Essential Pathological Processes Research Articles

System analysis based on weighted gene co-expression analysis identifies SOX7 as a novel regulator of hepatic stellate cell activation and liver fibrosis.

Hepatic stellate cell (HSC) activation is the essential pathological process of liver fibrosis (LF). The molecular mechanisms regulating HSC activation and LF are incompletely understood. Here, we explored the effect of transcription factor SRY-related high mobility group box7 (SOX7) on HSC activation and LF, and the underlying molecular mechanism. We found the expression levels of SOX7 were decreased in human and mouse fibrotic livers, particularly at the fibrotic foci. SOX7 was also downregulated in primary activated HSCs and TGF-β1 stimulated LX-2 cells. SOX7 knockdown promoted activation and proliferation of LX-2 cells while inhibiting their apoptosis. On the other hand, overexpression of SOX7 suppressed the activation and proliferation of HSCs. Mechanistically, SOX7 attenuates HSC activation and LF by decreasing the expression of β-catenin and phosphorylation of Smad2 and Smad3 induced by TGF-β1. Furthermore, overexpression of SOX7 using AAV8-SOX7 mouse models ameliorated the extent of LF in response to CCl4 treatment invivo. Collectively, SOX7 suppressed HSC activation and LF. Targeting SOX7, therefore, could be a potential novel strategy to protect against LF.

USP7 promotes the osteoclast differentiation of CD14+ human peripheral blood monocytes in osteoporosis via HMGB1 deubiquitination.

Abnormal osteoclast and osteoblast differentiation is an essential pathological process in osteoporosis. As an important deubiquitinase enzyme, ubiquitin-specific peptidase 7 (USP7) participates in various disease processes through posttranslational modification. However, the mechanism by which USP7 regulates osteoporosis remains unknown. Herein, we aimed to investigate whether USP7 regulates abnormal osteoclast differentiation in osteoporosis. The gene expression profiles of blood monocytes were preprocessed to analyze the differential expression of USP genes. CD14+ peripheral blood mononuclear cells (PBMCs) were isolated from whole blood collected from osteoporosis patients (OPs) and healthy donors (HDs), and the expression pattern of USP7 during the differentiation of CD14+ PBMCs into osteoclasts was detected by western blotting. The role of USP7 in the osteoclast differentiation of PBMCs treated with USP7 siRNA or exogenous rUSP7 was further investigated by the F-actin assay, TRAP staining and western blotting. Moreover, the interaction between high-mobility group protein 1 (HMGB1) and USP7 was investigated by coimmunoprecipitation, and the regulation of the USP7-HMGB1 axis in osteoclast differentiation was further verified. Osteoporosis in ovariectomized (OVX) mice was then studied using the USP7-specific inhibitor P5091 to identify the role of USP7 in osteoporosis. The bioinformatic analyses and CD14+ PBMCs from osteoporosis patients confirmed that the upregulation of USP7 was associated with osteoporosis. USP7 positively regulates the osteoclast differentiation of CD14+ PBMCs in vitro. Mechanistically, USP7 promoted osteoclast formation by binding to and deubiquitination of HMGB1. In vivo, P5091 effectively attenuates bone loss in OVX mice. We demonstrate that USP7 promotes the differentiation of CD14+ PBMCs into osteoclasts via HMGB1 deubiquitination and that inhibition of USP7 effectively attenuates bone loss in osteoporosis in vivo.The translational potential of this article:The study reveals novel insights into the role of USP7 in the progression of osteoporosis and provides a new therapeutic target for the treatment of osteoporosis.

Three-dimensional-cultured MSC-derived exosome with hydrogel for cerebral ischemia repair

Microglia-mediated neuroinflammatory response, one of the most essential pathological processes of cerebral ischemia-reperfusion (I/R) injury, is acknowledged as the main factors leading to poor prognosis of cerebral ischemia. Exosome derived from mesenchymal stem cell (MSC-Exo) exhibits neuroprotective functions by reducing cerebral ischemia-induced neuroinflammatory response and promoting angiogenesis. However, MSC-Exo has disadvantages such as insufficient targeting capability and low production, which limits their clinical applications. Here, we fabricated gelatin methacryloyl (GelMA) hydrogel for three-dimensional (3D) culture of MSCs. It is indicated that 3D environment could simulate the biological niches of MSCs, thereby significantly increasing the cell stemness of MSCs and improving the yield of MSCs-derived exosomes (3D-Exo). In this study, we utilized the modified Longa method to induce middle cerebral artery occlusion (MCAO) model. Additionally, in vitro and in vivo studies were conducted to interrogate the mechanism of the stronger neuroprotective effect of 3D-Exo. Furthermore, the administration of 3D-Exo in MCAO model could promote neovascularization in infarct region and result in a significant suppression of inflammatory response. This study proposed an exosome-based targeting delivery system for cerebral ischemia and provided a promising strategy for efficient and large-scale production of MSC-Exo.

Cardiomyocyte-specific Peli1 contributes to the pressure overload-induced cardiac fibrosis through miR-494-3p-dependent exosomal communication.

Cardiac fibrosis is an essential pathological process in pressure overload (PO)-induced heart failure. Recently, myocyte-fibroblast communication is proven to be critical in heart failure, in which, pathological growth of cardiomyocytes (CMs) may promote fibrosis via miRNAs-containing exosomes (Exos). Peli1 regulates the activation of NF-κB and AP-1, which has been demonstrated to engage in miRNA transcription in cardiomyocytes. Therefore, we hypothesized that Peli1 in CMs regulates the activation of cardiac fibroblasts (CFs) through an exosomal miRNA-mediated paracrine mechanism, thereby promoting cardiac fibrosis. We found that CM-conditional deletion of Peli1 improved PO-induced cardiac fibrosis. Moreover, Exos from mechanical stretch (MS)-induced WT CMs (WT MS-Exos) promote activation of CFs, Peli1-/- MS-Exos reversed it. Furthermore, miRNA microarray and qPCR analysis showed that miR-494-3p was increased in WT MS-Exos while being down regulated in Peli1-/- MS-Exos. Mechanistically, Peli1 promoted miR-494-3p expression via NF-κB/AP-1 in CMs, and then miR-494-3p induced CFs activation by inhibiting PTEN and amplifying the phosphorylation of AKT, SMAD2/3, and ERK. Collectively, our study suggests that CMs Peli1 contributes to myocardial fibrosis via CMs-derived miR-494-3p-enriched exosomes under PO, and provides a potential exosomal miRNA-based therapy for cardiac fibrosis.

Chrysin protects cardiac H9c2 cells against H2O2-induced endoplasmic reticulum stress by up-regulating the Nrf2/PERK pathway.

Oxidative and endoplasmic reticulum (ER) stress-mediated cardiac apoptosis is an essential pathological process in cardiovascular diseases (CVDs). Chrysin (Chy) is a natural flavonoid that exerts several health benefits, particularly anti-oxidative and anti-apoptotic effects. However, its protective effect against CVDs and its mechanism of action at a molecular level remains unclear. Therefore, the present study aimed to investigate the interaction of ER stress response protein with Chy by computational analysis and molecular action in H2O2-induced oxidative and ER stress in cardiomyoblast cells. H9c2 cells were pre-treated with 50μM of Chy for 24h and exposed to H2O2 for 1h. Explore the Chy-mediated Nrf2 signalling on ER stress reduction, H9c2 cell lines were transfected with Nrf2 siRNA for 48h and further treated with Chy for 24h and subjected to H2O2 for 1h. Chy pre-treatment increased the Nrf2-regulated gene expression, reduced the ER stress signalling genes such as CHOP and GRP78, and increased the PERK and AFT6 expression compared to H2O2-treated cells. Chy preincubation down-regulated the expression of PI3K, NF-κB, and caspase-3. Fluorescence staining revealed that Chy reduced intracellular ROS generation, ER stress, apoptosis, and increased MMP. This beneficial effect of Chy was abolished when silencing Nrf2 in H9c2 cells. Overall, the present study confirmed that Chy showed the cardioprotective effect by attenuating ER stress via the activation of Nrf2 signalling. Therefore, the study concluded that improving Nrf2 signalling by Chy supplementation could provide a promising therapeutic target in oxidative and ER stress-mediated CVDs complications.

Roles of Micro Ribonucleic Acids in Astrocytes After Cerebral Stroke

Cerebral stroke is one of the highest-ranking causes of death and the leading cause of disability globally, particularly with an increasing incidence and prevalence in developing countries. Steadily more evidence has indicated that micro ribonucleic acids (miRNAs) have important regulatory functions in gene transcription and translation in the course of cerebral stroke. It is beyond arduous to understand the pathophysiology of cerebral stroke, due in part to the perplexity of influencing the network of the inflammatory response, brain edema, autophagy and neuronal apoptosis. The recent research shows miRNA plays a key role in regulating aquaporin 4 (AQP4), and many essential pathological processes after cerebral stroke. This article reviews the recent knowledge on how miRNA influences the inflammatory response, brain edema, infarction size, and neuronal injury after cerebral stroke. In addition, some miRNAs may serve as potential biomarkers in stroke diagnosis and therapy since the expression of some miRNAs in the blood is stable after cerebral stroke.

Role of ferroptosis-related genes in Stanford type a aortic dissection and identification of key genes: new insights from bioinformatic analysis

ABSTRACT Stanford type A aortic dissection (TAAD) is one of the most dangerous vascular diseases worldwide, and the mechanisms of its development remain unclear. Further molecular pathology studies may contribute to a comprehensive understanding of TAAD and provide new insights into diagnostic markers and potential therapeutic targets. Recent studies have identified that ferroptosis, a form of cell death, may play a previously unrecognized role in influencing the development of TAAD. In this study, we explored the pathological role of ferroptosis in TAAD by performing bioinformatics analyses. Gene set enrichment analysis (GSEA) showed that the ferroptosis-related gene (FRG) set was significantly different between normal and TAAD aortic samples at an overall level (p < 0.001). Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses explored the potential functions and pathways of FRG in TAAD. We further identified six key genes (CA9, HMOX1, IL6, CDKN1A, HIF1A, MYC) from differentially expressed FRGs in TAAD by constructing a protein–protein interaction (PPI) network, all key genes were upregulated in TAAD. Four of the key genes (CA9, IL6, CDKN1A, and HIF1A) were demonstrated to be correlated with cigarette smoke extract-induced ferroptosis in aortic vascular smooth muscle cells. These results suggest that ferroptosis is one of the essential pathological processes in the development of TAAD, and some FRGs affect TAAD development by mediating cellular ferroptosis, which provides deepening insights into the molecular mechanisms and potential therapeutic targets of TAAD.

Toll-like receptor 4-mediated necroptosis in the development of necrotizing enterocolitis

BackgroundDramatic intestinal epithelial cell death leading to barrier dysfunction is one of the mechanism of neonatal necrotizing enterocolitis (NEC), in which Toll-like receptor 4 (TLR4) plays a pivotal role. This study explored the role of necroptosis, a drastic way of cell death in NEC.MethodsThe expression of necroptotic proteins was tested in NEC intestinal tissue and compared with controls. NEC was induced in neonatal wild-type mice and a necroptosis inhibitor was given to investigate whether NEC could be relieved. The general condition, macroscopic scoring, and histological evaluations were performed. The expression of tight junction proteins, inflammatory cytokines, and necroptosis-related proteins was measured, and barrier function was examined. Then, NEC was induced in TLR4-knockout pups to confirm the role of TLR4 in necroptosis.ResultsNecroptotic proteins were significantly upregulated in both NEC patient and animal models, together with the expression of TLR4. NEC could be relieved and inflammatory infiltration was decreased by necrostatin-1s. TLR4-knockout mice showed milder tissue degradation and less necroptosis after NEC induction.ConclusionsNecroptosis is an essential pathological process of NEC. TLR4 may be one stimulator of necroptosis in NEC. Inhibiting the intestinal cell necroptosis might be a useful strategy in the treatment of NEC.ImpactNecroptosis is a key pathological process in NEC, which appears to involve TLR4.Anti-necroptosis treatment is a promising strategy that could significantly relieve the symptoms of NEC.

Augmenting Therapeutic Potential of Polyphenols by Hydrogen-Bonding Complexation for the Treatment of Acute Lung Inflammation.

Dysregulated inflammation is considered as an essential pathological process in inflammation-associated diseases, which would be aggravated by high levels of reactive oxygen species (ROS) generation inducing oxidative stress. Currently, extensive attention has been paid to polyphenolic compounds owing to their broad spectrum biological activities, such as antioxidant and anti-inflammatory effects, while their therapeutic potential has been compromised by the poor stability, short plasma half-life, and low bioavailability. Given that polyphenols have a wide range of structural characteristics and various physicochemical properties, there remains a real challenge toward green, mass production of universal nanocarriers for effective entrapment of these active pharmaceutical ingredients. In this study, we adopted a flash nanocomplexation (FNC) platform to prepare nanocomplexes comprising polyphenols and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) enabled by hydrogen bonding. We confirmed that the molecular structure of polyphenols has a great influence on their complexation with TPGS, and stable nanocomplexes were formed when the number of phenolic hydroxyl groups of polyphenols was above the value of 8. These hydrogen-bonded nanocomplexes produced by an FNC apparatus exhibited well-controlled quality with uniform size, good colloidal stability, and high batch-to-batch repeatability, thus improving the druggability as potent nanotherapeutics for antioxidant and anti-inflammatory applications. In vivo experiments indicated that the optimal nanocomplex (EGCG-NC) can be applied to ameliorate acute lung injury in a mice model after nasal administration. These results proved that polyphenols formulated with TPGS for nanocomplex formation through hydrogen-bonding complexation could augment their therapeutic potential for modulating hyperactive inflammation in the treatment of acute lung inflammation.

Neuroprotective role of glutathione peroxidase 4 in experimental subarachnoid hemorrhage models

Background and purposeEarly brain injury is an essential pathological process after subarachnoid hemorrhage (SAH), with many cell death modalities. Ferroptosis is a newly discovered regulated cell death caused by the iron-dependent accumulation of lipid peroxidation, which can be prevented by glutathione peroxidase 4 (GPX4). Our study aimed to investigate the role of GPX4 in neuronal cell death after experimental SAH. MethodsIn vivo experimental SAH was induced by injecting autologous arterial blood into the prechiasmatic cistern in male Sprague-Dawley rats. Meanwhile, the in vitro SAH model was performed with primary rat cortical neurons cultured in medium containing hemoglobin (Hb). Adenovirus was used to overexpress GPX4 before experimental SAH. GPX4 expression was detected by western blot and immunofluorescence experiments. Malondialdehyde (MDA) was measured to evaluate the level of lipid peroxidation. Nissl staining was employed to assess cell death in vivo, whereas lactate dehydrogenase (LDH) release was used to evaluate cell damage in vitro. The brain water content and neurological deficits were evaluated to determine brain injury. ResultsEndogenous GPX4 was mainly expressed in neurons, and its expression decreased at 24 h after experimental SAH. Overexpression of GPX4 significantly reduced lipid peroxidation and cell death in the experimental SAH models both in vivo and in vitro. Moreover, overexpression of GPX4 ameliorated brain edema and neurological deficits at 24 h after SAH. ConclusionsThe decrease of GPX4 expression potentially plays an important role in ferroptosis during early brain injury after SAH. Overexpression of GPX4 has a neuroprotective effect after SAH.

ROS production and mitochondrial dysfunction driven by PU.1-regulated NOX4-p22phox activation in Aβ-induced retinal pigment epithelial cell injury.

Rationale: Amyloid β (Aβ) deposition, an essential pathological process in age-related macular degeneration (AMD), causes retinal pigment epithelium (RPE) degeneration driven mostly by oxidative stress. However, despite intense investigations, the extent to which overoxidation contributes to Aβ-mediated RPE damage and its potential mechanism has not been fully elucidated.Methods: We performed tandem mass-tagged (TMT) mass spectrometry (MS) and bioinformatic analysis of the RPE-choroid complex in an Aβ1-40-induced mouse model of retinal degeneration to obtain a comprehensive proteomic profile. Key regulators in this model were confirmed by reactive oxygen species (ROS) detection, mitochondrial ROS assay, oxygen consumption rate (OCR) measurement, gene knockout experiment, chromatin immunoprecipitation (ChIP), and luciferase assay.Results: A total of 4243 proteins were identified, 1069 of which were significantly affected by Aβ1-40 and found to be enriched in oxidation-related pathways by bioinformatic analysis. Moreover, NADPH oxidases were identified as hub proteins in Aβ1-40-mediated oxidative stress, as evidenced by mitochondrial dysfunction and reactive oxygen species overproduction. By motif and binding site analyses, we found that the transcription factor PU.1/Spi1 acted as a master regulator of the activation of NADPH oxidases, especially the NOX4-p22phox complex. Also, PU.1 silencing impeded RPE oxidative stress and mitochondrial dysfunction and rescued the retinal structure and function.Conclusion: Our study suggests that PU.1 is a novel therapeutic target for AMD, and the regulation of PU.1 expression represents a potentially novel approach against excessive oxidative stress in Aβ-driven RPE injury.

Oridonin protects LPS-induced acute lung injury by modulating Nrf2-mediated oxidative stress and Nrf2-independent NLRP3 and NF-\u03baB pathways

BackgroundOxidative stress and the resulting inflammation are essential pathological processes in acute lung injury (ALI). Nuclear factor erythroid 2-related factor 2 (Nrf2), a vital transcriptional factor, possesses antioxidative potential and has become a primary target to treat many diseases. Oridonin (Ori), isolated from the plant Rabdosia Rrubescens, is a natural substance that possesses antioxidative and anti-inflammatory effects. Our aim was to study whether the anti-inflammatory and antioxidant effects of Ori on LPS-induced ALI were mediated by Nrf2.MethodsMTT assays, Western blotting analysis, a mouse model, and hematoxylin-eosin (H & E) staining were employed to explore the mechanisms by which Ori exerts a protective effect on LPS-induced lung injury in RAW264.7 cells and in a mouse model.ResultsOur results indicated that Ori increased the expression of Nrf2 and its downstream genes (HO-1, GCLM), which was mediated by the activation of Akt and MAPK. Additionally, Ori inhibited LPS-induced activation of the pro-inflammatory pathways NLRP3 inflammasome and NF-κB pathways. These two pathways were also proven to be Nrf2-independent by the use of a Nrf2 inhibitor. In keeping with these findings, Ori alleviated LPS-induced histopathological changes, the enhanced production of myeloperoxidase and malondialdehyde, and the depleted expression of GSH and superoxide dismutase in the lung tissue of mice. Furthermore, the expression of LPS-induced NLRP3 inflammasome and NF-κB pathways was more evident in Nrf2-deficient mice but could still be reversed by Ori.ConclusionsOur results demonstrated that Ori exerted protective effects on LPS-induced ALI via Nrf2-independent anti-inflammatory and Nrf2-dependent antioxidative activities.

A novel experimental rat model of peripheral nerve scarring that reliably mimics post-surgical complications and recurring adhesions.

ABSTRACTInflammation, fibrosis and perineural adhesions with the surrounding tissue are common pathological processes following nerve injury and surgical interventions on peripheral nerves in human patients. These features can reoccur following external neurolysis, currently the most common surgical treatment for peripheral nerve scarring, thus leading to renewed nerve function impairment and chronic pain. To enable a successful evaluation of new therapeutic approaches, it is crucial to use a reproducible animal model that mimics the main clinical symptoms occurring in human patients. However, a clinically relevant model combining both histological and functional alterations has not been published to date. We therefore developed a reliable rat model that exhibits the essential pathological processes of peripheral nerve scarring. In our study, we present a novel method for the induction of nerve scarring by applying glutaraldehyde-containing glue that is known to cause nerve injury in humans. After a 3-week contact period with the sciatic nerve in female Sprague Dawley rats, we could demonstrate severe intra- and perineural scarring that resulted in grade 3 adhesions and major impairments in the electrophysiological peak amplitude compared with sham control (P=0.0478). Immunohistochemical analysis of the nerve structure revealed vigorous nerve inflammation and recruitment of T cells and macrophages. Also, distinct nerve degeneration was determined by immunostaining. These pathological alterations were further reflected in significant functional deficiencies, as determined by the analysis of relevant gait parameters as well as the quantification of the sciatic functional index starting at week 1 post-operation (P<0.01). Moreover, with this model we could, for the first time, demonstrate not only the primary formation, but also the recurrence, of severe adhesions 1 week after glue removal, imitating a major clinical challenge. As a comparison, we tested a published model for generating perineural fibrotic adhesions, which did not result in significant pathological changes. Taken together, we established an easily reproducible and reliable rat model for peripheral nerve scarring that allows for the effective testing of new therapeutic strategies.

Stem Cells for Modeling and Therapy of Parkinson's Disease.

Parkinson's disease (PD) is the second most frequent neurodegenerative disease after Alzheimer's disease, which is characterized by a low level of dopamine being expressing in the striatum and a deterioration of dopaminergic neurons (DAn) in the substantia nigra pars compacta. Generation of PD-derived DAn, including differentiation of human embryonic stem cells, human neural stem cells, human-induced pluripotent stem cells, and direct reprogramming, provides an ideal tool to model PD, creating the possibility of mimicking key essential pathological processes and charactering single-cell changes in vitro. Furthermore, thanks to the understanding of molecular neuropathogenesis of PD and new advances in stem-cell technology, it is anticipated that optimal functionally transplanted DAn with targeted correction and transgene-free insertion will be generated for use in cell transplantation. This review elucidates stem-cell technology for modeling PD and offering desired safe cell resources for cell transplantation therapy.

Protection of sulforaphane against hydrogen peroxide-induced bovine trabecular meshwork cell apoptosis

Background Evidences indicated that oxidative stress damage is an essential pathological process in primary open angle glaucoma.Sulforaphane (SFN) can play an antioxidative stress role to many tissues and cells by activating Nrf2/ARE single pathway.However, whether SFN has a protective role to oxidative stress induced damage of trabecular meshwork cells is still unclear. Objective This study was to investigate the antioxidant effect of SFN against H2O2-induced oxidative damage in bovine trabecular meshwork cells. Methods Trabecular cells were isolated from fresh black bovine eyeballs and primarily cultured and passaged.The third generation of cells were incubated to 96-well dish at a density of 1×103/well for 24 hours and divided into 4 groups.The cells were incubated using 100 μl serum-free medium in the blank control group.Oxidative damage models were established by adding 100 μmol/L H2O2 (100 μl) in medium in the H2O2 group.The cells were cultured with the medium containing 10 μmol/L SFN (100 μl) in the SFN group, and 100 μl H2O2at the final concentration of 100 μmol/L was added in the SFN-treated cell medium in the SFN+ H2O2 group.The cell vitality in various groups was assayed by using cell counting kit-8 (CCK-8). The apoptosis rate of the cells was detected by Annexin V-FITC/PI double-staining with flow cytometry. Results Cultured cells showed a spindle shape with uniform size, abundant cytoplasm, numberous pigmented particles and big nucleolus.The relative cell vitality reduced to (67.00±1.27)% and (80.00±6.25)% in the H2O2 group and SFN+ H2O2 group in comparison with 100% in the blank control group, and the cell vitality in the SFN+ H2O2 group was lower than that in the SFN group but higher than that in the H2O2 group (both at P<0.01). The mean apoptosis rate was (11.33±0.77)%, (32.31±1.03)%, (10.44±0.68)% and (17.68±0.21)% in the blank control group, H2O2 group, SFN group and SFN+ H2O2 group, respectively, showing a significant difference among the groups (F=539.96, P<0.01), and the apoptosis rate in the SFN+ H2O2 group was significantly lower than that in the H2O2 group but higher than that in the blank control group and SFN group (all at P<0.01). Conclusions SFN can improve the antioxidative stress ability of trabecular meshwork cells and alleviate the damage induced by oxidative stress. Key words: Isothiocyanates; Thiocyanates/pharmacology; Cells, cultured; Hydrogen peroxide/toxicity; Oxidative stress/drug effects; Trabecular meshwork cells/drug effects; Apoptosis; Animals, cattle; Sulforaphane

Interleukin-18 and Atherosclerosis: Mediator or Biomarker

Atherosclerosis, a progressive disorder of the vessel walls with the formation of plaques throughout the arterial system, is an essential pathological process in the development of various Cardiovascular Diseases (CVDs). Inflammation has been demonstrated to play an inevitable role in all the stages of atherosclerosis though its pathogenesis is complicated and still remains enigmatic. Interleukin-18 (IL-18) is a pleiotropic pro-inflammatory cytokine, which belongs to the Interleukin-1 (IL-1) family. This pro-inflammatory cytokine is among the more recently recognized cytokines to be involved in the development of various cardiovascular diseases and their related manifestations. At one end, studies indicate that IL-18 is a key player that orchestrates the inflammatory cascade associated with the pathogenesis of atherosclerosis, whereas others showed circulating levels of IL-18 to be a prognostic marker. Present article summarizes the scientific rationale which highlights the signatures of interleukin-18 as a mediator in the pathogenesis as well as a diagnostic marker.

Ex Situ Atomic Force Microscopy Analysis of β-Amyloid Self-Assembly and Deposition on a Synthetic Template

The beta-amyloid (Abeta) deposition, which is the conversion of soluble Abeta peptides to insoluble plaques on a surface, is an essential pathological process in Alzheimer's disease (AD). The identification and characterization of possible environmental factors that may influence amyloid deposition in vivo are important to unveil the underlying etiology of AD. According to the amyloid cascade hypothesis, diffuse plaques are initial and visual deposits in the early event of AD, leading to amyloid plaques. To study amyloid deposition and growth in vitro, we prepared a synthetic template by immobilizing Abeta seeds on an N-hydroxysuccinimide ester-activated solid surface. According to our analysis with an ex situ atomic force microscope, the formation of amyloid plaque-like aggregates was mediated by the interaction between Abeta in a solution and on a synthetic template, suggesting that Abeta oligomers function well as seeds for amyloid deposition. It was observed that insoluble amyloid aggregates formed on the template surface serve as a sink of soluble Abeta in a solution as well as mediate the formation of intermediates in the pathway of amyloid fibrillization in a solution. Relative seeding efficiencies of fresh monomers, oligomers, and fully grown fibrils were analyzed by measuring the deposited plaque volume and its height distribution through atomic force microscopy. The result revealed that oligomeric forms of Abeta act more efficiently as seeds than monomers or fibrils do. Fluorescence spectroscopy with thioflavin T confirmed that amyloid aggregate formation proceeds in a concentration-dependent manner. Analysis with Fourier transform infrared spectroscopy indicated a progressive transition of soluble Abeta42 monomer to amyloid fibrils having antiparallel beta-sheet structure on the template. Furthermore, studies on the interaction between Abeta40 and 42, two major variants of Abeta derived from the amyloid precursor protein, showed that amyloid aggregate formation on the surface was accelerated further by the homogeneous association of soluble Abeta42 onto Abeta42 seeds than by other combinations. A slightly acidic condition was found to be unfavorable for amyloid formation. This study gives insight into understanding the effects of environmental factors on amyloid formation via the use of a synthetic template system.

Making progress on the natural history of multiple sclerosis

Typically, the clinical course of multiple sclerosis is characterized by episodes, from which recovery may occur, and by progression. These phases usually evolve in sequence as part of the natural history. The number and frequency of episodes and the interval between first presentation and the often somewhat blurred transition to disease progression are generally held to be rather unpredictable. By definition, progression is not preceded by episodes in individuals with primary progressive multiple sclerosis. At one time, the essential pathological process in multiple sclerosis was thought to be loss of the myelin sheath that normally surrounds axons in the CNS, as a result of local inflammation, from which followed a cascade of secondary events culminating in development of the multifocal sclerotic lesions from which the disease gets its name. Thus, episodes were considered to be the critical component of the disease, and their reduction presented a natural and sufficient target for treatment. That perspective changed with the rediscovery of axonal pathology as a significant additional component of the disease process and its correlation with the accumulation of disability, especially during the progressive phase. The concept of multiple sclerosis as a focal inflammatory demyelinating disorder took a further step backwards with the recognition that, in this disorder, normal appearing white matter is far from normal. The evidence is both histological and radiological, but the available observations do not resolve the ambiguous relationship between inflammation and neurodegeneration that remains central to understanding mechanisms of tissue injury in multiple sclerosis, and the relative contribution of each to clinical deficits occurring during different phases of the disease. Thus, magnetic resonance spectroscopic studies of whole brain white matter in multiple sclerosis show abnormalities indicating widespread axonal changes in the absence of apparent tissue inflammation (Filippi et al ., 2003). But, while MRI and spectroscopy allow …

HIV-1 induces renal epithelial dedifferentiation in a transgenic model of HIV-associated nephropathy

Human immunodeficiency virus-associated nephropathy (HIVAN) is the most common cause of renal failure in HIV-1-seropositive patients. Recent studies using an HIV-1 transgenic mouse model have demonstrated that expression of HIV-1 in the kidney is required for the development of HIVAN. What has remained unclear, however, is the renal cell type responsible for pathogenesis and the essential pathological process. To address these issues, we used a transgenic murine model of HIVAN. We identified the cell types in kidney in which HIV transgene expression occurs using in situ hybridization. We evaluated evidence of proliferation by immunocytochemical analysis using an antibody to Ki-67 and cell type-specific markers, including WT-1, synaptopodin, Na+,K+-ATPase, adducin, and desmin. TUNEL assay was used to evaluate apoptosis. We found that glomerular and tubular epithelial cells express the HIV-1 transgene early in the disease process when renal architecture is well preserved. Transgene expression is lost, however, in tubular epithelial cells when they lose their differentiated cuboidal phenotype. In glomerular epithelial cells, dedifferentiation occurs with reduced expression of WT-1 and synaptopodin, in association with activation of desmin expression. Tubular microcysts also form with mislocalization of Na+,K+-ATPase expression to the lateral and apical cellular membranes. These studies support the hypothesis that the glomerular and renal epithelial cells are the primary targets of HIV-1 pathogenesis in the kidney. The essential pathologic process is dysregulation of the epithelial cell cycle with increased proliferation, apoptosis, cellular dedifferentiation, and altered cellular polarity.

CLINICAL AND PHOTOGRAPHIC ASSESSMENT OF THE RETINAL NERVE FIBER LAYER

The essential pathologic process in glaucoma is loss of ganglion cell axons. The atrophy of ganglion cell axons can be observed in the optic nerve head and the retinal nerve fiber layer (RNFL). The axons are gathered together in the optic nerve head but are spread out in a thin layer in the retina. Because of this, the examination of the RNFL may provide information of the minor losses of axons that cannot be detected by evaluating the neuroretinal rim of the optic nerve head.