B and naïve CD8 T cells percentage, GSSG/GSH ratio, and GSH content were already changed before the onset of AD, at the age of 2 months. Furthermore, the changes in some parameters such as CD5+ B1 cells, phagocytosis, lymphoproliferation, and xanthine oxidase activity continue at 15 months of age, when AD pathophysiology is completely established. Because the immune system parameters studied are markers of health and longevity, the premature immunosenescence could explain the shorter life span shown by 3xTgAD observed in the present work. These results suggest that peripheral immune cell functions and their oxidative stress status could be good early peripheral markers of the preclinical and prodromal stages and progression of AD.

A higher anxiety state in old rats after social isolation is associated to an impairment of the immune response.

Social isolation is common in the elderly exerting negative effects on neuroimmunoendocrine communication. Nevertheless physiological responses to a stressful situation may vary according to diverse factors. This work studies the differences in the immune response of aged male rats socially isolated depending on the anxiety levels produced. Social isolation impaired certain immunological parameters, but a more anxious response to isolation was associated to global severe immunosuppression and greater oxidative state. Thus, responding anxiously to isolation may suppose a more potent risk of morbidity and mortality further than isolation and anxiety by themselves, particularly in elderly subjects.

The effect of psychological stress and social isolation on neuroimmunoendocrine communication.

The adaptive response to physical or psychological challenges or threats involves the modulation of the three regulatory systems: the nervous, endocrine and immune systems. Correct communication between these systems is required to maintain a homeostatic balance, and to guarantee the health and survival of the individual. While the stress response is essential for survival, failure to cope with a stress can impair the function of these regulatory systems and prevent effective communication between them. Under such circumstances, the loss of homeostasis ultimately leads to the development of pathologies that can compromise survival. Social species live in groups, the maintenance of which ensures the survival of the individual by providing protection from environmental threats. However, the disruption of social bonds in such species constitutes a potent emotional stress. Thus, social isolation is considered a risk factor for morbidity and mortality. The response to isolation or loneliness can vary greatly between individuals due to the influence of many factors, some of which will be considered in this Review. These factors can exert a significant influence on the three regulatory systems throughout the lifespan of the organism, and they include characteristics of the stressor itself (e.g., duration), as well as those of the organism (e.g., biological age), in addition to external factors (e.g., environmental events).

Lifelong treatment with atenolol decreases membrane fatty acid unsaturation and oxidative stress in heart and skeletal muscle mitochondria and improves immunity and behavior, without changing mice longevity.

The membrane fatty acid unsaturation hypothesis of aging and longevity is experimentally tested for the first time in mammals. Lifelong treatment of mice with the ß1-blocker atenolol increased the amount of the extracellular-signal-regulated kinase signaling protein and successfully decreased one of the two traits appropriately correlating with animal longevity, the membrane fatty acid unsaturation degree of cardiac and skeletal muscle mitochondria, changing their lipid profile toward that present in much more longer-lived mammals. This was mainly due to decreases in 22:6n-3 and increases in 18:1n-9 fatty acids. The atenolol treatment also lowered visceral adiposity (by 24%), decreased mitochondrial protein oxidative, glycoxidative, and lipoxidative damage in both organs, and lowered oxidative damage in heart mitochondrial DNA. Atenolol also improved various immune (chemotaxis and natural killer activities) and behavioral functions (equilibrium, motor coordination, and muscular vigor). It also totally or partially prevented the aging-related detrimental changes observed in mitochondrial membrane unsaturation, protein oxidative modifications, and immune and behavioral functions, without changing longevity. The controls reached 3.93 years of age, a substantially higher maximum longevity than the best previously described for this strain (3.0 years). Side effects of the drug could have masked a likely lowering of the endogenous aging rate induced by the decrease in membrane fatty acid unsaturation. We conclude that it is atenolol that failed to increase longevity, and likely not the decrease in membrane unsaturation induced by the drug.

Inmunosenescencia prematura en ratones triple-transgénicos para la enfermedad del Alzheimer / Premature immunosenescence in triple-transgenic mice for Alzheimer's disease

Introducción. En la enfermedad del Alzheimer (EA) se ha comprobado que existe un deterioro en la comunicación neuroinmunoendocrina. Sin embargo, apenas hay estudios a un nivel periférico en esta enfermedad neurodegenerativa, en concreto en lo que respecta a la función inmunitaria. Dado que recientemente se ha establecido que ciertos parámetros de función inmunitaria son marcadores de la velocidad de envejecimiento y pueden predecir la longevidad, el propósito del presente trabajo fue valorar algunas de esas funciones en leucocitos esplénicos de ratones transgénicos para la EA de diversas edades. Material y métodos. Se emplearon ratones triple-transgénicos para la EA (3 xTgAD) hembras, así como sus controles no transgénicos (NTg) jóvenes (4 ± 1 meses), adultos (9 ± 1 meses) y maduros (12 ± 1 meses). Se valoraron la quimiotaxis, la actividad citotóxica de las «natural killer» (NK) y la respuesta linfoproliferativa en presencia de los mitógenos concanavalina A y lipopolisacárido en leucocitos esplénicos, funciones que disminuyen al envejecer. Además, se realizó una curva de supervivencia en otro grupo de animales 3 xTgAD y NTg. Resultados. En los 3 xTgAD, con respecto a los NTg, la quimiotaxis se encuentra disminuida en todas las edades, mientras que dicha disminución se observa a los 4 y 9 meses en la linfoproliferación y solo en los jóvenes en el caso de la actividad NK. Los 3 xTgAD mostraron una menor supervivencia que los NTg. Conclusiones. Los ratones 3 xTgAD presentan una inmunosenescencia prematura, lo que podría explicar su temprana mortalidad. La valoración a nivel periférico de las funciones inmunológicas estudiadas podría ser un indicador del desarrollo de la enfermedad de Alzheimer (AU)

Introduction. A deterioration of the neuroimmunoendocrine network has been observed in Alzheimer's disease (AD). However, the peripheral immune response has hardly been investigated in this pathology. Since some immune function parameters have been established as good markers of the rate of ageing, and can predict longevity, the aim of the present work was to study some of these functions in splenic leucocytes in transgenic mice for AD of different ages. Material and methods. Young female (4 ± 1 months), adult (9 ± 1 months), and mature (12 ± 1 months) triple-transgenic mice for AD (3 xTgAD) and non-transgenic (NTg) control mice of the same ages were used. The chemotaxis, the anti-tumour activity of «natural killer» (NK) cells and the lymphoproliferative response in the presence of the mitogens concanavalin A and lipopolysaccharide, functions that decrease with age, were determined in splenic leucocytes. In addition, the differences in lifespan between 3 xTgAD and NTg were studied in parallel using other animals, until their death through natural causes. Results. In 3 xTgAD, with respect to NTg, chemotaxis decreased at all ages studied, whereas in lymphoproliferative response this reduction was shown at 4 months and 9 months. NK activity was diminished only in young 3 xTgAD with respect to NTg. The 3 xTgAD showed a shorter lifespan than the NTg control group. Conclusions. The 3 xTgAD mice show a premature immunosenescence, which could explain their early mortality. The determination of these immune functions at peripheral level could serve as a marker of the progression of the Alzheimer's disease (AU)

[Premature immunosenescence in triple-transgenic mice for Alzheimer's disease]. / Inmunosenescencia prematura en ratones triple-transgénicos para la enfermedad del Alzheimer.

INTRODUCTION: A deterioration of the neuroimmunoendocrine network has been observed in Alzheimer's disease (AD). However, the peripheral immune response has hardly been investigated in this pathology. Since some immune function parameters have been established as good markers of the rate of ageing, and can predict longevity, the aim of the present work was to study some of these functions in splenic leucocytes in transgenic mice for AD of different ages. MATERIAL AND METHODS: Young female (4 ± 1 months), adult (9 ± 1 months), and mature (12 ± 1 months) triple-transgenic mice for AD (3 xTgAD) and non-transgenic (NTg) control mice of the same ages were used. The chemotaxis, the anti-tumour activity of « natural killer ¼ (NK) cells and the lymphoproliferative response in the presence of the mitogens concanavalin A and lipopolysaccharide, functions that decrease with age, were determined in splenic leucocytes. In addition, the differences in lifespan between 3 xTgAD and NTg were studied in parallel using other animals, until their death through natural causes. RESULTS: In 3 xTgAD, with respect to NTg, chemotaxis decreased at all ages studied, whereas in lymphoproliferative response this reduction was shown at 4 months and 9 months. NK activity was diminished only in young 3 xTgAD with respect to NTg. The 3 xTgAD showed a shorter lifespan than the NTg control group. CONCLUSIONS: The 3 xTgAD mice show a premature immunosenescence, which could explain their early mortality. The determination of these immune functions at peripheral level could serve as a marker of the progression of the Alzheimer's disease.

The vertebrae of prematurely aging mice as a skeletal model of involutional osteoporosis.

Oxidative stress in bone increases with age, which leads to bone frailty and a high fracture risk. Animal models show that early changes in trabecular structure occur in age-related osteopenia. These models might be valuable to assess the contribution of oxidative stress in age-related bone loss. Premature aging mice (PAM) have previously been characterized as a model of premature immunological and neurological senescence. PAM long bones (mainly consisting of cortical bone) display features of aging bone. Thus, we aimed to evaluate the vertebrae, representing a unique poorly loaded type of trabecular bone in mice, in PAM and no PAM (NPAM) controls. PAM showed an anxious behaviour, based on physical activity evaluation. These mice had decreased bone mineral density (0.078 mg/cm² in NPAM vs 0.070 g/cm² in PAM; p⟨0.05); a decreased number of osteocytes per bone field (404±36 in NPAM vs 320±27 in PAM; p⟨0.01); and downregulation of various osteoblastic genes and low eroded surface/bone surface, 4.2±0.5 in NPAM vs 1.9±0.2 in PAM; p⟨0.01). This was associated with increased expression of oxidative stress markers, Foxo1 and GADD45, in PAM vertebrae. Mesenchymal progenitors in the bone marrow of PAM have a poor mineralization capacity (assessed by the number of mineralized nodules and suface), and showed a lower response to an osteogenic input -represented by parathormone-related protein-, compared to NPAM. Collectively, these results indicate that PAM vertebrae show osteopenia related to diminished bone formation and remodeling. Our findings further support the validity of PAM as a suitable model for involutional osteoporosis and its treatment.

Strategies to improve the functions and redox state of the immune system in aged subjects.

The aging process is accompanied by an impairment of the physiological systems including the immune system. This system is an excellent indicator of health. We have also observed that several functions of the immune cells are good markers of biological age and predictors of longevity. In agreement with the oxidation-inflammation theory that we have proposed, the chronic oxidative stress that appears with age affects all cells and especially those of the regulatory systems, such as the nervous, endocrine and immune systems and the communication between them. This fact prevents an adequate homeostasis and, therefore, the preservation of health. We have also proposed an involvement of the immune system in the aging process of the organism, concretely in the rate of aging, since there is a relation between the redox state and functional capacity of the immune cells and the longevity of individuals. A confirmation of the central role of the immune system in oxi-inflamm-aging is that several lifestyle strategies such as the administration of adequate amounts of antioxidants in the diet, physical exercise, physical and mental activity through environmental enrichment and hormetic interventions improve functions of immune cells, decreasing their oxidative stress, and consequently increasing the longevity of individuals. Recent results in mice of investigations on the effects of a new environmental enrichment (bathing in waters) as well as a hormetic intervention with slight infections (caused by injection of E.coli lipopolysaccharide, LPS), on several functions and redox parameters are shown. The advantages and possible problems of the use of those interventions to achieve a healthy aging and longevity are discussed.