Intermittent systemic exposure to lipopolysaccharide-induced inflammation disrupts hippocampal long-term potentiation and impairs cognition in aging male mice.

Age-related cognitive decline, a common component of the brain aging process, is associated with significant impairment in daily functioning and quality of life among geriatric adults. While the complexity of mechanisms underlying cognitive aging are still being elucidated, microbial exposure and the multifactorial inflammatory cascades associated with systemic infections are emerging as potential drivers of neurological senescence. The negative cognitive and neurobiological consequences of a single pathogen-associated inflammatory experience, such as that modeled through treatment with lipopolysaccharide (LPS), are well documented. Yet, the brain aging impacts of repeated, intermittent inflammatory challenges are less well studied. To extend the emerging literature assessing the impact of infection burden on cognitive function among normally aging mice, here, we repeatedly exposed adult mice to intermittent LPS challenges during the aging period. Male 10-month-old C57BL6 mice were systemically administered escalating doses of LPS once every two weeks for 2.5 months. We evaluated cognitive consequences using the non-spatial step-through inhibitory avoidance task, and both spatial working and reference memory versions of the Morris water maze. We also probed several potential mechanisms, including cortical and hippocampal cytokine/chemokine gene expression, as well as hippocampal neuronal function via extracellular field potential recordings. Though there was limited evidence for an ongoing inflammatory state in cortex and hippocampus, we observed impaired learning and memory and a disruption of hippocampal long-term potentiation. These data suggest that a history of intermittent exposure to LPS-induced inflammation is associated with subtle but significantly impaired cognition among normally aging mice. The broader impact of these findings may have important implications for standard of care involving infections in aging individuals or populations at-risk for dementia.

Role of B cells and the aging brain in stroke recovery and treatment.

As mitigation of brain aging continues to be a key public health priority, a wholistic and comprehensive consideration of the aging body has identified immunosenescence as a potential contributor to age-related brain injury and disease. Importantly, the nervous and immune systems engage in bidirectional communication and can exert profound influence on each other. Emerging evidence supports numerous impacts of innate, inflammatory immune responses and adaptive T cell-mediated immunity in neurological function and diseased or injured brain states, such as stroke. Indeed, a growing body of evidence supports key impacts of brain-resident immune cell activation and peripheral immune infiltration in both the post-stroke acute injury phase and the long-term recovery period. As such, modulation of the immune system is an attractive strategy for novel therapeutic interventions for a devastating age-related brain injury for which there are few readily available neuroprotective treatments or neurorestorative approaches. However, the role of B cells in the context of brain function, and specifically in response to stroke, has not been thoroughly elucidated and remains controversial, leaving our understanding of neuroimmune interactions incomplete. Importantly, emerging evidence suggests that B cells are not pathogenic contributors to stroke injury, and in fact may facilitate functional recovery, supporting their potential value as novel therapeutic targets. By summarizing the current knowledge of the role of B cells in stroke pathology and recovery and interpreting their role in the context of their interactions with other immune cells as well as the immunosenescence cascades that alter their function in aged populations, this review supports an increased understanding of the complex interplay between the nervous and immune systems in the context of brain aging, injury, and disease.

Over-expression of miR-34a induces rapid cognitive impairment and Alzheimer's disease-like pathology.

Autosomal dominant Alzheimer disease (AD) is caused by rare mutations in one of three specific genes. This is in contrast to idiopathic, late-onset AD (LOAD), which has a more polygenetic risk profile and represents more than 95% of cases. Previously, we have demonstrated that increased expression of microRNA (miRNA)-34a (miR-34a) in AD brain targets genes linked to synaptic plasticity, energy metabolism, and resting state network activity. Here we report the generation of a heterozygous, conditional miR-34a overexpression mouse (miR-34a+/-(TetR-TetO-miR-34a) Transgenic Mice). Doxycycline-treated mice of either sex exhibited profound behavioral impairment compared to untreated groups with only 1-2 months of over-expression of miR-34a. Cognitive impairment of individual mice in T- and Y-maze tasks correlated with elevated miR-34a expression in many parts of the brain including the hippocampus and prefrontal cortex, regions which are known to be involved in this task and implicated in LOAD dysfunction. Immunocytochemistry of brain sections from mice show high amyloid ß and phosphorylated tau-specific staining in the hippocampus and cortex. Analysis of protein samples from these mice revealed that miR-34a targets specific genes involved in memory formation, amyloid precursor protein (APP) metabolism and phosphorylation-dephosphorylation of tau. Thus, our results suggest that the polygenetic dysfunction caused by miR-34a may occur in LOAD and disclose miR-34a as a potential therapeutic target. SIGNIFICANCE STATEMENT: Late-onset Alzheimer disease (LOAD) is associated with multiple gene alleles, a polygenetic profile of risk factors that is difficult to model in animals. Our approach to modeling LOAD was to produce a conditional over-expressing, miR-34a mouse using doxycycline-induction to activate expression. We observed that miR-34a over-expression results in a rapid cognitive impairment, associated with accumulation of intracellular Aß and tau hyperphosphorylation in multiple brain regions. Targets for miR-34a, including ADAM10, NMDAR 2B, and SIRT1 RNAs, were profoundly reduced by miR-34a over-expression. Collectively, these results indicate that a rapid, profound cognitive decline and Alzheimer's disease neuropathology can be induced with miR-34a over-expression, suggesting that this animal model may represent a polygenetic risk factor model for LOAD.

Estrogens as neuroprotectants: Estrogenic actions in the context of cognitive aging and brain injury.

There is ample empirical evidence to support the notion that the biological impacts of estrogen extend beyond the gonads to other bodily systems, including the brain and behavior. Converging preclinical findings have indicated a neuroprotective role for estrogen in a variety of experimental models of cognitive function and brain insult. However, the surprising null or even detrimental findings of several large clinical trials evaluating the ability of estrogen-containing hormone treatments to protect against age-related brain changes and insults, including cognitive aging and brain injury, led to hesitation by both clinicians and patients in the use of exogenous estrogenic treatments for nervous system outcomes. That estrogen-containing therapies are used by tens of millions of women for a variety of health-related applications across the lifespan has made identifying conditions under which benefits with estrogen treatment will be realized an important public health issue. Here we provide a summary of the biological actions of estrogen and estrogen-containing formulations in the context of aging, cognition, stroke, and traumatic brain injury. We have devoted special attention to highlighting the notion that estrogen appears to be a conditional neuroprotectant whose efficacy is modulated by several interacting factors. By developing criteria standards for desired beneficial peripheral and neuroprotective outcomes among unique patient populations, we can optimize estrogen treatments for attenuating the consequences of, and perhaps even preventing, cognitive aging and brain injury.

Homologous platelet-rich plasma for the treatment of knee involvement in primary Sjögren’s syndrome.

Primary Sjögren’s syndrome (pSS) is a chronic autoimmune disease characterized by dry eyes, dry mouth, and other clinical manifestations. The most common extraglandular manifestation of pSS is articular involvement and to date their management is unclear. The aims of the current pilot study were to assess the safety and the outcomes of homologous platelet-rich plasma (HPRP) injections in pSS cohort affected by knee arthralgia/arthritis at short-term follow up. This pilot study provides the first evidence that HPRP injections are a safe treatment and induce a short-term clinical improvement. Although the lack of a control group, randomization and long-term follow up prevents the assessment of the real effectiveness of this treatment, further studies are needed to confirm these findings and to determine the mechanism of action, biological changes and disease-modifying properties of PRP.

Reprint of: From the 90׳s to now: A brief historical perspective on more than two decades of estrogen neuroprotection.

UNLABELLED: Historical perspective abstract:From the 90׳s to now: a historical perspective on more than two decades of estrogen neuroprotection: In the early 90׳s, estrogens were known to exert organizational and activational effects on reproductive tissues and sexual behavior. As well, the role of sex and gonadal hormones in altering the risk for developing Alzheimer׳s Disease (AD) was only beginning to be elucidated. Preliminary investigations suggested that estrogen-containing therapies typically given for the management of disruptive menopausal symptoms could reduce AD risk, attenuate disease-associated cognitive deficits, and modulate brain substrates known to be dysregulated by the condition, such as the cholingeric system. The findings from our seminal paper demonstrating cognitive benefits and cholinergic impacts with exogenous estrogen treatment in a rodent model of surgical hormone depletion provided initial support for use of estrogen-containing therapies as a treatment for age-related brain disorders. We then went on to demonstrate neuroprotective actions of estrogen in several other in vivo and in vitro models of neurological challenge, including stroke and AD. Further, our findings of the chemical structure requirements for estrogen׳s neuroprotective effects identified a novel approach for optimizing future estrogen-containing hormone therapy options. These early efforts laid the groundwork for later, large-scale clinical investigations into the potential of estrogen-based menopausal hormone therapies for the prevention of a variety of age-related disorders. Although findings of these studies were equivocal, the neuroprotective actions of estrogen, and specifically 17ß-estradiol, identified by early investigations, remain well-documented. Future development of interventions that optimize cognitive aging are crucial and, with proper understanding of the factors that influence the realization of beneficial impacts, estrogen-containing treatments may still be among these. ORIGINAL ARTICLE ABSTRACT: Ovarian steroid deprivation results in a reversible learning impairment and compromised cholinergic function in female Sprague-Dawley rats: We hypothesized that estradiol (E2) serves as a neurotrophomodulatory substance for basal forebrain cholinergic neurons thought to be involved in learning and memory. Learning/memory was assessed using the two-way active avoidance paradigm and the Morris water task. Female Sprague-Dawley rats were either ovariectomized (OVX) or OVX for 3 weeks, followed by s.c. implantation of a Silastic pellet containing 17-ßE2 (E2 pellet), resulting in a replacement of E2 to physiological levels. Ovary-intact (INTACT) animals served as our positive control. Active avoidance behavior and choline acetyltransferase (ChAT) activity in the frontal cortex and hippocampus were assessed at 5 and 28 weeks postovariectomy while performance on the Morris water task and high-affinity choline uptake (HACU) were measured only at the 5-week time point. At the 5-week time point, E2 replacement caused a significant elevation in the level of active avoidance performance relative to OVX animals. At the 28-week time point, OVX animals demonstrated a significantly lower number of avoidances relative to controls (61%) whereas E2-pellet animals not only demonstrated superior performance relative to OVX animals but also showed an accelerated rate of learning. Morris water task performance, on the other hand, was not significantly affected by estrogenic milieu despite a trend towards better performance in the E2-pellet group. Neurochemical analyses revealed that 5 weeks of ovariectomy was sufficient to reduce HACU in both the frontal cortex and hippocampus by 24 and 34%, respectively, while E2 replacement was successful in elevating HACU relative to OVX animals in both regions. ChAT activity was decreased in the hippocampus but not the frontal cortex of 5-week OVX animals. E2 replacement resulted in a reversal of this effect. At the 28-week time period, an unexpected decrease in ChAT activity was observed across all treatment groups. Interestingly, E2-pellet animals demonstrated the least severe decline in ChAT. This phenomenon was most evident in the frontal cortex where ChAT decreased by 61 and 56% in INTACT and OVX animals, respectively, whereas the decline in E2-pellet animals was only 16% over the same time period, suggesting a previously unreported cytoprotective effect of E2. Taken together, these findings demonstrate important effects of estrogens on cholinergic neurons and support the potential use of estrogen therapy in treatment of dementias in postmenopausal women. © 1994. This article is part of a Special Issue entitled SI:50th Anniversary Issue.

From the 90's to now: A brief historical perspective on more than two decades of estrogen neuroprotection.

Historical perspective abstract:From the 90's to now: a historical perspective on more than two decades of estrogen neuroprotection: In the early 90's, estrogens were known to exert organizational and activational effects on reproductive tissues and sexual behavior. As well, the role of sex and gonadal hormones in altering the risk for developing Alzheimer's Disease (AD) was only beginning to be elucidated. Preliminary investigations suggested that estrogen-containing therapies typically given for the management of disruptive menopausal symptoms could reduce AD risk, attenuate disease-associated cognitive deficits, and modulate brain substrates known to be dysregulated by the condition, such as the cholingeric system. The findings from our seminal paper demonstrating cognitive benefits and cholinergic impacts with exogenous estrogen treatment in a rodent model of surgical hormone depletion provided initial support for use of estrogen-containing therapies as a treatment for age-related brain disorders. We then went on to demonstrate neuroprotective actions of estrogen in several other in vivo and in vitro models of neurological challenge, including stroke and AD. Further, our findings of the chemical structure requirements for estrogen's neuroprotective effects identified a novel approach for optimizing future estrogen-containing hormone therapy options. These early efforts laid the groundwork for later, large-scale clinical investigations into the potential of estrogen-based menopausal hormone therapies for the prevention of a variety of age-related disorders. Although findings of these studies were equivocal, the neuroprotective actions of estrogen, and specifically 17ß-estradiol, identified by early investigations, remain well-documented. Future development of interventions that optimize cognitive aging are crucial and, with proper understanding of the factors that influence the realization of beneficial impacts, estrogen-containing treatments may still be among these. ORIGINAL ARTICLE ABSTRACT: Ovarian steroid deprivation results in a reversible learning impairment and compromised cholinergic function in female Sprague-Dawley rats: We hypothesized that estradiol (E2) serves as a neurotrophomodulatory substance for basal forebrain cholinergic neurons thought to be involved in learning and memory. Learning/memory was assessed using the two-way active avoidance paradigm and the Morris water task. Female Sprague-Dawley rats were either ovariectomized (OVX) or OVX for 3 weeks, followed by s.c. implantation of a Silastic pellet containing 17-ßE2 (E2 pellet), resulting in a replacement of E2 to physiological levels. Ovary-intact (INTACT) animals served as our positive control. Active avoidance behavior and choline acetyltransferase (ChAT) activity in the frontal cortex and hippocampus were assessed at 5 and 28 weeks postovariectomy while performance on the Morris water task and high-affinity choline uptake (HACU) were measured only at the 5-week time point. At the 5-week time point, E2 replacement caused a significant elevation in the level of active avoidance performance relative to OVX animals. At the 28-week time point, OVX animals demonstrated a significantly lower number of avoidances relative to controls (61%) whereas E2-pellet animals not only demonstrated superior performance relative to OVX animals but also showed an accelerated rate of learning. Morris water task performance, on the other hand, was not significantly affected by estrogenic milieu despite a trend towards better performance in the E2-pellet group. Neurochemical analyses revealed that 5 weeks of ovariectomy was sufficient to reduce HACU in both the frontal cortex and hippocampus by 24 and 34%, respectively, while E2 replacement was successful in elevating HACU relative to OVX animals in both regions. ChAT activity was decreased in the hippocampus but not the frontal cortex of 5-week OVX animals. E2 replacement resulted in a reversal of this effect. At the 28-week time period, an unexpected decrease in ChAT activity was observed across all treatment groups. Interestingly, E2-pellet animals demonstrated the least severe decline in ChAT. This phenomenon was most evident in the frontal cortex where ChAT decreased by 61 and 56% in INTACT and OVX animals, respectively, whereas the decline in E2-pellet animals was only 16% over the same time period, suggesting a previously unreported cytoprotective effect of E2. Taken together, these findings demonstrate important effects of estrogens on cholinergic neurons and support the potential use of estrogen therapy in treatment of dementias in postmenopausal women. © 1994. This article is part of a Special Issue entitled SI:50th Anniversary Issue.

EFFECT OF PLATELET RICH PLASMA CONCENTRATION ON SKELETAL MUSCLE REGENERATION: AN EXPERIMENTAL STUDY.

Skeletal muscle injuries are common causes of severe long-term pain and physical disability, accounting for up to 55% of all sports injuries. The phases of the healing processes after direct or indirect muscle injury are complex but clearly defined and include well-coordinated steps: degeneration, inflammation, regeneration, and fibrosis. Despite this frequent occurrence and the presence of a body of data on the pathophysiology of muscle injuries, none of the current treatment strategies have shown to be really effective in strictly controlled trials. Platelet-rich plasma (PRP) is a promising alternative approach based on the ability of autologous growth factors (GFs) to accelerate tissue healing, improve muscular regeneration, increase neovascularization and reduce fibrosis. The present study is focused on the use of different concentrations of PRP as a source of GFs. Unilateral muscle lesions were created on the longissimus dorsi muscle of Wistar rats. Twenty-four h after surgical trauma, the lesion was filled with an intramuscular injection of PRP at 2 different concentrations. A group of rats were left untreated (controls). Animals were sacrificed at 3, 15 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The PRP-treated muscles showed better muscle regeneration, more neovascularization and a slight reduction of fibrosis compared with the control muscles in a dose dependent manner. However, further studies also assessing pain and functional recovery are scheduled.

Sulfated N-(carboxymethyl)chitosans: novel blood anticoagulants.

N-(Carboxymethyl)chitosan was subjected to sulfation in a mixture of concentrated sulfuric acid (oleum) and N,N-dimethylformamide, under anhydrous conditions. The resulting product contained 11% of sulfur and degree of substitution: N-acetyl, 42%; N-carboxymethyl, 58%; and sulfate, 100%. Sonication of the sulfated N-(carboxymethyl)chitosan gave two main fractions whose molecular weights were 39,000 and 80,000. In human blood, complexes of sulfated N-(carboxymethyl)chitosan and antithrombin inhibited both thrombin and factor Xa, and produced neither hemolysis nor alterations in erythrocytes and lymphocytes. Sulfated N-(carboxymethyl)chitosan is therefore proposed as a blood anticoagulant.

[Antiplatelet antibodies. Evaluation of a method of indirect immunofluorescence]. / Anticorpi anti-piastrine. Valutazione di una metodica di immunofluorescenza indiretta.

The sera of 55 primary autoimmune thrombocytopenic purpura patients were examined with indirect immunofluorescence method. The authors intended to verify the sensibility of an indirect method and to determine the class of detected antibody. The test has been positive in 28 of the 55 examined patients (51%). In these patients isolated or associated IgG, IgM, IgA have been detected. The method has shown a fair sensibility, a good reliability and a sure utility in those patients whose severe thrombocytopenia does not allow the execution of a direct method.