PCSK9 causes inflammation and cGAS/STING pathway activation in diabetic nephropathy.

Our previous research revealed that an increase in PCSK9 is linked to aggravated inflammation in the kidneys of mice affected by a high-fat diet and streptozotocin (HFD/STZ) or in HGPA-induced HK-2 cells. Furthermore, the cGAS/STING pathway has been reported to be involved in diabetic nephropathy (DN). Therefore, in this study, we aimed to examine the correlation between the proinflammatory effect of PCSK9 and the cGAS/STING pathway in DN. We used PCSK9 mAbs to inhibit PCSK9 in vivo and PCSK9 siRNA in vitro and measured the inflammatory phenotype in HFD/STZ-treated mice or HGPA-induced HK-2 cells, and observed decreased blood urea nitrogen, creatinine, UACR, and kidney injury in response to the PCSK9 mAb in HFD/STZ-treated mice. Moreover, IL-1 ß, MCP-1, and TNF-α levels were reduced by the PCSK9 mAb in vivo and PCSK9 siRNA in vitro. We observed increased mtDNA damage and activation of the cGAS-STING signaling pathway during DN, as well as the downstream targets p-TBK1, p-NF-κB p65, and IL-1ß. In a further experiment with an HGPA-induced DN model in HK-2 cells, we revealed that mtDNA damage was increased, which led to the activation of the cGAS/STING system and its downstream targets. Notably, the cGAS-STING signaling pathway was inhibited by the PCSK9 mAb in vivo and PCSK9 siRNA in vitro. In addition, inhibition of STING with C-176 in HGPA-induced HK-2 cells markedly blocked inflammation. In conclusion, we report for the first time that PCSK9 triggers mitochondrial DNA damage and activates the cGAS-STING pathway in DN, which leads to a series of inflammation cascades. PCSK9-targeted intervention can effectively reduce DN inflammation and delay its progression. Moreover, the inhibition of STING significantly abrogated the inflammation triggered by HGPA in HK-2 cells.

Urinary SIRT2 Reflects Kidney Injury in Type 2 Diabetes.

INTRODUCTION: The early diagnosis of kidney injury in type 2 diabetes (T2DM) is important to prevent the long-term damaging effects of kidney loss and is decisive for patient outcomes. While SIRT2 is implicated in diabetes pathogenesis, its correlation with diabetic nephropathy remains unexplored. This study was designed to evaluate the association of urine SIRT2 levels with diabetic kidney injury, as well as potential underlying mechanisms. METHODS: In T2DM patients, db/db mice, and high glucose plus palmitic acid treated HK2 cell models, ELISA, Immunoturbidimetry, Immunohistochemistry, Western blot, and Quantitative real-time polymerase chain reaction were used to detect SIRT2 levels and kidney damage. According to urinary albumin/creatinine ratio (UACR), 163 T2DM patients were divided into three groups. Spearman correlation analysis was used to investigate the relationship between urinary sirtuin2/creatinine ratio (USCR) and biomarkers of kidney injury. The influencing factors of albuminuria in T2DM patients were analyzed by logistic regression model. RESULTS: In our findings, the Macro group exhibited the highest USCR levels as UACR increased. There was a positive association between USCR and UACR, α1-microglobulin/creatinine ratio (UαCR), ß2-microglobulin/creatinine ratio (UßCR), and retinol-binding protein/creatinine ratio (URCR), with a negative correlation observed with eGFR. Logistic ordered multiclassification regression analysis, adjusting for confounding variables, confirmed that USCR remained a significant risk factor for the severity of albuminuria in T2DM patients. In the db/db mice kidney SIRT2 protein level increased significantly. Increased SIRT2 protein levels were also observed in renal tubular epithelial cells treated with high glucose plus palmitic acid. Moreover, SIRT2 promotes the expression of proinflammatory factors TNF-α and IL-6 by modulating the phosphorylation of p38 MAPK and p-JNK in renal tubular cells induced by high glucose and palmitic acid. CONCLUSION: Urinary SIRT2 is closely related to eGFR, renal tubule injury, and urinary albumin excretion in T2DM patients, which is expected to be an important indicator to comprehensively reflect renal injury.

Increased serum PCSK9 levels are associated with renal function impairment in patients with type 2 diabetes mellitus.

PURPOSE: The purpose of this study was to investigate the association between serum proprotein convertase subtilisin/kexin type 9 (PCSK9) levels and renal function impairment in type 2 diabetes mellitus (T2DM) patients. METHODS: PCSK9 levels were measured in T2DM patients, streptozotocin plus high-fat diet (STZ + HFD) mice, human proximal tubular epithelial (HK-2) cells treated with high glucose plus palmitic acid (HGPA) and the corresponding control groups. The T2DM patients were further divided into three groups according to serum PCSK9 levels. An analysis of clinical data was conducted, and a binary logistic regression model was used to test the relationship between potential predictors and urine albumin/urine creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR). RESULTS: PCSK9 levels were higher in the DM group than in the control group in humans, mice and HK-2 cells. The systolic blood pressure (SBP), serum creatinine (Scr), blood urea nitrogen (BUN), triglyceride (TG), and urine α1-MG/urine creatinine ratio (UαCR) values in PCSK9 tertile 3 were significantly higher than those in PCSK9 tertile 1 (p < 0.05). The DBP and UACR values were significantly higher in PCSK9 tertile 3 than in PCSK9 tertile 1 and PCSK9 tertile 2 (both p < 0.05). In addition, URCR values were significantly higher in PCSK9 tertile 3 and PCSK9 tertile 2 than in PCSK9 tertile 1 (both p < 0.05). Serum PCSK9 levels were positively correlated with SBP, Scr, BUN, TG, URCR, UαCR and UACR but inversely correlated with eGFR. In STZ + HFD mice, serum PCSK9 levels were positively correlated with Scr, BUN and UACR, which was consistent with the findings in the patients. A logistic regression model revealed that serum PCSK9 is an independent risk factor for UACR ≥30 mg/g and eGFR <60 mL/min/1.73 m2. The ROC curve showed that 170.53 ng/mL and 337.26 ng/mL PCSK9 were the best cutoff values for UACR ≥30 mg/g and eGFR <60 mL/min/1.73 m2, respectively. CONCLUSION: Serum PCSK9 levels are associated with renal function impairment in T2DM patients and in some patients lower PCSK9 may be helpful to decrease chronic kidney disease.

An efficient classification algorithm for NGS data based on text similarity.

With the advancement of high-throughput sequencing technologies, the amount of available sequencing data is growing at a pace that has now begun to greatly challenge the data processing and storage capacities of modern computer systems. Removing redundancy from such data by clustering could be crucial for reducing memory, disk space and running time consumption. In addition, it also has good performance on reducing dataset noise in some analysis applications. In this study, we propose a high-performance short sequence classification algorithm (HSC) for next generation sequencing (NGS) data based on efficient hash function and text similarity. First, HSC converts all reads into k-mers, then it forms a unique k-mer set by merging the duplicated and reverse complementary elements. Second, all unique k-mers are stored in a hash table, where the k-mer string is stored in the key field, and the ID of the reads containing the k-mer are stored in the value field. Third, each hash unit is transformed into a short text consisting of reads. Fourth, texts that satisfy the similarity threshold are combined into a long text, the merge operation is executed iteratively until there is no text that satisfies the merge condition. Finally, the long text is transformed into a cluster consisting of reads. We tested HSC using five real datasets. The experimental results showed that HSC cluster 100 million short reads within 2 hours, and it has excellent performance in reducing memory consumption. Compared to existing methods, HSC is much faster than other tools, it can easily handle tens of millions of sequences. In addition, when HSC is used as a preprocessing tool to produce assembly data, the memory and time consumption of the assembler is greatly reduced. It can help the assembler to achieve better assemblies in terms of N50, NA50 and genome fraction.

A new mutation site in the AIRE gene causes autoimmune polyendocrine syndrome type 1.

Autoimmune polyendocrine syndrome type 1 (APS-1, OMIM 2403000) is a rare autosomal recessive disease that is caused by autoimmune regulator (AIRE). The main symptoms of APS-1 are chronic mucocutaneous candidiasis, autoimmune adrenocortical insufficiency (Addison's disease) and hypoparathyroidism. We collected APS-1 cases and analysed them. The AIRE genes of the patient and his family members were sequenced to identify whether the APS-1 patient had an AIRE mutation. We discovered a mutation site (c.206A>C) that had never before been reported in the AIRE gene located in exon 2 of the AIRE gene. This homogyzous mutation caused a substitution of the 69th amino acid of the AIRE protein from glutamine to proline (p.Q69P). A yeast two-hybrid assay, which was used to analyse the homodimerization properties of the mutant AIRE protein, showed that the mutant AIRE protein could not interact with the normal AIRE protein. Flow cytometry and RT-qPCR analyses indicated that the new mutation site could decrease the expression levels of the AIRE, glutamic acid decarboxylase 65 (GAD65) and tryptophan hydroxylase-1 (TPH1) proteins to affect central immune tolerance. In conclusion, our research has shown that the new mutation site (c.206A>C) may influence the homodimerization and expression levels and other aspects of the AIRE protein. It may also impact the expression levels of tissue-restricted antigens (TRAs), leading to a series of autoimmune diseases.

Expression of Toll-like receptors in the cerebellum during pathogenesis of prion disease.

Prion diseases, such as scrapie, entail the accumulation of disease-specific prion protein (PrPSc) within the brain. Toll-like receptors (TLRs) are crucial components of the pattern recognition system. They recognize pathogen-associated molecular patterns (PAMPs) and play a central role in orchestrating host innate immune responses. The expression levels of Toll-like receptors (TLRs) in the central nervous system (CNS) were not well-defined. To establish a model of prion diseases in BALB/C mice, the 22L strain was employed. The features of the 22L strain were analyzed, and the cerebellum exhibited severe pathological changes. TLR1-13 levels in the cerebellum were measured using quantitative polymerase chain reaction (qPCR) at time points of 60, 90, 120, and the final end point (145 days post-infection). During the pathogenesis, the expression levels of Toll-like receptors (TLRs) 1, 2, 7, 8, and 9 increased in a time-dependent manner. This trend mirrored the expression patterns of PrPSc (the pathological isoform of the prion protein) and glial fibrillary acidic protein. Notably, at the end point, TLR1-13 levels were significantly elevated. Protein level of TLR7 and TLR9 showed increasing at the end point of the 22L-infected mice. A deeper understanding of the increased Toll-like receptors (TLRs) in prion diseases could shed light on their role in initiating immune responses at various stages during pathogenesis. This insight is particularly relevant when considering TLRs as potential therapeutic targets for prion diseases.

Overexpressing autoimmune regulator regulates the expression of toll-like receptors by interacting with their promoters in RAW264.7 cells.

Autoimmune regulator (Aire) is a transcriptional activator that regulates the ectopic expression of many tissue-restricted antigens in medullary thymic epithelial cells, and that has an important role in the negative selection of autoreactive T cells. However, the roles of Aire expression in peripheral lymphoid tissues and hematopoietic cells, especially monocytes/macrophages, remain poorly understood. In this study, we found that the mRNA and protein expression levels of toll-like receptor (TLR)1, TLR3, and TLR8 were notably up-regulated in a mouse macrophage-like cell line (RAW264.7) stably expressing Aire, while the expression of TLR2, TLR4, TLR5, TLR6, TLR7, and TLR9 were not significantly changed. In addition, the mRNA expression of TLR3 and TLR8 were significantly increased in primary peritoneal macrophages transiently transfected with Aire. Using chromatin immunoprecipitation and a luciferase activity assay, we also found that Aire interacted with the TLR1, TLR3, and TLR8 promoters and increased the luciferase transcriptional activity of these promoters in RAW264.7 cells. Moreover, after stimulation by Pam(3)CSK(4), a TLR1 ligand, and poly(I:C), a TLR3 ligand, we found that the mRNA expression levels of IL-1α, TNFα, iNOS, and IFNα were increased in RAW264.7 cells stably expressing Aire. Together, these data suggest that Aire has a crucial role in the recognition of pathogenic microorganisms and peripheral immune tolerance in antigen-presenting cells (APCs) by regulating the expression of TLRs.

The Silence of PSMC6 Inhibits Cell Growth and Metastasis in Lung Adenocarcinoma.

The proteasome has been validated as an anticancer drug target, while the role of a subunit of proteasome, PSMC6, in lung adenocarcinoma (LUAD) has not been fully unveiled. In this study, we observed that both the RNA and protein of PSMC6 were highly upregulated in LUAD compared with the adjacent normal tissues. Moreover, a high PSMC6 expression was associated with poor prognosis. In accordance with this finding, PSMC6 was associated with poor tumor differentiation. Furthermore, the silence of PSMC6 by small interference RNAs (siRNAs) could significantly inhibit cell growth, migration, and invasion in lung cancer cell lines, suggesting that PSMC6 might serve as a promising therapeutic target in LUAD. To further explore the molecular mechanism of PSMC6 in LUAD, we observed that the proteasome subunits, such as PSMD10, PSMD6, PSMD9, PSMD13, PSMB3, PSMB1, PSMA4, PSMC1, PSMC2, PSMD7, and PSMD14, were highly correlated with PSMC6 expression. Based on the gene set enrichment analysis, we observed that these proteasome subunits were involved in the degradation of AXIN protein. The correlation analysis revealed that the positively correlated genes with PSMC6 were highly enriched in WNT signaling-related pathways, demonstrating that the PSMC6 overexpression may activate WNT signaling via degrading the AXIN protein, thereby promoting tumor progression. In summary, we systematically evaluated the differential expression levels and prognostic values of PSMC6 and predicted its biological function in LUAD, which suggested that PSMC6 might act as a promising therapeutic target in LUAD.