Extravasation Of Erythrocytes Research Articles

Tranexamic Acid in the Treatment of Postsclerotherapy Hyperpigmentation

Tranexamic acid (TA) is a well-known antifibrinolytic drug used in several medical fields. In Dermatology, it has been proposed as an off-label indication in acquired hyperpigmentation, especially for the treatment of melasma, a condition that shares similar histologic features with postsclerotherapy hyperpigmentation (PSH). TA has antiangiogenic effects that reduce the expression of vascular endothelial growth factor (VEGF), endothelin-1, and antimelanogenic effects by inhibiting the tyrosine kinase receptor. Sclerotherapy is a common treatment for chronic venous insufficiency that obliterates the vessels by a chemical endothelial reaction. One of its adverse effects is hyperpigmentation due to an accumulation of hemosiderin in the superficial dermis following erythrocyte extravasation; however, both, melasma and PSH patients, express an elevated number of melanocytes and blood vessels in the affected areas. Since there is a lack of studies in this field, we present a systematic review of TA usefulness in acquired hyperpigmentation. We conducted a systematic review of studies published between 1962 and 2020, available in the databases Pubmed, Web of Science, Scopus, and Google Scholar after searching the following MeSH terms: "tranexamic acid" and "sclerotherapy" or "hyperpigmentation" or "melasma." After extensive review 12 studies met eligibility criteria and were included. Despite no studies having been conducted assessing the role or effectiveness of TA in PSH, we found 12 articles about the use of TA in melasma, which is also an acquired pigmentary disorder with several histologic similarities with PSH. According to these studies, patients treated with TA 250 mg by mouth two times per day for 4 months reached a 90% rate of improvement, with a 27.2% rate of recurrence. Treated patients also expressed histologic resolution of the pigmentations, given by a reduced number of vessels, mast cell counts, and epidermal pigmentation. In vitro results exhibit effects on the neutralization of VEGF-1 and VEGF-2 and inhibiting tyrosinase activity, melanin production, and melanogenic proteins. TA has been proved to be effective in the treatment of melasma, due to its antiangiogenic and antimelanocytic properties. Therefore, we believe that TA might also be effective for treating PSH. We propose this agent as a valuable tool in vascular surgery due to its antiangiogenic and antimelanogenic properties. This study is the first step for the assessment of the clinical effectiveness of TA in PSH. It is also necessary to investigate if it could also help to remove hemosiderin residues from the epidermis in PSH.

Lichen Aureus with Dermoscopic Findings: A case report

Lichen aureus is a rare variant of pigmented purpuric dermatosis, which often affects young adults and is localized mainly on the lower extremities. We present here a 31-year-old female who had a solitary golden-brown-color patch on her right leg for 1 year. Punch biopsy of the lesion revealed lymphohistiocytic band-like infiltrate of the papillary dermis with erythrocyte extravasation and hemosiderin deposits. The diagnosis of Lichen aureus was made based on clinicopathologic findings. The dermoscopic findings that support this diagnosis were brownish yellow diffuse coloration of the background, round to oval red dots, globules and patches and twisted red loops. Herein, we present the dermoscopic findings of a 31-year-old female patient with a diagnosis of lichen aureus established with clinical and histopathological features. Keywords: pigmented purpuric dermatosis, lichen aureus, dermoscopy

Vascular obliteration because of endothelial and myointimal growth in COVID-19 patients.

Coronavirus disease 2019 (COVID-19) is a systemic multi-organ viral illness. Previous studies have found that many patients had a procoagulant state and/or severe hypoxemia with relatively well-preserved lung mechanics. Mechanisms underlying the damage to vascular tissues are not well-elucidated yet. Histological data in COVID-19 patients are still limited and are mainly focused on post-mortem analysis. Given that the skin is affected by COVID-19 and the relative ease of its histological examination, we aimed to examine the histology of skin lesions in COVID-19 patients to better understand the disease's pathology. Five skin lesions from COVID-19 adult patients were selected for a deep histological tissue examination. A strong vasculopathic reaction pattern based on prominent vascular endothelial and myointimal cell growth was identified. Endothelial cell distortion generated vascular lumen obliteration and striking erythrocyte and serum extravasation. Significant deposition of C4d and C3 throughout the vascular cell wall was also identified. A regenerative epidermal hyperplasia with tissue structure preservation was also observed. COVID-19 could comprise an obliterative microangiopathy consisting on endothelial and myointimal growth with complement activation. This mechanism, together with the increased vascular permeability identified, could contribute to obliteration of the vascular lumen and hemorrhage in COVID-19. Thus, anticoagulation by itself could not completely reverse vascular lumen obliteration, with consequent increased risk of hemorrhage. Findings of this study could contribute to a better understanding of physiopathological mechanisms underlying COVID-19 on living patients and could help further studies find potential targets for specific therapeutic interventions in severe cases.

Positive calretinin stain with immunohistochemistry in a 49 year-old female with cardiac myxoma: A case report

Background: Primary tumors of the heart are scarce. Cardiac myxoma is a primary benign heart tumor most often found with an incidence of 0.5-1.0 cases per million population per year and 90% diagnosed in the fourth to seventh decades of life, rarely found in children. Cardiac myxoma is three times more common in women than in men. These tumors are mostly found in the left atrium.Case description: Female, a 49-year-old patient, came with palpitations, shortness of breath, and weakness since the previous six months. On echocardiography, found a mass in the left atrium suspected of a left atrial myxoma. Surgery was performed, and the specimen was sent for histopathological examination. Macroscopically, the tumor mass shows an irregular shape, brownish color, and spongy consistency. Microscopic examination shows the tumor consisting of proliferation of spindle-shaped and stellate cells, with oval to round nuclei, eosinophilic cytoplasm, mostly scattered, some of which are arranged cord and nest, infiltrative between the myxoid stroma and partially surround small blood vessels to form a vasoformative ring. The specimen also contains the proliferation of blood vessels, extravasation of erythrocytes, and the distribution of inflammatory cells and hemosiderophages. The result of the immunohistochemical examination with calretinin was positive.Conclusion: This case was concluded as cardiac myxoma based on clinical features, echocardiography, macroscopic, routine histopathological, and immunohistochemical examinations.

A clinical, histopathological and laboratory study of 19 consecutive Italian paediatric patients with chilblain-like lesions: lights and shadows on the relationship with COVID-19 infection.

BackgroundAcral chilblain‐like lesions are being increasingly reported during COVID‐19 pandemic. However, only few patients proved positivity for SARS‐CoV‐2 infection. The relationship between this skin manifestation and COVID‐19 infection has not been clarified yet.ObjectiveTo thoroughly characterize a prospective group of patients with chilblain‐like lesions and to investigate the possible relationship with SARS‐CoV‐2 infection.MethodsFollowing informed consent, patients underwent (i) clinical evaluation, (ii) RT‐PCR and serology testing for SARS‐CoV‐2, (iii) digital videocapillaroscopy of finger and toe nailfolds, (iv) blood testing to screen for autoimmune diseases and coagulation anomalies, and (v) skin biopsy for histopathology, direct immunofluorescence and, in selected cases, electron microscopy.ResultsNineteen patients, all adolescents (mean age: 14 years), were recruited. 11/19 (58%) of them and/or their cohabitants reported flu‐like symptoms one to two months prior to skin manifestation onset. Lesions were localized to toes and also heels and soles. Videocapillaroscopy showed pericapillary oedema, dilated and abnormal capillaries, and microhaemorrhages both in finger and toe in the majority of patients. Major pathological findings included epidermal basal layer vacuolation, papillary dermis oedema and erythrocyte extravasation, perivascular and perieccrine dermal lymphocytic infiltrate, and mucin deposition in the dermis and hypodermis; dermal vessel thrombi were observed in two cases. Blood examinations were normal. Nasopharyngeal swab for SARS‐CoV‐2 and IgG serology for SARS‐CoV‐2 nucleocapsid protein were negative. Importantly, IgA serology for S1 domain of SARS‐CoV‐2 spike protein was positive in 6 patients and borderline in 3.ConclusionsChilblain‐like lesions during COVID‐19 pandemic have specific epidemiologic, clinical, capillaroscopic and histopathological characteristics, which distinguish them from idiopathic perniosis. Though we could not formally prove SARS‐CoV‐2 infection in our patients, history data and the detection of anti‐SARS‐COV‐2 IgA strongly suggest a relationship between skin lesions and COVID‐19. Further investigations on the mechanisms of SARS‐CoV‐2 infection in children and pathogenesis of chilblain‐like lesions are warranted.

A detailed comparison between the endoscopic images using blue laser imaging and three-dimensional reconstructed pathological images of colonic lesions.

Blue laser/light imaging (BLI) is an image-enhanced endoscopy (IEE) technique that can provide an accurate diagnosis by closely observing the surface structure of various colonic lesions. However, complete correspondence between endoscopic images and pathological images has not been demonstrated. The aim of this study was to accurately compare endoscopic images and the pathological images using a three-dimensionally (3D) reconstructed pathological model. Continuous thin layer sections were prepared from colonic tissue specimens and immunohistochemically stained for CD34 and CAM5.2. Three-dimensional reconstructed images were created by superimposing immunohistochemically stained pathological images. The endoscopic image with magnifying BLI was compared with the top view of the 3D reconstructed image to identify any one-to-one correspondence between the endoscopic images and histopathological images using the gland orifices and microvessels as a guide.Using 3D reconstructed pathological images, we were able to identify the location on the endoscope image in cases of colonic adenocarcinoma, adenoma and normal mucosa. As a result, the horizontal plane of the endoscopic image and the vertical plane of the 2D pathological specimen were able to be compared, and we successfully determined the visible blood vessel depth and performed a detailed evaluation on magnifying BLI. Examples are as follows: (1) The median vasculature depth from the mucosal surface that could be recognized as vasculature on magnifying BLI was 29.4 μm. The median depth of unrecognizable vessels on magnifying BLI was 218.8 μm, which was significantly deeper than recognizable vessels. (2) Some brownish structures were suggested to potentially be not only dense vessels, vessel expansions, corrupted vessels but also bleeding or extravasation of erythrocytes. Overall, we demonstrated a new approach to matching endoscopic images and pathological findings using a 3D-reconstructed pathological model immunohistochemically stained for CD34 and CAM5.2. This approach may increase the overall understanding of endoscopic images and positively contribute to making more accurate endoscopic diagnoses.

Meningeal lymphatics clear erythrocytes that arise from subarachnoid hemorrhage

Extravasated erythrocytes in cerebrospinal fluid (CSF) critically contribute to the pathogenesis of subarachnoid hemorrhage (SAH). Meningeal lymphatics have been reported to drain macromolecules and immune cells from CSF into cervical lymph nodes (CLNs). However, whether meningeal lymphatics are involved in clearing extravasated erythrocytes in CSF after SAH remains unclear. Here we show that a markedly higher number of erythrocytes are accumulated in the lymphatics of CLNs and meningeal lymphatics after SAH. When the meningeal lymphatics are depleted in a mouse model of SAH, the degree of erythrocyte aggregation in CLNs is significantly lower, while the associated neuroinflammation and the neurologic deficits are dramatically exacerbated. In addition, during SAH lymph flow is increased but without significant lymphangiogenesis and lymphangiectasia. Taken together, this work demonstrates that the meningeal lymphatics drain extravasated erythrocytes from CSF into CLNs after SAH, while suggesting that modulating this draining may offer therapeutic approaches to alleviate SAH severity.

Aneurysmal Fibrous Histiocytoma: A Rare Variant

Aneurysmal fibrous histiocytoma (AFH) is a rare variant of benign fibrous histiocytoma. This tumor accounts for less than 2% of all fibrous histiocytomas, 1.7% of all cutaneous fibrous histiocytoma and it is typically known to occur in the extremities of middle-aged patients. A 23 year old male presented with slow growing, pigmented, nodular lesion on the left leg for the past 2 years. The swelling was initially non-tender, but there was a sudden increase in size associated with pain for the past 2 months. With a clinical suspicion of malignant melanoma an excision biopsy was performed and further evaluated by histopathology. The skin covered pigment lesion measuring 1.5x0.8x0.5cm showed fibrohistiocytic cellular proliferations containing blood filled spaces lacking endothelium on microscopy. Ancillary testing with bleaching, perls prussion blue reaction demonstrated the pigment as hemosiderin. Subsequently the lesion was negative for CD34 and positive for Factor XIIIA. Based on the histomorphology, ancillary testing and IHC, the diagnosis of Aneurysmal fibrous histiocytoma was made. Aneurysmal fibrous histiocytoma can be a challenging diagnostic entity due to its close clinical resemblance to melanoma and hemngioma. Although the pathogenesis is unclear, it is believed to be caused by extravasation of erythrocytes from capillaries leading to formation of the cystic blood spaces.

Afebrile and Leukopenic Sweet's Syndrome Following Partial Ileectomy in an Elderly Woman

Afebrile and Leukopenic Sweet's Syndrome Following Partial Ileectomy in an Elderly Woman

Multiple Progressive Thermopreconditioning Improves Cardiac Ischemia/Reperfusion-induced Left Ventricular Contractile Dysfunction and Structural Abnormality in Rat.

Triple progressive thermopreconditioning (3PTP) may induce high Hsp-70 expression to maintain cardiac function. We suggest that 3PTP may reduce myocardial ischemia/reperfusion (I/R) injury during organ transplantation through Bag3/Hsp-70 mediated defense mechanisms. Male Wistar rats were divided into sham control group and 72 h after 3PTP in a 42°C water bath (3PTP) group. Rats underwent 60 min of ischemia by occlusion of the left anterior descending coronary artery followed by 240 min reperfusion. Hemodynamic parameters, including the electrocardiogram, microcirculation, heart rate, left ventricular end-diastolic pressure, maximal rate of rise (+dp/dt), and fall (-dp/dt) in the left ventricular pressure for index of contraction and relaxation were determined. Myocardial infarct size was evaluated by the Evans blue-2,3,5-triphenyltetrazolium chloride method. 3PTP-induced protective mechanisms were determined by Western blot and immunohistochemistry. Cardiac I/R depressed cardiac microcirculation, induced S-T segment elevation, and R-R and P-R interval elongation increased infarct size associated with erythrocyte extravasation, leukocytes and macrophage/monocyte infiltration, granulocyte colony-stimulating factor, poly(ADP-ribose) polymerase 1 stain, and transferase-mediated dUTP-biotin nick end labeling positive cells. However, 3PTP evoked significant cardioprotection against I/R injury, characterized by the increased +dp/dt value and the decreased elevated left ventricular end-diastolic pressure, erythrocyte extravasation, leukocyte and macrophage/monocyte infiltration, granulocyte colony-stimulating factor expression, poly(ADP-ribose) polymerase 1 expression, transferase-mediated dUTP-biotin nick end labeling positive cells, and fragmentation and infarct area. In addition, 3PTP increased Hsp-70 and Bag3 expression and decreased Bax/Bcl-2 ratio, but did not affect the Beclin-1 and LC3-II/LC3-I ratio in the heart with I/R injury. 3PTP therapies may through Bag3 upregulation alleviate I/R injury-induced left ventricular structural deterioration and dysfunction.

Clinical characteristics, CT signs, and pathological findings of Pyrrolizidine alkaloids-induced sinusoidal obstructive syndrome: a retrospective study

BackgroundOne major etiology of hepatic sinusoidal obstruction syndrome (HSOS) in China is the intake of pyrrolizidine alkaloids (PAs). Since PAs-induced HSOS is a rare disease that has not been clearly characterized until now, the aim of this study was to investigate clinical characteristics, CT features, and pathological findings of PA-induced HSOS.MethodsThis retrospective cohort study included 116 patients with PAs-induced HSOS and 68 patients with Budd-Chiari syndrome from Jan 2006 to Sep 2016. We collected medical records of the patients, and reviewed image features of CT, and analyzed pathological findings.ResultsCommon clinical manifestations of PAs-induced HSOS were abdominal distention (98.26%), ascites (100%), jaundice (52.94%), abdominal pain (36.36%). Abnormal liver function was observed in most of PAs-induced HSOS. On CT scan, common findings included: ascites, hepatomegaly, the thickening of gallbladder wall, pleural effusion, patchy liver enhancement, and heterogeneous hypoattenuation. Most of the patients had a low ascitic total protein (< 25 g/L) and a high SAAG (≥ 11.0 g/L). In acute stage, pathologic features were massive sinusoidal dilatation, sinusoidal congestion, the extravasation of erythrocytes, hepatocellular necrosis, the accumulation of macrophages, the deposition of hemosiderin. In subacute stage, complete loss of pericentral hepatocytes, sinusoidal dilatation, the deposition of pigment granules were observed.ConclusionsThe PAs-induced HSOS patients displayed distinct clinical characteristics, imaging features, and pathological findings, which provided some evidences for the diagnosis of PAs-induced HSOS.Trial registrationChiCTR-DRD-17010709.

Abstract WP412: Important Role of Scavenging Receptors on Hemoglobin-Injected Intracerebral Hemorrhage Model

Introduction: Clinical and experimental studies have linked the presence of oxidative damage and neuroinflammation from free hemoglobin (Hb) to the innate immune response. CD36 has been identified as a macrophage/microglia surface receptor as part of a scavenging system, notably by RBC phagocytosis. CD163 is another surface receptor binding to Haptoglobin-Hb complexes with high affinity and Hb with lower affinity. These receptors participate in the clearance of extravasated erythrocytes and Hb, and also prevent triggering a pro-inflammatory cascade. Hypothesis: We hypothesize CD36 and CD163 knockout would play a role in oxidative stress and inflammation as indicated by neurological function, hemispheric, cortical volumes, and iron staining. Methods: Wildtype and CD36 -/- , CD163 -/- and double CD36 -/- xCD163 -/- mice were injected with 40μL of cerebrospinal fluid (vehicle) or stroma-free Hb. Behavioral rotarod, latency of fall and ambulatory distance tests were utilized to score neurological dysfunction. Brain sections were stained with Cresyl violet and Perls’ Prussian blue. Scanned images were analyzed by an observer blinded to genotypes using algorithm positive pixel counts. Results: At 24h, the CD36 -/- xCD163 -/- mice resulted in an average neurological deficit score of 4.75 (n=9, p&lt;.001), CD36 -/- of 6.34 (n=8, p&lt;.05), CD163 -/- of 6.50 (n=10, p&lt;.05) and WT of 8.23 (n=13). The CD36 -/- ipsilateral and contralateral hemispheric volumes increased respectively 12.4±1.6% (n=11, p=.0005) and 19.4±2.7% that of WT mice (n=6, p=.0001). Double knockouts showed 4.3±1.1% and 6.8±1.9% decreases in ipsilateral and contralateral cortical volumes (n=6, p=.0422, p=.0396). The CD36, CD36 -/- xCD163 -/- and CD163 -/- showed 68.5±13.7% (n=10, p=.003), 41.2±10.3% (n=10, p=.0317), and 30.0±9.8% (n=7, p=.0216) increase in iron staining than WT mice, respectively. Conclusions: Together, the behavioral data, the variations in brain volume, and the significant changes in deposited iron suggest the CD36 and CD163 receptors do play major roles in brain damage and neurological deficits following intracranial bleeding and could be targeted as a potential therapeutic intervention.

Histopathological changes in myocardial tissue due to coronary venous hypertension.

In chronic venous insufficiency (CVI), an increase in venous pressure causes the passage of intravascular blood cells and molecules into the surrounding tissues and induces histopathological changes in the lower extremities, leading to increased pigmentation in the legs, ulceration, and tissue loss to various degrees. This study aimed to investigate whether an increase in venous pressure in the coronary veins can lead to the aforementioned histopathological changes. Twenty-four New Zealand rabbits were divided into the following three groups: experimental model of coronary venous hypertension (CVH) (n = 8), sham group (n = 8), and control group (n = 8). After 21 days postoperatively, tissue samples from each group were compared for perivascular inflammation, erythrocyte extravasation, macrophage infiltration, and hemosiderin deposits by histopathological scoring under a light microscope. Matrix metalloproteinase-2 (MMP-2) activation was evaluated using immunohistochemical staining. In the CVH group, hemosiderin accumulation was significantly higher than in the sham and control groups (1.0 (1.0-3.0), 0.0 (0.0-1.0), 0.0 (0.0-0.0); p < 0.001). Immunohistochemically, in the CVH group, MMP-2 levels were significantly higher than in the sham and control groups (2.0 (1.0-3.0), 0.0 (0.0-1.0), 0.0 (0.0-0.0); p < 0.001). This experimental study showed for the first time the histopathological and immunohistochemical changes in myocardial tissue, similar to those observed in CVI, as a result of increased coronary venous pressure due to coronary vein ligation. Further studies are needed to understand the clinical implications of these results.

Therapeutic ultrasound combined with microbubbles improves atherosclerotic plaque stability by selectively destroying the intraplaque neovasculature.

Objective: The current antiangiogenic therapy for atherosclerotic plaques was mainly achieved by the use of antiangiogenic drugs, but serious side effects have limited the clinical application. The present study investigated whether therapeutic ultrasound (TUS) treatment with appropriate pressure could selectively deplete the neovasculature in vulnerable plaques to improve its stability with no side effects on the body; the underlying mechanisms were also explored.Methods and Results: A mouse model of advanced atherosclerosis was generated by maintaining apolipoprotein E-deficient (ApoE-/-) mice on a hypercholesterolemic diet (HCD). Plaque, skeletal muscle, mesentery and skin tissue from 114 atheroma-bearing mice were subjected to sham therapy, an ultrasound application combined with microbubbles at four different ultrasound pressures (1.0, 2.0, 3.0, 5.0 MPa), or ultrasound at 5.0 MPa alone. Microvessel density (MVD) was assessed by immunofluorescence and immunohistochemical methods. The plaque necrotic center/fiber cap (NC/FC) ratio and vulnerability index were calculated to evaluate plaque vulnerability. Twenty-four hours after TUS treatment at 3.0 MPa, the MVD in the plaque was substantially decreased by 84% (p < 0.05), while there was almost no change in MVD and neovessel density (NVD) in normal tissues, including skeletal muscle, mesentery and skin. Additionally, a marked reduction in the number of immature vessels was observed in the plaques (reduced by 90%, p < 0.05), whereas the number of mature vessels was not significantly decreased. Furthermore, TUS treatment at 3.0 MPa significantly improved plaque stability, as reflected by the NC/FC ratio and vulnerability index, which may be due to the selective destruction of intraplaque neovascularization by TUS treatment, thereby decreasing the extravasation of erythrocytes and leading to vascular inflammation alleviation and thin-cap fibroatheroma reduction.Conclusions: TUS treatment at 3.0 MPa selectively depleted plaque neovessels and improved the stability of vulnerable plaques through a reduction in erythrocyte extravasation and inflammatory mediator influx, with no significant effect on normal tissue.

Evaluation of specific heavy metal levels of pregnant women complicated by neural tube defects

Aim: The etiology of neural tube defect (NTD) is still not clear enough. In our study, we aimed to evaluate plasma heavy metal levels of pregnant women with NTD and to determine whether there is a relationship between heavy metal levels and NTD severity.Material and Methods: TThis study was conducted in Adiyaman University, Department of Gynaecology and Obstetrics. The study included 38 pregnant women with NTD and 42 pregnant women with healthy infants. Pregnant women who have NTD were divided into two groups as NTD Type 1 and NTD Type 2 according to the anomaly type. Levels of heavy metals such as Mercury (Hg), Cadmium (Cd), Cobalt (Co), Lead (Pb), Manganese (Mn) and Arsenic (As) were compared between groups.Results: Plasma Hg, Co, Cd and Pb levels were higher in NTD group than control group. (p values, respectively; p 0.001, p = 0.001, p 0.001, p 0.001). As and Mn levels were not statistically different between the two groups (p values; p = .519, p = .819, respectively). In the NTD group, Hg was found to be higher in NTD Type 1 than NTD Type 2 (p 0.001).Conclusion: It is obvious that some histomorphological changes are formed in the cardinal ligaments of patients with uterine prolapse due to pressure on the uterus. We believe that the increase in the number of extravasated erythrocytes and the thickness of the vascular wall and peripheral nerve should be supported by further studies.

Defective Platelet Thromboxane A2 Signaling and Serotonin Release in the Pathogenesis of Bleeding during Viral Infection

Viral hemorrhagic fever (VHF) refers to a group of diverse acute human diseases caused by single stranded RNA viruses typically associated with fever, vascular damage and abnormal vascular barrier function. These infections are a continuing threat to public health due to the high case-fatality rate and potential bioterrorism threats. Critically infected VHF patients with unfavorable prognosis often present bleeding symptoms and shock. Thrombocytopenia associated with endothelial, coagulation and platelet dysfunction has been reported during these infections, but their relationship to bleeding is still poorly defined. We have previously established that infection by lymphocytic choriomeningitis virus (LCMV) in extremely thrombocytopenic mice causes severe mucocutaneous bleeding and death mediated by interferon α/β receptor (IFNAR) signaling. We now show in vivo that IFNAR is expressed on megakaryocytes but not on circulating platelets, contrary to previously reported evidence. To explain how increased IFN-I in LCMV-infected mice alters the function of platelets lacking IFNAR, we cross-transplanted WT or IFNAR-/- bone marrow (BM) cells into IFNAR-/- and WT mice. Upon platelet depletion and LCMV infection, only chimeras with WT bone marrow died, suggest that IFN-I-sensitive bone marrow-derived cells are responsible for the mucocutaneous bleeding observed in conditions of extreme thrombocytopenia. Moreover, the results of BM transplantation studies prove that endothelial cell alterations and infection-related inflammatory conditions are not alone sufficient to cause hemorrhage. Circulating platelets during LCMV infection show a generalized aggregation disfunction that persists longer for the arachidonic acid/thromboxane A2 (AA/TBXA2) activation pathway. These aggregation defects are associated, and possibly linked to an impaired secretory ability of both α- and δ-granule. Since circulating platelets are unresponsive to IFN-I, these findings are consistent with the possibility that bone marrow-resident megakaryocytes are targets of IFN-I stimulation during LCMV infection and are the origin of structural and functional platelet abnormalities observed in the circulation. Indeed, megakaryocytes from LCMV-infected mice exhibited fewer granules limited to the perinuclear zone rather than normally diffused throughout the demarcation membrane system; the latter was also underdeveloped. Moreover, platelet transcriptome evaluation of genes involved in platelet production and function showed that IFN-I downregulates bone marrow expression of NF-E2 - a key transcription factor for thrombocytopoiesis - as well as of cyclooxygenase-1 and thromboxane-A synthase. The latter enzymes are required for TBXA2 synthesis from AA amplifying platelet activation. Thus, in addition to being decreased in number, circulating platelets of LCMV-infected animals have impaired activation-induced cargo release from storage granules supporting hemostasis. Experimentally, we observed that bleeding during LCMV infection is increased following aspirin, but not clopidogrel, administration. This suggested that serotonin secretion may be the final effector required to control erythrocyte extravasation. Accordingly, bleeding associated with LCMV infection was markedly enhanced in mice lacking platelet serotonin (TPH1-/-mice), and this was ameliorated by transfusion of normal platelets. In conclusion, we have identified a IFN-I targeting of megakaryocytes leading to reduced production of dysfunctional platelets with abnormal serotonin release as the cause of potentially lethal bleeding in a mouse model of arenavirus infection. Our demonstration that infusion of viable platelets can prevent lethal anemia in LCMV-infected susceptible mouse strains indicates that the same therapeutic intervention monitored by platelet response to AA stimulation may aid in treating severe VHF cases in human patients. Disclosures Aiolfi: MERU-VasImmune, Inc: Other: Stock option. Ruggeri:MERU-VasImmune Inc.: Equity Ownership, Other: CEO and Founder.

副银屑病81例临床及病理分析

Objective To analyze clinicopathological features of parapsoriasis. Methods Clinical and pathological data were collected from 81 patients with parapsoriasis in Department of Dermatology, Peking University First Hospital between January 2016 and May 2018, and analyzed retrospectively. Results Among the 81 patients with parapsoriasis, 44 were male and 37 were female, with age ranging from 6 to 77 years. Their disease course ranged from 7 days to 30 years, and the median disease course was 12 months. Moreover, 61 (75.3%) patients were aged less than 40 years, and 20 (24.7%) were aged 41 years and older. Of the 81 patients, 16 (19.8%) were diagnosed with small plaque parapsoriasis, 20 (24.7%) with large plaque parapsoriasis, 37 (45.7%) with pityriasis lichenoides chronica, and 8 (9.9%) with pityriasis lichenoides et varioliformis acuta. Additionally, distribution patterns of lesions included diffuse type in 65 cases (80.2%) , central type in 6 cases (7.4%) , and peripheral type in 10 cases (12.3%) . Histopathological examination of skin lesions revealed liquefaction degeneration of basal cells in 69 cases (85.2%) , migration of lymphocytes into the epidermis in 67 cases (82.7%) , focal parakeratosis in 42 cases (51.9%) , keratinocyte necrosis in 29 cases (35.8%) , extravasation of erythrocytes in 23 cases (28.4%) , epidermal spongiosis in 21 cases (25.9%) , and dermal perivascular focal infiltration in 61 cases (75.3%) . Conclusion Parapsoriasis has characteristic clinical and pathological manifestations, and a close combination of clinical manifestations with pathological features is necessary for its accurate diagnosis. Key words: Parapsoriasis; Pityriasis lichenoides

Lysed Erythrocyte Membranes Promote Vascular Calcification.

Intraplaque hemorrhage promotes atherosclerosis progression, and erythrocytes may contribute to this process. In this study we examined the effects of red blood cells on smooth muscle cell mineralization and vascular calcification and the possible mechanisms involved. Erythrocytes were isolated from human and murine whole blood. Intact and lysed erythrocytes and their membrane fraction or specific erythrocyte components were examined in vitro using diverse calcification assays, ex vivo by using the murine aortic ring calcification model, and in vivo after murine erythrocyte membrane injection into neointimal lesions of hypercholesterolemic apolipoprotein E-deficient mice. Vascular tissues (aortic valves, atherosclerotic carotid artery specimens, abdominal aortic aneurysms) were obtained from patients undergoing surgery. The membrane fraction of lysed, but not intact human erythrocytes promoted mineralization of human arterial smooth muscle cells in culture, as shown by Alizarin red and van Kossa stain and increased alkaline phosphatase activity, and by increased expression of osteoblast-specific transcription factors (eg, runt-related transcription factor 2, osterix) and differentiation markers (eg, osteopontin, osteocalcin, and osterix). Erythrocyte membranes dose-dependently enhanced calcification in murine aortic rings, and extravasated CD235a-positive erythrocytes or Perl iron-positive signals colocalized with calcified areas or osteoblast-like cells in human vascular lesions. Mechanistically, the osteoinductive activity of lysed erythrocytes was localized to their membrane fraction, did not involve membrane lipids, heme, or iron, and was enhanced after removal of the nitric oxide (NO) scavenger hemoglobin. Lysed erythrocyte membranes enhanced calcification to a similar extent as the NO donor diethylenetriamine-NO, and their osteoinductive effects could be further augmented by arginase-1 inhibition (indirectly increasing NO bioavailability). However, the osteoinductive effects of erythrocyte membranes were reduced in human arterial smooth muscle cells treated with the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide or following inhibition of NO synthase or the NO receptor soluble guanylate cyclase. Erythrocytes isolated from endothelial NO synthase-deficient mice exhibited a reduced potency to promote calcification in the aortic ring assay and after injection into murine vascular lesions. Our findings in cells, genetically modified mice, and human vascular specimens suggest that intraplaque hemorrhage with erythrocyte extravasation and lysis promotes osteoblastic differentiation of smooth muscle cells and vascular lesion calcification, and also support a role for erythrocyte-derived NO.

Noninvasive, Targeted Creation of Neuromyelitis Optica Pathology in AQP4-IgG Seropositive Rats by Pulsed Focused Ultrasound.

Neuromyelitis optica spectrum disorders (herein called NMO) is an autoimmune disease of the CNS characterized by astrocyte injury, inflammation, and demyelination. In seropositive NMO, immunoglobulin G autoantibodies against aquaporin-4 (AQP4-IgG) cause primary astrocyte injury. A passive transfer model of NMO was developed in which spatially targeted access of AQP4-IgG into the CNS of seropositive rats was accomplished by pulsed focused ultrasound through intact skin. Following intravenous administration of microbubbles, pulsed ultrasound at 0.5 MPa peak acoustic pressure was applied using a 1 MHz transducer with 6-cm focal length. In brain, the transient opening of the blood-brain barrier (BBB) in an approximately prolate ellipsoidal volume of diameter ∼3.5 mm and length ∼44 mm allowed entry of IgG-size molecules for up to 3-6 hours. The ultrasound treatment did not cause erythrocyte extravasation or inflammation. Ultrasound treatment in AQP4-IgG seropositive rats produced localized NMO pathology in brain, with characteristic astrocyte injury, inflammation, and demyelination after 5 days. Pathology was not seen when complement was inhibited, when non-NMO human IgG was administered instead of AQP4-IgG, or in AQP4-IgG seropositive AQP4 knockout rats. NMO pathology was similarly created in cervical spinal cord in seropositive rats. These results establish a noninvasive, spatially targeted model of NMO in rats, and demonstrate that BBB permeabilization, without underlying injury or inflammation, is sufficient to create NMO pathology in AQP4-IgG seropositive rats.

Blockade of vascular endothelial growth factor receptor 2 inhibits intraplaque haemorrhage by normalization of plaque neovessels.

BackgroundPlaque angiogenesis is associated with atherosclerotic lesion growth, plaque instability and negative clinical outcome. Plaque angiogenesis is a natural occurring process to fulfil the increasing demand of oxygen and nourishment of the vessel wall. However, inadequate formed, immature plaque neovessels are leaky and cause intraplaque haemorrhage.ObjectiveBlockade of VEGFR2 normalizes the unbridled process of plaque neovessel formation and induces maturation of nascent vessels resulting in prevention of intraplaque haemorrhage and influx of inflammatory cells into the plaque and subsequently increases plaque stability.Methods and ResultsIn human carotid and vein graft atherosclerotic lesions, leaky plaque neovessels and intraplaque haemorrhage co‐localize with VEGF/VEGFR2 and angiopoietins. Using hypercholesterolaemic ApoE3*Leiden mice that received a donor caval vein interposition in the carotid artery, we demonstrate that atherosclerotic vein graft lesions at t28 are associated with hypoxia, Hif1α and Sdf1 up‐regulation. Local VEGF administration results in increased plaque angiogenesis. VEGFR2 blockade in this model results in a significant 44% decrease in intraplaque haemorrhage and 80% less extravasated erythrocytes compared to controls. VEGFR2 blockade in vivo results in a 32% of reduction in vein graft size and more stable lesions with significantly reduced macrophage content (30%), and increased collagen (54%) and smooth muscle cell content (123%). Significant decreased VEGF, angiopoietin‐2 and increased Connexin 40 expression levels demonstrate increased plaque neovessel maturation in the vein grafts. VEGFR2 blockade in an aortic ring assay showed increased pericyte coverage of the capillary sprouts.ConclusionInhibition of intraplaque haemorrhage by controlling neovessels maturation holds promise to improve plaque stability.