Late onset of Ccl2 blockade with the Spiegelmer mNOX-E36-3'PEG prevents glomerulosclerosis and improves glomerular filtration rate in db/db mice

The mechanisms underlying Chinese medicines to treat inflammation in diabetic kidney disease

ETHNIC PHARMACOLOGICAL RELEVANCE

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease (ESRD), which is a public health problem with a significant economic burden. Serious adverse effects, such as hypotension, hyperkalemia, and genitourinary infections, as well as increasing adverse cardiovascular events, limit the clinical application of available drugs. Plenty of randomized controlled trials(RCTs), meta-analysis(MAs) and systematic reviews(SRs) have demonstrated that many therapies that have been used for a long time in medical practice including Chinese patent medicines(CPMs), Chinese medicine prescriptions, and extracts are effective in alleviating DKD, but the mechanisms by which they work are still unknown. Currently, targeting inflammation is a central strategy in DKD drug development. In addition, many experimental studies have identified many Chinese medicine prescriptions, medicinal herbs and extracts that have the potential to alleviate DKD. And part of the mechanisms by which they work have been uncovered.

AIM OF THIS REVIEW

This review aims to summarize therapies that have been proven effective by RCTs, MAs and SRs, including CPMs, Chinese medicine prescriptions, and extracts. This review also focuses on the efficiency and potential targets of Chinese medicine prescriptions, medicinal herbs and extracts discovered in experimental studies in improving immune inflammation in DKD.

METHODS

We searched for relevant scientific articles in the following databases: PubMed, Google Scholar, and Web of Science. We summarized effective CPMs, Chinese medicine prescriptions, and extracts from RCTs, MAs and SRs. We elaborated the signaling pathways and molecular mechanisms by which Chinese medicine prescriptions, medicinal herbs and extracts alleviate inflammation in DKD according to different experimental studies.

RESULTS

After overviewing plenty of RCTs with the low hierarchy of evidence and MAs and SRs with strong heterogeneity, we still found that CPMs, Chinese medicine prescriptions, and extracts exerted promising protective effects against DKD. However, there is insufficient evidence to prove the safety of Chinese medicines. As for experimental studies, Experiments in vitro and in vivo jointly demonstrated the efficacy of Chinese medicines(Chinese medicine prescriptions, medicinal herbs and extracts) in DKD treatment. Chinese medicines were able to regulate signaling pathways to improve inflammation in DKD, such as toll-like receptors, NLRP3 inflammasome, Nrf2 signaling pathway, AMPK signaling pathway, MAPK signaling pathway, JAK-STAT, and AGE/RAGE.

CONCLUSION

Chinese medicines (Chinese medicine prescriptions, medicinal herbs and extracts) can improve inflammation in DKD. For drugs that are effective in RCTs, the underlying bioactive components or extracts should be identified and isolated. Attention should be given to their safety and pharmacokinetics. Acute, subacute, and subchronic toxicity studies should be designed to determine the magnitude and tolerability of side effects in humans or animals. For drugs that have been proven effective in experimental studies, RCTs should be designed to provide reliable evidence for clinical translation. In a word, Chinese medicines targeting immune inflammation in DKD are a promising direction.

Fiery Connections: Macrophage-Mediated Inflammation, the Journey from Obesity to Type 2 Diabetes Mellitus and Diabetic Kidney Disease

The high prevalence of diabetes mellitus (DM) poses a significant public health challenge, with diabetic kidney disease (DKD) as one of its most serious consequences. It has become increasingly clear that type 2 DM (T2D) and the complications of DKD are not purely metabolic disorders. This review outlines emerging evidence related to the step-by-step contribution of macrophages to the development and progression of DKD in individuals who specifically develop T2D as a result of obesity. The macrophage is a prominent inflammatory cell that contributes to obesity, where adipocyte hypertrophy leads to macrophage recruitment and eventually to the expansion of adipose tissue. The recruited macrophages secrete proinflammatory cytokines, which cause systemic inflammation, glucose dysregulation, and insulin sensitivity, ultimately contributing to the development of T2D. Under such pathological changes, the kidney is susceptible to elevated glucose and thereby activates signaling pathways that ultimately drive monocyte recruitment. In particular, the early recruitment of proinflammatory macrophages in the diabetic kidney produces inflammatory cytokines/chemokines that contribute to inflammation and tissue damage associated with DKD pathology. Macrophage activation and recruitment are crucial inciting factors that also persist as DKD progresses. Thus, targeting macrophage activation and function could be a promising therapeutic approach, potentially offering significant benefits for managing DKD at all stages of progression.

Targeting Macrophages: Therapeutic Approaches in Diabetic Kidney Disease

Diabetes is not solely a metabolic disorder but also involves inflammatory processes. The immune response it incites is a primary contributor to damage in target organs. Research indicates that during the initial phases of diabetic nephropathy, macrophages infiltrate the kidneys alongside lymphocytes, initiating a cascade of inflammatory reactions. The interplay between macrophages and other renal cells is pivotal in the advancement of kidney disease within a hyperglycemic milieu. While M1 macrophages react to the inflammatory stimuli induced by elevated glucose levels early in the disease progression, their subsequent transition to M2 macrophages, which possess anti-inflammatory and tissue repair properties, also contributes to fibrosis in the later stages of nephropathy by transforming into myofibroblasts. Comprehending the diverse functions of macrophages in diabetic kidney disease and regulating their activity could offer therapeutic benefits for managing this condition.

Role of MCP-1/CCR2 axis in renal fibrosis: Mechanisms and therapeutic targeting

Renal fibrosis is a common pathological manifestation in various chronic kidney diseases. Inflammation plays a central role in renal fibrosis development. Owing to their significant participation in inflammation and autoimmunity, chemokines have always been the hot spot and focus of scientific research and clinical intervention. Among the chemokines, monocyte chemoattractant protein-1 (MCP-1), also known as C-C motif chemokine ligand 2, together with its main receptor C-C chemokine receptor type 2 (CCR2) are important chemokines in renal fibrosis. The MCP-1/CCR2 axis is activated when MCP-1 binds to CCR2. Activation of MCP-1/CCR2 axis can induce chemotaxis and activation of inflammatory cells, and initiate a series of signaling cascades in renal fibrosis. It mediates and promotes renal fibrosis by recruiting monocyte, promoting the activation and transdifferentiation of macrophages. This review summarizes the complex physical processes of MCP-1/CCR2 axis in renal fibrosis and addresses its general mechanism in renal fibrosis by using specific examples, together with the progress of targeting MCP-1/CCR2 in renal fibrosis with a view to providing a new direction for renal fibrosis treatment.

Depletion of CUL4B in macrophages ameliorates diabetic kidney disease via miR-194-5p/ITGA9 axis

Diabetic kidney disease (DKD) is the most prevalent chronic kidney disease. Macrophage infiltration in the kidney is critical for the progression of DKD. However, the underlying mechanism is far from clear. Cullin 4B (CUL4B) is the scaffold protein in CUL4B-RING E3 ligase complexes. Previous studies have shown that depletion of CUL4B in macrophages aggravates lipopolysaccharide-induced peritonitis and septic shock. In this study, using two mouse models for DKD, we demonstrate that myeloid deficiency of CUL4B alleviates diabetes-induced renal injury and fibrosis. In vivo and in vitro analyses reveal that loss of CUL4B suppresses migration, adhesion, and renal infiltration of macrophages. Mechanistically, we show that high glucose upregulates CUL4B in macrophages. CUL4B represses expression of miR-194-5p, which leads to elevated integrin α9 (ITGA9), promoting migration and adhesion. Our study suggests the CUL4B/miR-194-5p/ITGA9 axis as an important regulator for macrophage infiltration in diabetic kidneys.

Low nephron endowment increases susceptibility to renal stress and chronic kidney disease

Preterm birth results in low nephron endowment and increased risk of acute kidney injury (AKI) and chronic kidney disease (CKD). To understand the pathogenesis of AKI and CKD in preterm humans, we generated potentially novel mouse models with a 30%-70% reduction in nephron number by inhibiting or deleting Ret tyrosine kinase in the developing ureteric bud. These mice developed glomerular and tubular hypertrophy, followed by the transition to CKD, recapitulating the renal pathological changes seen in humans born preterm. We injected neonatal mice with gentamicin, a ubiquitous nephrotoxic exposure in preterm infants, and detected more severe proximal tubular injury in mice with low nephron number compared with controls with normal nephron number. Mice with low nephron number had reduced proliferative repair with more rapid development of CKD. Furthermore, mice had more profound inflammation with highly elevated levels of MCP-1 and CXCL10, produced in part by damaged proximal tubules. Our study directly links low nephron endowment with postnatal renal hypertrophy, which in this model is maladaptive and results in CKD. Underdeveloped kidneys are more susceptible to gentamicin-induced AKI, suggesting that AKI in the setting of low nephron number is more severe and further increases the risk of CKD in this vulnerable population.

Sustained inhibition of CC-chemokine receptor-2 via intraarticular deposition of polymeric microplates in post-traumatic osteoarthritis

Posttraumatic osteoarthritis (PTOA) is mostly treated via corticosteroid administration, and total joint arthroplasty continues to be the sole effective intervention in severe conditions. To assess the therapeutic potential of CCR2 targeting in PTOA, we used biodegradable microplates (µPLs) to achieve a slow and sustained intraarticular release of the CCR2 inhibitor RS504393 into injured knees and followed joint damage during disease progression. RS504393-loaded µPLs (RS-µPLs) were fabricated via a template-replica molding technique. A mixture of poly(lactic-co-glycolic acid) (PLGA) and RS504393 was deposited into 20 × 10 μm (length × height) wells in a polyvinyl alcohol (PVA) square-patterned template. After physicochemical and toxicological characterizations, the RS504393 release profile from µPL was assessed in PBS buffer. C57BL/6 J male mice were subjected to destabilization of the medial meniscus (DMM)/sham surgery, and RS-µPLs (1 mg/kg) were administered intraarticularly 1 week postsurgery. Administrations were repeated at 4 and 7 weeks post-DMM. Drug free-µPLs (DF-µPLs) and saline injections were performed as controls. Mice were euthanized at 4 and 10 weeks post-DMM, corresponding to the early and severe PTOA stages, respectively. Knees were evaluated for cartilage structure score (ACS, H&E), matrix loss (safranin O score), osteophyte formation and maturation from cartilage to bone (cartilage quantification), and subchondral plate thickness. The RS-µPL architecture ensured the sustained release of CCR2 inhibitors over several weeks, with ~ 20% of RS504393 still available at 21 days. This prolonged release improved cartilage structure and reduced bone damage and synovial hyperplasia at both PTOA stages. Extracellular matrix loss was also attenuated, although with less efficacy. The results indicate that local sustained delivery is needed to optimize CCR2-targeted therapies.

Aptamer-Based Probes for Cancer Diagnostics and Treatment

Aptamers are single-stranded DNA or RNA oligomers that have the ability to generate unique and diverse tertiary structures that bind to cognate molecules with high specificity. In recent years, aptamer researches have witnessed a huge surge, owing to its unique properties, such as high specificity and binding affinity, low immunogenicity and toxicity, and simplicity of synthesis with negligible batch-to-batch variation. Aptamers may bind to targets, such as various cancer biomarkers, making them applicable for a wide range of cancer diagnosis and treatment. In cancer diagnostic applications, aptamers are used as molecular probes instead of antibodies. They have the potential to detect various cancer-associated biomarkers. For cancer therapeutic purposes, aptamers can serve as therapeutic or delivery agents. The chemical stabilization and modification strategies for aptamers may expand their serum half-life and shelf life. However, aptamer-based probes for cancer diagnosis and therapy still face several challenges for successful clinical translation. A deeper understanding of nucleic acid chemistry, tissue distribution, and pharmacokinetics is required in the development of aptamer-based probes. This review summarizes their application in cancer diagnostics and treatments based on different localization of target biomarkers, as well as current challenges and future prospects.

Immune responses in diabetic nephropathy: Pathogenic mechanisms and therapeutic target

Diabetic nephropathy (DN) is a chronic, inflammatory disease affecting millions of diabetic patients worldwide. DN is associated with proteinuria and progressive slowing of glomerular filtration, which often leads to end-stage kidney diseases. Due to the complexity of this metabolic disorder and lack of clarity about its pathogenesis, it is often more difficult to diagnose and treat than other kidney diseases. Recent studies have highlighted that the immune system can inadvertently contribute to DN pathogenesis. Cells involved in innate and adaptive immune responses can target the kidney due to increased expression of immune-related localization factors. Immune cells then activate a pro-inflammatory response involving the release of autocrine and paracrine factors, which further amplify inflammation and damage the kidney. Consequently, strategies to treat DN by targeting the immune responses are currently under study. In light of the steady rise in DN incidence, this timely review summarizes the latest findings about the role of the immune system in the pathogenesis of DN and discusses promising preclinical and clinical therapies.

Diabetic Kidney Disease: From Pathogenesis to Novel Treatment Possibilities

One of the microvascular complications of diabetes is diabetic kidney disease (DKD), often leading to end stage renal disease (ESRD) in which patients require costly dialysis or transplantation. The silent onset and irreversible progression of DKD are characterized by a steady decline of the estimated glomerular filtration rate, with or without concomitant albuminuria. The diabetic milieu allows the complex pathophysiology of DKD to enter a vicious cycle by inducing the synthesis of excessive amounts of reactive oxygen species (ROS) causing oxidative stress, inflammation, and fibrosis. As no cure is available, intensive research is required to develop novel treatments possibilities. This chapter provides an overview of the important pathomechanisms identified in diabetic kidney disease, the currently established therapies, as well as recently developed novel therapeutic strategies in DKD.

p-Coumaric acid attenuates high-fat diet-induced oxidative stress and nephropathy in diabetic rats

The prevalence of persistent hyperglycaemia during diabetes, impair antioxidant defence system and generate reactive oxygen species, which majorly contribute to its progression and associated complications. Phytochemicals were suggested to scavenge-free radicals and exert antioxidant effects required to improve insulin sensitivity and reduce the occurrence of diabetes-associated complications. We hypothesise that a phenolic phytochemical p-coumaric can reduce diabetes-induced oxidative stress and improve diabetes-associated nephropathy in rats. The aim of this study is to analyse the protective effects of p-coumaric acid against diabetes-induced oxidative stress and nephropathy in high-fat diet-induced diabetic rats. The oral feeding of p-coumaric acid (20 mg/kg for 12 weeks) was found to significantly decrease the elevated levels of blood glucose in high-fat diet-induced type 2 diabetic rats. p-Coumaric acid treatment also decreases the kidney weight whilst increasing the total body weight of diabetic rats. Furthermore whilst evaluation of the different renal functioning tests, p-coumaric acid significantly improves histopathological changes and the levels of urea, creatinine and uric acid in serum of diabetic rats, which was otherwise elevated under diabetic conditions. Our results also highlight that p-coumaric acid is an efficient compound with antioxidant properties and improves the diabetes-induced change in lipid peroxidation and activities of antioxidant enzymes: catalase, glutathione-S-transferase and superoxide dismutase. p-Coumaric acid thus possesses the potential to prevent diabetic nephropathy by reducing oxidative stress and can thus serve as a potential drug target for pharmaceutical companies.

Mechanisms of podocyte injury and implications for diabetic nephropathy

Albuminuria is the hallmark of both primary and secondary proteinuric glomerulopathies, including focal segmental glomerulosclerosis (FSGS), obesity-related nephropathy, and diabetic nephropathy (DN). Moreover, albuminuria is an important feature of all chronic kidney diseases (CKDs). Podocytes play a key role in maintaining the permselectivity of the glomerular filtration barrier (GFB) and injury of the podocyte, leading to foot process (FP) effacement and podocyte loss, the unifying underlying mechanism of proteinuric glomerulopathies. The metabolic insult of hyperglycemia is of paramount importance in the pathogenesis of DN, while insults leading to podocyte damage are poorly defined in other proteinuric glomerulopathies. However, shared mechanisms of podocyte damage have been identified. Herein, we will review the role of haemodynamic and oxidative stress, inflammation, lipotoxicity, endocannabinoid (EC) hypertone, and both mitochondrial and autophagic dysfunction in the pathogenesis of the podocyte damage, focussing particularly on their role in the pathogenesis of DN. Gaining a better insight into the mechanisms of podocyte injury may provide novel targets for treatment. Moreover, novel strategies for boosting podocyte repair may open the way to podocyte regenerative medicine.

Exendin-4 may improve type 2 diabetes by modulating the epigenetic modifications of pancreatic histone H3 in STZ-induced diabetic C57BL/6 J mice

Type 2 diabetes (T2D) is a complicated systemic disease that might be improved by exendin-4, although the epigenetic role remains unclear. In the current study, C57BL/6 J mice were used to generate a T2D model, followed by treatment with exendin-4 (10 μg/kg). Histone H3K9 and H3K23 acetylation, H3K4 mono-methylation, and H3K9 di-methylation were explored by western blot analysis of pancreatic histone extracts. Real-time polymerase chain reaction (PCR) was used to examine the expression levels of pancreatic beta cell development-related genes, and chromatin immunoprecipitation (ChIP) was applied to analyze H3 and H3K9 acetylation, H3K4 mono-methylation, and H3K9 di-methylation in the promoter region of the pancreatic and duodenal homeobox 1 (Pdx1) gene. The results showed that total H3K9 di-methylation and H3K9 and H3K23 acetylation increased in pancreatic tissues of diabetic mice, whereas H3K4 mono-methylation was reduced. All of these changes could be abrogated by treatment with exendin-4. Our data indicated that T2D progression might be improved by exendin-4 treatment through the reversal of global pancreatic histone H3K9 and H3K23 acetylation, H3K4 mono-methylation, and H3K9 di-methylation. A better understanding of these epigenetic alterations may, therefore, lead to novel therapeutic strategies for T2D.

Role of Macrophages and Related Cytokines in Kidney Disease

Inflammation is a key characteristic of kidney disease, but this immune response is two-faced. In the acute phase of kidney injury, there is an activation of the immune cells to fight against the insult, contributing to kidney repair and regeneration. However, in chronic kidney diseases (CKD), immune cells that infiltrate the kidney play a deleterious role, actively participating in disease progression, and contributing to nephron loss and fibrosis. Importantly, CKD is a chronic inflammatory disease. In early CKD stages, patients present sub-clinical inflammation, activation of immune circulating cells and therefore, anti-inflammatory strategies have been proposed as a common therapeutic target for renal diseases. Recent studies have highlighted the plasticity of immune cells and the complexity of their functions. Among immune cells, monocytes/macrophages play an important role in all steps of kidney injury. However, the phenotype characterization between human and mice immune cells showed different markers; therefore the extrapolation of experimental studies in mice could not reflect human renal diseases. Here we will review the current information about the characteristics of different macrophage phenotypes, mainly focused on macrophage-related cytokines, with special attention to the chemokine CCL18, and its murine functional homolog CCL8, and the macrophage marker CD163, and their role in kidney pathology.

Regulation of Monocytes/Macrophages by the Renin-Angiotensin System in Diabetic Nephropathy: State of the Art and Results of a Pilot Study

Diabetic nephropathy (DN) is characterized by albuminuria, loss of renal function, renal fibrosis and infiltration of macrophages originating from peripheral monocytes inside kidneys. DN is also associated with intrarenal overactivation of the renin-angiotensin system (RAS), an enzymatic cascade which is expressed and controlled at the cell and/or tissue levels. All members of the RAS are present in the kidneys and most of them are also expressed in monocytes/macrophages. This review focuses on the control of monocyte recruitment and the modulation of macrophage polarization by the RAS in the context of DN. The local RAS favors the adhesion of monocytes on renal endothelial cells and increases the production of monocyte chemotactic protein-1 and of osteopontin in tubular cells, driving monocytes into the kidneys. There, proinflammatory cytokines and the RAS promote the differentiation of macrophages into the M1 proinflammatory phenotype, largely contributing to renal lesions of DN. Finally, resolution of the inflammatory process is associated with a phenotype switch of macrophages into the M2 anti-inflammatory subset, which protects against DN. The pharmacologic interruption of the RAS reduces albuminuria, improves the trajectory of the renal function, decreases macrophage infiltration in the kidneys and promotes the switch of the macrophage phenotype from M1 to M2.

Hydroxyl Groups on Annular Ring-B Dictate the Affinities of Flavonol-CCL2 Chemokine Binding Interactions

Owing to the astounding biological properties, dietary plant flavonoids have received considerable attention toward developing unique supplementary food sources to prevent various ailments. Chemokines are chemotactic proteins involved in leukocyte trafficking through their interactions with G-protein-coupled receptors and cell surface glycosaminoglycans (GAGs). CCL2 chemokine, a foremost member of CC chemokines, is associated with the pathogenesis of various inflammatory infirmities, thus making the CCL2-Receptor (CCR2)/GAG axis a potential pharmacological target. The current study is designed to unravel the structural details of CCL2-flavonol interactions. Molecular interactions between flavonols (kaempferol, quercetin, and myricetin) with human/murine CCL2 orthologs and their monomeric/dimeric variants were systematically investigated using a combination of biophysical approaches. Fluorescence studies have unveiled that flavonols interact with CCL2 orthologs specifically but with differential affinities. The dissociation constants (K _d) were in the range of 10^-5-10^-7 μM. The NMR- and computational docking-based outcomes have strongly suggested that the flavonols interact with CCL2, comprising the N-terminal and β1- and β3-sheets. It has also been observed that the number of hydroxyl groups on the annular ring-B imposed a significant cumulative effect on the binding affinities of flavonols for CCL2 chemokine. Further, the binding surface of these flavonols to CCL2 orthologs was observed to be extensively overlapped with that of the receptor/GAG-binding surface, thus suggesting attenuation of CCL2-CCR2/GAG interactions in their presence. Considering the pivotal role of CCL2 during monocyte/macrophage trafficking and the immunomodulatory features of these flavonols, their direct interactions highlight the promising role of flavonols as nutraceuticals.

Recent Progress in Aptamer Discoveries and Modifications for Therapeutic Applications

Aptamers are oligonucleotide sequences with a length of about 25-80 bases which have abilities to bind to specific target molecules that rival those of monoclonal antibodies. They are attracting great attention in diverse clinical translations on account of their various advantages, including prolonged storage life, little batch-to-batch differences, very low immunogenicity, and feasibility of chemical modifications for enhancing stability, prolonging the half-life in serum, and targeted delivery. In this Review, we demonstrate the emerging aptamer discovery technologies in developing advanced techniques for producing aptamers with high performance consistently and efficiently as well as requiring less cost and resources but offering a great chance of success. Further, the diverse modifications of aptamers for therapeutic applications including therapeutic agents, aptamer-drug conjugates, and targeted delivery materials are comprehensively summarized.

Up-regulation of PKR pathway contributes to L-NAME induced hypertension and renal damage

Objective

Hypertension induced kidney damage is often associated with fibrosis and tubular apoptosis. Double-stranded protein kinase (PKR) is a well recognized inducer of inflammation and apoptosis. However, role of PKR in hypertension coupled renal damage is still not explored. Therefore here we sought to investigate the role of PKR in the pathogenesis of L-NAME induced hypertension and renal damage in Wistar rats and the underneath molecular mechanism.

Methods

L-NAME (40 mg/kg, p.o) and imoxin (0.5 mg/kg, i.p) was given to Wistar rats for 4 weeks. Increased eNOS expression, serum creatinine, BUN and changes in mean arterial pressure confirmed for hypertensive renal damage. Western blot and immunohistochemistry was carried out for PKR and markers for fibrosis and apoptosis. Morphological alterations were assessed by H&E staining. Sirius red and Masson's Trichrome staining was performed for collagen and fibrosis. TUNEL assay was done for tubular cell death and apoptosis.

Results

Increased expression of PKR and its downstream markers were reported in L-NAME rats, attenuation was observed with imoxin treatment. L-NAME treated rats showed a significant increase in MAP, serum calcium, creatinine and BUN along with the significant morphological changes, attenuation was reported with the imoxin treatment.

Conclusion

PKR is a core contributor in the pathogenesis of L-NAME induced renal damage and tubular apoptosis. Therapeutically targeting of PKR could be an attractive approach to treat the renal complications associated with hypertension.

C-C chemokine receptor type 2 mediates glomerular injury and interstitial fibrosis in focal segmental glomerulosclerosis

BACKGROUND

Glomerulosclerosis and tubulointerstitial fibrosis are hallmarks of chronic kidney injury leading to end-stage renal disease. Inflammatory mechanisms contribute to glomerular and interstitial scarring, including chemokine-mediated recruitment of leucocytes. In particular, accumulation of C-C chemokine receptor type 2 (CCR2)-expressing macrophages promotes renal injury and fibrotic remodelling in diseases like glomerulonephritis and diabetic nephropathy. The functional role of CCR2 in the initiation and progression of primary glomerulosclerosis induced by podocyte injury remains to be characterized.

METHODS

We analysed glomerular expression of CCR2 and its chemokine ligand C-C motif chemokine ligand 2 (CCL2) in human focal segmental glomerulosclerosis (FSGS). Additionally, CCL2 expression was determined in stimulated murine glomeruli and glomerular cells in vitro. To explore pro-inflammatory and profibrotic functions of CCR2 we induced adriamycin nephropathy, a murine model of FSGS, in BALB/c wild-type and Ccr2-deficient mice.

RESULTS

Glomerular expression of CCR2 and CCL2 significantly increased in human FSGS. In adriamycin-induced FSGS, progressive glomerular scarring and reduced glomerular nephrin expression was paralleled by induced glomerular expression of CCL2. Adriamycin exposure stimulated secretion of CCL2 and tumour necrosis factor-α (TNF) in isolated glomeruli and mesangial cells and CCL2 in parietal epithelial cells. In addition, TNF induced CCL2 expression in all glomerular cell populations, most prominently in podocytes. In vivo, Ccr2-deficient mice with adriamycin nephropathy showed reduced injury, macrophage and fibrocyte infiltration and inflammation in glomeruli and the tubulointerstitium. Importantly, glomerulosclerosis and tubulointerstitial fibrosis were significantly ameliorated.

CONCLUSIONS

Our data indicate that CCR2 is an important mediator of glomerular injury and progression of FSGS. CCR2- targeting therapies may represent a novel approach for its treatment.

Elucidating the Molecular Interactions of Chemokine CCL2 Orthologs with Flavonoid Baicalin

An integrated and controlled migration of leukocytes is necessary for the legitimate functioning and maintenance of the immune system. Chemokines and their receptors play a decisive role in regulating the leukocyte migration to the site of inflammation, a phenomena often referred to as chemotaxis. Chemokines and their receptors have become significant targets for therapeutic intervention considering their potential to regulate the immune system. Monocyte chemoattractant protein-1 (MCP-1/CCL2) is a preeminent member of CC chemokine family that facilitates crucial roles by orchestrating the recruitment of monocytes into inflamed tissues. Baicalin (BA), a major bioactive flavonoid, has been reported to attenuate chemokine-regulated leukocyte trafficking. However, no molecular details pertaining to its direct binding to chemokine(s)/receptor(s) are available till date. In the current study, using an array of monomers/dimers of human and murine CCL2 orthologs (hCCL2/mCCL2), we have shown that BA binds to the CCL2 protein specifically with nanomolar affinity (K _d = 270 ± 20 nM). NMR-based studies established that BA binds CCL2 in a specific pocket involving the N-terminal, β1- and β3-sheets. Docking studies suggested that the residues T16, N17, R18, I20, R24, K49, E50, I51, and C52 are majorly involved in complex formation through a combination of H-bonds and hydrophobic interactions. As the residues R18, R24, and K49 of hCCL2 are crucial determinants of monocyte trafficking through receptor/glycosaminoglycans (GAG) binding in CCL2 human/murine orthologs, we propose that baicalin engaging these residues in complex formation will result in attenuation of CCL2 binding to the receptor/GAGs, thus inhibiting the chemokine-regulated leukocyte trafficking.

Drug Testing for Residual Progression of Diabetic Kidney Disease in Mice Beyond Therapy with Metformin, Ramipril, and Empagliflozin

BACKGROUND

Progression of CKD in type 2 diabetes, despite dual inhibition of sodium-glucose transporter-2 and the renin-angiotensin system, remains a concern. Bromoindirubin-3'-oxime (BIO), previously reported to promote podocyte survival and regeneration, is a candidate additional drug to elicit renoprotective effects beyond therapy with metformin, ramipril, and empagliflozin (MRE). Evaluating a drug with standard therapeutics more closely mimics the clinical setting than evaluating the drug alone.

METHODS

Uninephrectomized BKS-Lepr-/- (db/db) mice treated with or without MRE served as a model of progressive CKD in type 2 diabetes. Mice on or off MRE were randomized to only 4 weeks of add-on BIO or vehicle. The primary end point was slope of GFR (ΔGFR).

RESULTS

Four weeks of MRE treatment alone did not affect ΔGFR, but significantly attenuated hyperglycemia, albuminuria, and glomerulosclerosis and increased podocyte filtration slit density, as assessed by STED super-resolution microscopy upon tissue clearing. BIO alone improved albuminuria, podocyte density in superficial and juxtamedullary nephrons, and podocyte filtration slit density. MRE+BIO combination therapy had additive protective effects on ΔGFR, glomerulosclerosis, podocyte density in juxtamedullary nephrons, and filtration slit density.

CONCLUSIONS

Add-on treatment with BIO for only 4 weeks attenuates progression of CKD beyond MRE therapy in mice with type 2 diabetes. Additional drug combinations may help to further delay ESKD in type 2 diabetes.

Epigenetic Modifiers as Potential Therapeutic Targets in Diabetic Kidney Disease

Diabetic kidney disease is one of the fastest growing causes of death worldwide. Epigenetic regulators control gene expression and are potential therapeutic targets. There is functional interventional evidence for a role of DNA methylation and the histone post-translational modifications-histone methylation, acetylation and crotonylation-in the pathogenesis of kidney disease, including diabetic kidney disease. Readers of epigenetic marks, such as bromodomain and extra terminal (BET) proteins, are also therapeutic targets. Thus, the BD2 selective BET inhibitor apabetalone was the first epigenetic regulator to undergo phase-3 clinical trials in diabetic kidney disease with an endpoint of kidney function. The direct therapeutic modulation of epigenetic features is possible through pharmacological modulators of the specific enzymes involved and through the therapeutic use of the required substrates. Of further interest is the characterization of potential indirect effects of nephroprotective drugs on epigenetic regulation. Thus, SGLT2 inhibitors increase the circulating and tissue levels of β-hydroxybutyrate, a molecule that generates a specific histone modification, β-hydroxybutyrylation, which has been associated with the beneficial health effects of fasting. To what extent this impact on epigenetic regulation may underlie or contribute to the so-far unclear molecular mechanisms of cardio- and nephroprotection offered by SGLT2 inhibitors merits further in-depth studies.

Aptamers as Therapeutic Agents: Has the Initial Euphoria Subsided?

Aptamers are synthetic DNA or RNA oligonucleotide ligands with great potential for therapeutic applications. A vast number of disease-related targets have been used to identify agonistic, antagonistic, or inhibitory aptamers, or aptamer-based targeting ligands. However, only a few aptamers have reached late-stage clinical trials so far and the commercial infrastructure is still far behind that of other therapeutic agents such as monoclonal antibodies. The desirable properties of aptamers such as selectivity, chemical flexibility, or cost-efficiency are faced by challenges, including a short half-life in vivo, immunogenicity, and entrapment in cellular organelles. Aptamer research is still in an early stage, and a deeper understanding of their structure, target interactions, and pharmacokinetics is necessary to catch up to the clinical market. In this review, we will discuss the benefits and limitations in the development of therapeutic aptamers, as well as the advances and future directions of aptamer research. The progress towards effective therapies seems to be slow, but it has not stopped and the best is yet to come.

Monocytes and Macrophages as Protagonists in Vascular Complications of Diabetes

With the increasing prevalence of diabetes worldwide, vascular complications of diabetes are also on the rise. Diabetes results in an increased risk of macrovascular complications, with atherosclerotic cardiovascular disease (CVD) being the leading cause of death in adults with diabetes. The exact mechanisms for how diabetes promotes CVD risk are still unclear, although it is evident that monocytes and macrophages are key players in all stages of atherosclerosis both in the absence and presence of diabetes, and that phenotypes of these cells are altered by the diabetic environment. Evidence suggests that at least five pro-atherogenic mechanisms involving monocytes and macrophages contribute to the accelerated atherosclerotic lesion progression and hampered lesion regression associated with diabetes. These changes include (1) increased monocyte recruitment to lesions; (2) increased inflammatory activation; (3) altered macrophage lipid accumulation and metabolism; (4) increased macrophage cell death; and (5) reduced efferocytosis. Monocyte and macrophage phenotypes and mechanisms have been revealed mostly by different animal models of diabetes. The roles of specific changes in monocytes and macrophages in humans with diabetes remain largely unknown. There is an ongoing debate on whether the changes in monocytes and macrophages are caused by altered glucose levels, insulin deficiency or insulin resistance, lipid abnormalities, or combinations of these factors. Current research in humans and mouse models suggests that reduced clearance of triglyceride-rich lipoproteins and their remnants is one important mechanism whereby diabetes adversely affects macrophages and promotes atherosclerosis and CVD risk. Although monocytes and macrophages readily respond to the diabetic environment and can be seen as protagonists in diabetes-accelerated atherosclerosis, they are likely not instigators of the increased CVD risk.

Inflammatory Targets in Diabetic Nephropathy

One of the most frequent complications in patients with diabetes mellitus is diabetic nephropathy (DN). At present, it constitutes the first cause of end stage renal disease, and the main cause of cardiovascular morbidity and mortality in these patients. Therefore, it is clear that new strategies are required to delay the development and the progression of this pathology. This new approach should look beyond the control of traditional risk factors such as hyperglycemia and hypertension. Currently, inflammation has been recognized as one of the underlying processes involved in the development and progression of kidney disease in the diabetic population. Understanding the cascade of signals and mechanisms that trigger this maladaptive immune response, which eventually leads to the development of DN, is crucial. This knowledge will allow the identification of new targets and facilitate the design of innovative therapeutic strategies. In this review, we focus on the pathogenesis of proinflammatory molecules and mechanisms related to the development and progression of DN, and discuss the potential utility of new strategies based on agents that target inflammation.

Combined inhibition of CCR2 and ACE provides added protection against progression of diabetic nephropathy in Nos3-deficient mice

Macrophage-mediated renal injury promotes the development of diabetic nephropathy. Blockade of chemokine (C-C motif) receptor 2 (CCR2) inhibits kidney macrophage accumulation and early glomerular damage in diabetic animals. This study tested early and late interventions with a CCR2 antagonist (CCR2A) in a model of progressive diabetic glomerulosclerosis and determined whether CCR2A provides added benefit over conventional treatment with an angiotensin-converting enzyme inhibitor (ACEi). Diabetes was induced in hypertensive endothelial nitric oxide synthase (Nos3)-deficient mice by administration of five low-dose streptozotocin (STZ) injections daily. Groups of diabetic Nos3^-/- mice received a CCR2A (30 mg·kg^-1·day^-1 PF-04634817 in chow) as an early intervention (weeks 2-15 after STZ). The late intervention (weeks 8-15 after STZ) involved PF-04634817 alone, ACEi (captopril in water 10 mg·kg^-1·day^-1) alone, or combined ACEi + CCR2A. Control diabetic and nondiabetic Nos3^-/- mice received normal chow and water. Early intervention with a CCR2A inhibited kidney inflammation and glomerulosclerosis, albuminuria, podocyte loss, and renal function impairment but not hypertension in diabetic Nos3^-/- mice. Late intervention with a CCR2A also inhibited kidney inflammation, glomerulosclerosis, and renal dysfunction but did not affect albuminuria. ACEi alone suppressed hypertension and albuminuria and partially reduced podocyte loss and glomerulosclerosis but did not affect renal dysfunction. Compared with ACEi alone, the combined late intervention with ACEi + CCR2A provided better protection against kidney damage (inflammation, glomerulosclerosis, and renal function impairment) but not albuminuria. In conclusion, this study demonstrates that combining CCR2A and ACEi provides broader and superior renal protection than ACEi alone in a model of established diabetic glomerulosclerosis with hypertension.

The diabetes pandemic suggests unmet needs for 'CKD with diabetes' in addition to 'diabetic nephropathy'-implications for pre-clinical research and drug testing

Curing 'diabetic nephropathy' is considered an unmet medical need of high priority. We propose to question the concept of 'diabetic nephropathy' that implies diabetes as the predominant cause of kidney disease, which may not apply to the majority of type 2 diabetics approaching end-stage kidney disease. With the onset of diabetes, hyperglycaemia/sodium-glucose co-transporter-2-driven glomerular hyperfiltration promotes nephron hypertrophy, which, however, on its own, causes proteinuria not before a decade later, probably because podocyte hypertrophy can usually accommodate an increase in the filtration surface. In contrast, precedent chronic kidney disease (CKD), that is, few nephrons per body mass, e.g. due to poor nephron endowment from birth, obesity, pregnancy, or renal ageing or injury-related nephron loss, usually precedes the onset of type 2 diabetes. This applies in particular in older adults, and each on its own, but especially in combination, further aggravates single nephron hyperfiltration and glomerular hypertrophy. Whenever this additional hyperglycaemia-driven enlargement of the glomerular filtration surface exceeds the capacity of podocytes for hypertrophy, podocytes detachment leads to glomerulosclerosis and nephron loss, i.e. CKD progression. Animal models of 'diabetic nephropathy' based only on hyperglycaemia do not mimic this aspect and therefore poorly predict outcomes of clinical trials usually performed on elderly CKD patients with type 2 diabetes. Thus, we advocate the use of renal mass (nephron) ablation in type 2 diabetic animals to better mimic the pathophysiology of 'CKD with diabetes' in the target patient population and the use of the glomerular filtration rate as a primary endpoint to more reliably predict trial outcomes.

Increased Antiangiogenic Effect by Blocking CCL2-dependent Macrophages in a Rodent Glioblastoma Model: Correlation Study with Dynamic Susceptibility Contrast Perfusion MRI

When glioblastoma multiforme (GBM) is treated with anti-vascular endothelial growth factor (VEGF) agents, it commonly exhibits tumor progression due to the development of resistance, which results in a dismal survival rate. GBM tumors contain a large number of monocytes/macrophages, which have been shown to be resistant to the effects of bevacizumab. It has been reported that tumor-associated macrophages (TAMs) promote resistance to bevacizumab treatment. Therefore, it is important to target TAMs in the GBM microenvironment. TAMs, which depend on chemokine ligand 2 (CCL2) for differentiation and survival, induce the expression of proangiogenic factors such as VEGF. Dynamic susceptibility contrast (DSC)-MR imaging is an advanced technique that provides information on tumor blood volume and can potentially predict the response to several treatments, including anti-angiogenic agents such as bevacizumab, in human GBM. In this study, we used a CCL2 inhibitor, mNOX-E36, to suppress the recruitment of TAMs in a CCL2-expressing rat GBM model and investigated the effect of combination therapy with bevacizumab using DSC-MR imaging. We demonstrated that the inhibition of CCL2 blocked macrophage recruitment and angiogenesis, which resulted in decreased tumor volume and blood volume in CCL2-expressing GBM in a rat model. Our results provide direct evidence that CCL2 expression can increase the resistance to bevacizumab, which can be assessed noninvasively with the DSC-MR imaging technique. This study shows that the suppression of CCL2 can play an important role in increasing the efficacy of anti-angiogenic treatment in GBM by inhibiting the recruitment of CCL2-dependent macrophages.

Interleukin-1β Inhibition for Chronic Kidney Disease in Obese Mice With Type 2 Diabetes

Inflammasome-driven release of interleukin(IL)-1β is a central element of many forms of sterile inflammation and has been evident to promote the onset and progression of diabetic kidney disease. We microdissected glomerular and tubulointerstitial samples from kidney biopsies of patients with diabetic kidney disease and found expression of IL-1β mRNA. Immunostaining of such kidney biopsies across a broad spectrum of diabetic kidney disease stages revealed IL-1β positivity in a small subset of infiltrating immune cell. Thus, we speculated on a potential of IL-1β as a therapeutic target and neutralizing the biological effects of murine IL-1β with a novel monoclonal antibody in uninephrectomized diabetic db/db mice with progressive type 2 diabetes- and obesity-related single nephron hyperfiltration, podocyte loss, proteinuria, and progressive decline of total glomerular filtration rate (GFR). At 18 weeks albuminuric mice were randomized to intraperitoneal injections with either anti-IL-1β or control IgG once weekly for 8 weeks. During this period, anti-IL-1β IgG had no effect on food or fluid intake, body weight, and fasting glucose levels. At week 26, anti-IL-1β IgG had reduced renal mRNA expression of kidney injury markers (Ngal) and fibrosis (Col1, a-Sma), significantly attenuated the progressive decline of GFR in hyperfiltrating diabetic mice, and preserved podocyte number without affecting albuminuria or indicators of single nephron hyperfiltration. No adverse effect were observed. Thus, IL-1β contributes to the progression of chronic kidney disease in type 2 diabetes and might therefore be a valuable therapeutic target, potentially in combination with drugs with different mechanisms-of-action such as RAS and SGLT2 inhibitors.

Sustained Klotho delivery reduces serum phosphate in a model of diabetic nephropathy

Diabetic nephropathy (DN) is a primary cause of end-stage renal disease and is becoming more prevalent because of the global rise in type 2 diabetes. A model of DN, the db/db uninephrectomized ( db/db-uni) mouse, is characterized by obesity, as well as compromised renal function. This model also manifests defects in mineral metabolism common in DN, including hyperphosphatemia, which leads to severe endocrine disease. The FGF23 coreceptor, α-Klotho, circulates as a soluble, cleaved form (cKL) and may directly influence phosphate handling. Our study sought to test the effects of cKL on mineral metabolism in db/db-uni mice. Mice were placed into either mild or moderate disease groups on the basis of the albumin-to-creatinine ratio (ACR). Body weights of db/db-uni mice were significantly greater across the study compared with lean controls regardless of disease severity. Adeno-associated cKL administration was associated with increased serum Klotho, intact, bioactive FGF23 (iFGF23), and COOH-terminal fragments of FGF23 ( P < 0.05). Blood urea nitrogen was improved after cKL administration, and cKL corrected hyperphosphatemia in the high- and low-ACR db/db-uni groups. Interestingly, 2 wk after cKL delivery, blood glucose levels were significantly reduced in db/db-uni mice with high ACR ( P < 0.05). Interestingly, several genes associated with stabilizing active iFGF23 were also increased in the osteoblastic UMR-106 cell line with cKL treatment. In summary, delivery of cKL to a model of DN normalized blood phosphate levels regardless of disease severity, supporting the concept that targeting cKL-affected pathways could provide future therapeutic avenues in DN. NEW & NOTEWORTHY In this work, systemic and continuous delivery of the "soluble" or "cleaved" form of the FGF23 coreceptor α-Klotho (cKL) via adeno-associated virus to a rodent model of diabetic nephropathy (DN), the db/db uninephrectomized mouse, normalized blood phosphate levels regardless of disease severity. This work supports the concept that targeting cKL-affected pathways could provide future therapeutic avenues for the severe mineral metabolism defects associated with DN.

Ursolic Acid Treatment Alleviates Diabetic Kidney Injury By Regulating The ARAP1/AT1R Signaling Pathway

PURPOSE

This study aimed to investigate whether ursolic acid (UA) mitigates renal inflammation, oxidative stress and fibrosis by regulating the angiotensin II type 1 receptor-associated protein (ARAP1)/angiotensin II type 1 receptor (AT1R) signaling pathway and subsequently alleviating renal damage.

METHODS

db/db mice were divided randomly into a diabetic nephropathy (DN) group and a UA treatment group. Light microscopy and electron microscopy were used to observe pathological changes in renal tissues. Immunohistochemistry (IHC) was employed to examine changes in the expression of ARAP1, AT1R, 8-hydroxydeoxyguanosine (8-OHdG), NADPH oxidase 2 (NOX2), the extracellular matrix protein fibronectin (FN), IL-1β and IL-18 in renal tissues. Western blotting and RT-qPCR were used to detect the respective changes in the protein and mRNA levels of ARAP1, AT1R, NOX4, NOX2, transforming growth factor-β1 (TGF-β1), FN, collagen IV, IL-1β and IL-18 in renal tissues and mesangial cells. In addition, immunofluorescence staining was employed to examine changes in FN and NOX2 expression in mesangial cells.

RESULTS

UA treatment effectively reduced the body weights and blood glucose levels of db/db mice (p<0.05) as well as the urinary albumin/creatinine ratio (p<0.05). In addition, the renal tissue lesions and glomerulosclerosis index of the db/db mice were significantly improved after treatment (p<0.01). Histochemical analysis results showed significantly lower expression levels of ARAP1, AT1R, FN, NOX2, 8-OHdG, IL-1β and IL-18 in renal tissues in the UA treatment group than in the DN group. Western blotting and RT-qPCR data also revealed UA-induced decreases in the renal levels of the ARAP1, AT1, NOX4, NOX2, TGF-β1, FN, collagen IV, IL-1β and IL-18 proteins in vivo and/or in vitro (p<0.01). ARAP1 knockdown effectively reduced the expression of NOX2 and FN in vitro.

CONCLUSION

UA alleviated renal damage in type 2 diabetic db/db mice by downregulating proteins in the ARAP1/AT1R signaling pathway to inhibit extracellular matrix accumulation, renal inflammation, fibrosis and oxidative stress.

Pharmacokinetics, pharmacodynamics and safety of aptamers

Aptamers are synthetic molecules structured as single-stranded DNA or RNA oligonucleotides that can be designed to mimic the functional properties of monoclonal antibodies. They bind to the target molecules (typically soluble or cell-bound proteins) with high affinity (with picomolar to low nanomolar range) and specificity, and therefore can be an alternative to therapeutic antibodies or peptide ligands. This paper reviews published data regarding pharmacokinetics, pharmacodynamics and safety of aptamers from preclinical and clinical studies. Aptamers have been developed for the treatment of a variety of diseases, including cancer, macular degeneration,g cardiovascular disease, diabetes and anaemia of chronic diseases. There are several preclinical studies with unmodified aptamers, but the vast majority of aptamer trials in humans have been conducted with modified aptamers, because unmodified aptamers demonstrate metabolic instability, as well as rapid renal filtration and elimination. Various strategies have been developed to improve the pharmacokinetic profile of aptamers. Aside from chemical modification of nucleotides in order to stabilize them against nuclease degradation, the main modification to extend the half-life is pegylation. Therefore, the process of pegylation as well as its benefits and possible shortcomings will briefly be discussed.

Therapeutic aptamers in discovery, preclinical and clinical stages

The aptamer field witnessed steady growth during the past 28 years as evident from the exponentially increasing number of related publications. The field is "coming of age", but like other biomedical research areas facing a global push towards translational research to carry ideas from bench- to bedside, there is pressure to show impact for aptamers at the clinical end. Being easy-to-make, non-immunogenic, stable and high-affinity nano-ligands, aptamers are perfectly poised to move in this direction. They can specifically bind targets ranging from small molecules to complex multimeric structures, making them potentially useful in a limitless variety of therapeutic approaches. This review will summarize efforts made to accomplish the therapeutic promise of aptamers, with a focus on aptamers directly acting as therapeutic molecules, rather than those used in targeted delivery of other drugs. The review will showcase representative examples at various stages of development, covering different disease categories.

Organ and tissue fibrosis: Molecular signals, cellular mechanisms and translational implications

Fibrosis denotes excessive scarring, which exceeds the normal wound healing response to injury in many tissues. Although the extracellular matrix deposition appears unstructured disrupting the normal tissue architecture and subsequently impairing proper organ function, fibrogenesis is a highly orchestrated process determined by defined sequences of molecular signals and cellular response mechanisms. Persistent injury and parenchymal cell death provokes tissue inflammation, macrophage activation and immune cell infiltration. The release of biologically highly active soluble mediators (alarmins, cytokines, chemokines) lead to the local activation of collagen producing mesenchymal cells such as pericytes, myofibroblasts or Gli1 positive mesenchymal stem cell-like cells, to a transition of various cell types into myofibroblasts as well as to the recruitment of fibroblast precursors. Clinical observations and experimental models highlighted that fibrosis is not a one-way road. Specific mechanistic principles of fibrosis regression involve the resolution of chronic tissue injury, the shift of inflammatory processes towards recovery, deactivation of myofibroblasts and finally fibrolysis of excess matrix scaffold. The thorough understanding of common principles of fibrogenic molecular signals and cellular mechanisms in various organs - such as liver, kidney, lung, heart or skin - is the basis for developing improved diagnostics including biomarkers or imaging techniques and novel antifibrotic therapeutics.

C-C motif-ligand 2 inhibition with emapticap pegol (NOX-E36) in type 2 diabetic patients with albuminuria

Background

Emapticap pegol (NOX-E36) is a Spiegelmer® that specifically binds and inhibits the pro-inflammatory chemokine C-C motif-ligand 2 (CCL2) (also called monocyte-chemotactic protein 1). The objective of this exploratory study was to evaluate the safety and tolerability as well as the renoprotective and anti-diabetic potential of emapticap in type 2 diabetic patients with albuminuria.

Methods

A randomized, double-blind, placebo-controlled Phase IIa study was initiated in 75 albuminuric type 2 diabetics. Emapticap at 0.5 mg/kg and placebo were administered subcutaneously twice weekly for 12 weeks to 50 and 25 patients, respectively, followed by a treatment-free phase of 12 weeks.

Results

Twice weekly subcutaneous treatment with emapticap over 3 months was generally safe and well tolerated and reduced the urinary albumin/creatinine ratio (ACR) from baseline to Week 12 by 29% (P < 0.05); versus placebo a non-significant ACR reduction of 15% was observed (P = 0.221). The maximum difference, 26% (P = 0.064) between emapticap and placebo, was seen 8 weeks after discontinuation of treatment. At Week 12, the HbA1c changed by −0.31% in the emapticap versus +0.05% in the placebo group (P = 0.146). The maximum difference for HbA1c was observed 4 weeks after the last dose with −0.35% for emapticap versus +0.12% for placebo (P = 0.026). No relevant change in blood pressure or estimated glomerular filtration rate was seen between the treatment groups throughout the study. A post hoc analysis with exclusion of patients with major protocol violations, dual RAS blockade or haematuria increased the ACR difference between the two treatment arms to 32% at Week 12 (P = 0.014) and 39% at Week 20 (P = 0.010).

Conclusions

Inhibition of the CCL2/CCL2 receptor axis with emapticap pegol was generally safe and well tolerated. Beneficial effects on ACR and HbA1c were observed in this exploratory study, which were maintained after cessation of treatment. Taken together, emapticap may have disease-modifying effects that warrant further investigation in adequately powered confirmatory studies.

Role of the Immune System in Diabetic Kidney Disease

PURPOSE OF REVIEW

The purpose of this review is to examine the proposed role of immune modulation in the development and progression of diabetic kidney disease (DKD).

RECENT FINDINGS

Diabetic kidney disease has not historically been considered an immune-mediated disease; however, increasing evidence is emerging in support of an immune role in its pathophysiology. Both systemic and local renal inflammation have been associated with DKD. Infiltration of immune cells, predominantly macrophages, into the kidney has been reported in a number of both experimental and clinical studies. In addition, increased levels of circulating pro-inflammatory cytokines have been linked to disease progression. Consequently, a variety of therapeutic strategies involving modulation of the immune response are currently being investigated in diabetic kidney disease. Although no current therapies for DKD are directly based on immune modulation many of the therapies in clinical use have anti-inflammatory effects along with their primary actions. Macrophages emerge as the most likely beneficial immune cell target and compounds which reduce macrophage infiltration to the kidney have shown potential in both animal models and clinical trials.

Macrophages in diabetic nephropathy in patients with type 2 diabetes

Background

Inflammation plays a role in the development of diabetic nephropathy (DN) in type 2 diabetes. Although macrophages have been found in experimental models of DN, little is known regarding the presence of macrophages in patients with DN. Therefore, we investigated the presence and phenotype of glomerular and interstitial macrophages in relation to clinical and histopathological parameters in patients with DN.

Methods

Renal autopsy samples were obtained from 88 type 2 diabetic patients with histologically proven DN and stained for CD68 and CD163 as general and M2/anti-inflammatory markers of macrophages. Renal damage was scored based on histopathological classification of DN. Control renal autopsy samples were obtained from patients without renal abnormalities and from diabetic patients without DN. Positive cells per glomerulus were counted. Interstitial macrophages were counted semi-quantitatively.

Results

Macrophages were present in all groups. In the DN group, the mean number of CD68+ cells per glomerulus and CD163+ cells per glomerulus was 4.2 (range 0-19) and 2.1 (range 0-14.47), respectively. The distribution was similar between all histopathological classes. Glomerular CD163+ macrophages were positively associated with DN class, interstitial fibrosis and tubular atrophy, and glomerulosclerosis. Interstitial CD68+ macrophages were correlated with glomerular filtration rate stage and albuminuria.

Conclusions

Our results demonstrate that macrophages are present in the glomeruli and interstitium of type 2 diabetic patients with DN and of controls. Although patients and controls had similar numbers of glomerular macrophages, glomerular anti-inflammatory CD163+ macrophages were associated with pathological lesions in DN. Taken together with the correlation between interstitial macrophages and interstitial fibrosis and tubular atrophy, DN class, and renal function, this finding suggests that macrophages may play a role in DN progression. Therefore, targeting macrophages may be a promising new therapy for inhibiting the progression of DN.

Probing and characterizing the high specific sequences of ssDNA aptamer against SGIV-infected cells

As the major viral pathogen of grouper aquaculture, Singapore grouper iridovirus (SGIV) has caused great economic losses in China and Southeast Asia. In the previous study, we have generated highly specific ssDNA aptamers against SGIV-infected grouper spleen cells (GS) by Systematic Evolution of Ligands by Exponential Enrichment technology (SELEX), in which Q2 had the highest binding affinity of 16.43 nM. In this study, we would try to identify the specific sequences in the aptamer Q2 that exhibited the high binding affinity to SGIV-infected cells by truncating the original Q2 into some different specific segments. We first evaluated the specificity and binding affinity of these truncated aptamers to SGIV-infected cells by flow cytometry, fluorescent imaging of cells and aptamer-based enzyme-linked apta-sorbent assay (ELASA). We then performed cytotoxicity analysis, assessment of the inhibitory effects upon SGIV infection and the celluar internalization kinetics of each truncated aptamer. Compared to the initial Q2, one of the truncated aptamer Q2-C5 showed a 3-fold increase in the binding affinity for SGIV-infected cells, and held more effective inhibitory effects, higher internalization kinetics and stability. Hence, the aptamer's truncated methods could be applied in the research of identifying aptamer's key sequences. The shorter, structure optimizing aptamer showed more excellent performance over the originally selected aptamer, which could potentially be applied in developing commercial detection probes for the early and rapid diagnosis of SGIV infection, and highly specific therapeutic drugs against SGIV infection.

Reprint of "Dual blockade of the pro-inflammatory chemokine CCL2 and the homeostatic chemokine CXCL12 is as effective as high dose cyclophosphamide in murine proliferative lupus nephritis"

Induction therapy of proliferative lupus nephritis still requires the use of unselective immunosuppressive drugs with significant toxicities. In search of more specific drugs with equal efficacy but fewer side effects we considered blocking pro-inflammatory chemokine monocyte chemoattractant protein-1 (MCP-1/CCL2) and homeostatic chemokine stromal cell-derived factor-1 (SDF-1/CXCL12), which both contribute to the onset and progression of proliferative lupus nephritis yet through different mechanisms. We hypothesized that dual antagonism could be as potent on lupus nephritis as the unselective immunosuppressant cyclophosphamide (CYC). We estimated serum levels of CCL2 and CXCL12 in patients with SLE (n=99) and compared the results with healthy individuals (n=21). In order to prove our hypothesis we used l-enantiomeric RNA Spiegelmer® chemokine antagonists, i.e. the CCL2-specific mNOX-E36 and the CXCL12-specific NOX-A12 to treat female MRL/lpr mice from week 12 to 20 of age with either anti-CXCL12 or anti-CCL2 alone or both. SLE patients showed elevated serum levels of CCL2 but not of CXCL12. Female MRL/lpr mice treated with dual blockade showed significantly more effective than either monotherapy in preventing proteinuria, immune complex glomerulonephritis, and renal excretory failure and the results are at par with CYC treatment. Dual blockade reduced leukocyte counts and renal IL-6, IL-12p40, CCL-5, CCL-2 and CCR-2 mRNA expression. Dual blockade of CCL2 and CXCL12 can be as potent as CYC to suppress the progression of proliferative lupus nephritis probably because the respective chemokine targets mediate different disease pathomechanisms, i.e. systemic autoimmunity and peripheral tissue inflammation.

Systemic Monocyte Chemotactic Protein-1 Inhibition Modifies Renal Macrophages and Restores Glomerular Endothelial Glycocalyx and Barrier Function in Diabetic Nephropathy

Inhibition of monocyte chemotactic protein-1 (MCP-1) with the Spiegelmer emapticap pegol (NOX-E36) shows long-lasting albuminuria-reducing effects in diabetic nephropathy. MCP-1 regulates inflammatory cell recruitment and differentiation of macrophages. Because the endothelial glycocalyx is also reduced in diabetic nephropathy, we hypothesized that MCP-1 inhibition restores glomerular barrier function through influencing macrophage cathepsin L secretion, thus reducing activation of the glycocalyx-degrading enzyme heparanase. Four weeks of treatment of diabetic Apoe knockout mice with the mouse-specific NOX-E36 attenuated albuminuria without any change in systemic hemodynamics, despite persistent loss of podocyte function. MCP-1 inhibition, however, increased glomerular endothelial glycocalyx coverage, with preservation of heparan sulfate. Mechanistically, both glomerular cathepsin L and heparanase expression were reduced. MCP-1 inhibition resulted in reduced CCR2-expressing Ly6C^hi monocytes in the peripheral blood, without affecting overall number of kidney macrophages at the tissue level. However, the CD206⁺/Mac3⁺ cell ratio, as an index of presence of anti-inflammatory macrophages, increased in diabetic mice after treatment. Functional analysis of isolated renal macrophages showed increased release of IL-10, whereas tumor necrosis factor and cathepsin L release was reduced, further confirming polarization of tissue macrophages toward an anti-inflammatory phenotype during mouse-specific NOX-E36 treatment. We show that MCP-1 inhibition restores glomerular endothelial glycocalyx and barrier function and reduces tissue inflammation in the presence of ongoing diabetic injury, suggesting a therapeutic potential for NOX-E36 in diabetic nephropathy.

SL2B aptamer and folic acid dual-targeting DNA nanostructures for synergic biological effect with chemotherapy to combat colorectal cancer

DNA nanostructures prepared by self-assembly possess good stability, high biocompatibility, and low immunogenicity as drug delivery vehicles. In this work, DNA tetrahedron (TD) was constructed and modified with SL2B aptamer (S) and folic acid (F). TD possessed a small diameter (~6 nm) and entered into the nucleus quickly. SL2B aptamer can inhibit cancer cell growth by disturbing vascular endothelial growth factor/Notch signaling pathways. To explore the effect of SL2B number on colorectal cancer inhibition, SL2B multimers (dimer, trimer, and tetramer) were constructed by functionalization of TD with different numbers of SL2B. One SL2B per TD was the most efficient anticancer strategy and showed significantly better anticancer efficacy than SL2B, probably due to the enhanced stability of SL2B by TD. Doxorubicin (DOX) is a potent anticancer agent that can intercalate into DNA double strands. Results showed that TD could facilitate DOX entrance into the nucleus and the intracellular delivery of DOX was further enhanced by functionalization of SL2B and F. DOX-intercalated TD modified with two F and two S (DOX@TD-2F2S) could cause sufficient HT-29 cell inhibition at a much lower DOX concentration. In sum, DOX@TD-2F2S exhibited a synergic anticancer biological effect with chemotherapy and can be a promising strategy for treating colorectal cancer.

Immunity and inflammation in diabetic kidney disease: translating mechanisms to biomarkers and treatment targets

Increasing incidences of obesity and diabetes have made diabetic kidney disease (DKD) the leading cause of chronic kidney disease and end-stage renal disease worldwide. Despite current pharmacological treatments, including strategies for optimizing glycemic control and inhibitors of the renin-angiotensin system, DKD still makes up almost one-half of all cases of end-stage renal disease in the United States. Compelling and mounting evidence has clearly demonstrated that immunity and inflammation play a paramount role in the pathogenesis of DKD. This article reviews the involvement of the immune system in DKD and identifies important roles of key immune and inflammatory mediators. One of the most recently identified biomarkers is serum amyloid A, which appears to be relatively specific for DKD. Novel and evolving treatment approaches target protein kinases, transcription factors, chemokines, adhesion molecules, growth factors, advanced glycation end-products, and other inflammatory molecules. This is the beginning of a new era in the understanding and treatment of DKD, and we may have finally reached a tipping point in our fight against the growing burden of DKD.

Aptamers as targeted therapeutics: current potential and challenges

Nucleic acid aptamers, often termed 'chemical antibodies', are functionally comparable to traditional antibodies, but offer several advantages, including their relatively small physical size, flexible structure, quick chemical production, versatile chemical modification, high stability and lack of immunogenicity. In addition, many aptamers are internalized upon binding to cellular receptors, making them useful targeted delivery agents for small interfering RNAs (siRNAs), microRNAs and conventional drugs. However, several crucial factors have delayed the clinical translation of therapeutic aptamers, such as their inherent physicochemical characteristics and lack of safety data. This Review discusses these challenges, highlighting recent clinical developments and technological advances that have revived the impetus for this promising class of therapeutics.

Esculetin ameliorates hepatic fibrosis in high fat diet induced non-alcoholic fatty liver disease by regulation of FoxO1 mediated pathway

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), a chronic metabolic disorder is associated with oxidative stress, inflammation and fibrotic cascades. In this study, we aimed to examine the effects of Esculetin, a well-known anti-oxidant on TGF-β1 mediated liver fibrosis and FoxO1 activity.

METHODS

A non-genetic murine model for NAFLD was developed by chronic high fat diet (HFD) (58% calories from fats) feeding in Wistar rats. The plasma biochemical parameters, liver function tests, oxidative stress, and histopathological alterations were assessed. The alterations in extracellular matrix (ECM) deposition and FoxO1 activity were assessed by immunohistochemistry.

RESULTS

The aberrations in plasma parameters, liver functioning, morphometric and microscopic changes in liver structure of HFD fed rats were significantly improved by treatment with Esculetin. Liver fibrosis, identified in the form of collagen deposition and expression of fibrotic proteins like TGF-β1 and fibronectin was also markedly controlled by Esculetin. The expression of phospho-FoxO1 was found to be reduced in HFD fed rats' liver, showing an increase in activation of FoxO1 under insulin resistant and hyperglycemic states. Esculetin treatment could improve phospho-FoxO1 expression, thus showing its ability to act on Akt/PI3K/FoxO1 pathway.

CONCLUSIONS

As per the previous studies, a potential therapy for NAFLD may be the one with multi-faceted actions on insulin resistance, oxidative stress, inflammation and fibrosis. This study demonstrates the efficiency of Esculetin in improving liver fibrosis in HFD induced NAFLD.

ABCs of DNA aptamer and related assay development

This review is intended to guide the novice in aptamer research and development to understand virtually all of the aptamer development options and currently available assay modalities. Aptamer development topics range from discussions of basic and advanced versions of Systematic Evolution of Ligands by EXponential Enrichment (SELEX) and SELEX variations involving incorporation of exotic unnatural nucleotides to expand library diversity for even greater aptamer affinity and specificity to improved next generation methods of DNA sequencing, screening and tracking aptamer development throughout the SELEX process and characterization of lead aptamer candidates. Aptamer assay development topics include descriptions of various colorimetric and fluorescent assays in microplates or on membranes including homogeneous beacon and multiplexed Fluorescence Resonance Energy Transfer (FRET) assays. Finally, a discussion of the potential for marketing successful aptamer-based assays or test kits is included.

Aptamers: novel diagnostic and therapeutic tools for diabetes mellitus and metabolic diseases

Diabetes mellitus is one of the most common chronic diseases that threatens human health in worldwide populations. Despite enormous efforts invested in the study of diabetes mellitus, the development of precise diagnoses and treatments for this disease remains difficult due to the limitations of current techniques. Therefore, new methods are currently being developed. Aptamers are oligonucleotides that bind to specific target molecules and have been widely applied as diagnostic and therapeutic tools. In recent years, aptamers have been utilized in the study of diabetes mellitus and metabolic diseases. In this review, we highlight recent developments and new perspectives on aptamers in the field of diabetes mellitus and other metabolic diseases. Aptamers could potentially provide the means for efficient diagnoses and therapies against diabetes mellitus.

Multiparametric Functional MRI: A Tool to Uncover Subtle Changes following Allogeneic Renal Transplantation

PURPOSE

To investigate multiparametric functional MRI to characterize acute rejection in a murine allogeneic renal transplant model and evaluate the effect of novel therapeutics.

MATERIAL AND METHODS

We performed allogeneic and syngeneic orthotopic transplantations (Balb/c to C57Bl/6 and C57Bl/6 to C57Bl/6). Allogeneic Groups (n = 5) were either treated with the anti-CCL2-Spiegelmer (mNOX-E36) in monotherapy or in combination with low doses of Ciclosporin-A (10mg/kgBW/d) for 10 days. Controls received equivalent doses of a non-functional spiegelmer (revmNOX-E36) or low dose Ciclosporin-A. Diffusion-weighted (DWI) and Dynamic-contrast-enhanced (DCE-) MRI-scans were performed using a clinical 3T-scanner. DWI analysis (b-values from 0-800 s/mm2) was performed mono- and biexponentially, while DCE-MRI was assessed with deconvolution analysis. Therapy effects were assessed ex vivo with histopathology, immunohistochemistry and RT-PCR. Statistical analysis was performed with unpaired t-tests and Spearman´s correlation coefficient.

RESULTS

DWI showed a significant diffusion restriction in allogeneic compared to syngeneic transplants (ADC: 0.63±0.08 vs. 1.29±0.12 mm2/s*103) with decreasing diffusion restriction under therapy. DCE-MRI showed restored organ perfusion under Ciclosporin A alone and combination therapy (Plasma Flow: 43.43±12.49; 38.75±7.53ml/100ml/min) compared to syngeneic controls (51.03±12.49ml/100ml/min). Ex vivo analysis showed reduced monocytic infiltrates, attenuated levels of inflammatory cytokines under mNOX-E36 monotherapy with an additive effect of low dose Ciclosporin A. There was a significant (p<0.05) negative correlation between ADC and interstitial inflammation (r = -0.73) or macrophage infiltration (r = -0.81) and between organ perfusion and intimal arteritis (r = -0.63).

CONCLUSION

Multiparametric functional MRI is suited to detect renal allograft rejection in an experimental murine model and allows to characterize effects of immunosuppressive therapy alleviating acute rejection processes in allogeneic transplantation.

Monocyte chemoattractant protein-1 and the kidney

PURPOSE OF REVIEW

Recently, initial studies have been carried out in patients using monocyte chemoattractant protein-1 (MCP-1) inhibitors. This review summarizes the known function of MCP-1 in regulating monocytes during inflammation and its role in inflammatory disease of the kidney.

RECENT FINDINGS

MCP-1 is one of the first chemokines described and plays an important role in renal inflammatory disease. The function of MCP-1 has been investigated and analyzed in both animal models of renal disease and renal patients. MCP-1 mediates firstly the release of monocytes from the bone marrow, and then generates a gradient in the endothelial glycocalyx to direct monocytes to sites of inflammation, thereby alleviating the migration of blood leukocytes into the inflamed tissue. In addition, MCP-1 has direct signaling effects in monocytes and influences migration, proliferation, and differentiation of leukocytes. Blockade of MCP-1 in several models of renal disease has ameliorated the disease, suggesting that inhibition of MCP-1 is a promising and valid strategy to treat patients with renal inflammatory disease.

SUMMARY

Understanding the role of MCP-1 in monocyte homeostasis and the implications of MCP-1 inhibition in renal disease will help in designing better diagnostic and therapeutic strategies in patients with inflammatory renal disease.