CTGF in kidney fibrosis and glomerulonephritis

The role of macrophages in fibrosis of chronic kidney disease

Macrophages are widely distributed throughout various tissues of the body, and mounting evidence suggests their involvement in regulating the tissue microenvironment, thereby influencing disease onset and progression through direct or indirect actions. In chronic kidney disease (CKD), disturbances in renal functional homeostasis lead to inflammatory cell infiltration, tubular expansion, glomerular atrophy, and subsequent renal fibrosis. Macrophages play a pivotal role in this pathological process. Therefore, understanding their role is imperative for investigating CKD progression, mitigating its advancement, and offering novel research perspectives for fibrosis treatment from an immunological standpoint. This review primarily delves into the intrinsic characteristics of macrophages, their origins, diverse subtypes, and their associations with renal fibrosis. Particular emphasis is placed on the transition between M1 and M2 phenotypes. In late-stage CKD, there is a shift from the M1 to the M2 phenotype, accompanied by an increased prevalence of M2 macrophages. This transition is governed by the activation of the TGF-β1/SMAD3 and JAK/STAT pathways, which facilitate macrophage-to-myofibroblast transition (MMT). The tyrosine kinase Src is involved in both signaling cascades. By thoroughly elucidating macrophage functions and comprehending the modes and molecular mechanisms of macrophage-fibroblast interaction in the kidney, novel, tailored therapeutic strategies for preventing or attenuating the progression of CKD can be developed.

Potentials of Natural Antioxidants in Reducing Inflammation and Oxidative Stress in Chronic Kidney Disease

Chronic kidney disease (CKD) presents a substantial global public health challenge, with high morbidity and mortality. CKD patients often experience dyslipidaemia and poor glycaemic control, further exacerbating inflammation and oxidative stress in the kidney. If left untreated, these metabolic symptoms can progress to end-stage renal disease, necessitating long-term dialysis or kidney transplantation. Alleviating inflammation responses has become the standard approach in CKD management. Medications such as statins, metformin, and GLP-1 agonists, initially developed for treating metabolic dysregulation, demonstrate promising renal therapeutic benefits. The rising popularity of herbal remedies and supplements, perceived as natural antioxidants, has spurred investigations into their potential efficacy. Notably, lactoferrin, Boerhaavia diffusa, Amauroderma rugosum, and Ganoderma lucidum are known for their anti-inflammatory and antioxidant properties and may support kidney function preservation. However, the mechanisms underlying the effectiveness of Western medications and herbal remedies in alleviating inflammation and oxidative stress occurring in renal dysfunction are not completely known. This review aims to provide a comprehensive overview of CKD treatment strategies and renal function preservation and critically discusses the existing literature's limitations whilst offering insight into the potential antioxidant effects of these interventions. This could provide a useful guide for future clinical trials and facilitate the development of effective treatment strategies for kidney functions.

The Role of Collagen VIII in the Aging Mouse Kidney

The gradual loss of kidney function due to increasing age is accompanied by structural changes such as fibrosis of the tissue. The underlying molecular mechanisms are complex, but not yet fully understood. Non-fibrillar collagen type VIII (COL8) could be a potential factor in the fibrosis processes of the aging kidney. A pathophysiological significance of COL8 has already been demonstrated in the context of diabetic kidney disease, with studies showing that it directly influences both the development and progression of renal fibrosis occurring. The aim of this study was to investigate whether COL8 impacts age-related micro-anatomical and functional changes in a mouse model. The kidneys of wild-type (Col8-wt) and COL8-knockout (Col8-ko) mice of different age and sex were characterized with regard to the expression of molecular fibrosis markers, the development of nephrosclerosis and renal function. The age-dependent regulation of COL8 mRNA expression in the wild-type revealed sex-dependent effects that were not observed with collagen IV (COL4). Histochemical staining and protein analysis of profibrotic cytokines TGF-β1 (transforming growth factor) and CTGF (connective tissue growth factor) in mouse kidneys showed significant age effects as well as interactions of the factors age, sex and Col8 genotype. There were also significant age and Col8 genotype effects in the renal function data analyzed by urinary cystatin C. In summary, the present study shows, for the first time, that COL8 is regulated in an age- and sex-dependent manner in the mouse kidney and that the expression of COL8 influences the severity of age-induced renal fibrosis and function.

Connective Tissue Growth Factor: Regulation, Diseases, and Drug Discovery

In drug discovery, selecting targeted molecules is crucial as the target could directly affect drug efficacy and the treatment outcomes. As a member of the CCN family, CTGF (also known as CCN2) is an essential regulator in the progression of various diseases, including fibrosis, cancer, neurological disorders, and eye diseases. Understanding the regulatory mechanisms of CTGF in different diseases may contribute to the discovery of novel drug candidates. Summarizing the CTGF-targeting and -inhibitory drugs is also beneficial for the analysis of the efficacy, applications, and limitations of these drugs in different disease models. Therefore, we reviewed the CTGF structure, the regulatory mechanisms in various diseases, and drug development in order to provide more references for future drug discovery.

The clinical manifestations and molecular pathogenesis of radiation fibrosis

Advances in radiation techniques have enabled the precise delivery of higher doses of radiotherapy to tumours, while sparing surrounding healthy tissues. Consequently, the incidence of radiation toxicities has declined, and will likely continue to improve as radiotherapy further evolves. Nonetheless, ionizing radiation elicits tissue-specific toxicities that gradually develop into radiation-induced fibrosis, a common long-term side-effect of radiotherapy. Radiation fibrosis is characterized by an aberrant wound repair process, which promotes the deposition of extensive scar tissue, clinically manifesting as a loss of elasticity, tissue thickening, and organ-specific functional consequences. In addition to improving the existing technologies and guidelines directing the administration of radiotherapy, understanding the pathogenesis underlying radiation fibrosis is essential for the success of cancer treatments. This review integrates the principles for radiotherapy dosimetry to minimize off-target effects, the tissue-specific clinical manifestations, the key cellular and molecular drivers of radiation fibrosis, and emerging therapeutic opportunities for both prevention and treatment.

Molecular Targets of Novel Therapeutics for Diabetic Kidney Disease: A New Era of Nephroprotection

Diabetic kidney disease (DKD) is a chronic microvascular complication in patients with diabetes mellitus (DM) and the leading cause of end-stage kidney disease (ESKD). Although glomerulosclerosis, tubular injury and interstitial fibrosis are typical damages of DKD, the interplay of different processes (metabolic factors, oxidative stress, inflammatory pathway, fibrotic signaling, and hemodynamic mechanisms) appears to drive the onset and progression of DKD. A growing understanding of the pathogenetic mechanisms, and the development of new therapeutics, is opening the way for a new era of nephroprotection based on precision-medicine approaches. This review summarizes the therapeutic options linked to specific molecular mechanisms of DKD, including renin-angiotensin-aldosterone system blockers, SGLT2 inhibitors, mineralocorticoid receptor antagonists, glucagon-like peptide-1 receptor agonists, endothelin receptor antagonists, and aldosterone synthase inhibitors. In a new era of nephroprotection, these drugs, as pillars of personalized medicine, can improve renal outcomes and enhance the quality of life for individuals with DKD.

Fibrosis in Chronic Kidney Disease: Pathophysiology and Therapeutic Targets

Chronic kidney disease (CKD) is a slowly progressive condition characterized by decreased kidney function, tubular injury, oxidative stress, and inflammation. CKD is a leading global health burden that is asymptomatic in early stages but can ultimately cause kidney failure. Its etiology is complex and involves dysregulated signaling pathways that lead to fibrosis. Transforming growth factor (TGF)-β is a central mediator in promoting transdifferentiation of polarized renal tubular epithelial cells into mesenchymal cells, resulting in irreversible kidney injury. While current therapies are limited, the search for more effective diagnostic and treatment modalities is intensive. Although biopsy with histology is the most accurate method of diagnosis and staging, imaging techniques such as diffusion-weighted magnetic resonance imaging and shear wave elastography ultrasound are less invasive ways to stage fibrosis. Current therapies such as renin-angiotensin blockers, mineralocorticoid receptor antagonists, and sodium/glucose cotransporter 2 inhibitors aim to delay progression. Newer antifibrotic agents that suppress the downstream inflammatory mediators involved in the fibrotic process are in clinical trials, and potential therapeutic targets that interfere with TGF-β signaling are being explored. Small interfering RNAs and stem cell-based therapeutics are also being evaluated. Further research and clinical studies are necessary in order to avoid dialysis and kidney transplantation.

Dysregulated bidirectional epithelial-mesenchymal crosstalk: a core determinant of lung fibrosis progression

Progressive lung fibrosis is characterised by dysregulated extracellular matrix (ECM) homeostasis. Understanding of disease pathogenesis remains limited and has prevented the development of effective treatments. While an abnormal wound healing response is strongly implicated in lung fibrosis initiation, factors that determine why fibrosis progresses rather than regular tissue repair occurs are not fully explained. Within human lung fibrosis there is evidence of altered epithelial and mesenchymal lung populations as well as cells undergoing epithelial-mesenchymal transition (EMT), a dynamic and reversible biological process by which epithelial cells lose their cell polarity and down-regulate cadherin-mediated cell-cell adhesion to gain migratory properties. This review will focus upon the role of EMT and dysregulated epithelial-mesenchymal crosstalk in progressive lung fibrosis.

Total flavonoids of Astragalus protects glomerular filtration barrier in diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is a prevalent complication of diabetes and the leading cause of end-stage renal disease. Recent evidence suggests that total flavonoids of Astragalus (TFA) has promising effects on diabetes; however, its influence on DKD and the underlying mechanism remains unclear.

METHODS

In this study, we induced the DKD model using streptozotocin (STZ) in male C57BL/6J mice and utilized glomerular endothelial cell (GEC) lines for in vitro investigations. We constructed a network pharmacology analysis to understand the mechanism of TFA in DKD. The mechanism of TFA action on DKD was investigated through Western blot analysis and multi-immunological methods.

RESULTS

Our findings revealed that TFA significantly reduced levels of urinary albumin (ALB). Network pharmacology and intracellular pathway experiments indicated the crucial involvement of the PI3K/AKT signaling pathway in mediating these effects. In vitro experiments showed that TFA can preserve the integrity of the glomerular filtration barrier by inhibiting the expression of inflammatory factors TNF-alpha and IL-8, reducing oxidative stress.

CONCLUSION

Our findings demonstrated that TFA can ameliorates the progression of DKD by ameliorating renal fibrosis and preserving the integrity of the kidney filtration barrier. These results provide pharmacological evidence supporting the use of TFA in the treatment of kidney diseases.

Galectin-3 promotes fibrosis in ovarian endometriosis

Objective

This study aimed to investigate the potential role of galectin-3 (Gal-3) in the pathogenesis of fibrotic alterations in ovarian endometriosis (OVE).

Methods

In this study, we collected the ectopic endometrial tissues and eutopic endometrial tissues from 31 OVE patients treated by laparoscopy, and the eutopic endometrial tissues from 23 non-OVE patients with leiomyoma or other benign diseases were used as control. Hematoxylin and eosin (H&E) and Masson's trichrome staining were utilized for histopathological assessment. The primary normal endometrial stromal cells (NESC), ectopic endometrial stromal cells (ECSC), and eutopic endometrial stromal cells (EUSC) were isolated. Gal-3 overexpression plasmids (Gal-OE) and short hairpin RNA targeting Gal-3 (Gal-3-shRNA) were transfected into the immortalized human endometriotic cell line 12Z, respectively. RT-qPCR, Western blot analysis, and immunohistochemistry were used to detect the mRNA and protein expression levels of Gal-3, type I collagen (COL-1), connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA), respectively.

Results

H&E and Masson staining showed that ovarian ectopic endometrium exhibited glandular hyperplasia, high columnar glandular epithelium, apical plasma secretion, more subnuclear vacuoles, and obvious fibrosis, compared with normal endometrium. The mRNA and protein levels of Gal-3 , CTGF, α-SMA, and COL-1 were all upregulated in the ectopic endometrial tissues of OVE patients compared to the eutopic endometrial tissues from OVE patients and non-OVE patients. Moreover, ECSC expressed higher levels of Gal-3, CTGF, α-SMA, and COL-1 than EUSC and NESC. Follow-up investigations demonstrated that the Gal-3 overexpression substantially increased fibrosis-related markers including CTGF, α-SMA, and COL-1 within the 12Z cell line. Conversely, Gal-3 knockdown showed the opposite effects.

Conclusion

Gal-3 promotes fibrosis in OVE, positioning it as a prospective therapeutic target for mitigating fibrosis in endometriosis.

Time-Dependent Differences in Vancomycin Sensitivity of Macrophages Underlie Vancomycin-Induced Acute Kidney Injury

Although vancomycin (VCM)-frequently used to treat drug-resistant bacterial infections-often induces acute kidney injury (AKI), discontinuation of the drug is the only effective treatment; therefore, analysis of effective avoidance methods is urgently needed. Here, we report the differences in the induction of AKI by VCM in 1/2-nephrectomized mice depending on the time of administration. Despite the lack of difference in the accumulation of VCM in the kidney between the light (ZT2) and dark (ZT14) phases, the expression of AKI markers due to VCM was observed only in the ZT2 treatment. Genomic analysis of the kidney suggested that the time of administration was involved in VCM-induced changes in monocyte and macrophage activity, and VCM had time-dependent effects on renal macrophage abundance, ATP activity, and interleukin (IL)-1β expression. Furthermore, the depletion of macrophages with clodronate abolished the induction of IL-1β and AKI marker expression by VCM administration at ZT2. This study provides evidence of the need for time-dependent pharmacodynamic considerations in the prevention of VCM-induced AKI as well as the potential for macrophage-targeted AKI therapy. SIGNIFICANCE STATEMENT: There is a time of administration at which vancomycin (VCM)-induced renal injury is more and less likely to occur, and macrophages are involved in this difference. Therefore, there is a need for time-dependent pharmacodynamic considerations in the prevention of VCM-induced acute kidney injury as well as the potential for macrophage-targeted acute kidney injury therapy.

Quantitative Proteomics Combined with Network Pharmacology Analysis Unveils the Biological Basis of Schisandrin B in Treating Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a major complication of diabetes. Schisandrin B (Sch) is a natural pharmaceutical monomer that was shown to prevent kidney damage caused by diabetes and restore its function. However, there is still a lack of comprehensive and systematic understanding of the mechanism of Sch treatment in DN.

OBJECTIVE

We aim to provide a systematic overview of the mechanisms of Sch in multiple pathways to treat DN in rats.

METHODS

Streptozocin was used to build a DN rat model, which was further treated with Sch. The possible mechanism of Sch protective effects against DN was predicted using network pharmacology and was verified by quantitative proteomics analysis.

RESULTS

High dose Sch treatment significantly downregulated fasting blood glucose, creatinine, blood urea nitrogen, and urinary protein levels and reduced collagen deposition in the glomeruli and tubule-interstitium of DN rats. The activities of superoxide dismutase (SOD) and plasma glutathione peroxidase (GSH-Px) in the kidney of DN rats significantly increased with Sch treatment. In addition, the levels of IL-6, IL-1β, and TNF-α were significantly reduced in DN rats treated with Sch. 11 proteins that target both Sch and DN were enriched in pathways such as MAPK signaling, PI3K-Akt signaling, renal cell carcinoma, gap junction, endocrine resistance, and TNF signaling. Furthermore, quantitative proteomics showed that Xaf1 was downregulated in the model vs. control group and upregulated in the Sch-treated vs. model group. Five proteins, Crb3, Tspan4, Wdr45, Zfp512, and Tmigd1, were found to be upregulated in the model vs. control group and downregulated in the Sch vs. model group. Three intersected proteins between the network pharmacology prediction and proteomics results, Crb3, Xaf1, and Tspan4, were identified.

CONCLUSION

Sch functions by relieving oxidative stress and the inflammatory response by regulating Crb3, Xaf1, and Tspan4 protein expression levels to treat DN disease.

Artificial intelligence-assisted repurposing of lubiprostone alleviates tubulointerstitial fibrosis

Tubulointerstitial fibrosis (TIF) is the most prominent cause which leads to chronic kidney disease (CKD) and end-stage renal failure. Despite extensive research, there have been many clinical trial failures, and there is currently no effective treatment to cure renal fibrosis. This demonstrates the necessity of more effective therapies and better preclinical models to screen potential drugs for TIF. In this study, we investigated the antifibrotic effect of the machine learning-based repurposed drug, lubiprostone, validated through an advanced proximal tubule on a chip system and in vivo UUO mice model. Lubiprostone significantly downregulated TIF biomarkers including connective tissue growth factor (CTGF), extracellular matrix deposition (Fibronectin and collagen), transforming growth factor (TGF-β) downstream signaling markers especially, Smad-2/3, matrix metalloproteinase (MMP2/9), plasminogen activator inhibitor-1 (PAI-1), EMT and JAK/STAT-3 pathway expression in the proximal tubule on a chip model and UUO model compared to the conventional 2D culture. These findings suggest that the proximal tubule on a chip model is a more physiologically relevant model for studying and identifying potential biomarkers for fibrosis compared to conventional in vitro 2D culture and alternative of an animal model. In conclusion, the high throughput Proximal tubule-on-chip system shows improved in vivo-like function and indicates the potential utility for renal fibrosis drug screening. Additionally, repurposed Lubiprostone shows an effective potency to treat TIF via inhibiting 3 major profibrotic signaling pathways such as TGFβ/Smad, JAK/STAT, and epithelial-mesenchymal transition (EMT), and restores kidney function.

Decellularized diseased tissues: current state-of-the-art and future directions

Decellularized matrices derived from diseased tissues/organs have evolved in the most recent years, providing novel research perspectives for understanding disease occurrence and progression and providing accurate pseudo models for developing new disease treatments. Although decellularized matrix maintaining the native composition, ultrastructure, and biomechanical characteristics of extracellular matrix (ECM), alongside intact and perfusable vascular compartments, facilitates the construction of bioengineered organ explants in vitro and promotes angiogenesis and tissue/organ regeneration in vivo, the availability of healthy tissues and organs for the preparation of decellularized ECM materials is limited. In this paper, we review the research advancements in decellularized diseased matrices. Considering that current research focuses on the matrices derived from cancers and fibrotic organs (mainly fibrotic kidney, lungs, and liver), the pathological characterizations and the applications of these diseased matrices are mainly discussed. Additionally, a contrastive analysis between the decellularized diseased matrices and decellularized healthy matrices, along with the development in vitro 3D models, is discussed in this paper. And last, we have provided the challenges and future directions in this review. Deep and comprehensive research on decellularized diseased tissues and organs will promote in-depth exploration of source materials in tissue engineering field, thus providing new ideas for clinical transformation.

P2 X 7 receptor is a critical regulator of extracellular ATP-induced profibrotic genes expression in rat kidney: implication of transforming growth factor-β/Smad signaling pathway

This study was designed to investigate the potential of extracellular adenosine 5'-triphosphate (ATP) via the P2 X 7 receptor to activate the renal fibrotic processes in rats. The present study demonstrates that administration of ATP rapidly activated transforming growth factor-β (TGF-β) to induce phosphorylation of Smad-2/3. Renal connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA and protein expressions were also increased following ATP administration. A decrease in TGF-β amount in serum as well as renal Smad-2/3 phosphorylation was noticed in animals pre-treated with the specific antagonist of P2 X 7 receptor, A 438,079. In addition, a significant reduction in mRNA and protein expression of CTGF and TIMP-1were also observed in the kidneys of those animals. Collectively, the current findings demonstrate that ATP has the ability to augment TGF-β-mediated Smad-2/3 phosphorylation and enhance the expression of the pro-fibrotic genes, CTGF and TIMP-1, an effect that is largely mediated via P2 X 7 receptor.

New perspective on mechanism in muscle toxicity of ochratoxin A: Model of juvenile grass carp (Ctenopharyngodon idella)

Ochratoxin A (OTA) is a common fungal toxin that pollutes raw materials of aquatic feeds (such as corn, soybean meal, and wheat). This study explored the effects of OTA through diet on muscle toxicity in juvenile grass carp (Ctenopharyngodon idella). The following results were obtained for the muscle. (1) With an increase in dietary OTA, the residue of OTA in muscle increased, muscle fiber diameter and density decreased, and even muscle fiber breakage. (2) OTA caused oxidative stress by downregulating GPx1 (a, b) and Trx via inhibited the PGC1-α/Nrf2 signaling pathway. (3) OTA exacerbated endoplasmic reticulum stress in the muscle by causing endoplasmic reticulum expansion (results of transmission electron microscopy) and upregulating the expression of GRP78, eIF2α, ATF6, PERK, and CHOP. (4) OTA reduced muscle fiber diameter by inhibiting protein synthesis (AKT, TOR, and S6K1) and promoting the mRNA expression of protein degradation-related genes (MURF1, MAFBX, and FoxO3a), as well as by reducing AKT and promoting the immunofluorescence expression of FoxO3. (5) OTA inhibits collagen deposition by downregulating TGF-β1, TGF-βR1, Smad2, Smad3, Smad4, CTGF, TIMP, PHD, and LOX mRNA expressions as well as the CTGF immunofluorescence expression. Moreover, based on the GSH and collagen content contents, the upper safe dose for OTA-induced toxicity was 963.6 and 1129.6 μg/kg diet, respectively. Using the example of OTA, our research has provided new insights that raise concerns about the quality of aquatic products by exploring muscle toxicity caused by mycotoxins.

Extracellular Matrix Stiffness Regulates Microvascular Stability by Controlling Endothelial Paracrine Signaling to Determine Pericyte Fate

BACKGROUND

The differentiation of pericytes into myofibroblasts causes microvascular degeneration, ECM (extracellular matrix) accumulation, and tissue stiffening, characteristics of fibrotic diseases. It is unclear how pericyte-myofibroblast differentiation is regulated in the microvascular environment. Our previous study established a novel 2-dimensional platform for coculturing microvascular endothelial cells (ECs) and pericytes derived from the same tissue. This study investigated how ECM stiffness regulated microvascular ECs, pericytes, and their interactions.

METHODS

Primary microvessels were cultured in the TGM2D medium (tubular microvascular growth medium on 2-dimensional substrates). Stiff ECM was prepared by incubating ECM solution in regular culture dishes for 1 hour followed by PBS wash. Soft ECM with Young modulus of ≈6 kPa was used unless otherwise noted. Bone grafts were prepared from the rat skull. Immunostaining, RNA sequencing, RT-qPCR (real-time quantitative polymerase chain reaction), Western blotting, and knockdown experiments were performed on the cells.

RESULTS

Primary microvascular pericytes differentiated into myofibroblasts (NG2+αSMA+) on stiff ECM, even with the TGFβ (transforming growth factor beta) signaling inhibitor A83-01. Soft ECM and A83-01 cooperatively maintained microvascular stability while inhibiting pericyte-myofibroblast differentiation (NG2+αSMA-/low). We thus defined 2 pericyte subpopulations: primary (NG2+αSMA-/low) and activated (NG2+αSMA+) pericytes. Soft ECM promoted microvascular regeneration and inhibited fibrosis in bone graft transplantation in vivo. As integrins are the major mechanosensor, we performed RT-qPCR screening of integrin family members and found Itgb1 (integrin β1) was the major subunit downregulated by soft ECM and A83-01 treatment. Knocking down Itgb1 suppressed myofibroblast differentiation on stiff ECM. Interestingly, ITGB1 phosphorylation (Y783) was mainly located on microvascular ECs on stiff ECM, which promoted EC secretion of paracrine factors, including CTGF (connective tissue growth factor), to induce pericyte-myofibroblast differentiation. CTGF knockdown or monoclonal antibody treatment partially reduced myofibroblast differentiation, implying the participation of multiple pathways in fibrosis formation.

CONCLUSIONS

ECM stiffness and TGFβ signaling cooperatively regulate microvascular stability and pericyte-myofibroblast differentiation. Stiff ECM promotes EC ITGB1 phosphorylation (Y783) and CTGF secretion, which induces pericyte-myofibroblast differentiation.

Downregulation of PIK3IP1 in retinal microglia promotes retinal pathological neovascularization via PI3K-AKT pathway activation

Retinal pathological neovascularization involves endothelial cells, pericytes, photoreceptor cells, ganglion cells, and glial cells, whose roles remain unclear. Using the Scissor algorithm, we found that microglia are associated with formation of fibrovascular membranes and can promote pathological neovascularization. GO and KEGG results showed that PI3K-AKT pathway activation in retinal microglia was associated with pathological neovascularization, and PIK3IP1 was associated with retinal microglia activation. Then we used PCR, Western blot and Elisa techniques to confirm that the expression of VEGFA, FGF2, HGFα and MMP9 was increased in microglia after Lipopolysaccharide (LPS) induction. We also used cell flow cytometry and OIR models to verify the role of PI3K-AKT pathway and PIK3IP1 in microglia. Targeting of PIK3IP1 regulated the activation of the PI3K-AKT pathway in microglia, microglia function activation, and pro-angiogenic effects. These findings reveal the role of M1-type microglia in pathological neovascularization and suggests that targeting the PI3K-AKT pathway in microglia may be a new strategy for treating retinal pathological neovascularization.

Connective tissue growth factor: Role in trabecular meshwork remodeling and intraocular pressure lowering

Connective tissue growth factor (CTGF) is a distinct signaling molecule modulating many physiological and pathophysiological processes. This protein is upregulated in numerous fibrotic diseases that involve extracellular matrix (ECM) remodeling. It mediates the downstream effects of transforming growth factor beta (TGF-β) and is regulated via TGF-β SMAD-dependent and SMAD-independent signaling routes. Targeting CTGF instead of its upstream regulator TGF-β avoids the consequences of interfering with the pleotropic effects of TGF-β. Both CTGF and its upstream mediator, TGF-β, have been linked with the pathophysiology of glaucomatous optic neuropathy due to their involvement in the regulation of ECM homeostasis. The excessive expression of these growth factors is associated with glaucoma pathogenesis via elevation of the intraocular pressure (IOP), the most important risk factor for glaucoma. The raised in the IOP is due to dysregulation of ECM turnover resulting in excessive ECM deposition at the site of aqueous humor outflow. It is therefore believed that CTGF could be a potential therapeutic target in glaucoma therapy. This review highlights the CTGF biology and structure, its regulation and signaling, its association with the pathophysiology of glaucoma, and its potential role as a therapeutic target in glaucoma management.

Myocardin-related transcription factor contributes to renal fibrosis through the regulation of extracellular microenvironment surrounding fibroblasts

Fibroblast accumulation and extracellular matrix (ECM) deposition are common critical steps for the progression of organ fibrosis, but the precise molecular mechanisms remain to be fully investigated. We have previously demonstrated that lysophosphatidic acid contributes to organ fibrosis through the production of connective tissue growth factor (CTGF) via actin cytoskeleton-dependent signaling, myocardin-related transcription factor family (MRTF) consisting of MRTF-A and MRTF-B-serum response factor (SRF) pathway. In this study, we investigated the role of the MRTF-SRF pathway in the development of renal fibrosis, focusing on the regulation of ECM-focal adhesions (FA) in renal fibroblasts. Here we showed that both MRTF-A and -B were required for the expressions of ECM-related molecules such as lysyl oxidase family members, type I procollagen and fibronectin in response to transforming growth factor (TGF)-β1 . TGF-β1 -MRTF-SRF pathway induced the expressions of various components of FA such as integrin α subunits (αv , α2 , α11 ) and β subunits (β1 , β3 , β5 ) as well as integrin-linked kinase (ILK). On the other hand, the blockade of ILK suppressed TGF-β1 -induced MRTF-SRF transcriptional activity, indicating a mutual relationship between MRTF-SRF and FA. Myofibroblast differentiation along with CTGF expression was also dependent on MRTF-SRF and FA components. Finally, global MRTF-A deficient and inducible fibroblast-specific MRTF-B deficient mice (MRTF-AKO BiFBKO mice) are protected from renal fibrosis with adenine administration. Renal expressions of ECM-FA components and CTGF as well as myofibroblast accumulation were suppressed in MRTF-AKO BiFBKO mice. These results suggest that the MRTF-SRF pathway might be a therapeutic target for renal fibrosis through the regulation of components forming ECM-FA in fibroblasts.

Stem cell-derived exosomal MicroRNAs: Potential therapies in diabetic kidney disease

The diabetic kidney disease (DKD) is chronic kidney disease caused by diabetes and one of the most common comorbidities. It is often more difficult to treat end-stage renal disease once it develops because of its complex metabolic disorders, so early prevention and treatment are important. However, currently available DKD therapies are not ideal, and novel therapeutic strategies are urgently needed. The potential of stem cell therapies partly depends on their ability to secrete exosomes. More and more studies have shown that stem cell-derived exosomes take part in the DKD pathophysiological process, which may offer an effective therapy for DKD treatment. Herein, we mainly review potential therapies of stem cell-derived exosomes mainly stem cell-derived exosomal microRNAs in DKD, including their protective effects on mesangial cells, podocytes and renal tubular epithelial cells. Using this secretome as possible therapeutic drugs without potential carcinogenicity should be the focus of further research.

Towards a Unified Approach in Autoimmune Fibrotic Signalling Pathways

Autoimmunity is a chronic process resulting in inflammation, tissue damage, and subsequent tissue remodelling and organ fibrosis. In contrast to acute inflammatory reactions, pathogenic fibrosis typically results from the chronic inflammatory reactions characterizing autoimmune diseases. Despite having obvious aetiological and clinical outcome distinctions, most chronic autoimmune fibrotic disorders have in common a persistent and sustained production of growth factors, proteolytic enzymes, angiogenic factors, and fibrogenic cytokines, which together stimulate the deposition of connective tissue elements or epithelial to mesenchymal transformation (EMT) that progressively remodels and destroys normal tissue architecture leading to organ failure. Despite its enormous impact on human health, there are currently no approved treatments that directly target the molecular mechanisms of fibrosis. The primary goal of this review is to discuss the most recent identified mechanisms of chronic autoimmune diseases characterized by a fibrotic evolution with the aim to identify possible common and unique mechanisms of fibrogenesis that might be exploited in the development of effective antifibrotic therapies.

MicroRNA-26a-5p Restoration Ameliorates Unilateral Ureteral Obstruction-Induced Renal Fibrosis In Mice Through Modulating TGF-β Signaling

Renal fibrosis is a hallmark of chronic and progressive renal diseases characterized by excessive fibroblast proliferation, extracellular matrix accumulation, and loss of renal function, eventually leading to end-stage renal diseases. MicroRNA-26a-5p downregulation has been previously noted in the sera of unilateral ureteral occlusion (UUO)-injured mice, and exosome-mediated miR-26a-5p reportedly attenuated experimental pulmonary and cardiac fibrosis. This study evaluated the expression patterns of miR-26a in human tissue microarray with kidney fibrosis and in tissues from a mouse model of UUO-induced renal fibrosis. Histological analyses showed that miR-26a-5p was downregulated in human and mouse tissues with renal interstitial nephritis and fibrosis. Moreover, miR-26a-5p restoration by intravenous injection of a mimic agent prominently suppressed the expression of TGF-β1 and its cognate receptors, the inflammatory transcription factor NF-κB, epithelial-mesenchymal transition, and inflammatory markers in UUO-injured kidney tissues. In vitro miR-26a-5p mimic delivery significantly inhibited TGF-β1-induced activation of cultured rat kidney NRK-49F cells, in terms of downregulation of TGF-β1 receptors, restoration of epithelial marker E-cadherin, and suppression of mesenchymal markers, including vimentin, fibronectin, and α-smooth muscle actin, as well as TGF-β1/SMAD3 signaling activity. Our findings identified miR-26a-5p downregulation in kidney tissues from human interstitial nephritis and UUO-induced mouse kidney fibrosis. MiR-26a-5p restoration may exhibit an anti-fibrotic effect through the blockade of both TGF-β and NF-κB signaling axes and is considered a novel therapeutic target for treating obstruction-induced renal fibrosis.

Epigenetic regulation of chemokine (CC-motif) ligand 2 in inflammatory diseases

Appropriate responses to inflammation are conducive to pathogen elimination and tissue repair, while uncontrolled inflammatory reactions are likely to result in the damage of tissues. Chemokine (CC-motif) Ligand 2 (CCL2) is the main chemokine and activator of monocytes, macrophages, and neutrophils. CCL2 played a key role in amplifying and accelerating the inflammatory cascade and is closely related to chronic non-controllable inflammation (cirrhosis, neuropathic pain, insulin resistance, atherosclerosis, deforming arthritis, ischemic injury, cancer, etc.). The crucial regulatory roles of CCL2 may provide potential targets for the treatment of inflammatory diseases. Therefore, we presented a review of the regulatory mechanisms of CCL2. Gene expression is largely affected by the state of chromatin. Different epigenetic modifications, including DNA methylation, post-translational modification of histones, histone variants, ATP-dependent chromatin remodelling, and non-coding RNA, could affect the 'open' or 'closed' state of DNA, and then significantly affect the expression of target genes. Since most epigenetic modifications are proven to be reversible, targeting the epigenetic mechanisms of CCL2 is expected to be a promising therapeutic strategy for inflammatory diseases. This review focuses on the epigenetic regulation of CCL2 in inflammatory diseases.

Fibrosis: Types, Effects, Markers, Mechanisms for Disease Progression, and Its Relation with Oxidative Stress, Immunity, and Inflammation

Most chronic inflammatory illnesses include fibrosis as a pathogenic characteristic. Extracellular matrix (ECM) components build up in excess to cause fibrosis or scarring. The fibrotic process finally results in organ malfunction and death if it is severely progressive. Fibrosis affects nearly all tissues of the body. The fibrosis process is associated with chronic inflammation, metabolic homeostasis, and transforming growth factor-β1 (TGF-β1) signaling, where the balance between the oxidant and antioxidant systems appears to be a key modulator in managing these processes. Virtually every organ system, including the lungs, heart, kidney, and liver, can be affected by fibrosis, which is characterized as an excessive accumulation of connective tissue components. Organ malfunction is frequently caused by fibrotic tissue remodeling, which is also frequently linked to high morbidity and mortality. Up to 45% of all fatalities in the industrialized world are caused by fibrosis, which can damage any organ. Long believed to be persistently progressing and irreversible, fibrosis has now been revealed to be a very dynamic process by preclinical models and clinical studies in a variety of organ systems. The pathways from tissue damage to inflammation, fibrosis, and/or malfunction are the main topics of this review. Furthermore, the fibrosis of different organs with their effects was discussed. Finally, we highlight many of the principal mechanisms of fibrosis. These pathways could be considered as promising targets for the development of potential therapies for a variety of important human diseases.

Matrix Stiffness Activating YAP/TEAD1-Cyclin B1 in Nucleus Pulposus Cells Promotes Intervertebral Disc Degeneration

Intervertebral disc degeneration is a leading cause of disability in the elderly population. Rigid extracellular matrix is a critical pathological feature of disc degeneration, leading to aberrant nucleus pulposus cells (NPCs) proliferation. However, the underlying mechanism is unclear. Here, we hypothesize that increased matrix stiffness induces proliferation and thus degenerative phenotypes of NPCs through YAP/TEAD1 signaling pathway. We established hydrogel substrates to mimic stiffness of degenerated human nucleus pulposus tissues. RNA-sequencing identified differentially expressed genes between primary rat NPCs cultured on rigid and soft hydrogels. Dual luciferase assay and gain- and loss-function experiments evaluated the correlation between YAP/TEAD1 and Cyclin B1. Furthermore, single-cell RNA-sequencing of human NPCs was performed to identify specific cell clusters with high YAP expression. Matrix stiffness increased in severely degenerated human nucleus pulposus tissues (p < 0.05). Rigid substrate enhanced rat NPCs proliferation mainly through Cyclin B1, which was directly targeted and positively regulated by YAP/TEAD1. Depletion of YAP or Cyclin B1 arrested G2/M phase progression of rat NPCs and reduced fibrotic phenotypes including MMP13 and CTGF (p < 0.05). Fibro NPCs with high YAP expression were identified in human tissues and responsible for fibrogenesis during degeneration. Furthermore, inhibition of YAP/TEAD interaction by verteporfin suppressed cell proliferation and alleviated degeneration in the disc needle puncture model (p < 0.05). Our results demonstrate that elevated matrix stiffness stimulates fibro NPCs proliferation through YAP/TEAD1-Cyclin B1 axis, indicating a therapeutic target for disc degeneration.

The programming of kidney injury in offspring affected by maternal overweight and obesity: role of lipid accumulation, inflammation, oxidative stress, and fibrosis in the kidneys of offspring

Maternal overweight and obesity are considered important factors affecting fetal development with many potential consequences for offspring after delivery, including the increased risk of obesity and diabetes mellitus. Maternal obesity promotes adiposity in the offspring by increasing fat deposition and expansion in the body of the offspring. The expansion of adipose tissue changes adipokine levels, including a decrease in adiponectin and an increase in leptin. In addition to changes in adipokine levels, there are also increases in pro-inflammatory cytokines, pro-fibrotic cytokines, and reactive oxygen species, leading to oxidative stress in the offspring. These contribute to the promotion of insulin resistance in offspring, which is associated with kidney injury. Interestingly, maternal obesity can also promote renal lipid accumulation, which could activate inflammatory processes and promote renal oxidative stress and renal fibrosis. These alterations in the kidneys of the offspring imply that a mother being overweight/obese can program the development of kidney disease in offspring. This review will discuss the effects of a mother being overweight or obese on their offspring and the consequences with regard to the kidneys of their offspring. With a focus on the molecular mechanisms, including renal inflammation, renal oxidative stress, renal fibrosis, and renal lipid metabolism in offspring born to overweight and obese mothers, the causative mechanisms and perspective of these conditions will be included.

Western Blot Protocols for Analysis of CCN Proteins and Fragments in Exosomes, Vesicle-Free Fractions, and Cells

Cellular Communication Network (CCN) proteins are growth factors that play key roles in many pathophysiological events, including bone formation, wound healing, and cancer. CCN factors and fragments generated by metalloproteinases-dependent cleavage are often associated with extracellular matrix (ECM) or small extracellular vesicles (sEVs) such as exosomes or matrix-coated vesicles. We provide reliable methods and protocols for Western blotting to analyze CCN factors and fragments in cells, sEVs, and vesicle-free fractions.

Comprehensive Method for Exosome Isolation and Proteome Analysis for Detection of CCN Factors in/on Exosomes

Cellular Communication Network (CCN) proteins are secretory growth factors often associated with extracellular matrix (ECM) and extracellular vesicles (EVs) such as exosomes or matrix-coated vesicles. CCN factors and fragments loaded on/in EVs may play key roles in cell communication networks in cancer biology, bone and cartilage metabolism, wound healing, and tissue regeneration. CCN proteins and EVs/exosomes are found in body fluids, such as blood, urine, milk, and supernatants of the two-dimensionally (2D) cultured cells and three-dimensionally (3D) cultured tissues, such as spheroids or organoids. More than ten methods to isolate exosomes or EVs have been developed with different properties. Here, we introduce comprehensive protocols for polymer-based precipitation, affinity purification, ultracentrifugation methods combined with the ultrafiltration method for isolating CCN-loaded exosomes/EVs from 2D and 3D cultured tissues, and proteome analysis using mass spectrometry for comprehensive analysis of CCN proteins.

What's New in the Molecular Mechanisms of Diabetic Kidney Disease: Recent Advances

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease, including end-stage kidney disease, and increases the risk of cardiovascular mortality. Although the treatment options for DKD, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, sodium-glucose cotransporter 2 inhibitors, and mineralocorticoid receptor antagonists, have advanced, their efficacy is still limited. Thus, a deeper understanding of the molecular mechanisms of DKD onset and progression is necessary for the development of new and innovative treatments for DKD. The complex pathogenesis of DKD includes various different pathways, and the mechanisms of DKD can be broadly classified into inflammatory, fibrotic, metabolic, and hemodynamic factors. Here, we summarize the recent findings in basic research, focusing on each factor and recent advances in the treatment of DKD. Collective evidence from basic and clinical research studies is helpful for understanding the definitive mechanisms of DKD and their regulatory systems. Further comprehensive exploration is warranted to advance our knowledge of the pathogenesis of DKD and establish novel treatments and preventive strategies.

Serum IL-12p40: A novel biomarker for early prediction of minimal change disease relapse following glucocorticoids therapy

Background

Minimal change disease (MCD) has a high recurrence rate, but currently, no biomarker can predict its recurrence. To this end, this study aimed at identifying potential serum cytokines as valuable biomarkers for predicting the risk of MCD recurrence.

Materials and methods

Raybiotech 440 cytokine antibody microarray was used to detect the serum samples of eight relapsed, eight non-relapsed MCD patients after glucocorticoid treatment, and eight healthy controls. The differentially expressed cytokines were confirmed by enzyme-linked immunosorbent assay (ELISA) with serum samples from 29 non-relapsed and 35 relapsed MCD patients. The study used the receiver operating characteristic (ROC) curve analysis to investigate the sensitivity and specificity of a serum biomarker for predicting the MCD relapse.

Results

Serum IL-12p40 levels increased significantly in the relapsed group. The Area Under the ROC Curve (AUC) of IL-12p40 was 0.727 (95%CI: 0.597-0.856; P < 0.01). The RNA-sequencing analysis and qPCR assay performed on the IL-12 treated mouse podocytes and the control group showed increased expression of podocyte damage genes, such as connective tissue growth factor (CTGF), matrix metallopeptidase 9 (MMP9), secreted phosphoprotein 1 (SPP1), and cyclooxygenase-2 (COX-2) in the former group.

Conclusion

IL-12p40 may serve as a new biomarker for predicting the risk of MCD recurrence after glucocorticoid treatment, and it may be involved in the pathogenesis and recurrence of MCD.

Chuan Huang Fang combining reduced glutathione in treating acute kidney injury (grades 1–2) on chronic kidney disease (stages 2–4): A multicenter randomized controlled clinical trial

Lack of effective drugs for acute kidney injury (AKI) grades 1–2 is a crucial challenge in clinic. Our previously single-center clinical studies indicated Chuan Huang Fang (CHF) might have nephroprotection in AKI on chronic kidney disease (CKD) (A on C) patients by preventing oxidant damage and inhibiting inflammation. Reduced glutathione (RG) has recently been shown to increase the clinical effectiveness of high-flux hemodialysis among patients with severe AKI. In this multicenter randomized controlled clinical study, we designed a new protocol to assess the efficacy and safety of CHF combining RG in patients with A on C. We also explored therapeutic mechanisms from renal fibrosis biomarkers. 98 participants were randomly and equally divided into the RG and RG + CHF subgroups. The RG and RG + CHF groups received general treatments with RG and a combination of RG and CHF, respectively. The therapy lasted for 2 weeks. In this study, the primary assessment result was a difference in the slope of serum creatinine (Scr) over the course of 2 weeks. The secondary evaluation outcomes were alterations in blood urea nitrogen (BUN), uric acid (UA), estimated glomerular filtration rate (eGFR), urinary AKI biomarkers, renal fibrosis biomarkers (transforming growth factor-β₁ (TGF-β₁), connective tissue growth factor (CTGF)), and traditional Chinese medicine (TCM) symptoms. Furthermore, vital signs and adverse events (AEs) were observed. Both groups had a slower renal function decline after treatment than before treatment. Compared with RG group, more reductions of Scr, BUN, UA, and better improvement of eGFR were observed in RG + CHF group (p < 0.05). Additionally, the levels of urinary AKI biomarkers, renal fibrosis biomarkers, and TCM syndromes were decreased in RG + CHF group versus RG group (p < 0.05). No significant between-group differences were observed of AEs. We thus concluded this novel therapy of CHF combining RG might be a useful method for treating A on C patients.

CCAAT/Enhancer-Binding Proteins in Fibrosis: Complex Roles Beyond Conventional Understanding

CCAAT/enhancer-binding proteins (C/EBPs) are a family of at least six identified transcription factors that contain a highly conserved basic leucine zipper domain and interact selectively with duplex DNA to regulate target gene expression. C/EBPs play important roles in various physiological processes, and their abnormal function can lead to various diseases. Recently, accumulating evidence has demonstrated that aberrant C/EBP expression or activity is closely associated with the onset and progression of fibrosis in several organs and tissues. During fibrosis, various C/EBPs can exert distinct functions in the same organ, while the same C/EBP can exert distinct functions in different organs. Modulating C/EBP expression or activity could regulate various molecular processes to alleviate fibrosis in multiple organs; therefore, novel C/EBPs-based therapeutic methods for treating fibrosis have attracted considerable attention. In this review, we will explore the features of C/EBPs and their critical functions in fibrosis in order to highlight new avenues for the development of novel therapies targeting C/EBPs.

Oncostatin M: Risks and Benefits of a Novel Therapeutic Target for Atherosclerosis

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death worldwide. It is predicted that approximately 23.6 million people will die from CVDs annually by 2030. Therefore, there is a great need for an effective therapeutic approach to combat this disease. The European Cardiovascular Target Discovery (CarTarDis) consortium identified Oncostatin M (OSM) as a potential therapeutic target for atherosclerosis. The benefits of modulating OSM - an interleukin (IL)-6 family cytokine - have since been studied for multiple indications. However, as decades of high attrition rates have stressed, the success of a drug target is determined by the fine balance between benefits and the risk of adverse events. Safety issues should therefore not be overlooked.

OBJECTIVE

In this review, a risk/benefit analysis is performed on OSM inhibition in the context of atherosclerosis treatment. First, OSM signaling characteristics and its role in atherosclerosis are described. Next, an overview of in vitro, in vivo, and clinical findings relating to both the benefits and risks of modulating OSM in major organ systems is provided. Based on OSM's biological function and expression profile as well as drug intervention studies, safety concerns of inhibiting this target have been identified, assessed, and ranked for the target population.

CONCLUSION

While OSM may be of therapeutic value in atherosclerosis, drug development should also focus on de-risking the herein identified major safety concerns: tissue remodeling, angiogenesis, bleeding, anemia, and NMDA- and glutamate-induced neurotoxicity. Close monitoring and/or exclusion of patients with various comorbidities may be required for optimal therapeutic benefit.

Molecular mechanisms of histone deacetylases and inhibitors in renal fibrosis progression

Renal fibrosis is a common progressive manifestation of chronic kidney disease. This phenomenon of self-repair in response to kidney damage seriously affects the normal filtration function of the kidney. Yet, there are no specific treatments for the condition, which marks fibrosis as an irreversible pathological sequela. As such, there is a pressing need to improve our understanding of how fibrosis develops at the cellular and molecular levels and explore specific targeted therapies for these pathogenic mechanisms. It is now generally accepted that renal fibrosis is a pathological transition mediated by extracellular matrix (ECM) deposition, abnormal activation of myofibroblasts, and epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells under the regulation of TGF-β. Histone deacetylases (HDACs) appear to play an essential role in promoting renal fibrosis through non-histone epigenetic modifications. In this review, we summarize the mechanisms of renal fibrosis and the signaling pathways that might be involved in HDACs in renal fibrosis, and the specific mechanisms of action of various HDAC inhibitors (HDACi) in the anti-fibrotic process to elucidate HDACi as a novel therapeutic tool to slow down the progression of renal fibrosis.

Glomerular basement membrane deposition of collagen α1(III) in Alport glomeruli by mesangial filopodia injures podocytes via aberrant signaling through DDR1 and integrin α2β1

In Alport mice, activation of the endothelin A receptor (ETA R) in mesangial cells results in sub-endothelial invasion of glomerular capillaries by mesangial filopodia. Filopodia deposit mesangial matrix in the glomerular basement membrane (GBM), including laminin 211 which activates NF-κB, resulting in induction of inflammatory cytokines. Herein we show that collagen α1(III) is also deposited in the GBM. Collagen α1(III) localized to the mesangium in wild-type mice and was found in both the mesangium and the GBM in Alport mice. We show that collagen α1(III) activates discoidin domain receptor family, member 1 (DDR1) receptors both in vitro and in vivo. To elucidate whether collagen α1(III) might cause podocyte injury, cultured murine Alport podocytes were overlaid with recombinant collagen α1(III), or not, for 24 h and RNA was analyzed by RNA sequencing (RNA-seq). These same cells were subjected to siRNA knockdown for integrin α2 or DDR1 and the RNA was analyzed by RNA-seq. Results were validated in vivo using RNA-seq from RNA isolated from wild-type and Alport mouse glomeruli. Numerous genes associated with podocyte injury were up- or down-regulated in both Alport glomeruli and cultured podocytes treated with collagen α1(III), 18 of which have been associated previously with podocyte injury or glomerulonephritis. The data indicate α2β1 integrin/DDR1 co-receptor signaling as the dominant regulatory mechanism. This may explain earlier studies where deletion of either DDR1 or α2β1 integrin in Alport mice ameliorates renal pathology. © 2022 Boys Town National Research Hospital. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The progress and prospect of natural components in rhubarb (Rheum ribes L.) in the treatment of renal fibrosis

Background: Renal fibrosis is a key pathological change that occurs in the progression of almost all chronic kidney diseases . CKD has the characteristics of high morbidity and mortality. Its prevalence is increasing each year on a global scale, which seriously affects people’s health and quality of life. Natural products have been used for new drug development and disease treatment for many years. The abundant natural products in R. ribes L. can intervene in the process of renal fibrosis in different ways and have considerable therapeutic prospects.

Purpose: The etiology and pathology of renal fibrosis were analyzed, and the different ways in which the natural components of R. ribes L. can intervene and provide curative effects on the process of renal fibrosis were summarized. Methods: Electronic databases, such as PubMed, Life Science, MEDLINE, and Web of Science, were searched using the keywords ‘R. ribes L.’, ‘kidney fibrosis’, ‘emodin’ and ‘rhein’, and the various ways in which the natural ingredients protect against renal fibrosis were collected and sorted out.

Results: We analyzed several factors that play a leading role in the pathogenesis of renal fibrosis, such as the mechanism of the TGF-β/Smad and Wnt/β-catenin signaling pathways. Additionally, we reviewed the progress of the treatment of renal fibrosis with natural components in R. ribes L. and the intervention mechanism of the crucial therapeutic targets.

Conclusion: The natural components of R. ribes L. have a wide range of intervention effects on renal fibrosis targets, which provides new ideas for the development of new anti-kidney fibrosis drugs.

Intrarenal Single-Cell Sequencing of Hepatitis B Virus Associated Membranous Nephropathy

To date, the pathogenesis of hepatitis B virus (HBV)-associated membranous nephropathy (MN) remains elusive. This study aimed to decipher the etiopathogenesis of HBV-associated MN by performing single-cell RNA sequencing (scRNA-seq) of kidney biopsy specimens from a patient with HBV-associated MN and two healthy individuals. We generated 4,114 intrarenal single-cell transcriptomes from the HBV-associated MN patient by scRNA-seq. Compared to healthy individuals, podocytes in the HBV-associated MN patient showed an increased expression of extracellular matrix formation-related genes, including HSPA5, CTGF, and EDIL3. Kidney endothelial cells (ECs) in the HBV-associated MN were enriched in inflammatory pathways, including NF-kappa B signaling, IL-17 signaling, TNF signaling and NOD-like receptor signaling. Gene ontology (GO) functional enrichment analysis and Gene Set Variation Analysis (GSVA) further revealed that differentially expressed genes (DEGs) of ECs from the HBV-associated MN patients were enriched in apoptotic signaling pathway, response to cytokine and leukocyte cell-cell adhesion. The up-regulated DEGs in glomerular ECs of HBV-associated MN patients were involved in biological processes such as viral gene expression, and protein targeting to endoplasmic reticulum. We further verified that the overexpressed genes in ECs from HBV-associated MN were mainly enriched in regulation of protein targeting to endoplasmic reticulum, exocytosis, viral gene expression, IL-6 and IL-1 secretion when compared with anti-phospholipase A2 receptor (PLA2R)-positive idiopathic membranous nephropathy (IMN). The receptor-ligand crosstalk analysis revealed potential interactions between endothelial cells and other cells in HBV-associated-MN. These results offer new insight into the pathogenesis of HBV-associated MN and may identify new therapeutic targets for HBV-associated MN.

Ocular changes in nephrotic syndrome patients with preserved renal functions

BACKGROUND

Optical coherence tomography (OCT) measurements of central choroidal thickness (CCT) and retinal thickness have been proposed as inflammatory indicators for a variety of systemic disorders, particularly those with a vascular component. The relationship between nephrotic syndrome (NS) and visual impairment is not clear. The aim of this study was to evaluate the ocular changes in primary NS patients with preserved renal functions.

METHODS

A total of 60 participants (30 NS patients, 30 healthy control subjects) was recruited in this cross-sectional and comparative study. Retinal and choroidal examinations were performed via the spectral domain OCT. Enhanced depth imaging (EDI) mode of the OCT was used for choroidal analysis.

RESULTS

Although not statistically significant, CCT was found to be higher in the NS group compared to the control group (p=0.07). Central foveal thickness (CFT) and retinal arteriolar caliber (RAC) values were statistically significantly lower in the patients with nephrotic syndrome, whereas retinal venular caliber (RVC) and choroidal vascularity index (CVI) values were similar in both groups. RAC and RVC were not statistically significantly correlated with CCT or CFT in both groups (p>0.05).

CONCLUSION

The results of the current study showed a significant difference between the NS group and the control group in terms of some ocular changes (i.e., CFT and RAC). As a result, CCT, CFT and RAC measurements with OCT may be used as a marker of inflammation in NS patients.

The fibrogenic niche in kidney fibrosis: components and mechanisms

Kidney fibrosis, characterized by excessive deposition of extracellular matrix (ECM) that leads to tissue scarring, is the final common outcome of a wide variety of chronic kidney diseases. Rather than being distributed uniformly across the kidney parenchyma, renal fibrotic lesions initiate at certain focal sites in which the fibrogenic niche is formed in a spatially confined fashion. This niche provides a unique tissue microenvironment that is orchestrated by a specialized ECM network consisting of de novo-induced matricellular proteins. Other structural elements of the fibrogenic niche include kidney resident and infiltrated inflammatory cells, extracellular vesicles, soluble factors and metabolites. ECM proteins in the fibrogenic niche recruit soluble factors including WNTs and transforming growth factor-β from the extracellular milieu, creating a distinctive profibrotic microenvironment. Studies using decellularized ECM scaffolds from fibrotic kidneys show that the fibrogenic niche autonomously promotes fibroblast proliferation, tubular injury, macrophage activation and endothelial cell depletion, pathological features that recapitulate key events in the pathogenesis of chronic kidney disease. The concept of the fibrogenic niche represents a paradigm shift in understanding of the mechanism of kidney fibrosis that could lead to the development of non-invasive biomarkers and novel therapies not only for chronic kidney disease, but also for fibrotic diseases of other organs.

Targeting fibrosis, mechanisms and cilinical trials

Fibrosis is characterized by the excessive extracellular matrix deposition due to dysregulated wound and connective tissue repair response. Multiple organs can develop fibrosis, including the liver, kidney, heart, and lung. Fibrosis such as liver cirrhosis, idiopathic pulmonary fibrosis, and cystic fibrosis caused substantial disease burden. Persistent abnormal activation of myofibroblasts mediated by various signals, such as transforming growth factor, platelet-derived growth factor, and fibroblast growh factor, has been recongized as a major event in the occurrence and progression of fibrosis. Although the mechanisms driving organ-specific fibrosis have not been fully elucidated, drugs targeting these identified aberrant signals have achieved potent anti-fibrotic efficacy in clinical trials. In this review, we briefly introduce the aetiology and epidemiology of several fibrosis diseases, including liver fibrosis, kidney fibrosis, cardiac fibrosis, and pulmonary fibrosis. Then, we summarise the abnormal cells (epithelial cells, endothelial cells, immune cells, and fibroblasts) and their interactions in fibrosis. In addition, we also focus on the aberrant signaling pathways and therapeutic targets that regulate myofibroblast activation, extracellular matrix cross-linking, metabolism, and inflammation in fibrosis. Finally, we discuss the anti-fibrotic drugs based on their targets and clinical trials. This review provides reference for further research on fibrosis mechanism, drug development, and clinical trials.

Molecular Mechanisms and Therapeutic Targets for Diabetic Kidney Disease

Diabetic kidney disease has a high global disease burden and substantially increases risk of kidney failure and cardiovascular events. Despite treatment, there is substantial residual risk of disease progression with existing therapies. Therefore, there is an urgent need to better understand the molecular mechanisms driving diabetic kidney disease to help identify new therapies that slow progression and reduce associated risks. Diabetic kidney disease is initiated by diabetes-related disturbances in glucose metabolism, which then trigger other metabolic, hemodynamic, inflammatory, and fibrotic processes that contribute to disease progression. This review summarizes existing evidence on the molecular drivers of diabetic kidney disease onset and progression, focusing on inflammatory and fibrotic mediators-factors that are largely unaddressed as primary treatment targets and for which there is increasing evidence supporting key roles in the pathophysiology of diabetic kidney disease. Results from recent clinical trials highlight promising new drug therapies, as well as a role for dietary strategies, in treating diabetic kidney disease.

MEHP promotes liver fibrosis by down-regulating STAT5A in BRL-3A hepatocytes

OBJECTIVE

As an environmental endocrine disruptor, mono-2-ethylhexyl phthalate (MEHP) can interfere with liver metabolism and lead to liver diseases. We aimed to investigate the role of MEHP in liver fibrosis and its molecular mechanism.

METHODS

BRL-3A hepatocytes were exposed to MEHP (0, 10, 50, 100 and 200 μM) for 24 h. STAT5A gene was overexpressed by lentivirus transfection. The reactive oxygen species (ROS) was tested by the flow cytometer. The malondialdehyde (MDA), glutathione peroxidase (GSH-PX), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were detected by commercial kits. Real-Time PCR and Western blot were performed to test the relative mRNA and proteins levels, respectively.

RESULTS

MEHP exposure significantly induced oxidative damage in BRL-3A cells, which inhibited the expression of STAT5A and promoted the expression of fibrosis related proteins MMP2, MMP9, TIMP2 and CTGF. After over-expression of STAT5A gene in BRL-3A cells, the elevated expression levels of CTGF, MMP2, MMP9 and TIMP2 induced by MEHP exposure were significantly reversed.

CONCLUSION

This study demonstrated that MEHP exposure inhibited the expression of STAT5A by causing oxidative damage in BRL-3A hepatocytes, thus accelerating the expression of key molecules in fibrosis and promoting the occurrence of liver fibrosis.

Fibrosis of Peritoneal Membrane as Target of New Therapies in Peritoneal Dialysis

Peritoneal dialysis (PD) is an efficient renal replacement therapy for patients with end-stage renal disease. Even if it ensures an outcome equivalent to hemodialysis and a better quality of life, in the long-term, PD is associated with the development of peritoneal fibrosis and the consequents patient morbidity and PD technique failure. This unfavorable effect is mostly due to the bio-incompatibility of PD solution (mainly based on high glucose concentration). In the present review, we described the mechanisms and the signaling pathway that governs peritoneal fibrosis, epithelial to mesenchymal transition of mesothelial cells, and angiogenesis. Lastly, we summarize the present and future strategies for developing more biocompatible PD solutions.

Etlingera elatior Flower Aqueous Extract Protects against Oxidative Stress-Induced Nephropathy in a Rat Model of Type 2 Diabetes

Diabetes mellitus (DM) is a known systemic disease with increasing global prevalence and multi-organ complications including diabetic nephropathy (DN). The trend of using medicinal plants in the management of DM is increasing exponentially. Etlingera elatior is a medicinal plant that contains chemicals and antioxidants that delay the oxidation process. However, available data focusing on its use on DN are inconsistent and scarce. This study aims to investigate the antidiabetic and nephroprotective effects of E. elatior flower aqueous extract (EEAE) in a type 2 DM rat (T2DR) model. The T2DR model was developed using a combination of a high-fat diet (HFD) and a low dose of streptozotocin (STZ) at 35 mg/kg. Thirty-two Sprague Dawley male rats were randomly divided into four groups (n = 8): (1) control (normal rat), (2) T2DR (untreated-type 2 diabetic rat), (3) Met (250 mg/kg metformin-treated T2DR), and (4) EEAE (1000 mg/kg EEAE-treated T2DR). All treatments were administered orally for 6 weeks. EEAE significantly reduced fasting blood glucose (FBG), microalbuminuria, serum creatinine, and serum blood urea nitrogen. EEAE also reduced malondialdehyde (MDA) and enhanced the levels of antioxidant markers—superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and total antioxidant capacity (T-AOC). The inflammatory marker (interleukin (IL)-6) and fibrosis markers (transforming growth factor-beta (TGF-β), and connective tissue growth factor (CTGF)) were significantly decreased in the EEAE-treated group. The T2DR group developed DN, which was characterized by segmental sclerosis of the glomeruli associated with focal tubular atrophy and interstitial fibrosis. Interestingly, the histology of kidney tissue in the EEAE group was preserved. This effect was similar to that of the control drug metformin. In summary, the antidiabetic and nephroprotective effects might be related to the antioxidant properties and anti-inflammatory effects of the EEAE. The antidiabetic activity could be due to the presence of the active compound cyanidin-3-O-glycosides, which is an anthocyanin antioxidant, that is present in the EEAE. E. elatior has the potential to be developed as a natural source of antioxidants that can be used for the prevention or even the treatment of DM. These findings could lead to future research into the therapeutic use of E. elatior in alleviating the progression of DM and thus preventing nephropathy.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

The mmu_circRNA_37492/hsa_circ_0012138 function as potential ceRNA to attenuate obstructive renal fibrosis

Circular RNAs (circRNAs) are involved in the pathogenesis of certain renal diseases, however, the function and mechanism of them in renal fibrosis remains largely unknown. In the present study, RNA expression data in unilateral ureteral obstruction (UUO) kidneys was obtained from our previous circRNA Microarray and public Gene Expression Omnibus datasets to construct a ceRNA network. The effects of target circRNA as long as the homologous human circRNA on renal fibrosis was examined in vitro and in vivo. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was further performed among genes regulated by the human circRNA. We found that circRNA_37492, showing well connection degree in the ceRNA network, was abundant expression and high sequence conservation. We observed that the expression of circRNA_37492 was induced by the TGF-β1 or UUO in BUMPT cells and C57BL/6 mice, respectively. In vitro, cytoplasmic circRNA_37492 inhibited type I, III collagen and fibronectin deposition by sponging miR-7682-3p and then upregulated its downstream target Fgb. In vivo, overexpression of circRNA_37492 attenuated fibrotic lesions in the kidneys of UUO mice via targeting miR-7682-3p/Fgb axis. Furthermore, hsa_circ_0012138, homologous with circRNA_37492, may potentially target miR-651-5p/FGB axis in human renal fibrosis. Not only that, GO and KEGG enrichment revealed that hsa_circ_0012138-regulated genes were previously demonstrated to related to the fibrosis. In conclusion, we for the first time demonstrated that circRNA_37492 attenuated renal fibrosis via targeting miR-7682-3p/Fgb axis, and the homologous hsa_circRNA_0012138 was speculated as a possible ceRNA to regulate multiple gene expressions and involve in human renal fibrosis, suggesting that circRNA_37492/hsa_circ_0012138 may serve as potent therapy target for obstructive renal fibrosis disease.

Multiplexed droplet single-cell sequencing (Mux-Seq) of normal and transplant kidney

Maintenance of systemic homeostasis by kidney requires the coordinated response of diverse cell types. The use of single-cell RNA sequencing (scRNAseq) for patient tissue samples remains fraught with difficulties with cell isolation, purity, and experimental bias. The ability to characterize immune and parenchymal cells during transplant rejection will be invaluable in defining transplant pathology where tissue availability is restricted to needle biopsy fragments. Herein, we present feasibility data for multiplexing approach for droplet scRNAseq (Mux-Seq). Mux-Seq has the potential to minimize experimental batch bias and variation even with very small sample input. In this first proof-of-concept study for this approach, explant tissues from six normal and two transplant recipients after multiple early post-transplant rejection episodes leading to nephrectomy due to aggressive antibody mediated rejection, were pooled for Mux-Seq. A computational tool, Demuxlet was applied for demultiplexing the individual cells from the pooled experiment. Each sample was also applied individually in a single microfluidic run (singleplex) to correlate results with the pooled data from the same sample. Our applied protocol demonstrated that data from Mux-Seq correlated highly with singleplex (Pearson coefficient 0.982) sequencing results, with the ability to identify many known and novel kidney cell types including different infiltrating immune cells. Trajectory analysis of proximal tubule and endothelial cells demonstrated separation between healthy and injured kidney from transplant explant suggesting evolving stages of cell- specific differentiation in alloimmune injury. This study provides the technical groundwork for understanding the pathogenesis of alloimmune injury and host tissue response in transplant rejection and normal human kidney and provides a protocol for optimized processing precious and low input human kidney biopsy tissue for larger scale studies.

The Glomerulus According to the Mesangium

The glomerulus is the functional unit for filtration of blood and formation of primary urine. This intricate structure is composed of the endothelium with its glycocalyx facing the blood, the glomerular basement membrane and the podocytes facing the urinary space of Bowman's capsule. The mesangial cells are the central hub connecting and supporting all these structures. The components as a unit ensure a high permselectivity hindering large plasma proteins from passing into the urine while readily filtering water and small solutes. There has been a long-standing interest and discussion regarding the functional contribution of the different cellular components but the mesangial cells have been somewhat overlooked in this context. The mesangium is situated in close proximity to all other cellular components of the glomerulus and should be considered important in pathophysiological events leading to glomerular disease. This review will highlight the role of the mesangium in both glomerular function and intra-glomerular crosstalk. It also aims to explain the role of the mesangium as a central component involved in disease onset and progression as well as signaling to maintain the functions of other glomerular cells to uphold permselectivity and glomerular health.

CCN2 Binds to Tubular Epithelial Cells in the Kidney

Cellular communication network-2 (CCN2), also called connective tissue growth factor (CTGF), is considered a fibrotic biomarker and has been suggested as a potential therapeutic target for kidney pathologies. CCN2 is a matricellular protein with four distinct structural modules that can exert a dual function as a matricellular protein and as a growth factor. Previous experiments using surface plasmon resonance and cultured renal cells have demonstrated that the C-terminal module of CCN2 (CCN2(IV)) interacts with the epidermal growth factor receptor (EGFR). Moreover, CCN2(IV) activates proinflammatory and profibrotic responses in the mouse kidney. The aim of this paper was to locate the in vivo cellular CCN2/EGFR binding sites in the kidney. To this aim, the C-terminal module CCN2(IV) was labeled with a fluorophore (Cy5), and two different administration routes were employed. Both intraperitoneal and direct intra-renal injection of Cy5-CCN2(IV) in mice demonstrated that CCN2(IV) preferentially binds to the tubular epithelial cells, while no signal was detected in glomeruli. Moreover, co-localization of Cy5-CCN2(IV) binding and activated EGFR was found in tubules. In cultured tubular epithelial cells, live-cell confocal microscopy experiments showed that EGFR gene silencing blocked Cy5-CCN2(IV) binding to tubuloepithelial cells. These data clearly show the existence of CCN2/EGFR binding sites in the kidney, mainly in tubular epithelial cells. In conclusion, these studies show that circulating CCN2(IV) can directly bind and activate tubular cells, supporting the role of CCN2 as a growth factor involved in kidney damage progression.