High level of C3 is associated with Th2 immune response and liver fibrosis in patients with schistosomiasis

Long-term infection of schistosomiasis will seriously affect the liver health of patients. The serum of 334 chronic Schistosoma japonicum patients and 149 healthy volunteers was collected. Compared with heathy people, the level of C4 (complement 4) was increased, and the level of C3 (complement 3) was in an obvious skewed distribution. ELISA was performed to detect the serum cytokines, the results showed that the levels of IFN-γ (interferon-γ), IL (interleukin)-2 and TNF-α (tumour necrosis factor-α) were reduced, while the levels of Th2 cytokines (IL-4, IL-6 and IL-10) were increased. In the serum of patients with high C3, the secretion of HA (hyaluronic acid), LN (laminin), IV-C (type IV collagen) and PCIII (type III procollagen) were increased, the activation of hepatic stellate cells was promoted. Exogenous human recombinant C3 made mice liver structure of the mice damaged and collagen deposition. IFN-γ and IFN-γ/IL-4 were decreased, while HA, LN, PCIII and IV-C were increased, and the expressions of α-SMA and TGF-β1 in liver tissues were up-regulated. However, the addition of IFN-γ partially reversed the effect of C3 on promoting fibrosis. High level of C3 is associated with Th2 immune response and liver fibrosis in patients with schistosomiasis.

A retrospective study on the direct immunofluorescence findings in pigmented purpuric dermatosis

BACKGROUND

Pigmented purpuric dermatosis (PPD) is characterized by grouped petechiae, purpuric macules, and pigmentation in the bilateral lower extremities. It runs a chronic and relapsing course. Pathophysiology is poorly understood, but it has been proposed to be an immune-complex disease or capillaritis. This study aimed to determine the incidence and patterns of positive direct immunofluorescence (DIF) findings in patients with clinically and histopathologically confirmed PPD. The association between DIF deposition type and clinical profile was also analyzed.

METHODS

Patients with a clinical and histopathologic PPD diagnosis who had undergone DIF studies at a tertiary medical center with attached dermatopathology and immunofluorescence diagnostic centers between January 2002 and December 2021 were included in this study. Data on age, sex, disease duration, comorbidities, and drug intake were collected from medical records.

RESULTS

There were 65 patients who satisfied the inclusion criteria. Among them, 58 (89%) had at least one positive finding and 53 (82%) were vascular deposition of immunoglobulin (Ig), complement, or fibrinogen. The most common vascular deposition was fibrinogen (71%) followed by C3 (62%), IgM (18%), IgA (6%), and IgG (3%). Fibrinogen deposition was associated with hypertension (p < 0.03). There was no association between vascular DIF deposition of IgG, IgA, and C3, with age, sex, comorbidities, disease duration, and drug history.

CONCLUSION

The most common DIF findings in PPD were vascular deposition of fibrinogen and C3, with or without Ig presence. DIF findings supported a vascular origin in PPD but not an immune complex-mediated disease. Hypertension was associated with fibrinogen deposition and may play a role in its pathophysiology.

Intravitreal Neuroglobin Mitigates Primate Experimental Glaucomatous Structural Damage in Association with Reduced Optic Nerve Microglial and Complement 3-Astrocyte Activation

Current management of glaucomatous optic neuropathy is limited to intraocular pressure control. Neuroglobin (Ngb) is an endogenous neuroprotectant expressed in neurons and astrocytes. We recently showed that exogenous intravitreal Ngb reduced inflammatory cytokines and microglial activation in a rodent model of hypoxia. We thus hypothesised that IVT-Ngb may also be neuroprotective in experimental glaucoma (EG) by mitigating optic nerve (ON) astrogliosis and microgliosis as well as structural damage. In this study using a microbead-induced model of EG in six Cynomolgus primates, optical coherence imaging showed that Ngb-treated EG eyes had significantly less thinning of the peripapillary minimum rim width, retinal nerve fibre layer thickness, and ON head cupping than untreated EG eyes. Immunohistochemistry confirmed that ON astrocytes overexpressed Ngb following Ngb treatment. A reduction in complement 3 and cleaved-caspase 3 activated microglia and astrocytes was also noted. Our findings in higher-order primates recapitulate the effects of neuroprotection by Ngb treatment in rodent EG studies and suggest that Ngb may be a potential candidate for glaucoma neuroprotection in humans.

Astrocytic reactivity triggered by defective autophagy and metabolic failure causes neurotoxicity in frontotemporal dementia type 3

Frontotemporal dementia type 3 (FTD3), caused by a point mutation in the charged multivesicular body protein 2B (CHMP2B), affects mitochondrial ultrastructure and the endolysosomal pathway in neurons. To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) and confirmed our findings in CHMP2B mutant mice. Our data provide mechanistic insights into how defective autophagy causes perturbed mitochondrial dynamics with impaired glycolysis, increased reactive oxygen species, and elongated mitochondrial morphology, indicating increased mitochondrial fusion in FTD3 astrocytes. This shift in astrocyte homeostasis triggers a reactive astrocyte phenotype and increased release of toxic cytokines, which accumulate in nuclear factor kappa b (NF-κB) pathway activation with increased production of CHF, LCN2, and C3 causing neurodegeneration.

•

FTD3 iPSC-derived astrocytes display impaired autophagy

•

Impaired autophagy affects mitochondria turnover, glucose hypometabolism and TCA cycle

•

FTD3 astrocytes contribute to reactive gliosis by increased C3, LCN2, IL6, and IL8

•

Reactive astrocyte phenotypes are present in both in vitro and in vivo models

Complement 3 and the Prognostic Nutritional Index Distinguish Kawasaki Disease from Other Fever Illness with a Nomogram

Objective: This study aimed to establish a model to distinguish Kawasaki disease (KD) from other fever illness using the prognostic nutritional index (PNI) and immunological factors. Method: We enrolled a total of 692 patients (including 198 with KD and 494 children with febrile diseases). Of those, 415 patients were selected to be the training group and 277 patients to be the validation group. Laboratory data, including the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the prognostic nutritional index (PNI), and immunological factors, were retrospectively collected for an analysis after admission. We used univariate and multivariate logistic regressions and nomograms for the analysis. Result: Patients with KD showed significantly higher C3 and a lower PNI. After a multivariate logistic regression, the total leukocyte count, PNI, C3, and NLR showed a significance (p < 0.05) and then performed well with the nomogram model. The areas under the ROC in the training group and the validation group were 0.858 and 0.825, respectively. The calibration curves of the two groups for the probability of KD showed a near agreement to the actual probability. Conclusions: Compared with children with febrile diseases, patients with KD showed increased C3 and a decreased nutritional index of the PNI. The nomogram established with these factors could effectively identify KD from febrile illness in children.

Antineutrophil cytoplasmic antibody-positive infective endocarditis complicated by acute kidney injury: a case report and literature review

Patients with infective endocarditis (IE) may present with multisystem disturbances resembling autoimmune diseases, such as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The kidneys are susceptible to damage in IE and AAV, which is a source of diagnostic ambiguity. Therefore, distinguishing infection from an inflammatory process is pivotal for guiding appropriate therapy. We report a 22-year-old man with IE characterized by ANCA positivity and complicated by acute kidney injury. A renal biopsy showed crescentic nephritis with tubulointerstitial lesions. However, transthoracic echocardiography and blood culture provided evidence of IE, and AAV was ruled out. Surgical intervention and antibiotic treatments were successful. We summarized previously reported cases of ANCA-positive IE that had renal biopsy data. We found that ANCA-positive IE can involve multiple organs. The representative renal pathology was crescentic nephritis, focal segmental glomerulonephritis, mesangial cell proliferation, tubular injury, and interstitial oedema. Immunofluorescence showed predominate C3 deposits. Electron microscopy showed electron-dense deposits in the subendothelial or mesangial areas. Eight patients received immunosuppressive therapy with excellent results. Repeated testing for bacterial pathogens and multiple renal biopsies may be useful for diagnosing ANCA-positive IE. With ANCA-positive IE, immunosuppressive therapy along with antibiotic treatments may be beneficial for recovery of renal function.

Increased Complement 3 With Suppression of miR-145 Induces the Synthetic Phenotype in Vascular Smooth Muscle Cells From Spontaneously Hypertensive Rats

Background

We previously reported that vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHRs) show the increased expression of complement 3 (C3) and the synthetic phenotype. We targeted the SHR C3 gene (C3 knockout [C3KO] SHRs) by the zinc finger gene editing method. In the current study, we investigated the mechanisms underlying the increased expression of C3 and the role of endogenous C3 in the synthetic phenotype of SHR VSMCs in comparison to cells from Wistar‐Kyoto (WKY) rats and C3KO SHRs.

Methods and Results

Nonmuscle myosin heavy chain staining of aortas from SHRs at 1 day after birth was stronger in comparison to WKY rats and C3KO SHRs. DNA synthesis in VSMCs from SHRs was significantly higher in comparison to WKY rats and C3KO SHRs. Immunohistochemical staining of renin and liver X receptor α in VSMCs from SHRs was stronger in comparison to WKY rats and C3KO SHRs. The expression of renin, Krüppel‐like factor 5, and liver X receptor α proteins in VSMCs from SHRs was significantly higher in comparison to WKY rats and C3KO SHRs. The expression of synthetic phenotype markers osteopontin, matrix gla, and l‐caldesmon, growth factors transforming growth factor‐β1 and platelet‐derived growth factor‐A, transcription factors Krüppel‐like factor 5 and liver X receptor α, and angiotensinogen mRNAs in VSMCs from SHRs was significantly higher in comparison to WKY rats and C3KO SHRs. The expression of miR‐145 mRNA in VSMCs from SHRs was suppressed in comparison to cells from WKY rats. miR‐145 inhibitor significantly increased the expression of C3 in VSMCs from WKY rats, but not in cells from SHRs.

Conclusions

These findings indicate that the increased C3 with the suppression of miR‐145 induces the synthetic phenotype through Krüppel‐like factor 5 and the activation of the renin‐angiotensin system through liver X receptor α in VSMCs from SHRs.

Role of complement 3 in renin generation during the differentiation of mesenchymal stem cells to smooth muscle cells

We showed that increased expression of complement 3 (C3) induces dedifferentiation of mesenchymal cells and epithelial mesenchymal transition, which activate the local renin-angiotensin system (RAS) that contributes to cardiovascular and renal remodeling in spontaneously hypertensive rats (SHRs). In the present study, to investigate contributions of C3 to the development of the pathogenesis of hypertension, we evaluated the formation of renin-producing cells and roles of C3 in renin generation during differentiation of primary bone marrow-mesenchymal stem cells (MSCs) from C57BL/6 mice, Wistar-Kyoto (WKY) rats, and SHRs to smooth muscle cells (SMCs) with transforming growth factor-β1. The expression of renin transiently increased with increases in transcription factor liver X receptor α (LXRα), and expression of C3 and Krüppel-like factor 5 (KLF5) increased during differentiation of MSCs from C57BL/6 mice, WKY rats, and SHRs to SMCs. Exogenous C3a stimulated renin and LXRα expression accompanied by nuclear translocation of LXRα. C3a receptor antagonist SB290157 suppressed renin and LXRα expression, with inhibition of nuclear translocation of LXRα during the differentiation of mouse MSCs to SMCs. The expression of C3 and KLF5 was significantly higher in the differentiated cells from SHRs compared with the cells from WKY rats during differentiation. Renin-producing cells were formed during differentiation of MSCs to SMCs, and renin generation was observed in undifferentiated SMCs, in which transient expression of renin in the differentiated cells with lower differentiation stage was stronger from SHRs than that from WKY rats. Expression and nuclear localization of LXRα in the differentiated cells from SHRs were stronger than that from WKY rats. C3 was important in forming and maintaining this undifferentiated state of SMCs from MSCs to generate renin with increases in transcription factor LXRα and KLF5. Increases in C3 expression maintain the undifferentiated state of SMCs from MSCs to generate renin that activates RAS and contributes to the pathogenesis of hypertension in SHRs.

[Effect of PR-957 on the formation of A1 reactive astrocytes]

OBJECTIVE

To study the effect of PR-957 on the formation of A1 reactive astrocytes.

METHODS

The cerebral cortices of 1-day-old female rats were obtained and cultured for primary astrocytes. These cells were divided into 3 groups: control, lipopolysaccharide (LPS), and LPS+PR-957. The LPS group was treated with LPS (at a concentration of 5 μmol/L) for 48 hours; the LPS+PR-957 group was treated with PR-957 (at a final concentration of 200 nmol/L) for 1 hour and then LPS for 48 hours. Enzyme-linked immunosorbent assay was used to determine the expression of complement 3 (C3, a marker for A1 reactive astrocytes) and tumor necrosis factor alpha (TNF-α). Quantitative real-time PCR was used to determine the relative mRNA expression of glypican-6 (GPC6), SPARC-like 1 (SPARCL1), and lipocalin-2 (LCN2). All the above experiments were repeated three times independently.

RESULTS

C3 expression was almost not observed in the control group, but was observed in both the LPS group and the LPS+PR-957 group, with significantly lower expression observed in the LPS+PR-957 group (P<0.05). The expression of TNF-α was consistent with that of C3. Compared with the control group, the LPS and the PS+PR-957 groups had significantly reduced mRNA expression levels of GPC6 and SPARCL1 but significantly increased mRNA expression level of LCN2 (P<0.001). Compared with the LPS group, the LPS+PR-957 group had significantly increased mRNA expression levels of GPC6 and SPARCL1 but significantly reduced mRNA expression level of LCN2 (P<0.001).

CONCLUSIONS

LPS can induce the transformation from astrocytes to A1 reactive astrocytes, and PR-957 can inhibit the formation of LPS-induced A1 reactive astrocytes.

Involvement of complement 3 in the salt-sensitive hypertension by activation of renal renin-angiotensin system in spontaneously hypertensive rats

We previously showed that complement 3 (C3) is highly expressed in mesenchymal tissues in spontaneously hypertensive rats (SHR). We targeted C3 gene by zinc-finger nuclease (ZFN) gene-editing technology and investigated blood pressure and phenotype in SHR. Blood pressure was measured by tail-cuff and telemetry methods. Histology and expression of liver X receptor α (LXRα), renin, Krüppel-like factor 5 (KLF5), and E-cadherin were evaluated in kidneys. Mesangial cells (MCs) were removed from glomeruli from three strains, and we evaluated the phenotype in vitro. SHR showed the salt-sensitive hypertension that was abolished in C3 knockout (KO) SHR. Proliferation of MCs from SHR was higher than that from Wistar-Kyoto (WKY) rats and showed a synthetic phenotype. Renal injury scores were higher in SHR than in WKY rats and C3 KO SHR. Expression of E-cadherin was lower, and expression of renin was higher in the nephrotubulus from SHR than WKY rats and C3 KO SHR. Expression of C3 α-chain protein and α-smooth muscle actin protein was significantly higher in renal medulla from SHR than from WKY rats. Expression of angiotensinogen, LXRα, renin, and KLF5 mRNA was increased in kidney from SHR compared with C3 KO SHR. Intrarenal angiotensin II levels were significantly higher in kidney from SHR than WKY rats and C3 KO SHR. Urinary epinephrine and norepinephrine excretions were significantly higher in SHR than in WKY rats and C3 KO SHR. These findings showed that increased C3 induces salt-sensitive hypertension with increases in urinary catecholamine excretion and intrarenal activation of the renin-angiotensin system by the dedifferentiation of mesenchymal tissues in kidney from SHR.

C3a Enhances the Formation of Intestinal Organoids through C3aR1

C3a is important in the regulation of the immune response as well as in the development of organ inflammation and injury. Furthermore, C3a contributes to liver regeneration but its role in intestinal stem cell function has not been studied. We hypothesized that C3a is important for intestinal repair and regeneration. Intestinal organoid formation, a measure of stem cell capacity, was significantly limited in C3-deficient and C3a receptor (C3aR) 1-deficient mice while C3a promoted the growth of organoids from normal mice by supporting Wnt-signaling but not from C3aR1-deficient mice. Similarly, the presence of C3a in media enhanced the expression of the intestinal stem cell marker leucine-rich repeat G-protein-coupled receptor 5 (Lgr5) and of the cell proliferation marker Ki67 in organoids formed from C3-deficient but not from C3aR1-deficient mice. Using Lgr5.egfp mice we showed significant expression of C3 in Lgr5⁺ intestinal stem cells whereas C3aR1 was expressed on the surface of various intestinal cells. C3 and C3aR1 expression was induced in intestinal crypts in response to ischemia/reperfusion injury. Finally, C3aR1-deficient mice displayed ischemia/reperfusion injury comparable to control mice. These data suggest that C3a through interaction with C3aR1 enhances stem cell expansion and organoid formation and as such may have a role in intestinal regeneration.

C3 glomerulonephritis in multiple myeloma: A case report and literature review

BACKGROUND

C3 glomerulonephritis (C3 GN) is a recently defined entity characterized by predominant C3 deposition in glomeruli due to abnormal activation of the alternative pathway of complement system. C3 GN has been reported to be associated with several systemic diseases. However, the association between C3 GN and multiple myeloma (MM) has not been well established.

METHODS

We herein describe a case presenting with C3 GN on top of MM.

RESULTS

A 64-year-old Chinese female presented with gross hematuria, renal dysfunction, anemia, and weight loss. Results of serum immunofixation assay and bone marrow biopsy confirmed the diagnosis of IgG-λ-type MM. In addition, renal biopsy demonstrated histological findings characteristic of C3 GN, including mesangial and endocapillary proliferation under light microscope, electron-dense deposits under electron microscope, and diffuse granular deposition of C3 with no immunoglobulin under immunofluorescence microscope. These histological findings, combined with low serum C3 level, suggested the occurrence of C3 GN in the context of MM.

CONCLUSION

This case study provides additional evidence to the literature in terms of the association between C3 GN and MM. We hypothesize that C3 GN may present as a new variant of nephropathy in MM and the mechanism behind this association merits further study.

Complement 3 activates the renal renin-angiotensin system by induction of epithelial-to-mesenchymal transition of the nephrotubulus in mice

We have demonstrated that mesenchymal cells from spontaneously hypertensive rats genetically express complement 3 (C3). Mature tubular epithelial cells can undergo epithelial-to-mesenchymal transition (EMT) that is linked to the pathogenesis of renal fibrosis and injury. In this study, we investigated the contribution of C3 in EMT and in the renal renin-angiotensin (RA) systems associated with hypertension. C3a induced EMT in mouse TCMK-1 epithelial cells, which displayed increased expression of renin and Krüppel-like factor 5 (KLF5) and nuclear localization of liver X receptor α (LXRα). C3 and renin were strongly stained in the degenerated nephrotubulus and colocalized with LXRα and prorenin receptor in unilateral ureteral obstruction (UUO) kidneys from wild-type mice. In C3-deficient mice, hydronephrus and EMT were suppressed, with no expression of renin and C3. After UUO, systolic blood pressure was increased in wild-type but not C3-deficient mice. In wild-type mice, intrarenal angiotensin II (ANG II) levels were markedly higher in UUO kidneys than normal kidneys and decreased with aliskiren. There were no increases in intrarenal ANG II levels after UUO in C3-deficient mice. Thus C3 induces EMT and dedifferentiation of epithelial cells, which produce renin through induction of LXRα. These data indicate for the first time that C3 may be a primary factor to activate the renal RA systems to induce hypertension.

Downregulation of constitutive and cytokine-induced complement 3 expression by morphine in rat astrocytes

BACKGROUND

The effect of opioids on inflammation and immune responses is an important subject of investigation because immunoregulatory cytokines are produced in the central nervous system and opioid receptors are widespread in these cells.

OBJECTIVES

The aim of this study was to evaluate the immunomodulatory effect of morphine on the C3 expression (both constitutive and proinflammatory cytokine-induced C3 expression) in primary rat astrocytes.

METHODS

Primary rat astrocytes were untreated or treated with morphine in different concentrations (10(-6) to 10(-2) M) before incubation without or with 5 U/mL tumor necrosis factor-α (TNF-α), and C3 protein and mRNA expressions were measured. Similarly, astrocytes were treated with 10(-3) M morphine and stimulated with other proinflammatory cytokines, including 10 ng/mL interleukin-8 (IL-8) and 5 U/mL IL-1β. Astrocytes were exposed to 10(-5) M naloxone for 2 hours before adding morphine, and TNF-α and C3 protein was measured. Tumor growth factor-β (TGF-β) was measured from the supernatants of each proinflammatory cytokine.

RESULTS

All results are expressed as mean percentages of C3 production by normalizing C3 without morphine or any cytokine treatment as 100%. Constitutive C3 protein production was decreased at morphine 10(-3) M (57.2%) and 10(-2) M (30.1%). Pretreatment with morphine suppressed induction of C3 expression at both the protein and mRNA levels in astrocytes stimulated with TNF-α, IL-8, and IL-1β (P < 0.05) in a dose-dependent manner. The inhibition of C3 protein production by morphine (10(-3) M; 33%) was partially attenuated by naloxone (52.0%) (P < 0.05). The pretreatment of astrocytes with morphine (10(-3) M) before stimulation with TNF-α, IL-8, and IL-1β increased by 33% (P < 0.05), decreased by 15.2% (P < 0.05), and did not change the production of TGF-β protein, respectively.

CONCLUSIONS

Morphine downregulated both constitutive and proinflammatory cytokine-induced C3 expression of astrocytes at the transcriptional level, but not in a cytokine-specific manner.