Loss of FUT8 in renal tubules ameliorates ischemia-reperfusion injury-induced renal interstitial inflammation transition to fibrosis via the TLR3-NF-κB pathway.

Renal ischemia-reperfusion injury (IRI) is a common reason of acute kidney injury (AKI). AKI can progress to chronic kidney disease (CKD) in some survivors. Inflammation is considered the first-line response to early-stage IRI. We previously reported that core fucosylation (CF), specifically catalyzed by α-1,6 fucosyltransferase (FUT8), exacerbates renal fibrosis. However, the FUT8 characteristics, role, and mechanism in inflammation and fibrosis transition remain unclear. Considering renal tubular cells are the trigger cells that initiate the fibrosis in the AKI-to-CKD transition in IRI, we targeted CF by generating a renal tubular epithelial cell (TEC)-specific FUT8 knockout mouse and measured FUT8-driven and downstream signaling pathway expression and AKI-to-CKD transition. During the IRI extension phase, specific FUT8 deletion in the TECs ameliorated the IRI-induced renal interstitial inflammation and fibrosis mainly via the TLR3 CF-NF-κB signaling pathway. The results firstly indicated the role of FUT8 in the transition of inflammation and fibrosis. Therefore, the loss of FUT8 in TECs may be a novel potential strategy for treating AKI-CKD transition.

Positive association of serum FUT8 activity with renal tubulointerstitial injury in IgA nephropathy patients.

BACKGROUND: α-1,6 Fucosyltransferase (FUT8) appears to play an essential role in the pathogenesis of renal fibrosis. However, it remained unknown whether FUT8 also contributed to renal fibrosis in immunoglobulin A nephropathy (IgAN). In the present study, we explored the association of serum FUT8 activity with renal tubulointerstitial injury in IgAN patients. METHODS: Serum FUT8 activity was measured in 135 IgAN patients and 68 healthy controls from January 2016 to December 2018. The relationships of serum FUT8 activity with clinical and pathological features were analyzed. RESULTS: Relative to healthy controls, IgAN patients had significantly higher serum FUT8 activity and upregulation of renal FUT8 protein (p < .05). Among IgAN patients, there was a positive correlation of serum FUT8 activity with renal FUT8 protein expression (p < .05). Multivariable logistic regression analyses showed that serum FUT8 activity was significantly associated with serum creatinine and eGFR (p < .05). Based on a cut-off value determined from ROC curve analysis, we divided IgAN patients into a low serum FUT8 activity group (≤12.2 pmol/h/mL, n = 40) and a high serum FUT8 activity group (>12.2 pmol/h/ml, n = 95). The high serum FUT8 activity group had a higher Oxford T score, increased inflammatory cell infiltration, more severe fibrosis and poor renal function (p < .05). CONCLUSION: Serum FUT8 activity was positive association with renal tubulointerstitial injury in IgAN patients.

Core fucosylation involvement in the paracrine regulation of proteinuria-induced renal interstitial fibrosis evaluated with the use of a microfluidic chip.

Proteinuria is a clinical manifestation of chronic kidney disease that aggravates renal interstitial fibrosis (RIF), in which injury of peritubular microvessels is an important event. However, the changes in peritubular microvessels induced by proteinuria and their molecular mechanisms remain unclear. Thus, we aimed to develop a co-culture microfluidic device that contains renal tubules and peritubular microvessels to create a proteinuria model. We found that protein overload in the renal tubule induced trans-differentiation and apoptosis of endothelial cells (ECs) and pericytes. Moreover, profiling of secreted proteins in this model revealed that a paracrine network between tubules and microvessels was activated in proteinuria-induced microvascular injury. Multiple cytokine receptors in this paracrine network were core-fucosylated. Inhibition of core fucosylation significantly reduced ligand-receptor binding ability and blocked downstream pathways, alleviating trans-differentiation and apoptosis of ECs and pericytes. Furthermore, the protective effect of genetic FUT8 deficiency on proteinuria overload-induced RIF and pericyte-myofibroblast trans-differentiation was validated in FUT8 knockout heterozygous mice. In conclusion, we constructed and used a multiple-unit integrated microfluidic device to uncover the mechanism of proteinuria-induced RIF. Furthermore, FUT8 may serve as a hub-like therapeutic target to alleviate peritubular microvascular injury in RIF. STATEMENT OF SIGNIFICANCE: In this study, we constructed a multiple-unit integrated renal tubule-vascular chip. We reproduced human proteinuria on the chip and found that multiple receptors were modified by FUT8-catalyzed core fucosylation (CF) involved in the cross-talk between renal tubules and peritubular microvessels in proteinuria-induced RIF, and inhibiting the FUT8 of receptors could block the tubule-microvessel paracrine network and reverse the damage of peritubular microvessels and renal interstitial fibrosis. This tubule-vascular chip may provide a prospective platform to facilitate future investigations into the mechanisms of kidney diseases, and target-FUT8 inhibition may be an innovative and potential therapeutic strategy for RIF induced by proteinuria.

Bone marrow mesenchymal stem cell-derived exosomal miR-34c-5p ameliorates RIF by inhibiting the core fucosylation of multiple proteins.

Renal interstitial fibrosis (RIF) is an incurable pathological lesion in chronic kidney diseases. Pericyte activation is the major pathological characteristic of RIF. Fibroblast and macrophage activation are also involved in RIF. Studies have revealed that core fucosylation (CF), an important post-translational modification of proteins, plays a key role in pericyte activation and RIF by regulating multiple profibrotic signaling pathways as a hub-like target. Here, we reveal that mesenchymal stem cell (MSC)-derived exosomes reside specifically in the injured kidney and deliver microRNA (miR)-34c-5p to reduce cellular activation and RIF by inhibiting CF. Furthermore, we showed that the CD81-epidermal growth factor receptor (EGFR) ligand-receptor complex aids the entry of exosomal miR-34c-5p into pericytes, fibroblasts, and macrophages. Altogether, our findings reveal a novel role of MSC-derived exosomes in inhibiting multicellular activation via CF and provide a potential intervention strategy for renal fibrosis.

Inhibition of core fucosylation limits progression of diabetic kidney disease.

BACKGROUND: FUT8-mediated core fucosylation, which transfers a fucose residue from GDP-fucose to core-GlcNAc of the N-linked type glycoproteins, is crucial for signaling receptors function. Core fucosylation is involved in various biological processes such as cell proliferation, apoptosis, differentiation and immune regulation. Our previous studies demonstrated that inhibiting core fucosylation prevented renal interstitial fibrosis of UUO murine models, but its role in the development of diabetic kidney disease (DKD) remains unclear. This study aimed to clarify the protective effects and molecular mechanisms during the progress of DKD by inhibiting core fucosylation in vivo. METHODS: Core fucosylation was examined in streptozotocin (STZ)-induced diabetic mouse model. Then a new Fut8 mutation mouse model in which exon 7 of Fut8 gene is deleted was constructed for diabetes induction. Metabolic and renal parameters were measured. Renal structure, fibrosis, and podocyte injury were assessed, and underlying mechanisms were investigated. RESULTS: The levels of fasting blood glucose, glycated hemoglobin, kidney-weight-to- body-weight (KW/BW) and urine albumin-to-creatinine (ACR) were increased at 16 weeks post injection. KW/BW and urine ACR were decreased significantly by inhibiting core fucosylation. The renal pathology, fibrosis, and podocyte injury were mitigated significantly by inhibiting core fucosylation. The protective effects of inhibiting core fucosylation were mediated by downregulated of the phosphorylation of Smad2/3 and extracellular signal-regulated kinase (ERK). CONCLUSIONS: Our results indicate that FUT8-based treatment might be a promising intervention strategy in therapeutic paradigm of DKD.

Effects of epigallocatechin gallate on the cell-wall structure of Mycobacterial smegmatis mc²155.

Epigallocatechin gallate (EGCG) is the main component of green tea extracts that inhibits the growth of Mycobacterial smegmatis mc(2)155, and the mechanism is not clear. This study showed the effects of EGCG on the growth of mc(2)155. The content and the structure of EGCG in LB medium with mc(2)155 were identified by HPLC and LC/MS. Transmission electron microscopy was utilised to identify the cell envelope structure. As a result, the optional inhibition concentration was determined to be 20 µg mL(-1). Most of EGCG was transferred into its isomeride in LB medium, but the inhibition effects against mc(2)155 had yet been maintained. The changes of cell envelope structure were showed after EGCG treatment for 18 h. The cell wall appeared to have a less electron-translucent zone, turn rougher and thicker. The results show that EGCG impacts the integrity of mycobacterial cell wall and is likely be a better prophylactic agent against tuberculosis.