Anti-Ccl2 Spiegelmer permits 75% dose reduction of cyclophosphamide to control diffuse proliferative lupus nephritis and pneumonitis in MRL-Fas(lpr) mice

Glomerulonephritis: immunopathogenesis and immunotherapy

'Glomerulonephritis' (GN) is a term used to describe a group of heterogeneous immune-mediated disorders characterized by inflammation of the filtration units of the kidney (the glomeruli). These disorders are currently classified largely on the basis of histopathological lesion patterns, but these patterns do not align well with their diverse pathological mechanisms and hence do not inform optimal therapy. Instead, we propose grouping GN disorders into five categories according to their immunopathogenesis: infection-related GN, autoimmune GN, alloimmune GN, autoinflammatory GN and monoclonal gammopathy-related GN. This categorization can inform the appropriate treatment; for example, infection control for infection-related GN, suppression of adaptive immunity for autoimmune GN and alloimmune GN, inhibition of single cytokines or complement factors for autoinflammatory GN arising from inborn errors in innate immunity, and plasma cell clone-directed or B cell clone-directed therapy for monoclonal gammopathies. Here we present the immunopathogenesis of GN and immunotherapies in use and in development and discuss how an immunopathogenesis-based GN classification can focus research, and improve patient management and teaching.

Dysregulated balance in Th17/Treg axis of Pristane-induced lupus mouse model, are mesenchymal stem cells therapeutic?

BACKGROUND

Despite advances in general and targeted immunosuppressive therapies, limiting all mainstay treatment options in refractory systemic lupus erythematosus (SLE) cases has necessitated the development of new therapeutic strategies. Mesenchymal stem cells (MSCs) have recently emerged with unique properties, including a solid propensity to reduce inflammation, exert immunomodulatory effects, and repair injured tissues.

METHODS

An animal model of acquired SLE mice was induced via intraperitoneal immunization with Pristane and affirmed by measuring specific biomarkers. Bone marrow (BM) MSCs were isolated from healthy BALB/c mice and cultured in vitro, then were identified and confirmed by flow cytometry and cytodifferentiation. Systemic MSCs transplantation was performed and then several parameters were analyzed and compared, including specific cytokines (IL-17, IL-4, IFN-ɣ, TGF-β) at the serum level, the percentage of Th cell subsets (Treg/Th17, Th1/Th2) in splenocytes, and also the relief of lupus nephritis, respectively by enzyme-linked immunosorbent assay (ELISA), flow cytometry analysis and by hematoxylin & eosin staining and also immunofluorescence assessment. Experiments were carried out with different initiation treatment time points (early and late stages of disease). Analysis of variance (ANOVA) followed by post hoc Tukey's test was used for multiple comparisons.

RESULTS

The rate of proteinuria, anti-double-stranded deoxyribonucleic acid (anti-dsDNA) antibodies, and serum creatinine levels decreased with BM-MSCs transplantation. These results were associated with attenuated lupus renal pathology in terms of reducing IgG and C3 deposition and lymphocyte infiltration. Our findings suggested that TGF-β (associated with lupus microenvironment) can contribute to MSC-based immunotherapy by modulating the population of TCD4⁺ cell subsets. Obtained results indicated that MSCs-based cytotherapy could negatively affect the progression of induced SLE by recovering the function of Treg cells, suppressing Th1, Th2, and Th17 lymphocyte function, and downregulating their pro-inflammatory cytokines.

CONCLUSION

MSC-based immunotherapy showed a delayed effect on the progression of acquired SLE in a lupus microenvironment-dependent manner. Allogenic MSCs transplantation revealed the ability to re-establish the balance of Th17/Treg, Th1/Th2 and restore the plasma cytokines network in a pattern dependent on disease conditions. The conflicting results of early versus advanced therapy suggest that MSCs may produce different effects depending on when they are administered and their activation status.

Macrophages in Lupus Nephritis: Exploring a potential new therapeutic avenue

Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE) that occurs in about half of patients. LN is characterized by glomerular deposition of immune complexes, leading to subendothelial, mesangial and subepithelial electron dense deposits, triggering immune cell infiltration and glomerular as well as tubulointerstitial injury. Monocytes and macrophages are abundantly present in inflammatory lesions, both in glomeruli and the tubulointerstitium. Here we discuss how monocytes and macrophages are involved in this process and how monocytes and macrophages may represent specific therapeutic targets to control LN.

Molecular targets in cerebral malaria for developing novel therapeutic strategies

Cerebral malaria (CM) is the severe neurological complication associated with Plasmodium falciparum infection. In clinical settings CM is predominantly characterized by fever, epileptic seizures, and asexual forms of parasite on blood smears, coma and even death. Cognitive impairment in the children and adults even after survival is one of the striking consequences of CM. Poor diagnosis often leads to inappropriate malaria therapy which in turn progress into a severe form of disease. Activation of multiple cell death pathways such as Inflammation, oxidative stress, apoptosis and disruption of blood brain barrier (BBB) plays critical role in the pathogenesis of CM and secondary brain damage. Thus, understanding such mechanisms of neuronal cell death might help to identify potential molecular targets for CM. Mitigation strategies for mortality rate and long-term cognitive deficits caused by existing anti-malarial drugs still remains a valid research question to ask. In this review, we discuss in detail about critical neuronal cell death mechanisms and the overall significance of adjunctive therapy with recent trends, which provides better insight towards establishing newer therapeutic strategies for CM.

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.

Recent Advances in Aptamer Discovery and Applications

Aptamers are short, single-stranded DNA, RNA, or synthetic XNA molecules that can be developed with high affinity and specificity to interact with any desired targets. They have been widely used in facilitating discoveries in basic research, ensuring food safety and monitoring the environment. Furthermore, aptamers play promising roles as clinical diagnostics and therapeutic agents. This review provides update on the recent advances in this rapidly progressing field of research with particular emphasis on generation of aptamers and their applications in biosensing, biotechnology and medicine. The limitations and future directions of aptamers in target specific delivery and real-time detection are also discussed.

The CCR2+ Macrophage Subset Promotes Pathogenic Angiogenesis for Tumor Vascularization in Fibrotic Livers

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) typically arises in fibrotic or cirrhotic livers, which are characterized by pathogenic angiogenesis. Myeloid immune cells, specifically tumor-associated macrophages (TAMs), may represent potential novel therapeutic targets in HCC, complementing current ablative or immune therapies. However, the detailed functions of TAM subsets in hepatocarcinogenesis have remained obscure.

METHODS

TAM subsets were analyzed in-depth in human HCC samples and a combined fibrosis-HCC mouse model, established by i.p. injection with diethylnitrosamine after birth and repetitive carbon tetrachloride (CCl₄) treatment for 16 weeks. Based on comprehensively phenotyping TAM subsets (fluorescence-activated cell sorter, transcriptomics) in mice, the function of CCR2⁺ TAM was assessed by a pharmacologic chemokine inhibitor. Angiogenesis was evaluated by contrast-enhanced micro-computed tomography and histology.

RESULTS

We show that human CCR2⁺ TAM accumulate at the highly vascularized HCC border and express the inflammatory marker S100A9, whereas CD163⁺ immune-suppressive TAM accrue in the HCC center. In the fibrosis-cancer mouse model, we identified 3 major hepatic myeloid cell populations with distinct messenger RNA profiles, of which CCR2⁺ TAM particularly showed activated inflammatory and angiogenic pathways. Inhibiting CCR2⁺ TAM infiltration using a pharmacologic chemokine CCL2 antagonist in the fibrosis-HCC model significantly reduced pathogenic vascularization and hepatic blood volume, alongside attenuated tumor volume.

CONCLUSIONS

The HCC microenvironment in human patients and mice is characterized by functionally distinct macrophage populations, of which the CCR2⁺ inflammatory TAM subset has pro-angiogenic properties. Understanding the functional differentiation of myeloid cell subsets in chronically inflamed liver may provide novel opportunities for modulating hepatic macrophages to inhibit tumor-promoting pathogenic angiogenesis.

Icariin alleviates murine lupus nephritis via inhibiting NF-κB activation pathway and NLRP3 inflammasome

AIMS

Lupus nephritis (LN) is a kidney inflammatory disease caused by systemic lupus erythematosus (SLE). Both NF-κB activation and NLRP3 inflammasome activation are implicated in LN pathogenesis, suggesting they are potential targets for LN treatment. Icariin, which is isolated from Chinese medicine Horny Goat Weed (Ying Yang Huo), has been shown to have anti-inflammation activity, and inhibit activations of both NF-κB and NLRP3 inflammasome. In present study, the effects of icariin on LN were evaluated in MRL/lpr mice.

MAIN METHODS

We treated MRL/lpr mice with icariin for 8 weeks and then analyzed the renal function and kidney pathology. We monitored the levels of anti-dsDNA antibody and the deposition of immune complex after icariin treatment. We also detected the macrophage infiltration, NF-κB activation, NLRP3 inflammasome activation and inflammatory cytokine TNF-α production in MRL/lpr mice after icariin treatment.

KEY FINDINGS

We found that MRL/lpr mice treated with icariin displayed significantly attenuated the renal disease. Icariin-treated mice showed significantly reduced serum anti-dsDNA antibody level and immune complex deposition. Icariin inhibited NF-κB activation and TNF-α production in MRL/lpr mice. Icariin inhibited CCL2 production and macrophage infiltration in MRL/lpr mice. Finally, icariin suppressed NLRP3 inflammasome activation and IL-1β production in MRL/lpr mice.

SIGNIFICANCE

Icariin alleviated murine lupus nephritis via inhibiting NF-κB activation and NLRP3 inflammasome activation.

Characterization of M1 and M2 polarization of macrophages in vascularized human dermo-epidermal skin substitutes in vivo

AIMS AND OBJECTIVES

Vascularized bio-engineered human dermo-epidermal skin substitutes (vascDESS) hold promise for treating burn patients, including those with severe full-thickness wounds. We have previously shown that vascDESS promote wound healing by enhanced influx of macrophages and granulocytes. Immediately following transplantation, macrophages infiltrate the graft and differentiate into a pro-inflammatory (M1) or a pro-healing M2 phenotype. The aim of this study was to characterize the activation state of macrophages infiltrating skin transplants at distinct time points following transplantation.

METHODS

Keratinocytes and the stromal vascular fraction (SVF) were derived from human skin or adipose tissue, respectively. Human SVF containing both endothelial and mesenchymal/stromal cells was used to generate vascularized dermal component in vitro, which was subsequently covered with human keratinocytes. Finally, vascDESS were transplanted on the back of immuno-incompetent rats, excised, and analyzed after 1 and 3 weeks using immunohistological techniques.

RESULTS

A panel of markers of macrophage M1 (nitric oxide synthase: iNOS) and M2 (CD206) subclass was used. All skin grafts were infiltrated by both M1 and M2 rat macrophages between 1-3 weeks post-transplantation. CD68 (PG-M1) was used as a pan-macrophage marker. The number of CD68⁺CD206⁺ M2-polarized macrophages was higher in 3-week transplants as compared to early-stage transplants (1 week). In contrast, the number of CD68⁺iNOS⁺ M1 cells was markedly decreased in later stages in vivo.

CONCLUSIONS

Macrophages exhibit a heterogeneous and temporally regulated polarization during skin wound healing. Our results suggest that the phenotype of macrophages changes during healing from a more pro-inflammatory (M1) profile in early stages after injury, to a less inflammatory, pro-healing (M2) phenotype in later phases in vivo.

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.

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.

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.

Urinary biomarkers in childhood lupus nephritis

Juvenile-onset systemic lupus erythematosus (JSLE) is a rare, severe multisystem autoimmune disease affecting the kidney (Lupus Nephritis, LN) in up to 80% of children. LN is more severe in children than adults, with potential for irreversible kidney damage requiring dialysis or transplant. Renal biopsy is currently the gold standard for diagnosing and monitoring LN, however, it is invasive and associated with complications. Urine biomarkers have been shown to be better than serum biomarkers in differentiating renal disease from other organ manifestations. Over the past decade, there have been an increasing number of studies investigating specific candidate biomarkers implicated in the pathogenesis of LN or screening for urinary biomarkers using hypothesis free methods. In this review, developments in urine biomarkers for LN will be reviewed, highlighting those that are of relevance to children and have gone through validation in independent international patient cohorts, bringing them close to clinical translation.

Necroinflammation in Kidney Disease

The bidirectional causality between kidney injury and inflammation remains an area of unexpected discoveries. The last decade unraveled the molecular mechanisms of sterile inflammation, which established danger signaling via pattern recognition receptors as a new concept of kidney injury-related inflammation. In contrast, renal cell necrosis remained considered a passive process executed either by the complement-related membrane attack complex, exotoxins, or cytotoxic T cells. Accumulating data now suggest that renal cell necrosis is a genetically determined and regulated process involving specific outside-in signaling pathways. These findings support a unifying theory in which kidney injury and inflammation are reciprocally enhanced in an autoamplification loop, referred to here as necroinflammation. This integrated concept is of potential clinical importance because it offers numerous innovative molecular targets for limiting kidney injury by blocking cell death, inflammation, or both. Here, the contribution of necroinflammation to AKI is discussed in thrombotic microangiopathies, necrotizing and crescentic GN, acute tubular necrosis, and infective pyelonephritis or sepsis. Potential new avenues are further discussed for abrogating necroinflammation-related kidney injury, and questions and strategies are listed for further exploration in this evolving field.

What is damaging the kidney in lupus nephritis?

Despite marked improvements in the survival of patients with severe lupus nephritis over the past 50 years, the rate of complete clinical remission after immune suppression therapy is <50% and renal impairment still occurs in 40% of affected patients. An appreciation of the factors that lead to the development of chronic kidney disease following acute or subacute renal injury in patients with systemic lupus erythematosus is beginning to emerge. Processes that contribute to end-stage renal injury include continuing inflammation, activation of intrinsic renal cells, cell stress and hypoxia, metabolic abnormalities, aberrant tissue repair and tissue fibrosis. A deeper understanding of these processes is leading to the development of novel or adjunctive therapies that could protect the kidney from the secondary non-immune consequences of acute injury. Approaches based on a molecular-proteomic-lipidomic classification of disease should yield new information about the functional basis of disease heterogeneity so that the most effective and least toxic treatment regimens can be formulated for individual patients.

Crosstalk between Gut Microbiota and Dietary Lipids Aggravates WAT Inflammation through TLR Signaling

Dietary lipids may influence the abundance of circulating inflammatory microbial factors. Hence, inflammation in white adipose tissue (WAT) induced by dietary lipids may be partly dependent on their interaction with the gut microbiota. Here, we show that mice fed lard for 11 weeks have increased Toll-like receptor (TLR) activation and WAT inflammation and reduced insulin sensitivity compared with mice fed fish oil and that phenotypic differences between the dietary groups can be partly attributed to differences in microbiota composition. Trif(-/-) and Myd88(-/-) mice are protected against lard-induced WAT inflammation and impaired insulin sensitivity. Experiments in germ-free mice show that an interaction between gut microbiota and saturated lipids promotes WAT inflammation independent of adiposity. Finally, we demonstrate that the chemokine CCL2 contributes to microbiota-induced WAT inflammation in lard-fed mice. These results indicate that gut microbiota exacerbates metabolic inflammation through TLR signaling upon challenge with a diet rich in saturated lipids.

Unmet medical needs in lupus nephritis: solutions through evidence-based, personalized medicine

Lupus nephritis (LN) remains a kidney disease with significant unmet medical needs despite extensive clinical and translational research over the past decade. These include the need to (i) predict the individual risk for LN in a patient with systemic lupus erythematosus, (ii) identify the best therapeutic option for an individual patient, (iii) distinguish chronic kidney damage from active immunologic kidney injury, (iv) develop efficient treatments with acceptable or no side effects and improve the design of randomized clinical trials so that effective drugs demonstrate efficacy. This review discusses the underlying reasons for these unmet medical needs and options of how to overcome them in the future.

Transplantation of Adipose Tissue-Derived Mesenchymal Stem Cells Prevents the Development of Lupus Dermatitis

MRL/lpr mice spontaneously develop high titers of anti-dsDNA antibodies and symptoms such as glomerular nephritis and organ weight gain. They also develop spontaneous skin inflammation similar to the cutaneous lesions common in human lupus erythematosus. This study aimed to compare the effects of long-term serial administration of human adipose tissue-derived mesenchymal stem cells (ASCs), CTLA4Ig-overexpressing ASCs, and cyclophosphamide treatment in MRL/lpr mice. MRL/lpr mice were divided into saline (C), cyclophosphamide (Y), ASC early (E), ASC late (L), and CTLA4Ig-overexpressing ASC (CT) treatment groups. Background-matched control MRL/MPJ mice treated with saline (N) were also compared. The treatment period was 5-23 weeks, except for the L group (15-23 weeks). Blood and tissue samples were collected when the mice were 24 weeks old. Organ weight, anti-dsDNA antibodies, urine protein, skin and kidney histologic abnormalities, and trabecular bone volume were evaluated. The Y group showed the greatest decrease in anti-dsDNA antibodies, organ weight, degree of kidney inflammation and glomerular infiltration of C3, and incidence rate of severe proteinuria; the E, L, and CT treatment groups showed better results than the C group. ASC transplantation reduced anti-dsDNA antibody levels significantly. Mice treated with ASCs or CTLA4Ig-ASCs starting from the early disease stage did not show dermatitis upon gross examination; they demonstrated significant improvement in hyperkeratosis, acanthosis, and inflammatory cell infiltration scores in histopathology. Micro-CT analysis revealed that cyclophosphamide treatment significantly decreased bone volume and increased bone spacing in the trabecular bone. Thus, we found that ASC and CTLA4-ASC treatments prevent lupus dermatitis development in MRL/lpr mice without adverse effects.

The HSP90 Inhibitor Ganetespib Alleviates Disease Progression and Augments Intermittent Cyclophosphamide Therapy in the MRL/lpr Mouse Model of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex, systemic autoimmune disease with a diverse range of immunological and clinical manifestations. The introduction of broad spectrum immunosuppressive therapies and better management of acute disease exacerbations have improved outcomes for lupus patients over recent years. However, these regimens are burdened by substantial toxicities and confer significantly higher risks of infection, thus there remains a significant and unmet medical need for alternative treatment options, particularly those with improved safety profiles. Heat shock protein 90 (HSP90) is a ubiquitously expressed molecular chaperone that acts as an important modulator of multiple innate and adaptive inflammatory processes. Of note, accumulating clinical and experimental evidence has implicated a role for HSP90 in the pathogenesis of SLE. Here we evaluated the potential of HSP90 as a therapeutic target for this disease using the selective small molecule inhibitor ganetespib in the well-characterized MRL/lpr autoimmune mouse model. In both the prophylactic and therapeutic dosing settings, ganetespib treatment promoted dramatic symptomatic improvements in multiple disease parameters, including suppression of autoantibody production and the preservation of renal tissue integrity and function. In addition, ganetespib exerted profound inhibitory effects on disease-related lymphadenopathy and splenomegaly, and reduced pathogenic T and B cell lineage populations in the spleen. Ganetespib monotherapy was found to be equally efficacious and tolerable when compared to an effective weekly dosing regimen of the standard-of-care immunosuppressive agent cyclophosphamide. Importantly, co-treatment of ganetespib with a sub-optimal, intermittent dosing schedule of cyclophosphamide resulted in superior therapeutic indices and maximal disease control. These findings highlight the potential of HSP90 inhibition as an alternative, and potentially complementary, strategy for therapeutic intervention in SLE. Such approaches may have important implications for disease management, particularly for limiting or preventing treatment-related toxicities, a major confounding factor in current SLE therapy.

Lupus nephritis: from pathogenesis to targets for biologic treatment

BACKGROUND/AIMS

Lupus nephritis is an organ manifestation of systemic autoimmunity. Current treatment algorithms are still based on unselective immunosuppressive drugs. There is hope that highly selective biological drugs could be as or even more effective but less toxic. A profound understanding of the pathogenesis of lupus nephritis is necessary to identify the optimal molecular targets.

METHODS

PubMed and www.clincialtrials.gov were searched using 'lupus nephritis' as the key word.

RESULTS

The pathogenesis of lupus nephritis is based (1) on the mechanisms that lead to loss of tolerance against nuclear autoantigens, i.e. systemic lupus, and then (2) on the mechanisms of immune complex-induced intrarenal inflammation. Systemic lupus develops when genetic variants allow autoimmunization against nuclear autoantigens, e.g. by impairing lymphocyte depletion via apoptosis, opsonization, and rapid phagocytic clearance. This allows endogenous nucleic acids to directly activate Toll-like receptors on dendritic cells or B cells, a process that drives IFN-α-driven immunity, antigen presentation, and the activation of autoreactive lymphocyte subsets. Activation of B cells and their maturation to plasma cells promotes autoantibody production and subsequent immune complex glomerulonephritis. Complement and numerous proinflammatory cytokines drive the inflammatory process that can cause kidney injury, scarring, and chronic kidney disease.

CONCLUSION

Systemic lupus is more a variable syndrome than a single disorder based on heterogeneous genetic variants and complex aberrant immune alterations. This makes it less likely that a single specific biological drug will be as efficient as currently used unselective immunosuppressive drugs. Autoantibody production and intrarenal immune complex formation are the hallmark of lupus nephritis. However, kidney injury and scarring also result from local amplification of tissue inflammation. Therefore, a combination of unselective immunosuppressive and biological drugs that block immune cell recruitment or proinflammatory cytokines may be promising to improve disease outcomes in lupus nephritis.

L-Endoglin overexpression increases renal fibrosis after unilateral ureteral obstruction

Transforming growth factor-β (TGF-β) plays a pivotal role in renal fibrosis. Endoglin, a 180 KDa membrane glycoprotein, is a TGF-β co-receptor overexpressed in several models of chronic kidney disease, but its function in renal fibrosis remains uncertain. Two membrane isoforms generated by alternative splicing have been described, L-Endoglin (long) and S-Endoglin (short) that differ from each other in their cytoplasmic tails, being L-Endoglin the most abundant isoform. The aim of this study was to assess the effect of L-Endoglin overexpression in renal tubulo-interstitial fibrosis. For this purpose, a transgenic mouse which ubiquitously overexpresses human L-Endoglin (L-ENG+) was generated and unilateral ureteral obstruction (UUO) was performed in L-ENG+ mice and their wild type (WT) littermates. Obstructed kidneys from L-ENG+ mice showed higher amounts of type I collagen and fibronectin but similar levels of α-smooth muscle actin (α-SMA) than obstructed kidneys from WT mice. Smad1 and Smad3 phosphorylation were significantly higher in obstructed kidneys from L-ENG+ than in WT mice. Our results suggest that the higher increase of renal fibrosis observed in L-ENG+ mice is not due to a major abundance of myofibroblasts, as similar levels of α-SMA were observed in both L-ENG+ and WT mice, but to the higher collagen and fibronectin synthesis by these fibroblasts. Furthermore, in vivo L-Endoglin overexpression potentiates Smad1 and Smad3 pathways and this effect is associated with higher renal fibrosis development.

Turning mirror-image oligonucleotides into drugs: the evolution of Spiegelmer(®) therapeutics

Spiegelmers are synthetic target-binding oligonucleotides built from non-natural l-nucleotides. Like aptamers, Spiegelmers fold into distinct shapes that bind the targets with high affinity and selectivity. Furthermore, the mirror-image configuration confers plasma stability and immunological passivity. Various Spiegelmers against pharmacologically attractive targets were shown to be efficacious in animal models. Three Spiegelmer candidates: emapticap pegol (NOX-E36; anti-CCL2), olaptesed pegol (NOX-A12; anti-CXCL12) and lexaptepid pegol (NOX-H94; anti-hepcidin), underwent regulatory safety studies, demonstrated good safety profiles in healthy volunteers and were taken into Phase IIa studies in patients. Proof-of-concept for emapticap pegol has recently been demonstrated in diabetic nephropathy patients. Furthermore, promising interim Phase IIa data of olaptesed pegol and lexapteptid pegol also suggest efficacy in the respective patient populations.

Immune system modulation of kidney regeneration--mechanisms and implications

The immune system is an important guardian of tissue homeostasis. In response to injury, resident and infiltrating immune cells orchestrate all phases of danger control, resolution of inflammation and tissue regeneration or scar formation. As mammalian postnatal kidneys are not capable of de novo nephrogenesis, recovery is limited to the regeneration or repair of existing nephrons. The regenerative capacity of the nephron varies between compartments; the epithelial cells of the tubule regenerate more efficiently than the structurally highly organized podocytes. Cells of the surrounding environment modulate nephron regeneration by secreting paracrine mediators. This Review discusses immune mediators and pathways that regulate the intrinsic regenerative capacity of the nephron. Eliminating injurious triggers, modulating renal inflammation and specifically enhancing the regenerative capacity of nephrons might be a promising strategy to improve long-term outcomes in patients with acute kidney injury and/or chronic kidney disease.

Role of chemokines in proteinuric kidney disorders

Experimental and human studies have shown that proteinuria contributes to the progression of renal disease. Overexposure to filtered proteins promotes the expression and release of chemokines by tubular epithelial cells, thus leading to inflammatory cell recruitment and renal impairment. This review focuses on recent progress in cellular and molecular understanding of the role of chemokines in the pathogenesis of proteinuria-induced renal injury, as well as their clinical implications and therapeutic potential.

The pathogenesis of lupus nephritis

Lupus nephritis is an immune complex GN that develops as a frequent complication of SLE. The pathogenesis of lupus nephritis involves a variety of pathogenic mechanisms. The extrarenal etiology of systemic lupus is based on multiple combinations of genetic variants that compromise those mechanisms normally assuring immune tolerance to nuclear autoantigens. This loss of tolerance becomes clinically detectable by the presence of antinuclear antibodies. In addition, nucleic acids released from netting or apoptotic neutrophils activate innate and adaptive immunity via viral nucleic acid-specific Toll-like receptors. Therefore, many clinical manifestations of systemic lupus resemble those of viral infection. In lupus, endogenous nuclear particles trigger IFN-α signaling just like viral particles during viral infection. As such, dendritic cells, T helper cells, B cells, and plasma cells all contribute to the aberrant polyclonal autoimmunity. The intrarenal etiology of lupus nephritis involves antibody binding to multiple intrarenal autoantigens rather than the deposition of circulating immune complexes. Tertiary lymphoid tissue formation and local antibody production add to intrarenal complement activation as renal immunopathology progresses. Here we provide an update on the pathogenic mechanisms that lead to lupus nephritis and provide the rationale for the latest and novel treatment strategies.

Danger control programs cause tissue injury and remodeling

Are there common pathways underlying the broad spectrum of tissue pathologies that develop upon injuries and from subsequent tissue remodeling? Here, we explain the pathophysiological impact of a set of evolutionary conserved danger control programs for tissue pathology. These programs date back to the survival benefits of the first multicellular organisms upon traumatic injuries by launching a series of danger control responses, i.e., 1. Haemostasis, or clotting to control bleeding; 2. Host defense, to control pathogen entry and spreading; 3. Re-epithelialisation, to recover barrier functions; and 4. Mesenchymal, to repair to regain tissue stability. Taking kidney pathology as an example, we discuss how clotting, inflammation, epithelial healing, and fibrosis/sclerosis determine the spectrum of kidney pathology, especially when they are insufficiently activated or present in an overshooting and deregulated manner. Understanding the evolutionary benefits of these response programs may refine the search for novel therapeutic targets to limit organ dysfunction in acute injuries and in progressive chronic tissue remodeling.

Spiegelzymes: sequence specific hydrolysis of L-RNA with mirror image hammerhead ribozymes and DNAzymes

In this manuscript we describe for the first time mirror image catalytic nucleic acids (Spiegelzymes), which hydrolyze sequence specifically L-ribonucleic acid molecules. The mirror image nucleic acid ribozymes designed are based upon the known hammerhead ribozyme and DNAzyme structures that contain L-ribose or L-deoxyribose instead of the naturally occurring D-ribose or D-deoxyribose, respectively. Both Spiegelzymes show similar hydrolytic activities with the same L-RNA target molecules and they also exhibit extra ordinary stabilities when tested with three different human sera. In this respect they are very similar to Spiegelmers (mirror image aptamers), which we had previously developed and for which it has been shown that they are non-toxic and non-immunogenic. Since we are also able to demonstrate that the hammerhead and DNAzyme Spiegelzymes can also hydrolyze mirror image oligonucleotide sequences, like they occur in Spiegelmers, in vivo, it seems reasonable to assume that Spiegelzymes may in principle be used as an antidote against Spiegelmers. Since the Spiegelzymes contain the same building blocks as the Spiegelmers, it can be expected that they will have similar favorable biological characteristics concerning toxicity and immunogenety. In trying to understand the mechanism of action of the Spiegelzymes described in this study, we have initiated for the first time a model building system with L-nucleic acids. The models for L-hammerhead ribozyme and L-DNAzyme interaction with the same L-RNA target will be presented.

Macrophages and fibrosis: How resident and infiltrating mononuclear phagocytes orchestrate all phases of tissue injury and repair

Certain macrophage phenotypes contribute to tissue fibrosis, but why? Tissues host resident mononuclear phagocytes for their support to maintain homeostasis. Upon injury the changing tissue microenvironment alters their phenotype and primes infiltrating monocytes toward pro-inflammatory macrophages. Several mechanisms contribute to their deactivation and macrophage priming toward anti-inflammatory and pro-regenerative macrophages that produce multiple cytokines that display immunosuppressive as well as pro-regeneratory effects, such as IL-10 and TGF-beta1. Insufficient parenchymal repair creates a tissue microenvironment that becomes dominated by multiple growth factors that promote the pro-fibrotic macrophage phenotype that itself produces large amounts of such growth factors that further support fibrogenesis. However, the contribution of resident mononuclear phagocytes to physiological extracellular matrix turnover implies also their fibrolytic effects in the late stage of tissue scaring. Fibrolytic macrophages break down fibrous tissue, but their phenotypic characteristics remain to be described in more detail. Together, macrophages contribute to tissue fibrosis because the changing tissue environments prime them to assist and orchestrate all phases of tissue injury and repair. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Targeting chemokines in proteinuria-induced renal disease

INTRODUCTION

Proteinuria is a common finding in glomerular diseases that contributes to the progression of chronic kidney injury. Tubular cells reabsorb the excess of albumin and other plasma proteins from the tubular lumen, triggering several pathophysiologic responses, such as overexpression of fibrogenic mediators and inflammatory chemokines. Chemokines are implicated both in the recruitment of inflammatory infiltrate and in a number of physiological and pathological processes related to protein overload.

AREAS COVERED

In recent years, the specific chemokines and their receptors and the intracellular signaling pathways involved in proteinuria-induced renal damage have been identified. This review provides an overview of the role of chemokines and their receptors in proteinuria-related renal disease and summarizes novel therapeutic approaches to restrain the progression of renal damage.

EXPERT OPINION

Inhibition of chemokine-induced biological activities is a promising therapeutic strategy in proteinuric disorders. Neutralizing antibodies and small organic molecules targeting chemokines and chemokine receptors have been proven to prevent inflammation and renal damage in experimental models of protein overload. Some of these compounds are currently being tested in human clinical trials.

Tissues use resident dendritic cells and macrophages to maintain homeostasis and to regain homeostasis upon tissue injury: the immunoregulatory role of changing tissue environments

Most tissues harbor resident mononuclear phagocytes, that is, dendritic cells and macrophages. A classification that sufficiently covers their phenotypic heterogeneity and plasticity during homeostasis and disease does not yet exist because cell culture-based phenotypes often do not match those found in vivo. The plasticity of mononuclear phagocytes becomes obvious during dynamic or complex disease processes. Different data interpretation also originates from different conceptual perspectives. An immune-centric view assumes that a particular priming of phagocytes then causes a particular type of pathology in target tissues, conceptually similar to antigen-specific T-cell priming. A tissue-centric view assumes that changing tissue microenvironments shape the phenotypes of their resident and infiltrating mononuclear phagocytes to fulfill the tissue's need to maintain or regain homeostasis. Here we discuss the latter concept, for example, why different organs host different types of mononuclear phagocytes during homeostasis. We further discuss how injuries alter tissue environments and how this primes mononuclear phagocytes to enforce this particular environment, for example, to support host defense and pathogen clearance, to support the resolution of inflammation, to support epithelial and mesenchymal healing, and to support the resolution of fibrosis to the smallest possible scar. Thus, organ- and disease phase-specific microenvironments determine macrophage and dendritic cell heterogeneity in a temporal and spatial manner, which assures their support to maintain and regain homeostasis in whatever condition. Mononuclear phagocytes contributions to tissue pathologies relate to their central roles in orchestrating all stages of host defense and wound healing, which often become maladaptive processes, especially in sterile and/or diffuse tissue injuries.

Role of TWEAK in lupus nephritis: a bench-to-bedside review

There is significant unmet need in the treatment of lupus nephritis (LN) patients. In this review, we highlight the role of the TWEAK/Fn14 pathway in mediating key pathologic processes underlying LN involving both glomerular and tubular injury, and thus the potential for renal protection via blockade of this pathway. The specific pathological mechanisms of TWEAK - namely promoting inflammation, renal cell proliferation and apoptosis, vascular activation and fibrosis - are described, with supporting data from animal models and in vitro systems. Furthermore, we detail the translational relevance of these mechanisms to clinical readouts in human LN. We present the opportunity for an anti-TWEAK therapeutic as a renal protective agent to improve efficacy relative to current standard of care treatments hopefully without increased safety risk, and highlight a phase II trial with BIIB023, an anti-TWEAK neutralizing antibody, designed to assess efficacy in LN patients. Taken together, targeting the TWEAK/Fn14 axis represents a potential new therapeutic paradigm for achieving renal protection in LN patients.

Tissue microenvironments define and get reinforced by macrophage phenotypes in homeostasis or during inflammation, repair and fibrosis

Current macrophage phenotype classifications are based on distinct in vitro culture conditions that do not adequately mirror complex tissue environments. In vivo monocyte progenitors populate all tissues for immune surveillance which supports the maintenance of homeostasis as well as regaining homeostasis after injury. Here we propose to classify macrophage phenotypes according to prototypical tissue environments, e.g. as they occur during homeostasis as well as during the different phases of (dermal) wound healing. In tissue necrosis and/or infection, damage- and/or pathogen-associated molecular patterns induce proinflammatory macrophages by Toll-like receptors or inflammasomes. Such classically activated macrophages contribute to further tissue inflammation and damage. Apoptotic cells and an-tiinflammatory cytokines dominate in postinflammatory tissues which induce macrophages to produce more anti-inflammatory mediators. Similarly, tumor-associated macrophages also confer immunosuppression in tumor stroma. Insufficient parenchymal healing despite abundant growth factors pushes macrophages to gain a profibrotic phenotype and promote fibrocyte recruitment which both enforce tissue scarring. Ischemic scars are largely devoid of cytokines and growth factors so that fibrolytic macrophages that predominantly secrete proteases digest the excess extracellular matrix. Together, macrophages stabilize their surrounding tissue microenvironments by adapting different phenotypes as feed-forward mechanisms to maintain tissue homeostasis or regain it following injury. Furthermore, macrophage heterogeneity in healthy or injured tissues mirrors spatial and temporal differences in microenvironments during the various stages of tissue injury and repair.

Four danger response programs determine glomerular and tubulointerstitial kidney pathology: clotting, inflammation, epithelial and mesenchymal healing

Renal biopsies commonly display tissue remodeling with a combination of many different findings. In contrast to trauma, kidney remodeling largely results from intrinsic responses, but why? Distinct danger response programs were positively selected throughout evolution to survive traumatic injuries and to regenerate tissue defects. These are: (1) clotting to avoid major bleeding, (2) immunity to control infection, (3) epithelial repair and (4) mesenchymal repair. Collateral damages are acceptable for the sake of host survival but causes for kidney injury commonly affect the kidneys in a diffuse manner. This way, coagulation, inflammation, deregulated epithelial healing or fibrosis contribute to kidney remodeling. Here, I focus on how these ancient danger response programs determine renal pathology mainly because they develop in a deregulated manner, either as insufficient or overshooting processes that modulate each other. From a therapeutic point of view, immunopathology can be prevented by suppressing sterile renal inflammation, a useless atavism with devastating consequences. In addition, it appears as an important goal for the future to promote podocyte and tubular epithelial cell repair, potentially by stimulating the differentiation of their newly discovered intrarenal progenitor cells. By contrast, it is still unclear whether selectively targeting renal fibrogenesis can preserve or bring back lost renal parenchyma, which would be required to maintain or improve kidney function. Thus, renal pathology results from ancient danger responses that evolved because of their evolutional benefits upon trauma. Understanding these causalities may help to shape the search for novel treatments for kidney disease patients.

Targeting the hepcidin-ferroportin axis to develop new treatment strategies for anemia of chronic disease and anemia of inflammation

Anemia of chronic disease (ACD) or anemia of inflammation is prevalent in patients with chronic infection, autoimmune disease, cancer, and chronic kidney disease. ACD is associated with poor prognosis and lower quality of life. Management of ACD using intravenous iron and erythropoiesis stimulating agents are ineffective for some patients and are not without adverse effects, driving the need for new alternative therapies. Recent advances in our understanding of the molecular mechanisms of iron regulation reveal that increased hepcidin, the iron regulatory hormone, is a key factor in the development of ACD. In this review, we will summarize the role of hepcidin in iron homeostasis, its contribution to the pathophysiology of ACD, and novel strategies that modulate hepcidin and its target ferroportin for the treatment of ACD.

Exploring the role of chirality in nucleic acid recognition

The study of the base-pairing properties of nucleic acids with sugar moieties in the backbone belonging to the L-series (β-L-DNA, β-L-RNA, and their analogs) are reviewed. The major structural factors underlying the formation of stable heterochiral complexes obtained by incorporation of modified nucleotides into natural duplexes, or by hybridization between homochiral strands of opposite sense of chirality are highlighted. In addition, the perspective use of L-nucleic acids as candidates for various therapeutic applications, or as tools for both synthetic biology and etiology-oriented investigations on the structure and stereochemistry of natural nucleic acids is discussed.

RNA aptamers: a review of recent trends and applications

RNA aptamers, small oligonucleotides derived by an in-vitro selection process called SELEX (Systematic Evolution of Ligands by EXperimental enrichment), are important candidates for therapeutic and diagnostic applications. RNA aptamers have high affinity and specificity for their target molecules. In this review, we describe methods for generating RNA aptamers (the SELEX technique and modified SELEX processes) and therapeutic applications for diseases such as neovascular age-related macular degeneration (AMD), inflammatory diseases, and obesity. We also analyze the social networks among researchers and organizations (universities, research institutes, firms, etc.) that are active in the pursuit of aptamer-based therapeutic approaches. This study provides relevant information on recent research trends in RNA aptamers.

Recombinant chaperonin 10 suppresses cutaneous lupus and lupus nephritis in MRL-(Fas)lpr mice

BACKGROUND

Systemic lupus erythematosus (SLE) is still treated with global immunosuppressants with serious toxicities. We hypothesized that endogenous immunosuppressive molecules might be able to control SLE manifestations more specifically. Heat shock protein 10, or chaperonin 10 (Cpn10), is a secretory molecule that can suppress innate and adaptive immunity.

METHODS

Recombinant human Cpn10 (100 μg per mouse) was given intraperitoneally to healthy-appearing female MRL-(Fas)lpr mice from 12 to 22 weeks of age. At the age of 22 weeks, mice were analysed for treatment outcome by harvesting organs, plasma and urine.

RESULTS

Cpn10 entirely prevented cutaneous lupus lesions as compared to vehicle-treated mice. Cpn10 also suppressed lupus nephritis as evident from serum creatinine levels, albuminuria and the scores of disease activity and chronicity. Autoimmune lung disease was unaffected by Cpn10 treatment while overall survival of mice was prolonged. Cpn10 did not have any major effects on either dendritic cell or B-cell counts except T cells in spleen, plasma interferon-gamma, tumour necrosis factor-alpha, interleukin-10, anti-nuclear autoantibody levels or markers of lymphoproliferation.

CONCLUSIONS

In summary, recombinant Cpn10 selectively prevents cutaneous lupus and suppresses nephritis in MRL-(Fas)lpr mice without affecting the underlying systemic autoimmune process. Hence, Cpn10 might be useful for the treatment of skin and kidney manifestations of SLE.

Activated protein C attenuates systemic lupus erythematosus and lupus nephritis in MRL-Fas(lpr) mice

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease leading to inflammatory tissue damage in multiple organs (e.g., lupus nephritis). Current treatments including steroids, antimalarials, and immunosuppressive drugs have significant side effects. Activated protein C is a natural protein with anticoagulant and immunomodulatory effects, and its recombinant version has been approved by the U.S. Food and Drug Administration to treat severe sepsis. Given the similarities between overshooting immune activation in sepsis and autoimmunity, we hypothesized that recombinant activated protein C would also suppress SLE and lupus nephritis. To test this concept, autoimmune female MRL-Fas(lpr) mice were injected with either vehicle or recombinant human activated protein C from week 14-18 of age. Activated protein C treatment significantly suppressed lupus nephritis as evidenced by decrease in activity index, glomerular IgG and complement C3 deposits, macrophage counts, as well as intrarenal IL-12 expression. Further, activated protein C attenuated cutaneous lupus and lung disease as compared with vehicle-treated MRL-Fas(lpr) mice. In addition, parameters of systemic autoimmunity, such as plasma cytokine levels of IL-12p40, IL-6, and CCL2/MCP-1, and numbers of B cells and plasma cells in spleen were suppressed by activated protein C. The latter was associated with lower total plasma IgM and IgG levels as well as lower titers of anti-dsDNA IgG and rheumatoid factor. Together, recombinant activated protein C suppresses the abnormal systemic immune activation in SLE of MRL-Fas(lpr) mice, which prevents subsequent kidney, lung, and skin disease. These results implicate that recombinant activated protein C might be useful for the treatment of human SLE.

Lack of the long pentraxin PTX3 promotes autoimmune lung disease but not glomerulonephritis in murine systemic lupus erythematosus

The long pentraxin PTX3 has multiple roles in innate immunity. For example, PTX3 regulates C1q binding to pathogens and dead cells and regulates their uptake by phagocytes. It also inhibits P-selectin-mediated recruitment of leukocytes. Both of these mechanisms are known to be involved in autoimmunity and autoimmune tissue injury, e.g. in systemic lupus erythematosus, but a contribution of PTX3 is hypothetical. To evaluate a potential immunoregulatory role of PTX3 in autoimmunity we crossed Ptx3-deficient mice with Fas-deficient (lpr) C57BL/6 (B6) mice with mild lupus-like autoimmunity. PTX3 was found to be increasingly expressed in kidneys and lungs of B6lpr along disease progression. Lack of PTX3 impaired the phagocytic uptake of apoptotic T cells into peritoneal macrophages and selectively expanded CD4/CD8 double negative T cells while other immune cell subsets and lupus autoantibody production remained unaffected. Lack of PTX3 also aggravated autoimmune lung disease, i.e. peribronchial and perivascular CD3+ T cell and macrophage infiltrates of B6lpr mice. In contrast, histomorphological and functional parameters of lupus nephritis remained unaffected by the Ptx3 genotype. Together, PTX3 specifically suppresses autoimmune lung disease that is associated with systemic lupus erythematosus. Vice versa, loss-of-function mutations in the Ptx3 gene might represent a genetic risk factor for pulmonary (but not renal) manifestations of systemic lupus or other autoimmune diseases.

An orally active chemokine receptor CCR2 antagonist prevents glomerulosclerosis and renal failure in type 2 diabetes

The progression of diabetic nephropathy is associated with an infiltration of macrophages expressing different phenotypes. As classically activated chemokine receptor CCR2+ macrophages are thought to drive tissue inflammation and remodeling, we tested whether blocking CCR2 could reduce intrarenal inflammation and prevent glomerulosclerosis in type 2 diabetes. This was achieved with RO5234444, an orally active small-molecule CCR2 antagonist that blocks ligand binding, its internalization, and monocyte chemotaxis. Male type 2 diabetic db/db mice were uninephrectomized to increase glomerular hyperfiltration to accelerate the development of glomerulosclerosis. From 16 weeks until killing at 24 weeks of age, mice were chow fed with or without admixed antagonist to achieve a trough plasma concentration above IC50 for binding in the mouse. CCR2 blockade reduced circulating monocyte levels, but did not affect total leukocyte or neutrophil numbers, and was associated with a reduction in the number of macrophages and apoptotic podocytes in the glomerulus. This treatment resulted in a higher total number of podocytes, less glomerulosclerosis, reduced albuminuria, and a significantly improved glomerular filtration rate. This successful pre-clinical trial suggests that this antagonist may now be ready for testing in humans with the nephropathy of diabetes mellitus.

Targeting the recruitment of monocytes and macrophages in renal disease

Macrophages convert proinflammatory or anti-inflammatory signals of tissue microenvironments into response mechanisms. These response mechanisms largely derive from evolutionary conserved defense programs of innate host defense, wound healing, and tissue homeostasis. Hence, in many settings these programs lead to renal inflammation and tissue remodeling (ie, glomerulonephritis and sclerosis or interstitial nephritis and fibrosis). There is abundant experimental evidence that blocking macrophage recruitment or macrophage activation can ameliorate renal inflammation and fibrosis. In this review we discuss experimental tools to target renal macrophage recruitment by using antagonists against selectins, chemokines, integrins, or other important cytokines that mediate renal injury via macrophage recruitment, some of these already having been used in clinical trials.

Aptamers as therapeutics

Aptamers are single-stranded oligonucleotides that fold into defined architectures and bind to targets such as proteins.

In binding proteins they often inhibit protein–protein interactions and thereby may elicit therapeutic effects such as antagonism.

Aptamers are discovered using SELEX (systematic evolution of ligands by exponential enrichment), a directed in vitro evolution technique in which large libraries of degenerate oligonucleotides are iteratively and alternately partitioned for target binding. They are then amplified enzymatically until functional sequences are identified by the sequencing of cloned individuals.

For most therapeutic purposes, aptamers are truncated to reduce synthesis costs, modified at the sugars and capped at their termini to increase nuclease resistance, and conjugated to polyethylene glycol or another entity to reduce renal filtration rates.

The first aptamer approved for a therapeutic application was pegaptanib sodium (Macugen; Pfizer/Eyetech), which was approved in 2004 by the US Food and Drug Administration for macular degeneration.

Eight other aptamers are currently undergoing clinical evaluation for various haematology, oncology, ocular and inflammatory indications.

Aptamers are ultimately chemically synthesized in a readily scalable process in which specific conjugation points are introduced with defined stereochemistry.

Unlike some protein therapeutics, aptamers do not elicit antibodies, and because aptamers generally contain sugars modified at their 2′-positions, Toll-like receptor-mediated innate immune responses are also abrogated.

As aptamers are oligonucleotides they can be readily assembled into supramolecular multi-component structures using hybridization.

Owing to the fact that binding to appropriate cell-surface targets can lead to internalization, aptamers can also be used to deliver therapeutic cargoes such as small interfering RNA.

Supramolecular assemblies of aptamers and delivery agents have already been demonstrated in vivo and may pave the way for further therapeutic strategies with this modality in the future.

Aptamers are oligonucleotide sequences that are capable of recognizing target proteins with an affinity and specificity rivalling that of antibodies. In this article, Keefe and colleagues discuss the development, properties and therapeutic potential of aptamers, highlighting those currently in the clinic.

Nucleic acid aptamers can be selected from pools of random-sequence oligonucleotides to bind a wide range of biomedically relevant proteins with affinities and specificities that are comparable to antibodies. Aptamers exhibit significant advantages relative to protein therapeutics in terms of size, synthetic accessibility and modification by medicinal chemistry. Despite these properties, aptamers have been slow to reach the marketplace, with only one aptamer-based drug receiving approval so far. A series of aptamers currently in development may change how nucleic acid therapeutics are perceived. It is likely that in the future, aptamers will increasingly find use in concert with other therapeutic molecules and modalities.

4SC-101, a novel small molecule dihydroorotate dehydrogenase inhibitor, suppresses systemic lupus erythematosus in MRL-(Fas)lpr mice

Immunosuppressive treatments of systemic lupus (SLE) remain associated with significant toxicities; hence, compounds with better toxicity profiles are needed. Dihydroorotate dehydrogenase (DHODH) inhibition with leflunomide has proven to be effective in autoimmune diseases including SLE, but leflunomide can cause a variety of side effects. We hypothesized that 4SC-101, a novel DHODH inhibitor with a more favorable toxicity profile, would be as effective as high-dose cyclophosphamide (CYC) in controlling experimental SLE of female MRL(Fas)lpr mice. Daily oral gavage of 30, 100, and 300 mg/kg 4SC-101 from 12 to 22 weeks of age was compared with either vehicle or CYC treatment (30 mg/kg/week, i.p.) in terms of efficacy and toxicity. Three hundred milligrams per kilogram 4SC-101 was as effective as CYC in depleting spleen autoreactive T cells, B cells, and plasma cells as well as the respective DNA and RNA serum autoantibodies. This was associated with a comparable amelioration of the renal, dermal, and pulmonary SLE manifestations of MRL(Fas)lpr mice. However, even the highest dose of 4SC-101 had no effect on bone marrow neutrophil counts, which were significantly reduced in CYC-treated mice. Together, the novel DHODH inhibitor 4SC-101 is as effective as high dose CYC in controlling SLE without causing myelosuppression. Hence, DHODH inhibition with 4SC-101 might be suitable to treat active SLE with fewer side effects than CYC.

Lupus nephritis: lessons from murine models

Lupus nephritis is a challenging clinical condition for which current therapies are unsatisfactory with respect to both remission induction and unwanted toxic effects. Despite intervention, the rates of end-stage renal disease seem to be increasing in the USA. Discoveries over the past decade have greatly improved our understanding of immune activation and effector inflammatory pathways in lupus nephritis; however, this increased understanding has not yet translated into the approval of an effective new therapeutic agent. An analysis of the mechanisms of action of novel immunomodulatory drugs in multiple models of murine lupus clearly shows that interacting networks of immune and effector pathways are recruited as the disease progresses. Reversing established disease by targeting a single cell population or inflammatory pathway is, therefore, difficult once long-lived autoreactive lymphocyte populations are present and peripheral organs are inflamed. Data from murine models of lupus suggest that we need to consider new paradigms for the management of systemic lupus erythematosus that include earlier immune intervention, long-term maintenance therapies and protection of target organs.