Sex Dependent Disparities in the Central Innate Immune Response after Moderate Spinal Cord Contusion in Rat.

Subacute spinal cord injury (SCI) displays a complex pathophysiology associated with pro-inflammation and ensuing tissue damage. Microglia, the resident innate immune cells of the CNS, in concert with infiltrating macrophages, are the primary contributors to SCI-induced inflammation. However, subpopulations of activated microglia can also possess immunomodulatory activities that are essential for tissue remodeling and repair, including the production of anti-inflammatory cytokines and growth factors that are vital for SCI recovery. Recently, reports have provided convincing evidence that sex-dependent differences exist in how microglia function during CNS pathologies and the extent to which these cells contribute to neurorepair and endogenous recovery. Herein we employed flow cytometry and immunohistochemical methods to characterize the phenotype and population dynamics of activated innate immune cells within the injured spinal cord of age-matched male and female rats within the first week (7 days) following thoracic SCI contusion. This assessment included the analysis of pro- and anti-inflammatory markers, as well as the expression of critical immunomodulatory kinases, including P38 MAPK, and transcription factors, such as NFκB, which play pivotal roles in injury-induced inflammation. We demonstrate that activated microglia from the injured spinal cord of female rats exhibited a significantly diminutive pro-inflammatory response, but enhanced anti-inflammatory activity compared to males. These changes included lower levels of iNOS and TLR4 expression but increased levels of ARG-1 and CD68 in females after SCI. The altered expression of these markers is indicative of a disparate secretome between the microglia of males and females after SCI and that the female microglia possesses higher phagocytic capabilities (increased CD68). The examination of immunoregulatory kinases and transcription factors revealed that female microglia had higher levels of phosphorylated P38Thr180/Tyr182 MAPK and nuclear NFκB pp50Ser337 but lower amounts of nuclear NFκB pp65Ser536, suggestive of an attenuated pro-inflammatory phenotype in females compared to males after SCI. Collectively, this work provides novel insight into some of the sex disparities that exist in the innate immune response after SCI and indicates that sex is an important variable when designing and testing new therapeutic interventions or interpretating positive or negative responses to an intervention.

Comparison of the Efficacy and Safety of Sublingual Versus Oral Misoprostol for the Induction of Labor: A Randomized Open-Label Study.

Introduction Misoprostol (prostaglandin E1 analog) is being used for the induction of labor by vaginal, oral, and sublingual routes. Oral misoprostol is the preferred route for induction of labor, but the use of sublingual misoprostol appears promising due to a faster onset of action. This study was done to compare the efficacy and safety of oral and sublingual misoprostol for induction of labor in term pregnancy. Materials and methods One hundred and sixty patients were randomly allocated to one of the two groups to receive 50 micrograms of oral and sublingual misoprostol four hourly for a maximum of six doses. Primigravida at 37-42 weeks of gestation with singleton pregnancy, cephalic presentation, Bishop score (<5), and reassuring fetal heart rate were included in the study. Misoprostol dose was withheld if the active phase of labor was reached or if the cervix was favorable for amniotomy (Bishop score greater than or equal to eight). The change in the Bishop score with misoprostol was studied along with adverse effects and neonatal outcomes. Results The mean number of 50 mcg misoprostol doses required was significantly less in the sublingual group (2.94±0.97 versus 2.13±0.92; p<0.0001). The rate of change of the mean Bishop score was faster in the sublingual group. After four hours of the first dose, the mean Bishop score changed to 3.52±2.14 versus 4.68±2.34 (p=0.001), and, similarly, after eight hours, it was 10.48±2.59 versus 11.39±2.06, and this difference was statistically significant (p=0.015). The mean induction delivery interval was significantly lower in the sublingual group. The need for labor augmentation, mode of delivery, and adverse effects were similar in both groups. The incidence of meconium-stained liquor and NICU admission was also similar in both groups. Conclusion Sublingmisoprostolstol has a short induction delivery interval and comparable side effects when compared to omisoprostolstol. Sublingmisoprostolstol is recommended for induction of labor at term.

Schwann Cell-Derived Exosomal Vesicles: A Promising Therapy for the Injured Spinal Cord.

Exosomes are nanoscale-sized membrane vesicles released by cells into their extracellular milieu. Within these nanovesicles reside a multitude of bioactive molecules, which orchestrate essential biological processes, including cell differentiation, proliferation, and survival, in the recipient cells. These bioactive properties of exosomes render them a promising choice for therapeutic use in the realm of tissue regeneration and repair. Exosomes possess notable positive attributes, including a high bioavailability, inherent safety, and stability, as well as the capacity to be functionalized so that drugs or biological agents can be encapsulated within them or to have their surface modified with ligands and receptors to imbue them with selective cell or tissue targeting. Remarkably, their small size and capacity for receptor-mediated transcytosis enable exosomes to cross the blood-brain barrier (BBB) and access the central nervous system (CNS). Unlike cell-based therapies, exosomes present fewer ethical constraints in their collection and direct use as a therapeutic approach in the human body. These advantageous qualities underscore the vast potential of exosomes as a treatment option for neurological injuries and diseases, setting them apart from other cell-based biological agents. Considering the therapeutic potential of exosomes, the current review seeks to specifically examine an area of investigation that encompasses the development of Schwann cell (SC)-derived exosomal vesicles (SCEVs) as an approach to spinal cord injury (SCI) protection and repair. SCs, the myelinating glia of the peripheral nervous system, have a long history of demonstrated benefit in repair of the injured spinal cord and peripheral nerves when transplanted, including their recent advancement to clinical investigations for feasibility and safety in humans. This review delves into the potential of utilizing SCEVs as a therapy for SCI, explores promising engineering strategies to customize SCEVs for specific actions, and examines how SCEVs may offer unique clinical advantages over SC transplantation for repair of the injured spinal cord.

Influence of different LED wavelengths on retinal melatonin levels - A rodent study.

BACKGROUND: Retinal melatonin is crucial for neuroprotection. Exposure to light-emitting diodes (LEDs) affects retinal neurons, possibly influencing retinal melatonin levels. Hence, we aimed to quantify the retinal melatonin level with different LED wavelengths. METHOD: A total of 24 Sprague Dawley (SD) male rats were divided into four groups (n = 6 in each group) as normal controls (NC), blue light (BL), white light (WL), and yellow light (YL). The rats in the experimental groups were exposed to different wavelengths of LEDs for 28 days (12:12 h light-dark cycle) with uniform illumination of 450-500 lx. Following exposure, the rats were subjected to behavioral tests such as passive avoidance and elevated plus maze tests. Following the behavior tests, the rats were sacrificed, eyes were enucleated, and retinal tissue was stored at -80 °C. The homogenized retina was used for reactive oxygen species (ROS) and melatonin quantification using an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: Passive avoidance test revealed a significant difference across the groups (p < 0.0004). The BL exposure group demonstrated increased latency to enter the dark compartment (DC) and impaired motor memory. The elevated plus maze test revealed a significant difference across all the groups (p < 0.012), where the time spent in the closed arm was greater in the BL exposure group. Comparison of ROS levels revealed a significant difference across the groups (p < 0.0001), with increased nitric oxide concentrations in the experimental groups. Melatonin levels were significantly decreased in the light exposure groups (p < 0.0001) compared to the NC group. CONCLUSION: Cumulative exposure to different LED wavelengths resulted in increased anxiety with impaired motor activity. This was also complemented by the addition of oxidative stress leading to decreased melatonin levels in the retina, which might trigger retinal neuronal damage.

A novel flood risk mapping approach with machine learning considering geomorphic and socio-economic vulnerability dimensions.

Quantifying flood hazards by employing hydraulic/hydrodynamic models for flood risk mapping is a widely implemented non-structural flood management strategy. However, the unavailability of multi-domain and multi-dimensional input data and expensive computational resources limit its application in resource-constrained regions. The fifth and sixth IPCC assessment reports recommend including vulnerability and exposure components along with hazards for capturing risk on human-environment systems from natural and anthropogenic sources. In this context, the present study showcases a novel flood risk mapping approach that considers a combination of geomorphic flood descriptor (GFD)-based flood susceptibility and often neglected socio-economic vulnerability components. Three popular Machine Learning (ML) models, namely Decision Tree (DT), Random Forest (RF), and Gradient-boosted Decision Trees (GBDT), are evaluated for their abilities to combine digital terrain model-derived GFDs for quantifying flood susceptibility in a flood-prone district, Jagatsinghpur, located in the lower Mahanadi River basin, India. The area under receiver operating characteristics curve (AUC) along with Cohen's kappa are used to identify the best ML model. It is observed that the RF model performs better compared to the other two models on both training and testing datasets, with AUC score of 0.88 on each. The socio-economic vulnerability assessment follows an indicator-based approach by employing the Charnes-Cooper-Rhodes (CCR) model of Data Envelopment Analysis (DEA), an efficient non-parametric ranking method. It combines the district's relevant socio-economic sensitivity and adaptive capacity indicators. The flood risk classes at the most refined administrative scale, i.e., village level, are determined with the Jenks natural breaks algorithm using flood susceptibility and socio-economic vulnerability scores estimated by the RF and CCR-DEA models, respectively. It was observed that >40 % of the villages spread over Jagatsinghpur face high and very high flood risk. The proposed novel framework is generic and can be used to derive a wide variety of flood susceptibility, vulnerability, and subsequently risk maps under a data-constrained scenario. Furthermore, since this approach is relatively data and computationally parsimonious, it can be easily implemented over large regions. The exhaustive flood maps will facilitate effective flood control and floodplain planning.

Comparative Profiling of TG2 and Its Effectors in Human Relapsing Remitting and Progressive Multiple Sclerosis.

Multiple Sclerosis (MS) is a chronic CNS autoimmune disease characterized by immune-mediated demyelination, axon loss, and disability. Dysregulation of transglutaminase-2 (TG2) has been implicated in disease initiation and progression. Herein, TG2 expression in post-mortem human brain tissue from Relapsing Remitting MS (RRMS) or Progressive MS (PMS) individuals were examined and correlated with the presence of TG2 binding partners and effectors implicated in the processes of inflammation, scar formation, and the antagonism of repair. Tissues from Relapsing-Remitting Multiple Sclerosis (RRMS; n = 6), Progressive Multiple Sclerosis (PMS; n = 5), and non-MS control (n = 6) patients underwent immunohistochemistry for TG2, PLA2, COX-2, FN, CSPG, and HSPG. TG2 was strongly upregulated in active RRMS and PMS lesions, within blood vessels and the perivascular tissue of sclerotic plaques. TG2 colocalization was observed with GFAP+ astrocytes and ECM, including FN, HSPG, and CSPG, which also increased in either RRMS or PMS lesions. Although TG2 was not colocalized with inflammatory mediators COX-2 and PLA2, or the macrophage-microglia marker Iba1, its increased expression correlated with their elevation in active RRMS and PMS lesions. In summary, the correlation of strong TG2 induction in either RRMS or PMS with some of its binding partners but not others implicates potentially different roles for TG2 in disparate MS forms that may warrant further investigation.

Analysis of Pregnant Women Recovered From Antenatal SARS-CoV-2 Infection: An Observational Study.

Background and objective The global health care system is facing the challenge of diagnosing and treating the ongoing coronavirus disease 2019 (COVID-19) pandemic. Pregnant women belong to a vulnerable group, and the effect of the virus on the mother and fetus is not well established. The aim of the study was to understand the maternal and fetal outcomes after recovery from antenatal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods  This was a retrospective observational study conducted at Tata Main Hospital, Jamshedpur, India. It included all COVID-19-negative pregnant women who had delivered between 1st January 2021 and 31st August 2021 and had tested positive in the antenatal period (by reverse transcription-polymerase chain reaction (RT-PCR)), the details of which are available in the hospital database. Results A total of 53 women were included in our study who had tested positive in the antenatal period and had turned negative during delivery. Out of the 53 women, 5.7% were infected in the first trimester, 34% in the second trimester, and 60.3% were positive in the third trimester. We found an asymptomatic subgroup in 52.8% of women and mild symptoms in 41.5% of women. Two women were admitted in their antenatal period with moderate COVID-19 disease and one with severe. Preterm births between 34 weeks and 37 weeks were seen in 26.4% of women. Vaginal delivery accounted for 30.2% of cases. The most common indications for cesarean section were fetal distress (17%), previous cesarean section (17%), and unwillingness for vaginal delivery. Out of the 53 pregnant women included in the study, acute respiratory distress syndrome (ARDS) was seen in two women- one diagnosed intraoperatively during cesarean section and the other was diagnosed on the first postoperative day. Conclusion The study showed that pregnant women infected with SARS-CoV-2 usually have no/mild symptoms, and they recover well and have favorable maternal and neonatal outcomes. However, perinatal vigilance is advisable in these cases, as there is a risk of developing respiratory morbidity.

Torsion of Uterus Didelphys at Term: Once-in-a-Lifetime Experience for an Obstetrician.

Torsion of the gravid uterus is very rare in obstetric practice. We report a case of torsion in the uterus didelphys at term which is rare and a lifetime experience for an obstetrician. The patient, a 25-year-old gravida 2 para 1 was admitted to the labor ward at 37 weeks and six days of gestation with abdominal pain. Her previous delivery was a caesarean section performed four years back. She was taken to the operating room for an emergency caesarean section for fetal distress and the lie was transverse. On entering the peritoneal cavity, we found an engorged infundibulopelvic ligament with the fallopian tube and ovary covering the lower segment of the uterus. The baby was successfully delivered by breech extraction. Due to uterine torsion of more than 180 degrees, the posterior surface of the uterus was placed anteriorly, and the incision was made on the posterior surface of the uterus. There was a hemi uterus on the left side of the pelvic cavity with the fallopian tube and ovary attached to it; a diagnosis of uterus didelphys was made. The diagnosis of uterine torsion is intraoperative and prompt and timely decision by surgeons is crucial. We had favorable maternal and fetal outcomes in this rare and interesting case. The diagnosis, though rare, should be kept in mind in all cases of abdominal pain during pregnancy, especially in those with malpresentation.

Mosquito Bite and Adnexal Mass: The Unusual Diagnosis of Ovarian Filariasis.

Lymphatic filariasis is a major health problem in tropical regions especially in India. A large number of patients tend to be asymptomatic. Ovarian filariasis is an extremely rare manifestation of lymphatic filariasis. This is a case report of bilateral ovarian filariasis presenting as ovarian mass with associated lower abdominal pain, weight loss and chyluria. This is a very rare diagnosis, more so as it was diagnosed preoperatively by ultrasound and managed with anti-filarial drugs and confirmed by biopsy. Most cases of ovarian filariasis reported in literature are incidental diagnosis on histopathological examination of postoperative specimen.

Pregnancy and Childbirth: An Unexpected Cakewalk for a Mother With Beta Thalassemia Major Homozygous for IVS (G-C) Mutation.

The thalassemias are the most common single-gene disorders of hemoglobin synthesis. The salient features of beta thalassemia major, in which both alleles of the HBB gene are affected, are transfusion dependency and iron overload. Although with advances in treatment, the life expectancy in such patients has increased, they have difficulty in conceiving. We report a case of pregnancy in a beta thalassemia major patient who was transfusion independent and had no iron overload. Genetic analysis revealed IVS 1-5 (G-C) mutation in the homozygous state which usually manifests in severe disease and blood transfusion dependency. On the contrary, she did not need blood transfusion, had a smooth antenatal period and a vaginal delivery at term with a favorable childbirth experience. This case report highlights complex genetic interplay and the role of fetal hemoglobin (HbF) enhancer loci which modulates HbF levels thereby raising total hemoglobin levels.

Engineering polysialic acid on Schwann cells using polysialyltransferase gene transfer or purified enzyme exposure for spinal cord injury transplantation.

Polysialic acid (PolySia) is a critical post-translational modification on the neural cell adhesion molecule (NCAM, a.k.a., CD56), important for cell migration and axon growth during nervous system development, plasticity and repair. PolySia induction on Schwann cells (SCs) enhances their migration, axon growth support and ability to improve functional recovery after spinal cord injury (SCI) transplantation. In the current investigation two methods of PolySia induction on SCs, lentiviral vector transduction of the mouse polysialytransferase gene ST8SIA4 (LV-PST) or enzymatic engineering with a recombinant bacterial PST (PSTNm), were examined comparatively for their effects on PolySia induction, SC migration, the innate immune response and axon growth after acute SCI. PSTNm produced significant PolySia induction and a greater diversity of surface molecule polysialylation on SCs as evidenced by immunoblot. In the scratch wound assay, PSTNm was superior to LV-PST in the promotion of SC migration and gap closure. At 24 h after SCI transplantation, PolySia induction on SCs was most pronounced with LV-PST. Co-delivery of PSTNm with SCs, but not transient cell exposure, led to broader induction of PolySia within the injured spinal cord due to polysialylation upon both host cells and transplanted SCs. The innate immune response after SCI, measured by CD68 immunoreactivity, was similar among PolySia induction methods. LV-PST or PSTNm co-delivery with SCs provided a similar enhancement of SC migration and axon growth support above that of unmodified SCs. These studies demonstrate that LV-PST and PSTNm provide comparable acute effects on SC polysialation, the immune response and neurorepair after SCI.

Neuronal and Endothelial Transglutaminase-2 Expression during Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis.

Transglutiminase-2 (TG2) is a multifunctional enzyme that has been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS) using global knockout mice and TG2 selective inhibitors. Previous studies have identified the expression of TG2 in subsets of macrophages-microglia and astrocytes after EAE. The aims of the current investigation were to examine neuronal expression of TG2 in rodent models of chronic-relapsing and non-relapsing EAE and through co-staining with intracellular and cell death markers, provide insight into the putative role of TG2 in neuronal pathology during disease progression. Here we report that under normal physiological conditions there is a low basal expression of TG2 in the nucleus of neurons, however following EAE or MS, robust induction of cytoplasmic TG2 occurs in most neurons surrounding perivascular lesion sites. Importantly, TG2-positive neurons also labeled for phosphorylated Extracellular signal-regulated kinase 1/2 (ERK1/2) and the apoptotic marker cleaved caspase-3. In white and gray matter lesions, high levels of TG2 were also found within the vasculature and endothelial cells as well as in tissue migrating pericytes or fibroblasts, though rarely did TG2 colocalize with cells identified with glial cell markers (astrocytes, oligodendrocytes and microglia). TG2 induction occurred concurrently with the upregulation of the blood vessel permeability factor and angiogenic molecule Vascular Endothelial Growth Factor (VEGF). Extracellular TG2 was found to juxtapose with fibronectin, within and surrounding blood vessels. Though molecular and pharmacological studies have implicated TG2 in the induction and severity of EAE, the cell autonomous functions of this multifunctional enzyme during disease progression remains to be elucidated.

Programmed supramolecular nanoassemblies: enhanced serum stability and cell specific triggered release of anti-cancer drugs.

A bolaamphiphilic cross-linked nanoassembly endowed with pH responsive degradation features has been designed and fabricated for stable noncovalent guest encapsulation and controlled release. The self-assembled bolaamphiphile is utilized to prepare cross-linked nanoassemblies to further stabilize the noncovalent guest encapsulation at a concentration below its critical aggregation concentration (CAC) in a large volume of water or serum for drug delivery applications. Thus, this system can simultaneously address premature drug release and safety issues. The nanoassemblies integrated with a ß-thioester linker, which can be hydrolyzed selectively under mildly acidic conditions (pH ∼ 5.3) at a slow rate, thus enable controlled release of guest molecules. Biological evaluation revealed that doxorubicin loaded cross-linked nanoassemblies (CNs-DOX) are nontoxic to normal cells such as HEK-293 or PBMC, but in contrast, showed a robust apoptotic effect on colon cancer cells, HCT-116, indicating excellent specificity. Thus, the fabrication reproducibility, robust stability, triggered drug release and cell selective toxicity behavior make this small molecular system very promising in the field of chemotherapeutic applications.

Kinetics of lipid oxidation in omega fatty acids rich blends of sunflower and sesame oils using Rancimat.

Blended sunflower (SO) (50-80%) and sesame oils (SEO) (20-50%) were evaluated for thermo-oxidative stability (induction period, IP), oxidation kinetics (rate constant, k), synergy and shelf-life (25 °C) (IP25) using Rancimat (100, 110, 120, and 130 °C). The Arrhenius equation (ln k vs. 1/T) and activated complex theory (ln k/T vs. 1/T) were used to estimate activation energies, activation enthalpies and entropies, which varied from 92.05 to 99.17 kJ/mol, 88.83 to 95.94 kJ/mol, -35.58 to -4.81 J/mol K, respectively (R2 > 0.90, p < 0.05). Oil blend (OB) with 1:1 SO to SEO exhibited greatest synergy (115%), highest IP (100 °C) (13.2 vs. 6.1 h) and most extended IP25 (193 vs. 110 days) with a nutritionally stable composition of ω-fatty acids (ω9, 34.5 vs. 28.7%; ω6, 49 vs. 52%) compared with SO. Better retention of lignans (6205 vs. 3951 mg/kg) and tocopherols (332 vs. 189 mg/kg) were also noted in OB compared with SO alone.

Novel Arginine-containing Macrocyclic MMP Inhibitors: Synthesis, 99mTc-labeling, and Evaluation.

Matrix metalloproteinases (MMPs) are involved in tissue remodeling. Accordingly, MMP inhibitors and related radiolabeled analogs are important tools for MMP-targeted imaging and therapy in a number of diseases. Herein, we report design, synthesis, and evaluation of a new Arginine-containing macrocyclic hydroxamate analog, RYM, its hydrazinonicotinamide conjugate, RYM1 and 99mTc-labeled analog 99mTc-RYM1 for molecular imaging. RYM exhibited potent inhibition against a panel of recombinant human (rh) MMPs in vitro. RYM1 was efficiently labeled with 99mTcO4- to give 99mTc-RYM1 in a high radiochemical yield and high radiochemical purity. RYM1 and its decayed labeling product displayed similar inhibition potencies against rhMMP-12. Furthermore, 99mTc-RYM1 exhibited specific binding with lung tissue from lung-specific interleukin-13 transgenic mice, in which MMP activity is increased in conjunction with tissue remodeling and inflammation. The results support further development of such new water-soluble Arginine-containing macrocyclic hydroxamate MMP inhibitors for targeted imaging and therapy.

Schwann Cell Transplantation Subdues the Pro-Inflammatory Innate Immune Cell Response after Spinal Cord Injury.

The transplantation of Schwann cells (SCs) has been shown to provide tissue preservation and support axon growth and remyelination as well as improve functional recovery across a diverse range of experimental spinal cord injury (SCI) paradigms. The autologous use of SCs has progressed to Phase 1 SCI clinical trials in humans where their use has been shown to be both feasible and safe. The contribution of immune modulation to the protective and reparative actions of SCs within the injured spinal cord remains largely unknown. In the current investigation, the ability of SC transplants to alter the innate immune response after contusive SCI in the rat was examined. SCs were intraspinally transplanted into the lesion site at 1 week following a thoracic (T8) contusive SCI. Multicolor flow cytometry and immunohistochemical analysis of specific phenotypic markers of pro- and anti-inflammatory microglia and macrophages as well as cytokines at 1 week after SC transplantation was employed. The introduction of SCs significantly attenuated the numbers of cluster of differentiation molecule 11B (CD11b)⁺, cluster of differentiation molecule 68 (CD68)⁺, and ionized calcium-binding adapter molecule 1 (Iba1)⁺ immune cells within the lesion implant site, particularly those immunoreactive for the pro-inflammatory marker, inducible nitric oxide synthase (iNOS). Whereas numbers of anti-inflammatory CD68⁺ Arginase-1 (Arg1⁺) iNOS- cells were not altered by SC transplantation, CD68⁺ cells of an intermediate, Arg1⁺ iNOS⁺ phenotype were increased by the introduction of SCs into the injured spinal cord. The morphology of Iba1⁺ immune cells was also markedly altered in the SC implant, being elongated and in alignment with SCs and in-growing axons versus their amoeboid form after SCI alone. Examination of pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß), and anti-inflammatory cytokines, interleukin-4 (IL-4) and interleukin-10 (IL-10), by multicolor flow cytometry analysis showed that their production in CD11b⁺ cells was unaltered by SC transplantation at 1 week post-transplantation. The ability of SCs to subdue the pro-inflammatory iNOS⁺ microglia and macrophage phenotype after intraspinal transplantation may provide an important contribution to the neuroprotective effects of SCs within the sub-acute SCI setting.

Phosphodiesterase Inhibitors as a Therapeutic Approach to Neuroprotection and Repair.

A wide diversity of perturbations of the central nervous system (CNS) result in structural damage to the neuroarchitecture and cellular defects, which in turn are accompanied by neurological dysfunction and abortive endogenous neurorepair. Altering intracellular signaling pathways involved in inflammation and immune regulation, neural cell death, axon plasticity and remyelination has shown therapeutic benefit in experimental models of neurological disease and trauma. The second messengers, cyclic adenosine monophosphate (cyclic AMP) and cyclic guanosine monophosphate (cyclic GMP), are two such intracellular signaling targets, the elevation of which has produced beneficial cellular effects within a range of CNS pathologies. The only known negative regulators of cyclic nucleotides are a family of enzymes called phosphodiesterases (PDEs) that hydrolyze cyclic nucleotides into adenosine monophosphate (AMP) or guanylate monophosphate (GMP). Herein, we discuss the structure and physiological function as well as the roles PDEs play in pathological processes of the diseased or injured CNS. Further we review the approaches that have been employed therapeutically in experimental paradigms to block PDE expression or activity and in turn elevate cyclic nucleotide levels to mediate neuroprotection or neurorepair as well as discuss both the translational pathway and current limitations in moving new PDE-targeted therapies to the clinic.

Identifying the Long-Term Role of Inducible Nitric Oxide Synthase after Contusive Spinal Cord Injury Using a Transgenic Mouse Model.

Inducible nitric oxide synthase (iNOS) is a potent mediator of oxidative stress during neuroinflammation triggered by neurotrauma or neurodegeneration. We previously demonstrated that acute iNOS inhibition attenuated iNOS levels and promoted neuroprotection and functional recovery after spinal cord injury (SCI). The present study investigated the effects of chronic iNOS ablation after SCI using inos-null mice. iNOS-/- knockout and wild-type (WT) control mice underwent a moderate thoracic (T8) contusive SCI. Locomotor function was assessed weekly, using the Basso Mouse Scale (BMS), and at the endpoint (six weeks), by footprint analysis. At the endpoint, the volume of preserved white and gray matter, as well as the number of dorsal column axons and perilesional blood vessels rostral to the injury, were quantified. At weeks two and three after SCI, iNOS-/- mice exhibited a significant locomotor improvement compared to WT controls, although a sustained improvement was not observed during later weeks. At the endpoint, iNOS-/- mice showed significantly less preserved white and gray matter, as well as fewer dorsal column axons and perilesional blood vessels, compared to WT controls. While short-term antagonism of iNOS provides histological and functional benefits, its long-term ablation after SCI may be deleterious, blocking protective or reparative processes important for angiogenesis and tissue preservation.

Cyclic AMP is a key regulator of M1 to M2a phenotypic conversion of microglia in the presence of Th2 cytokines.

BACKGROUND: Microglia and macrophages play a central role in neuroinflammation. Pro-inflammatory cytokines trigger their conversion to a classically activated (M1) phenotype, sustaining inflammation and producing a cytotoxic environment. Conversely, anti-inflammatory cytokines polarize the cells towards an alternatively activated (M2), tissue reparative phenotype. Elucidation of the signal transduction pathways involved in M1 to M2 phenotypic conversion may provide insight into how the innate immune response can be harnessed during distinct phases of disease or injury to mediate neuroprotection and neurorepair. METHODS: Microglial cells (cell line and primary) were subjected to combined cyclic adenosine monophosphate (cyclic AMP) and IL-4, or either alone, in the presence of pro-inflammatory mediators, lipopolysaccharide (LPS), or tumor necrosis factor-α (TNF-α). Their effects on the expression of characteristic markers for M1 and M2 microglia were assessed. Similarly, the M1 and M2 phenotypes of microglia and macrophages within the lesion site were then evaluated following a contusive spinal cord injury (SCI) to the thoracic (T8) spinal cord of rats and mice when the agents were administered systemically. RESULTS: It was demonstrated that cyclic AMP functions synergistically with IL-4 to promote M1 to M2 conversion of microglia in culture. The combination of cyclic AMP and IL-4, but neither alone, induced an Arg-1(+)/iNOS(-)cell phenotype with concomitant expression of other M2-specific markers including TG2 and RELM-α. M2-converted microglia showed ameliorated production of pro-inflammatory cytokines (TNF-α and IP-10) and reactive oxygen species, with no alteration in phagocytic properties. M2a conversion required protein kinase A (PKA), but not the exchange protein directly activated by cyclic AMP (EPAC). Systemic delivery of cyclic AMP and IL-4 after experimental SCI also promoted a significant M1 to M2a phenotypic change in microglia and macrophage population dynamics in the lesion. CONCLUSIONS: Using primary microglia, microglial cell lines, and experimental models of CNS injury, we demonstrate that cyclic AMP levels are a critical determinant in M1-M2 polarization. High levels of cyclic AMP promoted an Arg-1(+) M2a phenotype when microglia were activated with pro-inflammatory stimuli and Th2 cytokines. Th2 cytokines or cyclic AMP independently did not promote these changes. Phenotypic conversion of microglia provides a powerful new therapeutic approach for altering the balance of cytotoxic to reparative microglia in a diversity of neurological diseases and injury.