Complement regulatory protein CD59a plays a protective role in immune liver injury of trichloroethylene-sensitized BALB/c mice

Bavachin combined with epimedin B induce idiosyncratic liver injury under immunological stress conditions

Reports on Chinese patent medicines preparations containing Epimedii Folium (EF) and Psoraleae Fructus (PF) resulting in idiosyncratic drug-induced liver injury (IDILI) have received widespread attention. Previous studies have shown that bavachin and epimedin B-two active ingredients derived from both EF and PF-are potential components associated with IDILI, but the underlying mechanism remains unclear. We evaluated bavachin and epimedin B-induced IDILI under TNF-α-mediated immunological stress conditions and generated liver lipid metabolism profiles using lipidomics and multivariate statistical analysis. We next applied transcriptomics to identify the differential gene expression on the transcription level. Our results showed that co-exposure to bavachin, epimedin B under immunological stress conditions resulted in obvious liver injury. The differential metabolites screened in our study were closely related to the immune homeostasis of the liver. Sixteen differentially expressed genes were found, Zc3h6 and R3hdml were upregulated, while Sumo2, Cd74, Banp, Oas3, Oas2, Gbp8, Slfn8, Gbp2b, Serpina3g, Zbtb40, H2-Ab1, Osgin1, Tgtp1 and Hspa1b were all downregulated. These differentially expressed genes were associated with biological processes concerning metabolic process and immune system process. Further integrative analysis indicated that bavachin combined with epimedin B affected genes that were not only related to immune system processes, but also to lipid metabolism. Ultimately, this led to an imbalance in the immune microenvironment in the liver and may have contributed to the observed liver injury.

Predictive value of soluble CD59 for poor 28-day neurological prognosis and all-cause mortality in patients after cardiopulmonary resuscitation: a prospective observatory study

BACKGROUND

sCD59, as a soluble form of CD59, is observed in multiple types of body fluids and correlated with the cell damage after ischemia/reperfusion injury. This study aims to observe the dynamic changes of serum sCD59 in patients after restoration of spontaneous circulation (ROSC) and explore the association of serum sCD59 with neurological prognosis and all-cause mortality in patients after ROSC.

METHODS

A total of 68 patients after ROSC were prospectively recruited and divided into survivors (n = 23) and non-survivors (n = 45) groups on the basis of 28-day survival. Twenty healthy volunteers were enrolled as controls. Serum sCD59 and other serum complement components, including sC5b-9, C5a, C3a, C3b, C1q, MBL, Bb, and pro-inflammatory mediators tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), neurological damage biomarkers neuron-specific enolase (NSE) and soluble protein 100β (S100β) were measured by enzyme linked immunosorbent assay on day 1, 3, and 7 after ROSC. Neurologic outcome was assessed using cerebral performance category scores, with poor neurologic outcome defined as 3-5 points.

RESULTS

In the first week after ROSC, serum levels of sCD59, sC5b-9, C5a, C3a, C3b, C1q, MBL, Bb, TNF-α, IL-6, NSE and S100β were significantly elevated in patients after ROSC compared to healthy volunteers, with a significant elevation in the non-survivors compared to survivors except serum C1q and MBL. Serum sCD59 levels were positively correlated with serum sC5b-9, TNF-α, IL-6, NSE, S100β, SOFA score and APACHE II score. Moreover, serum sCD59 on day 1, 3, and 7 after ROSC could be used for predicting poor 28-day neurological prognosis and all-cause mortality. Serum sCD59 on day 3 had highest AUCs for predicting poor 28-day neurological prognosis [0.862 (95% CI 0.678-0.960)] and 28-day all-cause mortality [0.891 (95% CI 0.769-0.962)]. In multivariate logistic regression analysis, the serum level of sCD59_D1 was independently associated with poor 28-day neurological prognosis and all-cause mortality.

CONCLUSIONS

The elevated serum level of sCD59 was positively correlated with disease severity after ROSC. Moreover, serum sCD59 could have good predictive values for the poor 28-day neurological prognosis and all-cause mortality in patients after ROSC.

Identification and functional characterization of complement regulatory protein CD59 in golden pompano (Trachinotus ovatus)

CD59, one of the essential inhibitors of the complement membrane attack complex (MAC), plays a crucial role in regulation of complement activation. In this study, we cloned and identified the CD59 gene (named ToCD59) of golden pompano (Trachinotus ovatus). The ORF sequence of ToCD59 is 357 bp long encoding 118 amino acids with a molecular weight of 13.09 kDa. Prediction of protein domains showed that ToCD59 contained an Lu domain and a C-terminal glycosylphosphatidylinositol (GPI) partial anchor. Homology comparisons indicated that ToCD59 shared the high sequence similarity with other fish CD59. RT-qPCR analysis showed that ToCD59 was expressed in all tested healthy tissues of golden pompano, with the highest level of expression in the brain. After stimulation with bacteria, ToCD59 expression levels were significantly up-regulated in head kidney, liver, gill and brain, but down-regulated in spleen. Subcellular localization results showed that ToCD59 localized to the cytoplasm of A549 cells. The hemolytic activity analysis showed that rToCD59 might have complement inhibitory activity through the alternative complement pathway. In addition, antibacterial test showed that rToCD59 had antibacterial ability against S. agalactiae and V. alginolyticus in vitro. These results suggest that ToCD59 might play an important role in the immune response against pathogens, which would provide basic information for elucidating the functional evolutionary history of complement system in teleost.

Membrane Attack Complex C5b-9 Promotes Renal Tubular Epithelial Cell Pyroptosis in Trichloroethylene-Sensitized Mice

Trichloroethylene (TCE), a commonly used organic solvent, is known to cause trichloroethylene hypersensitivity syndrome (THS), also called occupational medicamentosa-like dermatitis due to TCE (OMDT) in China. OMDT patients presented with severe inflammatory kidney damage, and we have previously shown that the renal damage is related to the terminal complement complex C5b-9. Here, we sought to determine whether C5b-9 participated in TCE-induced immune kidney injury by promoting pyroptosis, a new form of programed cell death linked to inflammatory response, with underlying molecular mechanisms involving the NLRP3 inflammasome. A BALB/c mouse-based model of OMDT was established by dermal TCE sensitization in the presence or absence of C5b-9 inhibitor (sCD59-Cys, 25μg/mouse) and NLRP3 antagonist (MCC950, 10 mg/kg). Kidney histopathology, renal function, expression of inflammatory mediators and the pyroptosis executive protein gasdermin D (GSDMD), and the activation of pyroptosis canonical NLRP3/caspase-1 pathway were examined in the mouse model. Renal tubular damage was observed in TCE-sensitized mice. GSDMD was mainly expressed on renal tubular epithelial cells (RTECs). The caspase-1-dependent canonical pathway of pyroptosis was activated in TCE-induced renal damage. Pharmacological inhibition of C5b-9 could restrain the caspase-1-dependent canonical pathway and rescued the renal tubular damage. Taken together, our results demonstrated that complement C5b-9 plays a central role in TCE-induced immune kidney damage, and the underlying mechanisms involve NLRP3-mediated pyroptosis.

Renal tubular cell necroptosis: A novel mechanism of kidney damage in trichloroethylene hypersensitivity syndrome mice

Trichloroethylene (TCE) hypersensitivity syndrome (THS), called occupational medicamentosa-like dermatitis due to TCE (OMDT) in China, is a fatal occupational disorder caused by TCE exposure. Visceral damage, including kidney injury, is one of the major complications. Necroptosis is a regulated cell death form linked to local inflammatory response. This study aimed to investigate whether renal cell necroptosis was involved in TCE-induced kidney injury. A Balb/c mouse model of TCE sensitization was utilized to study mechanisms of modulation of TCE-induced renal necroptosis. Renal histology (using light and transmission electron microscopy) and renal tubular impairment indexes, including α1-microglobulin (α1-MG), and β2-microglobulin (β2-MG), were evaluated. In addition, tissue expression of necroptosis-related proteins, including tumor necrosis factor (TNF)-α, TNF receptor 1 (TNFR1), receptor-interacting protein kinase 3 (RIPK3), p-RIK3, mixed lineage kinase domain-like protein (MLKL), and p-MLKL, were also evaluated. The study here confirmed TCE sensitization caused damage to renal tubules and renal tubular epithelial cell (RTEC) necroptosis. In mice treated with R7050 (a specific TNFα antagonist), it was also seen that inhibition of TNFα expression could effectively inhibit RTEC necroptosis and improve renal function in the TCE-sensitized mice. Taken together, these results help to define a novel mechanism by which RTEC necroptosis plays a key role in TCE-induced kidney damage.

C5b-9 membrane attack complex activated NLRP3 inflammasome mediates renal tubular immune injury in trichloroethylene sensitized mice

Trichloroethylene (TCE) induced occupational medicamentosa-like dermatitis (OMLDT) in patients is accompanied, typically, by renal damage. But the role of C5b-9 and IL-1β in TCE-sensitized mouse renal tubular damage is unclear. This study aimed to investigate whether TCE-sensitized mouse renal tubular epithelial cell damage was induced by NLRP3 inflammasome and whether NLRP3 inflammasome was activated by sublytic C5b-9. In total, 52 specific pathogen-free BALB/c female mice, 6- to 8-week-old, were used for establishing the TCE-sensitized mouse model. Renal tubular epithelial cells were isolated and used for determining the sublytic level of C5b-9. Kidney histological examination, serum neutrophil gelatinase associated lipocalin (NGAL) level were used for kidney damage evaluation. Renal protein levels of C5b-9, NLRP3, ASC, Caspase-1, IL-1β, and IL-18 were measured. The renal lesions, serum NGAL level, renal NLRP3, ASC, Caspase-1 and IL-1β protein levels all increased significantly in TCE sensitized positive group. However, pretreatment with recombinant protein sCD59-Cys inhibited the expression of C5b-9, NLRP3 inflammasome, IL-1β, IL-18, and attenuated renal tubular epithelial cell damage. The sublytic C5b-9 activated NLRP3 inflammasome and aggravated renal tubular epithelial cell damage. Pretreatment with recombinant protein sCD59-Cys blocked the expression of the NLRP3 inflammasome by inhibiting the expression of C5b-9, and alleviating renal tubular epithelial cell damage.

Sex-Dependent Effects on Liver Inflammation and Gut Microbial Dysbiosis After Continuous Developmental Exposure to Trichloroethylene in Autoimmune-Prone Mice

Trichloroethylene (TCE) is a common environmental toxicant linked with hypersensitivity and autoimmune responses in humans and animal models. While autoimmune diseases are more common in females, mechanisms behind this disparity are not clear. Recent evidence suggests that autoimmunity may be increasing in males, and occupational studies have shown that TCE-mediated hypersensitivity responses occur just as often in males. Previous experimental studies in autoimmune-prone MRL^+/+ mice have focused on responses in females. However, it is important to include both males and females in order to better understand sex-disparity in autoimmune disease. In addition, because of an alarming increase in autoimmunity in adolescents, developmental and/or early life exposures to immune-enhancing environmental pollutants should also be considered. Using MRL^+/+ mice, we hypothesized that TCE would alter markers related to autoimmunity to a greater degree in female mice relative to male mice, and that TCE would enhance these effects. Mice were continuously exposed to either TCE or vehicle beginning at gestation, continuing during lactation, and directly in the drinking water. Both male and female offspring were evaluated at 7 weeks of age. Sex-specific effects were evident. Female mice were more likely than males to show enhanced CD4⁺ T cell cytokine responses (e.g., IL-4 and IFN-γ). Although none of the animals developed pathological or serological signs of autoimmune hepatitis-like disease, TCE-exposed female mice were more likely than males in either group to express higher levels of biomarkers in the liver related to regeneration/repair and proliferation. Levels of bacterial populations in the intestinal ileum were also altered by TCE exposure and were more prominent in females as compared to males. Thus, our expectations were correct in that young adult female mice developmentally exposed to TCE were more likely to exhibit alterations in immunological and gut/liver endpoints compared to male mice.

Heavy ion radiation-induced DNA damage mediates apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway in mouse spermatogonia

The risk of exposure to ionizing radiation (IR) environments has increased with the development of nuclear technology. IR exposure induces excessive apoptosis of the spermatogonia, which leads to male infertility. Spermatogonia apoptosis may be involved in ribosomal stress triggered by DNA damage following exposure to IR because ribosomal proteins (RPs) directly interact with mouse double minute 2 homolog (MDM2) to induce apoptosis. This study aimed to use comparative proteomics and transcriptomics approach to screen the differential RPs and ribosomal mRNAs in mouse testes following high linear energy transfer (LET) carbon ion radiation (CIR). The expression of ribosomal large subunit protein 27a (Rpl27a) decreased at both protein and mRNA levels in the spermatogonia in vivo. After 6 h of CIR, the immunofluorescence signal of 8-oxo-dG and phosphorylated ataxia-telangiectasia-mutated protein (ATM)/histone H2Ax increased, but that of Rpl27a decreased in the spermatogonia of p53 wild-type and knockout mouse testes. Moreover, the nucleolin was scattered throughout the nucleoplasm after CIR. These results suggested that CIR-induced DNA damage might trigger ribosomal stress, and the reduction in the expression of Rpl27a was associated with DNA damage in the spermatogonia. Similarly, in vitro, the immunofluorescence signal of 8-oxo-dG increased in the GC-1 cells after CIR. Moreover, the expression of Rpl27a was regulated by DNA damage because the co-transfection of ATM and Rpl27a or inhibition of ATM-treated CIR could restore the expression of Rpl27a. Furthermore, the reduction in the expression of Rpl27a led to weakened binding of E2F transcription factor 1 (E2F1) and p53 to MDM2, causing p53 activation and E2F1 degradation in p53 wild-type and knockdown GC-1 cells. This study proposed that heavy ion radiation-induced DNA damage mediated spermatogonia apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway. The results provided the underlying molecular mechanisms of spermatogonia apoptosis following exposure to high LET radiation.

Local renal complement activation mediates immune kidney injury by inducing endothelin-1 signalling and inflammation in trichloroethylene-sensitised mice

Trichloroethylene (TCE) is a widely used industrial solvent that causes trichloroethylene hypersensitivity syndrome (THS) with multi-system damage, including kidney injury. Clinical studies have shown that the complement system is important for TCE-induced kidney injury. Our previous study found excessive deposition of complement C3, mainly on the glomerulus, indicating that local renal complement is activated after TCE sensitisation. However, whether local renal complement activation mediates TCE-induced immune kidney injury and the underlying mechanisms remain unknown. Therefore, we established a TCE percutaneous sensitisation BALB/c mouse model to explore the mechanisms by pretreating with or without the complement activation antagonist, cathepsin L inhibitor (CatLi). As expected, more C3 and C3a were detected mainly on glomerulus of TCE positive sensitisation (TCE⁺) mice. Renal dysfunction and pathological damage were also clearly observed in TCE⁺ mice. Moreover, the mRNA and protein expression of ET-1 increased significantly with local renal complement activation after TCE sensitisation, leading to cytokines release and inflammation. In addition, activation of p38MAPK and NF-κBp65 pathways were detected in kidneys of TCE⁺ mice, and CatLi pretreatment decreased these changes through complement activation antagonisation. Our research uncovered a novel role of local renal complement activation during immune kidney injury after TCE sensitisation through induction of ET-1 signalling and inflammation.

Trichloroethylene and trichloroethanol induce skin sensitization with focal hepatic necrosis in guinea pigs

OBJECTIVES

Occupational exposure to trichloroethylene (TCE) induces trichloroethylene hypersensitivity syndrome (TCEHS), which causes hypersensitivity dermatitis and hepatitis. However, whether TCE itself or its two metabolites, trichloroethanol (TCEOH) and trichloroacetic acid (TCA), are involved in TCEHS remains unclear. Therefore, in this study we explored the allergens causing TCEHS and characterized TCEHS-related liver injury in guinea pigs.

METHOD

The guinea pig maximization test was performed using TCE, TCEOH, and TCA as candidate allergens. Skin inflammation was scored, and liver function and histopathological changes were evaluated by biochemical tests and hematoxylin and eosin staining, respectively.

RESULTS

The sensitization rates for TCE, TCEOH, and TCA were 90.0%, 50.0%, and 0.0%, respectively. In the TCE and TCEOH experimental groups, the skin showed varying degrees of erythema with eosinophil granulocyte infiltration in the dermis. Additionally, serum alanine aminotransferase and γ-glutamyl transpeptidase levels increased significantly, and histological analysis revealed focal hepatocellular necrosis with inflammatory cell infiltration in the liver.

CONCLUSIONS

TCE is the main cause of allergy and TCEOH is a secondary factor for allergy in guinea pigs. TCE and TCEOH can cause immune-mediated skin sensitization complicated by focal hepatic necrosis.

Terminal complement complex C5b-9 reduced megalin and cubilin-mediated tubule proteins uptake in a mouse model of trichloroethylene hypersensitivity syndrome

Trichloroethylene (TCE), a commonly used industrial solvent and degreasing agent, is known to cause trichloroethylene hypersensitivity syndrome (THS) with multi-system damage, including skin, liver and kidney. Clinical evidence have shown that the kidney injury occurs in THS and our previous studies suggested that the terminal complement complex C5b-9 deposited in impaired renal tubules induced by TCE with unclear mechanisms. In the present study, we questioned whether activation of the complement system with renal deposition of C5b-9 contributes to TCE-induced kidney injury in THS. We established a BALB/c mouse model of TCE sensitization with or without pretreatment of exogenous CD59, a C5b-9 inhibitory protein. H&E staining, PAS staining, and biochemical detection of urinary proteins were performed to assess renal function. Deposition of C5b-9 and expression of CD59 were evaluated by immunohistochemistry. Sub-lytic effects of C5b-9 in tubular epithelial cells were assessed by lactate dehydrogenase (LDH) cytotoxicity assay. Expression of endocytosis receptors megalin and cubilin on proximal tubules were assessed by immunofluorescence and qRT-PCR. We found that TCE sensitization induced structural and functional changes of renal tubules in mice, associated with the deposition of sub-lytic C5b-9 on proximal tubular epithelial cells. TCE sensitization decreased proximal tubule uptake of filtered proteins and renal expression of megalin and cubilin, phenotypes that were attenuated by pretreatment with exogenous CD59. Overall, our findings reveal a novel mechanism underlying sub-lytic C5b-9 acting on megalin and cubilin, contributes to the renal tubules damage by TCE exposure.

Regulatory Roles of Pectin Oligosaccharides on Immunoglobulin Production in Healthy Mice Mediated by Gut Microbiota

SCOPE

The prebiotic regulation of the gut microbiota is a promising strategy to induce protective humoral and mucosal immune responses. The potential immune-improving effects of pectin oligosaccharides (POS) in healthy mice and the potential mechanism mediated by specific intestinal bacteria are investigated.

METHODS AND RESULTS

POS is prepared using a hydrogen-peroxide-assisted degradation. Mice that consumed diets containing POS are tested for microbial community shifts, short-chain fatty acids (SCFAs), and immunoglobulin (Ig) production using quantitative real-time polymerase chain reaction, gas chromatography, and ELISA kits. Pearson's correlation analyses are performed between Ig production and specific intestinal bacteria or SCFAs. POS treatment significantly improves the growth of healthy mice. Moreover, 4-week POS administration results in a profound change in intestinal microbial composition and a significantly higher fecal concentration of acetate, which leads to substantial increases of the levels of fecal secretory immunoglobulin A and serum IgG.

CONCLUSIONS

The results suggest that the inclusion of POS in a diet can increase Ig production and optimize the composition of the gut microbiota. A significant correlation is observed between changes in Ig production and specific intestinal bacteria or acetate, providing insight into the mechanism of POS as a potential immune-enhancing supplement.

A dye@MOF crystalline probe serving as a platform for ratiometric sensing of trichloroacetic acid (TCA), a carcinogen metabolite in human urine

Novel microporous dual-emitting dye@MOF FS@1 hybrid has been designed and prepared to effectively detect TCA, the biomarker for carcinogenic TCE in human urine.