Lorena Arranz

Neuropathy of haematopoietic stem cell niche is essential for myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are diseases caused by mutations in the haematopoietic stem cell (HSC) compartment. Most MPN patients have a common acquired mutation of Janus kinase 2 (JAK2) gene in HSCs that renders this kinase constitutively active, leading to uncontrolled cell expansion. The bone marrow microenvironment might contribute to the clinical outcomes of this common event. We previously showed that bone marrow nestin+ mesenchymal stem cells (MSCs) innervated by sympathetic nerve fibres regulate normal HSCs. Here we demonstrate that abrogation of this regulatory circuit is essential for MPN pathogenesis. Sympathetic nerve fibres, supporting Schwann cells and nestin+ MSCs are consistently reduced in the bone marrow of MPN patients and mice expressing the human JAK2(V617F) mutation in HSCs. Unexpectedly, MSC reduction is not due to differentiation but is caused by bone marrow neural damage and Schwann cell death triggered by interleukin-1β produced by mutant HSCs. In turn, in vivo depletion of nestin+ cells or their production of CXCL12 expanded mutant HSC number and accelerated MPN progression. In contrast, administration of neuroprotective or sympathomimetic drugs prevented mutant HSC expansion. Treatment with β3-adrenergic agonists that restored the sympathetic regulation of nestin+ MSCs prevented the loss of these cells and blocked MPN progression by indirectly reducing the number of leukaemic stem cells. Our results demonstrate that mutant-HSC-driven niche damage critically contributes to disease manifestation in MPN and identify niche-forming MSCs and their neural regulation as promising therapeutic targets.

The neural crest is a source of mesenchymal stem cells with specialized hematopoietic stem cell niche function

Mesenchymal stem cells (MSCs) and osteolineage cells contribute to the hematopoietic stem cell (HSC) niche in the bone marrow of long bones. However, their developmental relationships remain unclear. In this study, we demonstrate that different MSC populations in the developing marrow of long bones have distinct functions. Proliferative mesoderm-derived nestin− MSCs participate in fetal skeletogenesis and lose MSC activity soon after birth. In contrast, quiescent neural crest-derived nestin+ cells preserve MSC activity, but do not generate fetal chondrocytes. Instead, they differentiate into HSC niche-forming MSCs, helping to establish the HSC niche by secreting Cxcl12. Perineural migration of these cells to the bone marrow requires the ErbB3 receptor. The neonatal Nestin-GFP+ Pdgfrα− cell population also contains Schwann cell precursors, but does not comprise mature Schwann cells. Thus, in the developing bone marrow HSC niche-forming MSCs share a common origin with sympathetic peripheral neurons and glial cells, and ontogenically distinct MSCs have non-overlapping functions in endochondrogenesis and HSC niche formation. DOI: http://dx.doi.org/10.7554/eLife.03696.001

Early maternal deprivation and neonatal single administration with a cannabinoid agonist induce long-term sex-dependent psychoimmunoendocrine effects in adolescent rats

Maternal deprivation [24h on postnatal day 9] might represent an animal model of schizophrenia and behavioural and neurochemical alterations observed in adulthood may be mediated by hippocampal impairments induced by abnormally increased glucocorticoids due to neonatal stress. We aimed to provide new data for psychoimmunoendocrine characterization of this animal model by evaluating its effects in adolescent rats of both genders. In previous studies we found that cannabinoid compounds counteracted the enhanced impulsivity of maternally deprived animals and that the cannabinoid receptor agonist WIN 55,212-2 showed neuroprotective properties in neonatal rats. So, we hypothesised that this compound could counteract at least some of the detrimental effects that we expected to find in maternally deprived animals. Accordingly, the drug was administered immediately after the maternal deprivation period. Maternally deprived males showed significantly decreased motor activity in the holeboard and the plus-maze. The cannabinoid agonist induced, exclusively in males, a significant anxiogenic-like effect, which was reversed by maternal deprivation. In the forced swimming test, both treatments independently induced depressive-like responses. Maternal deprivation reduced immunological function whereas the drug exerted tissue-dependent effects on the immune parameters analysed. Maternally deprived females showed reduced corticosterone levels whereas the cannabinoid agonist increased hormone concentration in all groups. In general, the results show detrimental effects of both treatments as well as intriguing interactions, notably in relation to emotional behaviour and certain immunological responses.

Self-Renewing Human Bone Marrow Mesenspheres Promote Hematopoietic Stem Cell Expansion

Strategies for expanding hematopoietic stem cells (HSCs) include coculture with cells that recapitulate their natural microenvironment, such as bone marrow stromal stem/progenitor cells (BMSCs). Plastic-adherent BMSCs may be insufficient to preserve primitive HSCs. Here, we describe a method of isolating and culturing human BMSCs as nonadherent mesenchymal spheres. Human mesenspheres were derived from CD45- CD31- CD71- CD146+ CD105+ nestin+ cells but could also be simply grown from fetal and adult BM CD45--enriched cells. Human mesenspheres robustly differentiated into mesenchymal lineages. In culture conditions where they displayed a relatively undifferentiated phenotype, with decreased adherence to plastic and increased self-renewal, they promoted enhanced expansion of cord blood CD34+ cells through secreted soluble factors. Expanded HSCs were serially transplantable in immunodeficient mice and significantly increased long-term human hematopoietic engraftment. These results pave the way for culture techniques that preserve the self-renewal of human BMSCs and their ability to support functional HSCs.

A Model of Premature Aging in Mice Based on Altered Stress-Related Behavioral Response and Immunosenescence

The intensity of behavioral and neuroendocrine responses to stressful stimuli in rodent strains seems to be inversely related to their life span. We have previously shown that interindividual differences in members of outbred Swiss and inbred BALB/c mouse populations, both male and female, may be related to their behavior in a simple T-maze test. The animals that explore the maze slowly show impaired neuromuscular vigor and coordination, decreased locomotor activity, increased level of emotionality/anxiety, decreased levels of brain biogenic amines as well as immunosenescence and decreased life span, when compared to their control counterparts, which quickly explore the maze. These traits are similar to some of the alterations previously observed in aging animals and therefore we proposed that those ‘slow mice’ are biologically older than the fast animals and may be a model of prematurely aging mice (PAM). Although most of our work on this model has been performed on chronologically adult-mature animals, we have also shown that certain characteristics of PAM, such as increased anxiety and deficient immune response, are already present in chronologically young animals. Thus, it is tempting to hypothesize that chronic hyperreactivity to stress (trait anxiety) leading to immune dysfunction may have a causal relationship with impaired health and premature aging. In view of the link between oxidative stress and the aging process, the redox state of peritoneal leukocytes from PAM has been studied, showing an oxidative stress situation. In the present work we have determined the levels of a key antioxidant, reduced glutathione (GSH), and the oxidant malondialdehyde (MDA), a marker of lipid peroxidation, both in the spleen and brain of male and female PAM and non-PAM (NPAM). We found that GSH and MDA are decreased and increased, respectively, in PAM with respect to NPAM. Moreover, diet supplementation with antioxidants showed to be an effective strategy for protection against early immune and behavioral decline, altered redox state of leukocytes and premature mortality in PAM, which supports the validity of this model of premature aging as well as its link with oxidative stress.

Gender-Specific Neuroimmunoendocrine Aging in a Triple-Transgenic 3×Tg-AD Mouse Model for Alzheimer’s Disease and Its Relation with Longevity

In the present work, we briefly review the evidence on the key role played by the neuroimmunoendocrine network in the etiopathogenesis of Alzheimer’s disease (AD) and provide new behavioral, immune and endocrinological data obtained on old male and female triple-transgenic 3×Tg-AD mice harboring PS1M146V, APPSwe and tauP301L transgenes in contrast to wild-type animals. The results indicate that several aspects of the impairment of the neuroimmunoendocrine network that occurs with aging are more evident in the 3×Tg-AD mice, especially in males. This supports the hypothesis of a premature immunosenescence as a pathogenically relevant factor in AD which was found to be enhanced in the 3×Tg-AD males, suggesting that this could also be responsible for the increased morbidity and mortality of these subjects. Therefore, future research on strategies that could improve the immune system and the other regulatory systems, such as the nervous and the endocrine system, as well as their communication, could have preventive and/or therapeutical effects on that disease. The results also show the relevance of gender differences that should be taken into consideration in both basic and clinical research for assessing new strategies for the control of AD.

Effect of acupuncture treatment on the immune function impairment found in anxious women.

It is presently accepted that emotional disturbances lead to immune system impairment, and that therefore their treatment could restore the immune response. Thus, the aim of the present work was to study the effect of an acupuncture treatment, designed specifically to relieve the emotional symptoms stemming from anxiety, on several functions (adherence, chemotaxis, phagocytosis, basal and stimulated superoxide anion levels, lymphocyte proliferation in response to phytohemagglutinin A (PHA) and natural killer (NK) activity) of leukocytes (neutrophils and lymphocytes) from anxious women. The acupuncture protocol consisted of manual needle stimulation of 19 acupoints, with each session lasting 30 min. It was performed on 34 female 30-60 year old patients, suffering from anxiety, as determined by the Beck Anxiety Inventory (BAI). Before and 72 hours after receiving the first acupuncture session, peripheral blood samples were drawn. In 12 patients, samples were also collected immediately after the first single acupuncture session and one month after the end of the whole acupuncture treatment, which consisted of 10 sessions during a year, until the complete remission of anxiety. Twenty healthy non-anxious women in the same age range were used as controls. The results showed that the most favorable effects of acupuncture on the immune functions appear 72 hours after the single session and persist one month after the end of the complete treatment. Impaired immune functions in anxious women (chemotaxis, phagocytosis, lymphoproliferation and NK activity) were significantly improved by acupuncture, and augmented immune parameters (superoxide anion levels and lymphoproliferation of the patient subgroup whose values had been too high) were significantly diminished. Acupuncture brought the above mentioned parameters to values closer to those of healthy controls, exerting a modulatory effect on the immune system.

Preserved Immune Functions and Controlled Leukocyte Oxidative Stress in Naturally Long-lived Mice: Possible Role of Nuclear Factor Kappa B

In order to verify the survival biomarker role of several immune functions, and to determine the oxidation and inflammation mechanisms underlying variability in the aging process, we have investigated a variety of immune functions and oxidative stress parameters as well as activation of the nuclear factor kappa B (NF kappaB) in peritoneal leukocytes from four different age groups of mice, including natural extreme longevity. Immune cells from naturally long-lived animals showed preservation of immune function in response to stimuli and controlled oxidative stress as well as nuclear factor kappa B activation in resting conditions. Moreover, leukocytes from extreme long-lived animals showed increased catalase activity when compared with the adults. In contrast, the old and very old animal groups showed impaired immune function and increased oxidation as well as NF kappaB activation. Our results support preserved immune function as a biomarker of extended survival and point to controlled regulation of NF kappaB activity as a key mechanism restraining oxidative stress in immune cells and contributing to reach longevity.

The glutathione precursor N-acetylcysteine improves immune function in postmenopausal women

Aging is a chronic oxidation process in which the immune system is involved. Because leukocyte functions is a good health marker and longevity predictor, the effects of daily oral administration of N-acetylcysteine (NAC, 600 mg) on several lymphocyte (adherence, chemotaxis, proliferation, natural killer activity) and neutrophil (adherence, chemotaxis, phagocytosis, superoxide) functions, as well as cytokine levels (interleukin-2, tumor necrosis factor alpha, interleukin-8), were studied in 36 healthy postmenopausal women: 18 aged 50-69 years and 18 aged > 69 years. In addition, plasma and leukocyte oxidative stress markers (glutathione, superoxide, malondialdehyde) were evaluated. These parameters were analyzed within 2 and 4 months of of NAC intake and 3 months after the end of the supplementation. In parallel, samples from 18 healthy adult women aged 30-49 years were used as a control age group. the results showed general impairment of immune function and increased oxidation markers in postmenopausal women as compared with the control group; however, NAC administration significantly improved the parameters studied, bringing their values closer to those of younger women and thus exerting a modulatory, rather than a merely stimulatory, action on the immune system. These effects were also observed 3 months after the end of supplementation. The present finding suggest that a short period of NAC supply (i.e., 2-4 months) at the dose used may lead to prolonged strengthening of immune defence in postmenopausal women, likely by increasing the leukocyte glutathione pool. Thus, NAC could contribute to maintenance of good health and quality of life in postmenopausal women by decreasing the probability of immune system-related diseases, such as infections, in aging.

Environmental Enrichment Improves Age-Related Immune System Impairment: Long-Term Exposure Since Adulthood Increases Life Span in Mice

Age-related changes in immunity have been shown to highly influence morbidity and mortality. The aim of the present work was to study the effects of environmental enrichment (EE) (8-16 weeks) on several functions and oxidative stress parameters of peritoneal leukocytes, previously described as health and longevity markers, in mice at different ages, namely adult (44 +/- 4 weeks), old (69 +/- 4 weeks), and very old (92 +/- 4 weeks). Mortality rates were monitored in control and enriched animals, and effects on survival of long-term exposure to EE until natural death were determined. The results showed that exposure to EE was efficient in improving the function (i.e., macrophage chemotaxis and phagocytosis, lymphocyte chemotaxis and proliferation, natural killer cell activity, interleukin-2 and tumor necrosis factor-alpha levels) and decreasing the oxidative-inflammatory stress (i.e., lowered oxidized glutathione content, xanthine oxidase activity, expression of Toll-like receptors 2 and 4 on CD4 and CD8 cells, and increased reduced glutathione and glutathione peroxidase and catalase activities) of immune cells. These positive effects of EE were especially remarkable in animals at older ages. Importantly, long-term exposure to EE from adult age and until natural death stands out as a useful strategy to extend longevity. Thus, the present work confirms the importance of maintaining active mental and/or physical activity aiming to improve quality of life in terms of immunity, and demonstrates that this active life must be initiated at early stages of the aging process and preserved until death to improve life span.