Biomedical subjects

M De la Fuente

Publications and source records attributed to M De la Fuente.

At least 19 recordsLinked to original sources

PubMed2001

Neuropeptide Y effects on murine natural killer activity: changes with ageing and cAMP involvement.

Changes in the bidirectional interaction between the nervous and the immune systems have been proposed as a cause of ageing. Neuropeptides, such as neuropeptide Y (NPY), could show different effects on immune function with age. In the present work, we have studied the in vitro action of a wide range of NPY concentrations, i.e. from 10(-13) to 10(-7) M, on natural killer (NK) activity, a function which decreases with age. Spleen, axillary nodes, thymus and peritoneum leukocytes from mice of different ages: young (12+/-2 weeks), adult (24+/-2 weeks), mature (50+/-2 weeks) and old (72+/-2 weeks) were used. Stimulation by NPY of NK activity was observed in adult and mature animals in axillary nodes and thymus, and an inhibition in the spleen from young mice. The specificity of the NPY effect on cytotoxic activity was confirmed using a C-terminal fragment of NPY. Furthermore, cAMP levels in leukocytes were found to be decreased by NPY in adult mice, suggesting an involvement of this messenger system in the NK modulation by this neuropeptide.

Aging↗

PubMed2001

Changes with aging in the modulation by neuropeptide Y of murine peritoneal macrophage functions.

Some age-related changes in immune function may be due, at least in part, to a disturbance in the communication between the nervous and immune systems. In the present work, the effects in vitro of neuropeptide Y (NPY) (10(-13) to 10(-7) M) on different peritoneal macrophage functions (adherence to substrate, chemotaxis, phagocytosis, superoxide anion production, and the release of TNFalpha and IL-1beta) have been studied on cells from young (12+/-2 weeks), adult (24+/-2 weeks), mature (50+/-2 weeks) and old (72+/-2 weeks) BALB/c mice. The specificity of these actions was confirmed using two C-terminal fragments of NPY, and the intracellular messengers (protein kinase C and cAMP) involved in the action of the neuropeptide were also analyzed. The results show that the functions studied change with aging and that the effects of NPY on each function, which are carried out through specific receptors, as well as on intracellular pathway, differ depending on age, maintaining the immune functions at physiologically adequate levels in old animals.

Aging↗

PubMed2001

Behavioral characterization of a mouse model of premature immunosenescence.

In previous studies we have shown that differences in life span among members of Swiss mouse populations appear to be related to their performance in a T-maze, with a slow performance ("slow" mice) being linked to an impaired immune function and a shorter life span when compared to "fast" mice, which led us to propose the slow mice as a model of immunosenescence. In the present study we demonstrate that in a tightrope test of neuromuscular vigor and coordination the slow mice show a worse performance, needing more time to complete the task. Moreover, these animals show a decreased locomotor activity and an increased level of emotionality/anxiety in three standard behavioral tests (the holeboard, the open field and the plus-maze) when compared to fast mice. All these behavioral features were most marked in the slow females. The results also indicate that slow animals show a decreased chemotaxis of macrophages and lymphocytes, as well as a reduced lymphoproliferative response to mitogens. The data supports our claim that slow or hyperemotional mice, in which immune and neurobehavioural functions appear to be impaired, may be a useful model of premature aging.

Aging, Premature↗

PubMed2001

The immune response of thymic cells from the turtle Mauremys caspica.

In the present work several known mammalian leukocyte functions such as directed mobility, proliferative response to mitogens, antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK)-mediated cytotoxicity were studied in female and male Mauremys caspica turtles. Since the reptilian thymus shows seasonal variations in its structure, we have performed all the assays along the seasonal cycle. Our results show that thymic cells from M. caspica are able to migrate through a chemo-attractant gradient, to proliferate in response to the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A), and to kill tumoral target cells by both ADCC-mediated and NK-mediated cytotoxicity. Those functions were differentially affected by the seasonal cycle; in general, in autumn the functions studied showed the smallest values for both sexes, while in summer the highest values of cytotoxicity and chemotaxis were found in females. The proliferative responses to PHA and Con A were higher for both sexes in spring and for females in winter than in the other seasons. In summary, thymic cells from M. caspica show a wide range of immune functions, and these are modulated heterogeneously by the seasonal cycle in both sexes.

Animals↗

PubMed2000

The NPY effects on murine leukocyte adherence and chemotaxis change with age. Adherent cell implication.

The two-way communication between the nervous and immune system is currently well-known, but the age-related changes in this communication have been scarcely studied. In the present work, we have investigated the in vitro effects of neuropeptide Y (NPY) at concentrations ranging from 10(-13) to 10(-7) M on the adherence and chemotaxis capacities of spleen, axillary node, thymus and peritoneum leukocytes from BALB/c mice. The NPY effect on these functions was examined on cells from animals of four different ages, i.e. young (12+/-2 weeks old), adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). In young animals, NPY stimulates the adherence of leukocytes from spleen, axillary nodes and thymus and inhibits it in cells from peritoneum. In adult animals NPY inhibits the adherence of leukocytes from thymus. These effects disappear with ageing in all locations. Chemotaxis is stimulated by this neuropeptide at all ages in cells from axillary nodes and peritoneum, but this effect is absent in old mice. NPY exerts an inhibitory effect on the chemotaxis of leukocytes from thymus at all ages studied. These NPY effects on leukocytes seem to be carried out through adherent cells.

Aging↗

PubMed2000

Seasonal changes in peripheral blood leukocyte functions of the turtle Mauremys caspica and their relationship with corticosterone, 17-beta-estradiol and testosterone serum levels.

We have studied the most representative functions of lymphocytes such as adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), proliferative response to mitogens and antibody-dependent cellular cytotoxicity (ADCC), as well as natural killer (NK) activity in peripheral blood cells from the turtle Mauremys caspica, and the seasonal changes of these functions in both female and male animals. The plasma levels of steroid hormones were determined to study their relationship with the immune functions. Our results show high chemotaxis, lymphoproliferative response and ADCC as well as NK activity in winter when the levels of corticosterone, testosterone and 17-beta-estradiol were depleted. Proliferative responses to phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were increased in spring correlating with low levels of corticosterone and testosterone in middle and late spring. In summer, the proliferative response was decreased but adherence, chemotaxis, ADCC and NK activity were increased, although steroid hormones showed high plasma levels. In autumn, a depletion of both the hormone levels and the immune response were found except for adherence to substrate. The immune functions studied were strikingly influenced by the seasonal cycle, which induced a different pattern of response depending on the function analyzed. Moreover, these immune cells showed a different degree of dependence on steroids in relation to the function and the season considered, suggesting the existence of other factors that modulate the immune response studied.

Animals↗

PubMed2000

Changes with aging in the modulation of macrophages by norepinephrine.

The effect of aging on the norepinephrine (NE)-induced modulation of phagocytic and oxygen-dependent microbicidal processes of mouse peritoneal macrophages was studied. Phagocytosis of latex beads on culture plates and superoxide anion production was evaluated in young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) BALB/c mice after in vitro incubation with 10(-12), 10(-9), 10(-7), 10(-5) or 10(-3) M concentrations of NE. The results indicate that the phagocytic response to NE is quite similar in young and mature mice, with increased phagocytosis after incubation with 10(-7) and 10(-3) M, and decreased phagocytosis with 10(-5) M. Macrophages from adult mice increased their phagocytic capacity after incubation with the highest concentrations of NE (10(-5) and 10(-3) M) and macrophages from old animals only were stimulated with 10(-3) M. In addition, it was found that usually NE increased the extracellular superoxide anion production in the absence of phagocytosis in adult mice. No statistically significant changes were found in intracellular superoxide anion levels, but an increase was seen after phagocytosis in macrophages from adult, mature and old animals, especially after incubation with 10(-5) M. In conclusion, the results obtained indicate that the modulation of macrophages by NE does not only depend on the concentration of this neurotransmitter, but also on age.

Aging↗

PubMed2000

Effect of aging on the modulation of macrophage functions by neuropeptides.

The existence of a functional connection between the nervous and the immune system is supported by increasing recent evidence. In previous work we have shown that peptides from the nervous system, such as gastrin-releasing peptide (GRP), neuropeptide Y (NPY) and sulfated cholecystokinin octapeptide (CCK-8s), have modulatory effects on the immune functions in adult animals. Since the immunodepression found in aging organisms may be related to changes in the neuroimmune network, the aim of the present work was to study the changes with aging in the effect of CCK-8s, GRP and NPY on peritoneal macrophage functions (adherence to tissues, mobility, ingestion of foreign particles and superoxide anion production) from BALB/c mice of three different ages: adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). The results show that the increase in adherence capacity produced by neuropeptides in cells from adult and mature animals disappears in old mice. The stimulatory effect of GRP and NPY on mobility, ingestion and superoxide production in macrophages from adult mice disappears (GRP) or changes to inhibition (NPY) in cells from old animals. The decrease of these functions caused by CCK-8s in adult or mature animals continues in old mice. These data suggest that the modulation by neuropeptides of the macrophage function changes with the age of animals.

Aging↗

PubMed2000

Increased cerebrospinal fluid fas (Apo-1) levels in Alzheimer's disease. Relationship with IL-6 concentrations.

Increasing lines of evidence suggest a role of apoptosis in the neurodegeneration associated with Alzheimer's disease, in which it has been implicated in increasing the expression of p53 and Fas. On the other hand, inflammatory cytokines have also been implicated as important factors in the progression of neuronal damage in this disease. In an attempt to investigate the possible in vivo relationship between programmed cell death and the inflammatory response in patients with dementia of the Alzheimer type (DAT), we measured the levels of soluble Fas, interleukin-1beta (IL-lbeta) and IL-6 in cerebrospinal fluid (CSF) from ten DAT patients and ten age-matched controls. Our results show a significant increase in IL-6 and soluble Fas concentrations in the CSF of DAT patients compared with those from nondemented controls. Moreover, linear regression analysis demonstrated a significant correlation (r=0.703; P<0.05) between soluble Fas and IL-6 levels in the CSF in DAT patients. These results suggest that Fas is implicated in the inflammatory response observed in Alzheimer's brains.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Ascorbic acid modulates in vitro the function of macrophages from mice with endotoxic shock.

The toxic effects of oxygen radicals produced by immune cells can be controlled to certain degree by endogenous antioxidants because of their scavenger action. This control is specially important in a type of immune cell, i.e., the phagocyte, which produces oxygen-free radicals and uses antioxidants in order to support its functions. Antioxidants, such as ascorbic acid (AA), are free radical scavengers and improve the immune response. In the pathogenesis of endotoxic shock, a disease with high mortality caused by gram-negative bacterial endotoxin, the reactive oxygen species (ROS) produced by phagocytes have been implicated. In a previous study, we observed in peritoneal macrophages from BALB/c mice suffering lethal endotoxic shock caused by intraperitoneal (i.p.) injection of Escherichia coli lipopolysaccharide (LPS; 100 mg/kg) a high production of superoxide anion. Therefore, in the present work, we have studied the in vitro effect of AA, at different concentrations (0.001, 0.01, 0.1, 1 and 2.5 mM), on the various steps of the phagocytic process, i.e., adherence to substrate, chemotaxis, ingestion of particles and superoxide anion production of murine peritoneal macrophages obtained from BALB/c mice with that of endotoxic shock, at 2, 4, 12 and 24 h after LPS injection. The increased adherence, ingestion and superoxide anion production by macrophages from animals with endotoxic shock were lower in the presence of AA, reaching similar values to those of the control animals. The most effective AA concentration in cells from mice with endotoxic shock was 0.01 mM. These data suggest that AA can regulate the phagocytic process in endotoxic shock, principally decreasing free radical production and thus it could reduce endotoxic shock severity.

Animals↗

PubMed2000

Age-related changes in the neuropeptide Y effects on murine lymphoproliferation and interleukin-2 production.

Neuropeptide Y (NPY) modulates several aspects of the immune response but it is not known whether NPY responsiveness is altered with aging. In this work, the in vitro effect of NPY at concentrations ranging from 10(-)(14) M to 10(-)(7) M on lymphoproliferation has been studied in spleen, axillary node and thymus leukocytes from young, adult, mature and old BALB/c mice. The spontaneous proliferation of spleen lymphocytes from young mice was significantly stimulated by NPY. In response to the mitogen Con A, lymphoproliferation and IL-2 release by lymphocytes were inhibited significantly by NPY, these effects disappearing with aging. The results show that NPY is a modulator of lymphoproliferation and that this effect disappears progressively with age. Moreover, this regulatory role of NPY may be carried out through a decrease in IL-2 production.

Aging↗

PubMed2000

Modulation of adherence and chemotaxis of macrophages by norepinephrine. Influence of ageing.

We evaluated the in vitro effect of norepinephrine (NE), over the range of concentrations between 10(-12) M and 10(-3) M, on adherence (to plastic surfaces) and chemotaxis (in a Boyden chamber) of peritoneal macrophages from BALB/c mice of different ages: young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks). Increased adherence was induced by 10(-12) M of NE in macrophages from young, adult, mature and old mice. Also, 10(-9) M stimulated adherence in old animals, 10(-5) M in mature mice, and 10(-3) M in both young and old mices. With respect to chemotaxis, the low concentration of NE (10(-12) M) was stimulatory only in young and adult animals, higher concentrations (10(-5) M and 10(-7) M) were inhibitory for macrophages from mature and old animals, and the highest concentration of NE (10(-3) M) stimulated this capacity of macrophages only in young and mature animals. The conclusion is that while the mobility of macrophages to the focus of infection (i.e. chemotaxis) is stimulated by low concentrations of NE (10(-12) M) only in young-adult animals, this neurotransmitter induces a decline in this capacity in mature and old mice at high concentrations (10(-5) M-10(-7) M). Also, macrophages from old animals have lost the capacity to respond to pharmacological (10(-3) M) concentrations of NE. The lower capacity of response to NE by macrophages from old animals possibly contributes to immunosenescence.

Aging↗

PubMed2000

Anti-oxidants as modulators of immune function.

In order to confirm the hypothesis of the immunomodulating action of anti-oxidants (bringing back altered immune function to more optimum values), the possibility that anti-oxidants may be useful in two experimental models of altered immune function has been studied. The first is a pathological model, that is, lethal murine endotoxic shock caused by an LPS injection of 100 mg/kg, in which the lymphocytes show increased adherence and depressed chemotaxis. The injection of N-acetylcysteine (150 mg/kg), which increased both functions in control animals, decreased adherence and increased chemotaxis in mice with endotoxic shock. The second is a physiological model; aged human subjects (70 +/- 5-year-old men) who, in their largest segment of population ('standard' group) showed an increased lymphocyte adherence and decreased lymphoproliferative response to mitogens compared with younger adults. The ingestion of vitamin E (200 mg daily for 3 months in this standard group) lowered adherence and stimulated lymphoproliferation. However, a smaller segment of the human population tested showed 'non-standard' values in these lymphocyte functions, that is, very low adherence and very high proliferation. In those subjects, vitamin E showed the opposite effects, namely adherence increase and depressed lymphoproliferation. In both age groups of men, these functions reached adult levels after vitamin E ingestion. These data suggest that anti-oxidants preserve adequate function of immune cells against homeostatic disturbances such as those caused by endotoxic shock and ageing.

Acetylcysteine↗

PubMed2000

Changes in macrophage and lymphocyte functions in guinea-pigs after different amounts of vitamin E ingestion.

Vitamin E is the main biological lipid-soluble antioxidant and plays a crucial role in the maintenance of the immune system. In the present work, twenty-one guinea-pigs (3-weeks-old) were distributed into three groups, which during 5 weeks ingested different amounts of vitamin E (/kg diet): 15 mg (low vitamin E diet), 150 mg (medium vitamin E diet; control) or 1500 mg (high vitamin E diet). The function of lymphocytes and macrophages were then studied. In macrophages obtained from the peritoneum several steps of the phagocytic process (chemotaxis, ingestion and superoxide anion production) were assayed, as well as chemotaxis and proliferation of peritoneal and spleen lymphocytes. The results indicate that with respect to the medium vitamin E diet, low ingestion of vitamin E causes a decrease in chemotaxis and production of superoxide anion by macrophages and an increase in the phagocytic capacity. With the high vitamin E diet an increase in macrophage and lymphocyte chemotaxis, superoxide anion production and lymphoproliferative capacity, as well as a decrease in phagocytosis, were observed. Therefore, diet supplementation with higher than usual levels of vitamin E appears to be beneficial for the immune system.

Animals↗

PubMed2000

Comparative study of peritoneal macrophage functions in mice receiving lethal and non-lethal doses of LPS.

In previous studies, we have observed changes in several functions of peritoneal macrophages from female BALB/c mice with lethal endotoxic shock caused by intraperitoneal injection of Escherichia coli O55:B5 lipopolysaccharide (LPS; 100 mg/kg), which were associated with a high production of superoxide anion and tumor necrosis factor alpha (TNF-alpha). In the present work, both a lethal dose (250 mg/kg) and a non-lethal dose (100 mg/kg) of LPS were used in female Swiss mice. In peritoneal macrophages, the following functions were studied at 2, 4, 12 and 24 h after LPS injection: adherence to substrate, chemotaxis, ingestion of particles, and superoxide anion and TNF-alpha production. In both groups, the results showed a stimulation of adherence, ingestion and superoxide production as well as a decrease of chemotaxis, whereas TNF-alpha could not be detected in either of the two groups. These effects were more evident with the 250 mg/kg dose, especially as regards superoxide anion production, which was higher in the animals treated with a lethal dose of LPS.

Animals↗

PubMed1999

Changes in several functions of murine peritoneal macrophages by N-acetylcysteine and thioproline ingestion. Comparative effect between two strains of mice.

The administration of the thiol compounds, N-acetylcysteine (NAC) and in particular thioproline (thiazolidine-4-carboxylic acid) at 0.1% w/w concentration in the diet, improves lymphocyte functions in old female Swiss mice, as has been shown in our previous studies. In the present work, adult mice from two different strains, namely BALB/c (an inbred strain) and OF1-Swiss (noninbred strain), were fed a diet supplemented with the above dose of each thiol compound jointly for five weeks. At 28 weeks of age, peritoneal cell suspensions were obtained and different steps of the phagocytic process, the most representative activity of macrophages, as well as interleukin-1beta (IL-1beta) production, were studied. Thus, adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), ingestion of inert particles and superoxide anion production were analysed. The results show that diet supplementation with NAC plus thioproline increased all macrophage functions studied with the exception of superoxide anion production, which was decreased. These effects were more evident in macrophages from Swiss mice, whereas in BALB/c mice the stimulation of phagocytosis and IL-1beta production was lower and no differences were seen after treatment in adherence and superoxide anion production. These data suggest that immune function can be improved in adult mice by administration of the above thiol compounds, especially in the noninbred strain of OF1-Swiss mice.

Acetylcysteine↗

PubMed1999

N-Acetyl-cysteine inhibition of encephalomyelitis Theiler's virus-induced nitric oxide and tumour necrosis factor-alpha production by murine astrocyte cultures.

The pathological mechanisms that cause central nervous system (CNS) dysfunction in most neurological diseases are not well established. Theiler's murine encephalomyelitis virus (TMEV) is known to interact with cells of the CNS and its intracerebral inoculation to susceptible mice strains causes neurological disorders resembling multiple sclerosis (MS). In this study, we reported that primary astrocyte cultures from SJL/J susceptible mice when infected with TMEV released important amounts of nitrites (NO2-) to the culture medium, as measured in the supernatants 24 hours after infection. In addition, we observed an increment in the production of tumour necrosis factor alpha (TNF-alpha) by susceptible SJL/J strain derived astrocytes infected with TMEV. The treatment with the thiolic antioxidant N-acetyl-cysteine partially suppressed the virus-stimulated production of nitric oxide and TNF-alpha, in a dose response fashion. These results indicate that during viral infection astrocytes are an important cellular source of nitric oxide and TNF-alpha, substances which play important roles during CNS inflammatory events. The effects of the antioxidant N-acetyl-cysteine, modulating the production of the above compounds by TMEV-infected astrocytes may be a significant factor in preventing CNS demyelination.

Acetylcysteine↗

PubMed1999

Effect of a diet supplemented with thioproline on murine macrophage function in a model of premature ageing.

A previous study has shown that diet supplementation with thioproline (thiazolidine-4-carboxylic acid, TCA), an intracellular sulfhydril antioxidant and free radical scavenger, stimulates lymphocyte functions in old mice. In the present work, the effect of thioproline ingestion on the phagocytic functions of peritoneal macrophages, namely adherence, chemotaxis, phagocytosis and superoxide anion production was studied in adult female OF1-Swiss mice, that were fed thioproline (0.1% w/w) for five weeks, starting this ingestion at the age of 22 +/- 2 weeks. Mice were divided into a fast and a slow group based on their exploratory activity, which was assessed by their performance in a T-shaped maze. Slow mice showed a worse phagocytic activity with respect to fast animals. After thioproline treatment, a stimulation of all the functions studied as well as a neutralization of the superoxide radical were observed. The effect of this antioxidant was stronger in the slow than in the fast group. Thus, a diet supplemented with thioproline may enhance the immune functions, especially when they are depressed.

Aging↗