Abnormal myelination underlies the pathology of white matter diseases such as preterm white matte... more Abnormal myelination underlies the pathology of white matter diseases such as preterm white matter injury and multiple sclerosis. Osteopontin (OPN) has been suggested to play a role in myelination. Murine OPN mRNA is translated into a secreted isoform (sOPN) or an intracellular isoform (iOPN). Whether there is an isoform‐specific involvement of OPN in myelination is unknown. Here we generated mouse models that either lacked both OPN isoforms in all cells (OPN‐KO) or lacked sOPN systemically but expressed iOPN specifically in oligodendrocytes (OLs‐iOPN‐KI). Transcriptome analysis of isolated oligodendrocytes from the neonatal brain showed that genes and pathways related to increase of myelination and altered cell cycle control were enriched in the absence of the two OPN isoforms in OPN‐KO mice compared to control mice. Accordingly, adult OPN‐KO mice showed an increased axonal myelination, as revealed by transmission electron microscopy imaging, and increased expression of myelin‐related proteins. In contrast, neonatal oligodendrocytes from OLs‐iOPN‐KI mice compared to control mice showed differential regulation of genes and pathways related to the increase of cell adhesion, motility, and vasculature development, and the decrease of axonal/neuronal development. OLs‐iOPN‐KI mice showed abnormal myelin formation in the early phase of myelination in young mice and signs of axonal degeneration in adulthood. These results suggest an OPN isoform‐specific involvement, and a possible interplay between the isoforms, in myelination, and axonal integrity. Thus, the two isoforms of OPN need to be separately considered in therapeutic strategies targeting OPN in white matter injury and diseases.
Staphylococcus epidermidis (S. epidermidis) is the most common nosocomial pathogen in preterm inf... more Staphylococcus epidermidis (S. epidermidis) is the most common nosocomial pathogen in preterm infants and associated with increased risk of cognitive delay, however, underlying mechanisms are unknown. We employed morphological, transcriptomic and physiological methods to extensively characterize microglia in the immature hippocampus following S. epidermidis infection. 3D morphological analysis revealed activation of microglia after S. epidermidis. Differential expression combined with network analysis identified NOD‐receptor signaling and trans‐endothelial leukocyte trafficking as major mechanisms in microglia. In support, active caspase‐1 was increased in the hippocampus and using the LysM‐eGFP knock‐in transgenic mouse, we demonstrate infiltration of leukocytes to the brain together with disruption of the blood–brain barrier. Our findings identify activation of microglia inflammasome as a major mechanism underlying neuroinflammation following infection. The results demonstrate that neonatal S. epidermidis infection share analogies with S. aureus and neurological diseases, suggesting a previously unrecognized important role in neurodevelopmental disorders in preterm born children.
Galactomannan (GM) antigen is an aspergillus specific antigen that is released during the growth ... more Galactomannan (GM) antigen is an aspergillus specific antigen that is released during the growth phase of invasive aspergillosis. We aimed to find the optimum cutoff and accuracy of serum Galactomannan assay in immunocompromised patients. Immunocompromised patients diagnosed with invasive pulmonary aspergillosis (IPA) based on the European Organization for Research and Treatment of Cancer/Invasive Mycosis Study Group (EORTC/MSG) with three levels of certainty proven, probable and possible, referred for GM antigen measurement at Immunology, Asthma and Allergy Research Institute (IAARI) from 2006 to 2009 and if they met the criteria were enrolled in this study. Totally 49 patients with IPA were enrolled in our study. According to EORTC/MSG, patients categorized into three levels of certainty: They were diagnosed as 'proven' invasive pulmonary aspergillosis 16(32.7%), 'probable' 18(36.7%) and 'possible' 15(30.6%). The most common host risk factor was solid tumors 17(34.7%). The accuracy of Galactomannan assay increased from 0.5 to 2 cutoffs. The optimum sensitivity and specificity obtained at the index cutoff of ≥1.5 for diagnosis of "proven" IPA; which were respectively, 69.2% and 72.2%. Other cutoffs had high variance between sensitivity and specificity for diagnosis of IPA. The calculated cutoff gained by receiver operating characteristic (ROC) analysis for detecting proven IPA was 1.5. Intermediate accuracy of serum GM test in conjunct with clinical findings would help early IPA detection among immunocompromised patients.
Autism Spectrum Disorders (ASD) are heterogeneous neurodevelopmental disorders with considerably ... more Autism Spectrum Disorders (ASD) are heterogeneous neurodevelopmental disorders with considerably increased risk in male infants born preterm and with neonatal infection. Here we investigated the role of postnatal immune activation on hippocampal synaptopathology by targeting Reelin+ cells in mice with ASD-like behavior. C57/Bl6 mouse pups of both sexes received lipopolysaccharide (LPS, 1mg/kg) on postnatal day (P) 5. At P45, animal behavior was examined by marble burying and sociability test, followed by ex-vivo brain MRI diffusion kurtosis imaging (DKI). Hippocampal synaptogenesis, number and morphology of Reelin+ cells, and mRNA expression of trans-synaptic genes, including neurexin-3, neuroligin-1, and cell-adhesion molecule nectin-1 were analyzed at P12 and P45. Social withdrawal and increased stereotypic activities in males were related to increased mean diffusivity on MRI-DKI and overgrowth in hippocampus together with retention of long-thin immature synapses on apical dendrites, decreased volume and number of Reelin+ cells as well as reduced expression of trans-synaptic and cell-adhesion molecules. The study provides new insights into sex-dependent mechanisms that may underlie ASD-like behavior in males following PIA. We identify GABAergic interneurons as core components of dysmaturation of excitatory synapses in the hippocampus following postnatal infection and provide cellular and molecular substrates for the MRI findings with translational value.
The purpose of this study was to investigate any association between IgA deficiency (IgAD) and ju... more The purpose of this study was to investigate any association between IgA deficiency (IgAD) and juvenile rheumatoid arthritis (JRA) among Iranian children.This case-control study was carried out on 83 children who were diagnosed as JRA according to American College of Rheumatology (ACR) criteria; Patients were admitted at the rheumatology clinic of Children's Medical Center, (Tehran). Serum immunoglobulins concentrations were determined by nephelometry method. Control group was 112 healthy children who were matched for age and gender. Informed consent obtained from all parents.Selective IgA deficiency (sIgAD) was found only in a boy (1.2%) among JRA children; however, partial IgA deficiency was found in 6(7.1%) of patients with JRA and in 12(10.7%) of control subjects, this difference was not statistically significant (p=0.46). Immunoglobulins levels in patients with JRA (IgM: 126.7±57.2, IgG: 1182.3±351 and IgA:169.3±98) were significantly higher than their controls (IgM: 104±52, IgG:802±220 and IgA: 94.6±47) (p<0.05). Patients with growth failure had higher IgM, IgG and IgA levels in comparison with patients without growth failure; however, this difference was significant about IgM and IgG levels (p<0.05).In contrast to other similar studies, the number of IgAD did not differ significantly between JRA patients and their control counterpart; this might be partly due to the high rate of consanguineous marriages in Iran that resulted in increased prevalence of clinically undiagnosed partial IgAD in general population. Hence, future epidemiological studies are warranted to make it clear.
Schizophrenia (SCZ) is a psychiatric disorder that can include symptoms of disorganized speech an... more Schizophrenia (SCZ) is a psychiatric disorder that can include symptoms of disorganized speech and thoughts with uncertain underlying mechanisms possibly linked to over‐activated microglia. In this study, we used brain samples from sixteen donors with SCZ and thirteen control donors to assess the differential activation of microglia by quantifying density and 3D reconstruction of microglia stained with ionized calcium‐binding adaptor molecule‐1 (Iba1). Our samples consisted of sections from the frontal, temporal, and cingulate cortical gray matter, subcortical white matter regions (SCWM), and included the anterior corpus callosum. In the first series of studies, we performed a density analysis followed by a spatial analysis to ascertain the microglial density, distribution, and soma size in SCZ brains. Second, we performed a series of morphological quantification techniques to investigate the arborization patterns of the microglia in SCZ. The results demonstrated an increase in microglia density in the cortical gray matter regions in SCZ cases, while in the SCWM, there was a significant increase in microglia density in the frontal and temporal, but not in the other brain regions of interest (ROIs). Spatial analysis using the “nearest neighbor” demonstrated that there was no effect in “clustering”, but there were shorter distances between microglia seen in the SCZ cases. The morphological measures showed that there was a region‐dependent increase in the microglia soma size in the SCZ cases while the Sholl analysis revealed a significant decrease in the microglia arborization in the SCZ cases across all the ROI’s studied. An in‐depth 3D reconstruction of microglia in Brodmann area 9 cortical region found that there was a significant association between age and reduced microglial arborization in the SCZ cases. This region‐dependent age association can help determine whether longitudinal changes in microglial activation across age are brain region‐dependent, which may point to potential therapeutic targets.
Transient cerebral ischemia followed by reperfusion in an infarcted brain comes with predictable ... more Transient cerebral ischemia followed by reperfusion in an infarcted brain comes with predictable acute and chronic morphological alterations in neuronal and non-neuronal cells. An accurate delineation of the cerebral infarct is not a simple task due to the complex shapes and indistinct borders of the infarction. Thus, an exact macroscopic histological approach for infarct volume estimation can lead to faster and more reliable preclinical research results. This study investigated the effect(s) of confounding factors such as fixation and tissue embedding on the quality of macroscopic visualization of focal cerebral ischemia by anti-microtubule-associated-protein-2 antibody (MAP2) with conventional Hematoxylin and Eosin (HE) staining serving as the control. The aim was to specify the most reliable macroscopic infarct size estimation method after sub-acute focal cerebral ischemia based on the qualitative investigation. Our results showed that the ischemic area on the MAP2-stained sections could be identified macroscopically on both cryo-preserved and paraffin-embedded sections from both immersion- and perfusion-fixed brains. The HE staining did not clearly depict an infarct area for macroscopic visualization. Therefore both immersion-fixed and perfused-fixed-MAP2 stained sections can be used reliably to quantify cerebral infarcts.
Abnormal myelination underlies the pathology of white matter diseases such as preterm white matte... more Abnormal myelination underlies the pathology of white matter diseases such as preterm white matter injury and multiple sclerosis. Osteopontin (OPN) has been suggested to play a role in myelination. Murine OPN mRNA is translated into a secreted isoform (sOPN) or an intracellular isoform (iOPN). Whether there is an isoform‐specific involvement of OPN in myelination is unknown. Here we generated mouse models that either lacked both OPN isoforms in all cells (OPN‐KO) or lacked sOPN systemically but expressed iOPN specifically in oligodendrocytes (OLs‐iOPN‐KI). Transcriptome analysis of isolated oligodendrocytes from the neonatal brain showed that genes and pathways related to increase of myelination and altered cell cycle control were enriched in the absence of the two OPN isoforms in OPN‐KO mice compared to control mice. Accordingly, adult OPN‐KO mice showed an increased axonal myelination, as revealed by transmission electron microscopy imaging, and increased expression of myelin‐related proteins. In contrast, neonatal oligodendrocytes from OLs‐iOPN‐KI mice compared to control mice showed differential regulation of genes and pathways related to the increase of cell adhesion, motility, and vasculature development, and the decrease of axonal/neuronal development. OLs‐iOPN‐KI mice showed abnormal myelin formation in the early phase of myelination in young mice and signs of axonal degeneration in adulthood. These results suggest an OPN isoform‐specific involvement, and a possible interplay between the isoforms, in myelination, and axonal integrity. Thus, the two isoforms of OPN need to be separately considered in therapeutic strategies targeting OPN in white matter injury and diseases.
Staphylococcus epidermidis (S. epidermidis) is the most common nosocomial pathogen in preterm inf... more Staphylococcus epidermidis (S. epidermidis) is the most common nosocomial pathogen in preterm infants and associated with increased risk of cognitive delay, however, underlying mechanisms are unknown. We employed morphological, transcriptomic and physiological methods to extensively characterize microglia in the immature hippocampus following S. epidermidis infection. 3D morphological analysis revealed activation of microglia after S. epidermidis. Differential expression combined with network analysis identified NOD‐receptor signaling and trans‐endothelial leukocyte trafficking as major mechanisms in microglia. In support, active caspase‐1 was increased in the hippocampus and using the LysM‐eGFP knock‐in transgenic mouse, we demonstrate infiltration of leukocytes to the brain together with disruption of the blood–brain barrier. Our findings identify activation of microglia inflammasome as a major mechanism underlying neuroinflammation following infection. The results demonstrate that neonatal S. epidermidis infection share analogies with S. aureus and neurological diseases, suggesting a previously unrecognized important role in neurodevelopmental disorders in preterm born children.
Galactomannan (GM) antigen is an aspergillus specific antigen that is released during the growth ... more Galactomannan (GM) antigen is an aspergillus specific antigen that is released during the growth phase of invasive aspergillosis. We aimed to find the optimum cutoff and accuracy of serum Galactomannan assay in immunocompromised patients. Immunocompromised patients diagnosed with invasive pulmonary aspergillosis (IPA) based on the European Organization for Research and Treatment of Cancer/Invasive Mycosis Study Group (EORTC/MSG) with three levels of certainty proven, probable and possible, referred for GM antigen measurement at Immunology, Asthma and Allergy Research Institute (IAARI) from 2006 to 2009 and if they met the criteria were enrolled in this study. Totally 49 patients with IPA were enrolled in our study. According to EORTC/MSG, patients categorized into three levels of certainty: They were diagnosed as 'proven' invasive pulmonary aspergillosis 16(32.7%), 'probable' 18(36.7%) and 'possible' 15(30.6%). The most common host risk factor was solid tumors 17(34.7%). The accuracy of Galactomannan assay increased from 0.5 to 2 cutoffs. The optimum sensitivity and specificity obtained at the index cutoff of ≥1.5 for diagnosis of "proven" IPA; which were respectively, 69.2% and 72.2%. Other cutoffs had high variance between sensitivity and specificity for diagnosis of IPA. The calculated cutoff gained by receiver operating characteristic (ROC) analysis for detecting proven IPA was 1.5. Intermediate accuracy of serum GM test in conjunct with clinical findings would help early IPA detection among immunocompromised patients.
Autism Spectrum Disorders (ASD) are heterogeneous neurodevelopmental disorders with considerably ... more Autism Spectrum Disorders (ASD) are heterogeneous neurodevelopmental disorders with considerably increased risk in male infants born preterm and with neonatal infection. Here we investigated the role of postnatal immune activation on hippocampal synaptopathology by targeting Reelin+ cells in mice with ASD-like behavior. C57/Bl6 mouse pups of both sexes received lipopolysaccharide (LPS, 1mg/kg) on postnatal day (P) 5. At P45, animal behavior was examined by marble burying and sociability test, followed by ex-vivo brain MRI diffusion kurtosis imaging (DKI). Hippocampal synaptogenesis, number and morphology of Reelin+ cells, and mRNA expression of trans-synaptic genes, including neurexin-3, neuroligin-1, and cell-adhesion molecule nectin-1 were analyzed at P12 and P45. Social withdrawal and increased stereotypic activities in males were related to increased mean diffusivity on MRI-DKI and overgrowth in hippocampus together with retention of long-thin immature synapses on apical dendrites, decreased volume and number of Reelin+ cells as well as reduced expression of trans-synaptic and cell-adhesion molecules. The study provides new insights into sex-dependent mechanisms that may underlie ASD-like behavior in males following PIA. We identify GABAergic interneurons as core components of dysmaturation of excitatory synapses in the hippocampus following postnatal infection and provide cellular and molecular substrates for the MRI findings with translational value.
The purpose of this study was to investigate any association between IgA deficiency (IgAD) and ju... more The purpose of this study was to investigate any association between IgA deficiency (IgAD) and juvenile rheumatoid arthritis (JRA) among Iranian children.This case-control study was carried out on 83 children who were diagnosed as JRA according to American College of Rheumatology (ACR) criteria; Patients were admitted at the rheumatology clinic of Children's Medical Center, (Tehran). Serum immunoglobulins concentrations were determined by nephelometry method. Control group was 112 healthy children who were matched for age and gender. Informed consent obtained from all parents.Selective IgA deficiency (sIgAD) was found only in a boy (1.2%) among JRA children; however, partial IgA deficiency was found in 6(7.1%) of patients with JRA and in 12(10.7%) of control subjects, this difference was not statistically significant (p=0.46). Immunoglobulins levels in patients with JRA (IgM: 126.7±57.2, IgG: 1182.3±351 and IgA:169.3±98) were significantly higher than their controls (IgM: 104±52, IgG:802±220 and IgA: 94.6±47) (p<0.05). Patients with growth failure had higher IgM, IgG and IgA levels in comparison with patients without growth failure; however, this difference was significant about IgM and IgG levels (p<0.05).In contrast to other similar studies, the number of IgAD did not differ significantly between JRA patients and their control counterpart; this might be partly due to the high rate of consanguineous marriages in Iran that resulted in increased prevalence of clinically undiagnosed partial IgAD in general population. Hence, future epidemiological studies are warranted to make it clear.
Schizophrenia (SCZ) is a psychiatric disorder that can include symptoms of disorganized speech an... more Schizophrenia (SCZ) is a psychiatric disorder that can include symptoms of disorganized speech and thoughts with uncertain underlying mechanisms possibly linked to over‐activated microglia. In this study, we used brain samples from sixteen donors with SCZ and thirteen control donors to assess the differential activation of microglia by quantifying density and 3D reconstruction of microglia stained with ionized calcium‐binding adaptor molecule‐1 (Iba1). Our samples consisted of sections from the frontal, temporal, and cingulate cortical gray matter, subcortical white matter regions (SCWM), and included the anterior corpus callosum. In the first series of studies, we performed a density analysis followed by a spatial analysis to ascertain the microglial density, distribution, and soma size in SCZ brains. Second, we performed a series of morphological quantification techniques to investigate the arborization patterns of the microglia in SCZ. The results demonstrated an increase in microglia density in the cortical gray matter regions in SCZ cases, while in the SCWM, there was a significant increase in microglia density in the frontal and temporal, but not in the other brain regions of interest (ROIs). Spatial analysis using the “nearest neighbor” demonstrated that there was no effect in “clustering”, but there were shorter distances between microglia seen in the SCZ cases. The morphological measures showed that there was a region‐dependent increase in the microglia soma size in the SCZ cases while the Sholl analysis revealed a significant decrease in the microglia arborization in the SCZ cases across all the ROI’s studied. An in‐depth 3D reconstruction of microglia in Brodmann area 9 cortical region found that there was a significant association between age and reduced microglial arborization in the SCZ cases. This region‐dependent age association can help determine whether longitudinal changes in microglial activation across age are brain region‐dependent, which may point to potential therapeutic targets.
Transient cerebral ischemia followed by reperfusion in an infarcted brain comes with predictable ... more Transient cerebral ischemia followed by reperfusion in an infarcted brain comes with predictable acute and chronic morphological alterations in neuronal and non-neuronal cells. An accurate delineation of the cerebral infarct is not a simple task due to the complex shapes and indistinct borders of the infarction. Thus, an exact macroscopic histological approach for infarct volume estimation can lead to faster and more reliable preclinical research results. This study investigated the effect(s) of confounding factors such as fixation and tissue embedding on the quality of macroscopic visualization of focal cerebral ischemia by anti-microtubule-associated-protein-2 antibody (MAP2) with conventional Hematoxylin and Eosin (HE) staining serving as the control. The aim was to specify the most reliable macroscopic infarct size estimation method after sub-acute focal cerebral ischemia based on the qualitative investigation. Our results showed that the ischemic area on the MAP2-stained sections could be identified macroscopically on both cryo-preserved and paraffin-embedded sections from both immersion- and perfusion-fixed brains. The HE staining did not clearly depict an infarct area for macroscopic visualization. Therefore both immersion-fixed and perfused-fixed-MAP2 stained sections can be used reliably to quantify cerebral infarcts.
Uploads
Papers by Maryam Ardalan