Comparison of clinical outcomes in hospitalized patients with COVID-19 or non-COVID-19 community-acquired pneumonia in a prospective observational cohort study.

PURPOSE: Coronavirus disease 2019 (COVID-19) and non-COVID-19 community-acquired pneumonia (NC-CAP) often result in hospitalization with considerable risks of mortality, ICU treatment, and long-term morbidity. A comparative analysis of clinical outcomes in COVID-19 CAP (C-CAP) and NC-CAP may improve clinical management. METHODS: Using prospectively collected CAPNETZ study data (January 2017 to June 2021, 35 study centers), we conducted a comprehensive analysis of clinical outcomes including in-hospital death, ICU treatment, length of hospital stay (LOHS), 180-day survival, and post-discharge re-hospitalization rate. Logistic regression models were used to examine group differences between C-CAP and NC-CAP patients and associations with patient demography, recruitment period, comorbidity, and treatment. RESULTS: Among 1368 patients (C-CAP: n = 344; NC-CAP: n = 1024), C-CAP showed elevated adjusted probabilities for in-hospital death (aOR 4.48 [95% CI 2.38-8.53]) and ICU treatment (aOR 8.08 [95% CI 5.31-12.52]) compared to NC-CAP. C-CAP patients were at increased risk of LOHS over seven days (aOR 1.88 [95% CI 1.47-2.42]). Although ICU patients had similar in-hospital mortality risk, C-CAP was associated with length of ICU stay over seven days (aOR 3.59 [95% CI 1.65-8.38]). Recruitment period influenced outcomes in C-CAP but not in NC-CAP. During follow-up, C-CAP was linked to a reduced risk of re-hospitalization and mortality post-discharge (aOR 0.43 [95% CI 0.27-0.70]). CONCLUSION: Distinct clinical trajectories of C-CAP and NC-CAP underscore the need for adapted management to avoid acute and long-term morbidity and mortality amid the evolving landscape of CAP pathogens.

Expression of Staphylococcus aureus translation elongation factor P is regulated by a stress-inducible promotor.

Translation elongation factor P, expressed by the efp gene, is a conserved protein closely related to bacterial virulence and environmental stress regulation responses, however, little is known about the efp gene expression regulations. Here, the strain of Staphylococcus aureus subsp. aureus NCTC 8325 was taken as the research object and cultured under different conditions, including different culture temperatures, pH, and antibiotics, to study the expression of the efp gene in S. aureus by qRT-PCR, the results showed that the expression of the efp gene is upregulated under high temperature (40 °C), acidic (pH 5.4) or alkaline (pH 9.4) culture conditions, but upregulated early and downregulated later under the conditions of 0.5 MIC antibiotics (chloramphenicol at the final concentration of 2 µg/mL and vancomycin at the final concentration of 0.25 µg/mL), indicating that the efp promoter in S. aureus is inducible. The efp promoter sequence and structure in S. aureus were predicted by bioinformatics methods, and the predicted promoter was validated by constructing a promoter-probe vector and a series of promoter mutants, the results showed that the efp promoter sequence in S. aureus, named Pro, located in 1,548,179-1,548,250 of the S. aureus genome (NC_007795.1), and the sequence of - 10 element is CCTTATAGT, - 35 element is TTTACT. The results above could lay a foundation for screening transcription factors involved in the expression of the efp gene and then exploring the transcriptional regulation mechanism of EF-P in S. aureus.

Human NMO-IgG Induced Different Pathological and Immunological Changes in the CNS and Peripheral Tissues of Mice.

OBJECTIVES: The majority of neuromyelitis optica spectrum disorders (NMOSD) patients are seropositive for aquaporin-4 (AQP4)-specific antibodies [also named neuromyelitis optica immunoglobulin G antibodies (NMO-IgG)]. Although NMO-IgG can induce pathological changes in the central nervous system (CNS), the immunological changes in the CNS and peripheral tissue remain largely unknown. We investigated whether NMO-IgG binds to tissue expressing AQP4 and induces immunological changes in the peripheral tissue and CNS. METHODS: C57BL/6 female mice were assigned into an NMOSD or control group. Pathological and immunological changes in peripheral tissue and CNS were measured by immunostaining and flow cytometry, respectively. Motor impairment was measured by open-field test. RESULTS: We found that NMO-IgG did bind to astrocyte- and AQP4-expressing peripheral tissue, but induced glial fibrillary acidic protein and AQP4 loss only in the CNS. NMO-IgG induced the activation of microglia and modulated microglia polarization toward the classical (M1) phenotype, but did not affect innate or adaptive immune cells in the peripheral immune system, such as macrophages, neutrophils, Th17/Th1, or IL-10-producing B cells. In addition, NMOSD mice showed significantly less total distance traveled and higher immobility time in the open field. CONCLUSIONS: We found that injection of human NMO-IgG led to astrocytopathic lesions with microglial activation in the CNS. However, there were no significant pathological or immunological changes in the peripheral tissues.

Malnutrition and cerebral intraparenchymal damage in patients with thrombosis of dural sinuses and/or cerebral veins.

BACKGROUNDS: Thrombosis of dural sinuses and/or cerebral veins (CVT) is an uncommon form of cerebrovascular disease. Malnutrition is common in patients with cerebrovascular disease, and early assessment of malnutrition and individualized nutritional treatment have been reported to improve functional outcomes of these patients. As for CVT patients, little is known about whether these patients would suffer from malnutrition. Also, the correlation between malnutrition and cerebral intraparenchymal damage (CID) in CVT patients was rarely studied. METHODS: Patients with CVT were retrospectively included in this observational study. Multivariate logistic regressions were used to investigate the effects of nutritional indexes on the risk of CID. Subsequently, we used the independent risk factors to construct the nomogram model, and the consistency index (C-index), calibration curve and decision curve analysis (DCA) to assess the reliability and applicability of the model. RESULTS: A total of 165 patients were included in the final analysis. Approximately 72.7% of CVT patients were regarded as malnourished by our malnutrition screening tools, and malnutrition is associated with an increased risk of CID. Prognostic Nutritional Index (PNI) (OR = 0.873; CI: 0.791, 0.963, p = 0.007) remained as an independent predictor for CID after adjustment for other risk factors. The nomogram model showed that PNI and gender have a great contribution to prediction. Besides, the nomogram model was consistent with the actual observations of CID risk (C-index = 0.65) and was of clinical significance. CONCLUSIONS: We reported that malnutrition, as indicated by PNI, was associated with a higher incidence of CID in CVT patients. Also, we have constructed a nomogram for predicting the risk of CID in these patients.

Human adipose and synovial mesenchymal stem cells improve osteoarthritis in rats by reducing chondrocyte reactive oxygen species and inhibiting inflammatory response.

BACKGROUND: We explored the therapeutic effects of Adipose-derived mesenchymal stem cells (ADMSCs) and Synovial-derived mesenchymal stem cells (SDMSCs) on osteoarthritis (OA). METHODS: SDMSCs and ADMSCs were co-cultured with chondrocytes and stimulated with interleukin (IL)-1ß. An OA model was established on rats by intra-articular injection with ADMSCs and SDMSCs. After 8 weeks, the joint diameter difference was detected, and histological staining was used to observe the pathological changes in cartilage tissue. Enzyme-linked immunosorbent assay (ELISA) was used to detect the expressions of IL-6, tumor necrosis factor (TNF)-α and IL-1ß in joint fluid. The expressions of COL2A1, Aggrecan, Matrix metalloproteinase (MMP)-13, SOX9, IL-6, TNF-α and IL-1ß were detected by qRT-PCR and Western blotting in cartilage tissue. Reactive oxygen species (ROS) content in cells and cartilage tissues was detected by ROS kit. RESULTS: SDMSCs and ADMSCs co-cultured with chondrocytes could reduce MMP-13 expression, increase the expressions of COL2A1, Aggrecan and SOX9, as well as reverse the effects of IL-1ß on promoting ROS content and inflammatory factors levels. After the OA model was established, the injection of ADMSCs and SDMSCs reduced the differences in joint diameter and tissue lesions in OA rats. The OA model led to increased levels of IL-6, TNF-α and IL-1ß in joint fluid and cartilage tissue, while the injection of ADMSCs and SDMSCs inhibited the inflammatory factor levels in OA rats, and increased the expressions of COL2A1, Aggrecan and SOX9 in OA rats. CONCLUSION: ADMSCs and SDMSCs improve osteoarthritis in rats by reducing chondrocyte ROS and inhibiting inflammatory response.

miR-20a suppresses Treg differentiation by targeting Map3k9 in experimental autoimmune encephalomyelitis.

BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) is a model for inflammatory demyelinating diseases of the central nervous system (CNS), a group of autoimmune diseases characterized by inflammatory infiltration, demyelination, and axonal damage. miR-20a is dysregulated in patients with CNS inflammatory demyelinating diseases; however, the function of miR-20a remains unclear. In this study, we intended to explore the role of miR-20a in EAE. METHODS: The expression of miR-20a was detected by quantitative real-time PCR (qRT-PCR) in EAE mice and patients with MOG antibody-associated demyelinating diseases. CD4+ T cells of EAE mice were sorted, stimulated, and polarized with miR-20a knockdown. Activation and differentiation of CD4+ T cells were analyzed by flow cytometry. The expression of target gene Map3k9 was detected by qRT-PCR and western blot experiments. The binding of miR-20a to the 3' UTR of Map3k9 was tested by luciferase assays. The feasibility of miR-20a as a therapeutic target to alleviate the severity of EAE was explored by intravenous administration of miR-20a antagomirs to EAE mice. RESULTS: miR-20a was upregulated in splenocytes and lymph node cells, CD4+ T cells, and spinal cords of EAE mice. Moreover, miR-20a knockdown did not influence the activation of antigen-specific CD4+ T cells but promoted their differentiation into Treg cells. Map3k9 was predicted to be a target gene of miR-20a. The expressions of Map3k9 and miR-20a were negatively correlated, and miR-20a knockdown increased the expression of Map3k9. In addition, miR-20a binded to the 3' UTR of Map3k9, and simultaneous knockdown of miR-20a and Map3k9 counteracted the enhanced differentiation of Tregs observed when miR-20a was knocked down alone. Furthermore, injection of miR-20a antagomirs to EAE mice reduced the severity of the disease and increased the proportion of Treg cells in peripheral immune organs. CONCLUSIONS: miR-20a suppresses the differentiation of antigen-specific CD4+ T cells into Tregs in EAE by decreasing the expression of Map3k9. miR-20a antagomirs alleviate EAE, suggesting a new therapy for EAE and CNS inflammatory demyelinating diseases.

Using 17ß-estradiol heparin-poloxamer thermosensitive hydrogel to enhance the endometrial regeneration and functional recovery of intrauterine adhesions in a rat model.

Mechanical damage or infection to the endometrium can lead to the formation of adhesions in the uterine cavity, which may result in reduced reproductive outcome and/or pregnancy complications. The prognosis of this disease is poor due to few effective treatments and the complex environment of endometrium. Heparin-Poloxamer Hydrogel (HP hydrogel) is a nontoxic and biodegradable biomaterial, which has been commonly used as a sustained-release delivery system. In this study, we applied a mini-endometrial curette to scrape the endometrium of rats to mimic the process of curettage in patients. After the establishment of IUA model in rats, we injected the thermo-sensitive hydrogel(E2-HP hydrogel) into the injured uterine cavity and evaluated the therapeutic effect of E2-HP hydrogel on the recovery of IUA. Our results showed that E2-HP hydrogel can significantly facilitate the regeneration of injured endometrium along with inhibiting the cell apoptosis in IUA model. Furthermore, we revealed that E2-HP hydrogel on the recovery of IUA was closely associated with the upregulation of kisspeptin through activating the ERK1/2 and MAPKs p38 pathways. In conclusion, E2-HP hydrogel can effectively transfer E2 into the injured endometrium and it can be considered as a promising therapeutic method for the women with intrauterine adhesions.

A repeat region from the Brassica juncea HMA4 gene BjHMA4R is specifically involved in Cd2+ binding in the cytosol under low heavy metal concentrations.

BACKGROUND: HMA4 transporters are involved in the transport and binding of divalent heavy metals (Cd, Zn, Pb [lead] and Co [cobalt]). In general, as efflux pumps, HMA4 transporters can increase the heavy metal tolerance of yeast and Escherichia coli. Additional research has shown that the C-terminus of HMA4 contains a heavy metal-binding domain and that heterologous expression of a portion of peptides from this C-terminal domain in yeast provides a high level of Cd tolerance and Cd hyperaccumulation. RESULTS: We cloned BjHMA4 from Brassica juncea, and quantitative real-time PCR analysis revealed that BjHMA4 was upregulated by Zn and Cd in the roots, stems and leaves. Overexpression of BjHMA4 dramatically affects Zn/Cd distribution in rice and wheat seedlings. Interestingly, BjHMA4 contains a repeat region named BjHMA4R within the C-terminal region; this repeat region is not far from the last transmembrane domain. We further characterized the detailed function of BjHMA4R via yeast and E. coli experiments. Notably, BjHMA4R greatly and specifically improved Cd tolerance, and BjHMA4R transformants both grew on solid media that contained 500 µM CdCl2 and presented improved Cd accumulation (approximately twice that of wild-type [WT] strains). Additionally, visualization via fluorescence microscopy indicated that BjHMA4R clearly localizes in the cytosol of yeast. Overall, these findings suggest that BjHMA4R specifically improves Cd tolerance and Cd accumulation in yeast by specifically binding Cd2+ in the cytosol under low heavy metal concentrations. Moreover, similar results in E. coli experiments corroborate this postulation. CONCLUSION: BjHMA4R can specifically bind Cd2+ in the cytosol, thereby substantially and specifically improving Cd tolerance and accumulation under low heavy metal concentrations.

T3 level may be a helpful marker to predict disease prognosis of acute central nervous system viral infections.

AIM OF THE STUDY: Acute central nervous system viral infections are progressive and inflammatory diseases with inflammatory cells infiltrating into the central nervous system (CNS), and thyroid hormone (TH) level is associated with the oxidative and antioxidant status. Variations in oxidative stress and antioxidant status are related to the pathogenesis of inflammatory diseases. Our study aimed to investigate the possible correlation between viral infections in CNS and TH levels of thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3). MATERIALS AND METHODS: We measured serum concentrations of TSH, fT4, and fT3 in 206 individuals, including 59 viral meningitis (VM) patients, 60 viral encephalitis (VE) patients, and 87 healthy controls. RESULTS: Our findings showed that VE and VM patients had lower levels of fT3 and higher levels of fT4 compared with healthy controls, whether male or female. Moreover, levels of TSH and fT3 in patients with viral infections in CNS were inversely correlated with disease prognosis measured by the Glasgow Outcome Scale. CONCLUSIONS: Variations in TH level may represent the oxidative status and are surrogate biomarkers for disease prognosis of acute central nervous system viral infections.

Platelet volume indices for the prognosis of acute ischemic stroke patients with intravenous thrombolysis.

OBJECTIVE: We aimed to investigate whether platelet volume indices (PVIs) were associated with an unfavorable clinical outcome in acute ischemic stroke (AIS) patients undergoing intravenous thrombolysis (IVT). METHODS: We defined a modified Rankin Scale (mRS) score of 3-6 at 90 days as an unfavorable outcome. Logistic regression analysis was performed to find out whether mean platelet volume (MPV), platelet distribution width (PDW), MPV/platelet count (PC) ratio and PDW/PC ratio were associated with poor prognosis. A Spearman correlation test was carried out to assess the relationship between variables. RESULTS: Overall, 183 patients were included in this study. Multivariate logistic regression analysis revealed that MPV (adjusted odds ratio [OR] 1.52, 95% confidence interval [CI]: 1.01-2.29, p = 0.044) and PDW-sd (adjusted OR 1.30, 95% CI: 1.06-1.59, p = 0.011) were independent predictors of the poor outcome. There was a trend of incremental OR when compared higher tertile of MPV with lower ones (second tertile, adjusted OR 2.52,95% CI：1.02-6.21, p = 0.045； third tertile, adjusted OR 2.61, 95% CI: 1.12-6.09, p = 0.027). Besides, we found a significant positive correlation between MPV and PDW-sd (or =0.874, p < 0.001). CONCLUSION: MPV and PDW-sd were independent predictors for 90-day outcomes in stroke patients receiving thrombolysis.

The clinical significance of neutrophil-to-lymphocyte ratio and monocyte-to-lymphocyte ratio in Guillain-Barré syndrome.

Purpose/Aim of the study: Guillain Barré syndrome (GBS) is a severe peripheral nervous disease that leads to muscle weakness and areflexia. We now commonly accept a synthesis that inflammation and immunity play key role in GBS pathogenesis. Many studies pointed out that neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) are novel promising markers of inflammation or immunity. Our study aimed to evaluate whether the NLR and the MLR were associated to GBS or not. MATERIALS AND METHODS: We measured blood cell count in 334 individuals including 117 GBS and 217 healthy controls. RESULTS: Our findings demonstrated that the GBS patients had higher levels of NLR and MLR than the healthy controls. The severe group also had higher levels of NLR and MLR compared to the mild group. We took the method of receiver-operating characteristic curve to find out the cut-off value of NLR for GBS occurrence and severity; it was 2.295 and 3.05, respectively. The cut-off values of MLR for GBS incidence and severity were the same, it was 0.235. CONCLUSION: In the setting of GBS, the NLR and MLR were significantly increased and they may be pathophysiologically and clinically relevant in GBS. The NLR and MLR would be new biomarkers of medical application.

Dynamic remodeling of arteriolar collaterals after acute occlusion in chick chorioallantoic membrane.

OBJECTIVE: After arteriolar occlusion, collaterals enlarge and initially elevated WSS normalizes. While most previous studies focused on endpoints of such adaptive changes in larger collaterals, the present investigation aimed to continuously determine the relation between WSS and diameter in microvascular collaterals during adaptive reactions. METHODS: In Hamburger-Hamilton stage 40 CAMs, junction points between arteriolar segments were identified and the third upstream segment on one side was occluded. Intravital microscopy recordings were taken for 24 hours post-occlusion. Segment diameter and blood velocity were measured: WSS and capillary density were calculated. RESULTS: After occlusion, vascular diameters exhibited an immediate decrease, then increased with a time constant of 2.5 ± 0.8 hours and reached a plateau of up to 60% above baseline after about 7 hours. Vascular tone showed no significant change. WSS exhibited an immediate increase post-occlusion and linearly returned to baseline after about 12 hours. Local WSS change and diameter change rate showed similar patterns during the initial but not the later phase of post-occlusive adaptation. CONCLUSIONS: CAM collaterals undergo fast structural remodeling within 24 hours post-occlusion. This remodeling might be driven by local WSS and by other regulators within the vascular network.

Thyroid hormone level is associated with the frequency and severity of Guillain-Barré syndrome.

OBJECTIVE: Guillain-Barré syndrome (GBS) is a neurodegenerative and inflammatory demyelination disorder, and oxidative stress is concerned with the pathogenesis of the disease. Also, we found that thyroid hormone level is correlated to the oxidative and antioxidant status in previous studies. Our study was aimed to find the possible relationship between the frequency and severity of GBS and thyroid hormone levels. MATERIALS AND METHODS: We measured serum levels of thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) in 238 individuals, including 90 GBS, 44 multiple sclerosis and 104 healthy controls. RESULTS: Our findings demonstrate that the patients with GBS had lower TSH and higher FT4, FT4/FT3 than healthy controls in the normal range. Furthermore, it was also shown in our study that TSH levels in patients with GBS were correlated with disease severity measured by the Hughes Functional Grading Scale. CONCLUSION: Lower TSH, higher FT4 and FT4/FT3 stand for the oxidative status and are associated with the incidence and severity of GBS.

Structure and hemodynamics of vascular networks in the chorioallantoic membrane of the chicken.

The chick chorioallantoic membrane (CAM) is extensively used as an in vivo model. Here, structure and hemodynamics of CAM vessel trees were analyzed and compared with predictions of Murray's law. CAM microvascular networks of Hamburger-Hamilton stage 40 chick embryos were scanned by videomicroscopy. Three networks with ∼3,800, 580, and 480 segments were digitally reconstructed, neglecting the capillary mesh. Vessel diameters (D) and segment lengths were measured, and generation numbers and junctional exponents at bifurcations were derived. In selected vessels, flow velocities (v) and hematocrit were measured. Hemodynamic simulations, incorporating the branching of capillaries from preterminal vessels, were used to estimate v, volume flow, shear stress (τ), and pressure for all segments of the largest network. For individual arteriovenous flow pathways, terminal arterial and venous generation numbers are negatively correlated, leading to low variability of total topological and morphological pathway lengths. Arteriolar velocity is proportional to diameter (v∝D1.03 measured, v∝D0.93 modeling), giving nearly uniform τ levels (τ∝D0.05). Venular trees exhibit slightly higher exponents (v∝D1.3, τ∝D0.38). Junctional exponents at divergent and convergent bifurcations were 2.05 ± 1.13 and 1.97 ± 0.95 (mean ± SD) in contrast to the value 3 predicted by Murray's law. In accordance with Murray's law, τ levels are (nearly) maintained in CAM arterial (venular) trees, suggesting vascular adaptation to shear stress. Arterial and venous trees show an interdigitating arrangement providing homogeneous flow pathway properties and have preterminal capillary branches. These properties may facilitate efficient oxygen exchange in the CAM during rapid embryonic growth.

Synthesis and photoluminescence properties of high-quality reddish-orange emitting Ca4Nb2O9:Eu3+ phosphors for WLEDs and anti-counterfeiting.

In this report, we successfully synthesized a novel trivalent europium (Eu3+)-activated Ca4Nb2O9 phosphor emitting reddish-orange light via its 5D0 → 7F1 and 5D0 → 7F2 transitions. In the Ca4Nb2O9 host, Eu3+ ions exhibited optimal doping at a concentration of 15 mol%, with the concentration-quenching mechanism predominantly driven by electric dipole-dipole interactions. In addition, the Ca4Nb2O9:Eu3+ phosphor exhibited excellent thermal stability with a photoluminescence (PL) intensity of 71.6% at a working temperature of 423 K. Interestingly, the internal PL quantum yield (PLQY) of the optimal sample was obtained to be 87.43%, and the external PLQY was determined to be 47.81%. The fabricated white light-emitting diode that employed this optimized phosphor alongside commercial phosphors, via a novel silica epoxy gel (parts A and B)-based method, exhibited good color rendering index (color rendering index = 80.65), excellent warm-correlated color temperature (correlated color temperature = 3753 K), and Commission International de l'Eclairage chromaticity coordinate (0.3922, 0.3845). Moreover, the optimal phosphor was introduced into the polyvinyl alcohol (PVA) polymer film, creating a translucent film. These films were then fabricated on glass, plastic, and card, which showed a satisfying emission under ultraviolet radiation. Consequently, the proposed Eu3+-activated Ca4Nb2O9 phosphors can be used as light sources and the Ca4Nb2O9:Eu3+-PVA film is proposed for anti-counterfeiting applications.

Serum Albumin Level Can Predict Immunotherapy Response of Neuromyelitis Optica Spectrum Disorders in the Acute Phase.

Background: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune demyelinating disease of the central nervous system. However, few biomarkers have been found to predict the outcome of immunotherapy. We investigated the relationship between the serum albumin (S-Alb) and response to immunotherapy in acute NMOSD patients. Methods: A total of 107 consecutive Chinese patients with acute NMOSD diagnosed between January 2013 and January 2022 were included in our prospective observational study. S-Alb was measured by the use of bromocresol green and immunoturbidimetric methods on admission. The immunotherapy response was assessed by the percentage change in the expanded disability status scale (EDSS) score from admission to discharge after treatment. We evaluated the association between S-Alb and immunotherapy response through multivariate logistic regression analysis. Results: S-Alb levels were significantly lower in patients who were resistant to immunotherapy than in those who were responsive to treatment (p<0.001). S-Alb levels were positively related to a favorable response to immunotherapy (r=0.386, p<0.001). The odds ratio (95% CI) for the association between S-Alb level and response to immunotherapy was 1.27 (95% CI=1.08, 1.50; p=0.004) after adjusting for potential factors. ROC analysis showed that patients with S-Alb levels lower than 40.85 g/L were likely to be resistant to immunotherapy. Conclusion: Our study indicated that a higher S-Alb was an independent indicator of response to immunotherapy in acute NMOSD patients.

Fibrinogen deposition promotes neuroinflammation and fibrin-derived γ377-395 peptide ameliorates neurological deficits after ischemic stroke.

BACKGROUND: Fibrin(ogen) deposition in the central nervous system (CNS) contributes to neuropathological injury; however, its role in ischemic stroke is unknown. In this study, we identified fibrinogen as a novel proinflammatory regulator of post-stroke neuroinflammation and revealed the neuro-protection effect of fibrin-derived γ377-395peptide in stroke. METHODS: Fibrinogen depletion and fibrinogen-derived γ377-395peptide treatment were performed 2 h after establishing a permanent middle cerebral artery occlusion (pMCAO) model. The infarction volume, neurological score, fibrin(ogen) deposition, and inflammatory response were evaluated 24 h after occlusion. Both in vivo and in vitro studies were conducted to assess the therapeutic potential of the γ377-395peptide in blocking the interactions between fibrin(ogen) and neutrophils. RESULTS: Fibrin(ogen) deposited in the infarct core promoted post-stroke inflammation and exacerbated neurological deficits in the acute phase after stroke onset. Reducing fibrinogen deposition resulted in a decrease in infarction volume, improved neurological scores, and reduced inflammation in the brain. Additionally, the presence of neutrophil accumulation near fibrin(ogen) deposits was observed in ischemic lesions, and the engagement of fibrin(ogen) by integrin receptor αMß2 promoted neutrophil activation and post-stroke inflammation. Finally, inhibiting fibrin(ogen)-mediated neutrophil activation using a fibrinogen-derived γ377-395peptide significantly attenuated neurological deficits. CONCLUSIONS: Fibrin(ogen) is a crucial regulator of post-stroke inflammation and contributes to secondary brain injury. The inflammation induced by fibrin(ogen) is primarily driven by neutrophils during acute ischemic stroke and can be ameliorated using the fibrin-derived γ377-395peptide. Targeting the fibrin(ogen)-mediated neuropathological process represents a promising approach for neuroprotective therapy after stroke while preserving its beneficial coagulation function.

CD22 blockade aggravates EAE and its role in microglia polarization.

AIMS: Multiple sclerosis (MS) is a neuroinflammatory demyelinating disease. Microglia are reportedly involved in the pathogenesis of MS. However, the key molecules that control the inflammatory activity of microglia in MS have not been identified. METHODS: Experimental autoimmune encephalomyelitis (EAE) mice were randomized into CD22 blockade and control groups. The expression levels of microglial CD22 were measured by flow cytometry, qRT-PCR, and immunofluorescence. The effects of CD22 blockade were examined via in vitro and in vivo studies. RESULTS: We detected increased expression of microglial CD22 in EAE mice. In addition, an in vitro study revealed that lipopolysaccharide upregulated the expression of CD22 in microglia and that CD22 blockade modulated microglial polarization. Moreover, an in vivo study demonstrated that CD22 blockade aggravated EAE in mice and promoted microglial M1 polarization. CONCLUSION: Collectively, our study indicates that CD22 may be protective against EAE and may play a critical role in the maintenance of immune homeostasis in EAE mice.

Imaging of microglia in post-stroke inflammation.

Microglia constantly survey the central nervous system microenvironment and maintain brain homeostasis. Microglia activation, polarization and inflammatory response are of great importance in the pathophysiology of ischemic stroke. For exploring biochemical processes in vivo, positron emission tomography (PET) is a superior imaging tool. Translocator protein 18 kDa (TSPO), is a validated neuroinflammatory biomarker which is widely used to evaluate various central nervous system (CNS) pathologies in both preclinical and clinical studies. TSPO level can be elevated due to peripheral inflammatory cells infiltration and glial cells activation. Therefore, a clear understanding of the dynamic changes between microglia and TSPO is critical for interpreting PET studies and understanding the pathophysiology after ischemic stroke. Our review discusses alternative biological targets that have attracted considerable interest for the imaging of microglia activation in recent years, and the potential value of imaging of microglia in the assessment of stroke therapies.

Nitric oxide synthase and reduced arterial tone contribute to arteriovenous malformation.

Mechanisms underlying arteriovenous malformations (AVMs) are poorly understood. Using mice with endothelial cell (EC) expression of constitutively active Notch4 (Notch4*EC), we show decreased arteriolar tone in vivo during brain AVM initiation. Reduced vascular tone is a primary effect of Notch4*EC, as isolated pial arteries from asymptomatic mice exhibited reduced pressure-induced arterial tone ex vivo. The nitric oxide (NO) synthase (NOS) inhibitor NG-nitro-l-arginine (L-NNA) corrected vascular tone defects in both assays. L-NNA treatment or endothelial NOS (eNOS) gene deletion, either globally or specifically in ECs, attenuated AVM initiation, assessed by decreased AVM diameter and delayed time to moribund. Administering nitroxide antioxidant 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl also attenuated AVM initiation. Increased NOS-dependent production of hydrogen peroxide, but not NO, superoxide, or peroxynitrite was detected in isolated Notch4*EC brain vessels during AVM initiation. Our data suggest that eNOS is involved in Notch4*EC-mediated AVM formation by up-regulating hydrogen peroxide and reducing vascular tone, thereby permitting AVM initiation and progression.