An Increase in Peroxiredoxin 6 Expression Induces Neurotoxic A1 Astrocytes in the Lumbar Spinal Cord of Amyotrophic Lateral Sclerosis Mice Model

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease with selective degeneration of motor neurons. It has been reported that an increase in the levels of inflammatory cytokines and glial cells such as reactive astrocytes is closely involved in the pathological progression of ALS. Recently, the levels of neuropathic cytotoxic (A1) astrocytes among reactive astrocytes have reportedly increased in the central nervous system of ALS mice, which induce motor neuron degeneration through the production of inflammatory cytokines and secretion of neuropathic factors. Hence, elucidating the induction mechanism of A1 astrocytes in ALS is important to understand the mechanism of disease progression in ALS. In this study, we observed that the expression of peroxiredoxin 6 (PRDX6), a member of the peroxiredoxin family, was markedly upregulated in astrocytes of the lumbar spinal cord of SOD1G93A mice model for ALS. Additionally, when PRDX6 was transiently transfected into the mouse astrocyte cell line C8-D1A and human astrocytoma cell line U-251 MG, the mRNA expression of complement C3 (a marker for A1 astrocyte phenotype) and inflammatory cytokines was increased. Furthermore, the mRNA expression of C3 and inflammatory cytokine was increased in C8-D1A and U-251 MG cells stably expressing PRDX6, and the increased mRNA expression was significantly suppressed by MJ33 (lithium[1-hexadecoxy-3-(2,2,2-trifluoroethoxy) propan-2-yl] methyl phosphate), an inhibitor of the phospholipase A2 activity of PRDX6. Our results suggest that the expression of PRDX6 in astrocytes plays an important role in the induction of A1 astrocytes and expression of inflammatory cytokines in the ALS mice model.

High level of serum complement 3 is a risk factor for vascular stenosis progression in TA patients receiving tocilizumab: a prospective observational study

BACKGROUND

The IL-6R antibody tocilizumab has been proven effective in treating Takayasu arteritis (TA). However, some patients show silent vascular stenosis progression (VSP) despite treatment with tocilizumab. The aim of the study was to explore the related risk factors of VSP in patients treated with tocilizumab.

METHODS

Patients receiving tocilizumab were enrolled from the prospective living ongoing East China Takayasu Arteritis cohort. Their medical information was uniformly recorded with a homogenized evaluation method. Magnetic resonant angiography or computed tomographic angiography was employed to monitor VSP during the follow-up period, and Cox regression analysis was performed to explore the related risk factors.

RESULTS

Thirty-eight patients were enrolled, among whom 18 (47.4%) experienced VSP, and seven and three patients experienced new and worsened vascular ischemic symptoms and events (VISE) during follow-up, respectively. The median period for VSP occurrence was 6.9 months during follow-up. Patients with VSP showed higher levels of baseline complement 3 (C3) than those in the patients without VSP. Multivariate Cox regression analysis revealed baseline C3 level (hazard ratio [HR] = 7.05, 95% confidence interval: 1.50-33.07, p = 0.013) was independently associated with VSP, with a cut-off value of 1.22 g/L.

CONCLUSIONS

47.4% of TA patients treated with tocilizumab would suffer VSP. A high C3 level is a risk factor for VSP in TA patients receiving tocilizumab, which may facilitate the option of tocilizumab in the future.

The role of reactive astrocytes in neurotoxicity induced by ultrafine particulate matter

Epidemiological studies have shown that ambient fine particulate matter (PM) can cause various neurodegenerative diseases, including Alzheimer's disease. Reactive astrocytes are strongly induced by ambient fine PM, although their role is poorly understood. Herein, we show that A1 reactive astrocytes (A1s) were induced by neuroinflammatory microglia activated by PM with an aerodynamic diameter ≤ 0.2 μm (PM_0.2). The activated-microglia induced A1s by secreting interleukin-1α, tumor necrosis factor-α, and complement 1q, and these cytokines acting together were necessary and sufficient to induce A1s. PM_0.2-induced A1s could promote synaptic damage in neurons by secreting complement 3 (C3). SB 290157, a highly selective C3aR nonpeptide antagonist, partially ameliorated glial conditioned medium-induced synaptic injury. In vitro synaptic damage was partially prevented when A1 formation was blocked by minocycline. Finally, this study showed that N-acetyl-L-cysteine ameliorated PM_0.2-induced neural damage independent of A1 differentiation. Collectively, these findings explain why central nervous system neurons suffer synaptic damage and neuroinflammation after PM_0.2 exposure and suggest that this exposure induces A1s to contribute to synaptic damage of neurons. This study indicates a potential approach for developing improved treatment of these diseases induced by particulate exposure. SYNOPSIS: PM_0.2-activated neuroinflammatory microglia induced A1 reactive astrocytes (A1s) by secreting IL-1α, TNF-α, and C1q. PM_0.2-induced A1s could promote synaptic damage of neuron by secreting complement 3.

Chen flower saponins in rats with metabolic hypertension by inhibiting the activation of the renin-angiotensin-aldosterone system through complement 3

BACKGROUND

Metabolic hypertension (MH) has become the most common type of hypertension in recent years due to unhealthy eating habits and lifestyles of people, such as over-eating alcohol, high fat, and sugar diets (ACHFSDs). Therefore, effective means to combat MH are needed. Previous studies have shown that Panax notoginseng (Burkill) F. H. Chen flower saponins (PNFS) can lower blood pressure in spontaneously hypertensive rats (SHR). However, whether it acts on MH and its mechanism of action remain unclear.  METHODS: The pharmacodynamic effects of PNFS were evaluated in rats with ACHFSDs-induced MH. The blood pressure, blood biochemical, grip strength, face temperature, vertigo time, and liver index were estimated. The histological changes in the liver and aorta were observed using hematoxylin and eosin staining. The levels of ET-1, TXB₂, NO, PGI₂, Renin, ACE, Ang II, and ALD in plasma were detected using ELISA. The levels of C3, KLF5, LXRα, and Renin in kidney tissues were measured using qRT-PCR.The expression levels of C3, KLF5, LXRα, and Renin in kidney tissues were examined using Western blotting.

RESULTS

In the present study, PNFS was found to reduce blood pressure, face temperature, and vertigo time, increase grip strength and improve dyslipidemia in rats with MH. In addition, PNFS decreased the plasma levels of ET-1 and TXB₂, elevated the levels of NO and PGI₂, and improved pathological aortic injury. Meanwhile, PNFS decreased the plasma levels of Renin, ACE, Ang II, and ALD. QRT-PCR and Western bolt showed that PNFS downregulated C3, KLF5, LXRα, and Renin protein and mRNA expression in the kidneys of rats with MH.

CONCLUSION

The finding of the present study suggested that PNFS could downregulate C3 and KLF-5 expression in rats with MH, thereby inhibiting the overactivation of the renin-angiotensin-aldosterone system, while improving vascular endothelial function and ultimately reducing blood pressure in rats with MH.

[Effect of electroacupuncture on hippocampal synaptic plasticity and complement dependent memory impairment in Parkinson's disease dementia mice]

OBJECTIVE

To observe the effect of electroacupuncture (EA) of "Xiusanzhen" ［bilateral "Yingxiang"(LI20)+"Yintang"(GV24⁺)］ on synaptophysin (SYN), postsynaptic density protein-95 (PSD-95), Iba-1⁺ CD68⁺ microglia and complement C related protein expression of hippocampus in Parkinson's disease dementia (PDD) mice, so as to explore its mechanism in improving memory impairment of PDD.

METHODS

Male C57BL/6 mice were randomly divided into control, sham operation, model and EA groups, with 10 mice in each group. The PDD model was established by injecting 6-OHDA into the medial forebrain tract. EA (2 Hz, 1 mA) was applied to unilateral LI20 and GV29 for 20 min once daily for consecutive 14 days. Morris water maze and new object recognition test were used to evaluate the learning and memory ability. Western blot was used to detect the expression of SYN and PSD-95 proteins in hippocampus. Immunofluorescence was used to label Iba-1⁺ CD68⁺ microglia and C1q positive cells in hippocampal CA1 region. The content of C3 protein in hippocampus was detected by ELISA.

RESULTS

Compared with the control group, there was no statistical significance in all the observed indexes in the sham operation group. Compared with the sham operation group, the average escape latency (AEL) prolonged significantly (P<0.01), the target platform crossing times (TPCT) and new object recognition index (NORI) decreased remarkably (P<0.01); the expressions of SYN and PSD-95 proteins in hippocampal CA1 region were significantly decreased (P<0.01); the rate of Iba-1+CD68+ microglia, the rate of C1q positive cells and the content of C3 protein were significantly increased (P<0.01) in the model group. In comparison with the model group, the AEL was shortened (P<0.01), the TPCT and NORI were increased (P<0.05) remarkably; the expressions of SYN and PSD-95 proteins in hippocampal CA1 region were increased (P<0.01, P<0.05); the rate of Iba-1⁺ CD68⁺ microglia, the rate of C1q positive cells and the content of C3 protein were significantly decreased (P<0.01) in the EA group.

CONCLUSION

"Xiusanzhen" can alleviate the learning and memory impairment of PDD model mice, and improve the synaptic plasticity of hippocampal CA1 area. The mechanism may be related to the reduction of C1q and C3 deposition in hippocampal CA1 region and the reduction of microglia phagocytosis.

Changes in Maternal Serum Levels of C3 and C4 Complement Components in Different Delivery Methods and Postpartum Hemorrhage

BACKGROUND

Activation of the complement system may play a role in the pathophysiology of human labor. Yet no unanimous conclusion has been drawn.

OBJECTIVE

To compare the differences in maternal complement components C3 and C4 serum levels in cesarean section and the vaginal delivery at term and in the postpartum hemorrhage.

METHODS

One hundred and sixty six women delivered at term were enrolled in this study. Maternal blood samples were obtained from 47 cases of elective cesarean section and 119 cases of the vaginal delivery. Serum complement levels were measured subsequently by immuno-scatter turbidimetry.

RESULTS

The maternal complement levels declined significantly during delivery by both the cesarean section and the vaginal delivery (p＜0.01) in comparison with the baseline. A much larger drop of C3 serum level was found in the postpartum hemorrhage and in the vaginal delivery, and the incidence of the postpartum hemorrhage has a positive correlation with the complement decline rate.

CONCLUSION

The complement system may be involved in the delivery process and represents a predictive value in postpartum hemorrhage.

TWIST1 transcriptionally upregulates complement 3 in glomerular mesangial cells from spontaneously hypertensive rats

We have shown that complement 3 (C3) is upregulated in cardiovascular and renal organs, which induces the synthetic phenotype and exaggerates the growth of mesenchymal cells from spontaneously hypertensive rats (SHRs). However, the mechanisms of the upregulation of C3 have remained unclear. In the present study, we investigated the role of TWIST1, a transcription factor that regulates mesodermal embryogenesis, in the upregulation of C3 in glomerular mesangial cells (GMCs) from SHRs and Wistar-Kyoto (WKY) rats. Immunocytochemical staining and western blot analysis showed that the expression of TWIST1 in GMCs from SHRs was higher than that in GMCs from WKY rats in vivo and in vitro. Real-time PCR analysis showed increases in the expression of Twist1 mRNA with attenuated expression of miR-151-3p in GMCs from SHRs compared to that in cells from WKY rats. Chromatin immunoprecipitation assays showed increases in TWIST1 binding to the C3 promoter in GMCs from SHRs compared to that in cells from WKY rats. Transfection of Twist1 cDNA by a lentiviral vector increased the expression of C3 mRNA in GMCs from WKY rats. TWIST1 siRNA significantly decreased the mRNA expression of C3 and osteopontin in GMCs from SHRs. These results indicate that the increases in TWIST1 expression, attenuation of miR-151-3p, and strong binding of TWIST1 upregulate C3 gene expression in GMCs from SHRs. The enhanced TWIST1-C3 system induces the synthetic phenotype of mesenchymal tissue that may be associated with cardiovascular and renal remodeling in hypertension.

Serum complement 3 is a potential biomarker for assessing disease activity in Takayasu arteritis

BACKGROUND

Takayasu arteritis (TA) is a rare disease, lacking convenient and feasible biomarkers to identify disease activity. We aimed to evaluate the value of complements in distinguishing active TA.

METHODS

Consecutive patients were enrolled from the prospective East China TA cohort from April 2008 to June 2019. Patients were divided into two groups according to their baseline Kerr score. The value of complements and other biomarkers in identifying disease activity were analysed with cluster analysis, ROC curves, and combined tests. An independent group of patients from July 2019 to December 2019 were employed to validate the results.

RESULTS

Of the enrolled 519 patients, 406 (72.2%) cases were identified as active disease. Higher erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), interleukin-6 (IL-6), and complement 3 (C3) levels were observed in the active group. Elevated C3 (≥ 1.085 g/L) had a high value to identify active TA with a sensitivity of 69.9%, specificity of 66.7%, and AUC of 0.715. Combining the CRP (≥ 10.65 g/L; sensitivity, 50.7%; specificity, 82.4%) and C3, the sensitivity could be improved to 85.1% in parallel test and the specificity could be improved to 94.1% in serial test. Validation was further performed to confirm the value of C3 for disease activity assessment. The accuracy of the parallel test of CRP and C3 in external validation with independent 53 TA cases was 72.73% with the AUC of 0.721.

CONCLUSION

Elevated C3 could effectively evaluate the disease activity of TA, and C3 combining with CRP could further improve the disease activity evaluation.

Serum levels of immunoglobulin G and complement 3 differentiate non-diabetic renal disease from diabetic nephropathy in patients with type 2 diabetes mellitus

AIMS

Heavy proteinuria caused by non-diabetic renal disease (NDRD) is common in type 2 diabetes mellitus (T2DM). The aim of this study was to investigate specific predictors for NDRD in addition to traditional indicators in T2DM.

METHODS

A total of 341 patients with T2DM who underwent renal biopsy were retrospectively included. Eligible patients were divided into a nephrotic-range group (n = 194) and a non-nephrotic-range group (n = 147) based on proteinuria level. Risk factors for NDRD were evaluated using logistic regression, and the diagnostic implications of these variables were assessed by subgroup.

RESULTS

Multivariate logistic regression indicated that serum IgG level (OR, 0.762; 95% CI, 0.628-0.924; p = 0.006) was an independent predictor of NDRD in the nephrotic-range group. However, in the non-nephrotic-range group, increased C3 level was an independent risk factor for NDRD (OR, 1.313; 95% CI, 1.028-1.678; p = 0.029). In the nephrotic-range group, the optimal cutoff value of IgG for predicting NDRD was 734.0 mg/dl, with 67.8% sensitivity and 74.8% specificity, and IgG ≤ 734.0 mg/dl was the best predictor of NDRD. In the non-nephrotic-range group, the optimal cutoff value of C3 for predicting NDRD was 122.0 mg/dl with low sensitivity (30.9%) but high specificity (97.8%).

CONCLUSIONS

At different levels of proteinuria, reduced IgG and increased C3 levels were independent indicators of NDRD in T2DM. Insights into these factors will help to advance the clinical management of NDRD.

Up-regulated Complement 3 Production by Toll-like receptor 9/ Transforming Growth Factor-Beta 1/Complement 3 Pathway in Whole Blood Cells of Lupus Thrombocytopenia

Objectives

This study aims to assess the complement 3 (C3) expressions in whole blood cells and verify a pathway toll-like receptor 9 (TLR9)/ transforming growth factor-beta 1 (TGF-β1)/C3 for C3 regulation in mediating thrombocytopenia (TCP) in patients with systemic lupus erythematosus (SLE).

Patients and methods

The study included 63 newly diagnosed SLE patients (2 males, 61 females; mean age 39.5 years; range 15 to 67 years). Whole blood messenger ribonucleic acid expression for C3, TLR9 and TGF-β1 were measured by quantitative reverse transcription real-time polymerase chain reaction in SLE patients with TCP (n=38) and age- and sex-matched SLE patients without TCP (n=25) at baseline and in 10 SLE patients with TCP after four weeks of treatment. Whole blood cells from SLE patients with TCP were cultured in the presence of TLR9 ligand cytosine-phosphate- guanine, recombinant human TGF-β1, TGF-β receptor inhibitor/activin receptor-like kinase inhibitor SB431542. TGF-β1 and C3 levels in whole blood cells cultures were determined by quantitative reverse transcription real-time polymerase chain reaction and enzyme-linked immunosorbent assay.

Results

Whole blood cells from SLE patients with TCP displayed an enhanced gene expression for C3, TLR9 and TGF-β1 compared with that of SLE patients without TCP (p<0.01 for C3, p<0.05 for TLR9 and TGF-β1). SLE patients with TCP had decreased plasma levels of C3 suggesting excessive consumption. In whole blood cell culture, engagement of TLR9 led to the increased gene expression of C3. Furthermore, TGF-β1 inhibitor abolished TLR9 stimulation on C3 gene expression.

Conclusion

These results suggest that blood cells are the source of extra-hepatic synthesis of C3 in SLE patients with TCP and this synthesis of C3 was up-regulated by TLR9 via induction of TGF-β1. Thus TLR9/TGF-β1/C3 pathway might be in operation mediating lupus thrombocytopenia.

The relationship between complement factor C3, APOE ε4, amyloid and tau in Alzheimer's disease

Inflammation is becoming increasingly recognized as an important contributor to Alzheimer's disease (AD) pathogenesis. As a part of the innate immune system, the complement cascade enhances the body's ability to destroy and remove pathogens and has recently been shown to influence Alzheimer's associated amyloid and tau pathology. However, little is known in humans about the effects of the complement system and genetic modifiers of AD risk like the ε4 allele of apolioprotein E (APOE ε4) on AD pathobiology. We evaluated cerebrospinal fluid (CSF) protein levels from 267 individuals clinically diagnosed as cognitively normal, mild cognitive impairment, and AD. Using linear models, we assessed the relationship between APOE ε4 genotype, CSF Complement 3 (C3), CSF amyloid-β (amyloid) and CSF hyperphosphorylated tau (ptau). We found a significant interaction between APOE ε4 and CSF C3 on both CSF amyloid and CSF ptau. We also found that CSF C3 is only associated with CSF ptau after accounting for CSF amyloid. Our results support a conceptual model of the AD pathogenic cascade where a synergistic relationship between the complement cascade (C3) and APOE ε4 results in elevated Alzheimer's neurodegeneration and in turn, amyloid further regulates the effect of the complement cascade on downstream tau pathology.

Eupatorium lindleyanum DC. sesquiterpenes fraction attenuates lipopolysaccharide-induced acute lung injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Eupatorium lindleyanum DC. is widely used for its efficiency in treating cough, tracheitis and tonsillitis. Acute lung injury (ALI) induced by lipopolysaccharide (LPS) in mice was used to investigate therapeutic effects and possible mechanism of the sesquiterpenes fraction of E. lindleyanum DC. (EUP-SQT).

MATERIALS AND METHODS

Mice were orally administrated with EUP-SQT (15, 30 and 60mg/kg) per day for 7 days consecutively before LPS challenge. The lung specimens and bronchoalveolar lavage fluid (BALF) were harvested for histopathological examinations and biochemical analysis at 6h and 24h after LPS challenge. The level of complement 3 (C3) and complement 3c (C3c) in serum was quantified by a sandwich ELISA kit.

RESULTS

Pretreatment with EUP-SQT could significantly decrease lung wet-to-dry weight (W/D) ratio, nitric oxide (NO) and protein concentration in BALF, which was exhibited together with the lowered myeloperoxidase (MPO) activity, the increased superoxide dismutase (SOD) activity and down-regulation the level of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in ALI model. Additionally, EUP-SQT attenuated lung histopathological changes and significantly reduced complement deposition with decreasing the level of C3 and C3c in serum.

CONCLUSIONS

These results showed that EUP-SQT significantly attenuated LPS-induced ALI via reducing productions of pro-inflammatory mediators and decreasing the level of complement, indicating it as a potential therapeutic agent for ALI.