Laquinimod delays and suppresses nephritis in lupus-prone mice and affects both myeloid and lymphoid immune cells

The roles of adenosine signaling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multiple etiological factors. Immune disorder contributes to SLE development and is an important clinical manifestation of SLE patients. Immune dysfunction is characterized by abnormal of B cells, T cells, monocyte-macrophages and dendritic cells (DCs), in both quantity and quality. Adenosine is a critical factor for human immune homeostasis, which acts as an immunosuppressive signal and can prevent the hyperactivity of human immune system. Adenosine levels are significant decreased in serum from SLE patients. Adenosine level is regulated by the CD39, CD73 and adenosine deaminase (ADA). CD39/CD73/ADA catalyzed the cascade enzymatic reaction, which contained the adenosine generation and degradation. Adenosine affects the function of various immune cells via bind to the adenosine receptors, which are expressed on the cell surface. This review aims to export the changes of immune cells and adenosine signal pathway in SLE, as well as the effect of adenosine signal pathway in SLE development.

Dexamethasone promotes renal fibrosis by upregulating ILT4 expression in myeloid-derived suppressor cells

Studies have shown that adoptive transfer of myeloid-derived suppressor cells (MDSCs) can alleviate various inflammatory diseases, including glomerulonephritis, but the long-term effects of the transferred MDSCs are still unclear. In addition, although glucocorticoids exert immunosuppressive effects on inflammatory diseases by inducing the expansion of MDSCs, the impact of glucocorticoids on the immunosuppressive function of MDSCs and their molecular mechanisms are unclear. In this study, we found that adoptive transfer of MDSCs to doxorubicin-induced focal segmental glomerulosclerosis (FSGS) mice for eight consecutive weeks led to an increase in serum creatinine and proteinuria and aggravation of renal interstitial fibrosis. Similarly, 8 weeks of high-dose dexamethasone administration exacerbated renal interstitial injury and interstitial fibrosis in doxorubicin-induced mice, manifested as an increase in serum creatinine and proteinuria, collagen deposition and α-SMA expression. On this basis, we found that dexamethasone could enhance MDSC expression and secretion of the fibrosis-related cytokines TGF-β and IL-10. Mechanistically, we revealed that dexamethasone promotes the expression of immunoglobulin-like transcription factor 4 (ILT4), which enhances the T-cell inhibitory function of MDSCs and promotes the activation of STAT6, thereby strengthening the expression and secretion of TGF-β and IL-10. Knocking down ILT4 alleviated renal fibrosis caused by adoptive transfer of MDSCs. Therefore, our findings demonstrate that the role and mechanism of dexamethasone mediate the expression and secretion of TGF-β and IL-10 in MDSCs by promoting the expression of ILT4, thereby leading to renal fibrosis.

Promising Experimental Treatments for Lupus Nephritis: Key Talking Points and Potential Opportunities

Lupus nephritis (LN) is a frequent and serious complication of systemic lupus erythematosus (SLE), impairing patients' quality of life and significantly increasing mortality. Despite optimizing the use of conventional immunosuppressants and other biological drugs, its management remains unsatisfactory. This is mainly due to the heterogeneity of SLE, but also to insufficiently effective treatment regimens and clinical trial limitations (strict criteria, low number of patients included, and side effects). Most clinical trials of new biological therapies have failed to meet their primary endpoints in both general SLE and LN, with only two biological drugs (belimumab and anifrolumab) being approved by the Food and Drug Administration (FDA) for the treatment of SLE. Recently, several Phase II randomized controlled trials have evaluated the efficacy and safety of new biologics in LN, and some of them have demonstrated an improvement in clinical and laboratory measures. Multi-target therapies are also being successfully developed and encourage a belief that there will be an improvement in LN outcomes.

In situ gel-forming oil as rectally delivering platform of hydrophobic therapeutics for ulcerative colitis therapy

Because of their poor water-soluble properties and non-specific distribution, most hydrophobic therapeutics had limited benefit for patients with ulcerative colitis. Herein, an in-situ oil-based gel has been developed as a rectal delivery vehicle for these therapeutics. In situ gel-forming oil (BBLG) was composed of soybean phosphatidyl choline (40%, w/w), glyceryl dioleate (50%, w/w), and ethanol (10%, w/w). The hydrophobic laquinimod (LAQ) as a model drug was easily dissolved in gel-forming oil and its solubility was reaching to 7 ± 0.1 mg/mL. Importantly, upon contact with the colonic fluids, the gel-forming oil was quickly transited to a semi-solid gel, adhering to the inflamed colon mucosa and forming a protective barrier. Transmission Electron Microscopy showed that the gel network was arranged by the connected lipid spheres and LAQ was non-crystally encapsulated into the lipid spheres. Moreover, the universal adhesive test showed that the adhesive force and the adhesive energy of BBLG toward fresh colon tissues were 711±12 mN and 25 ± 2 J/m², which was 2.14-fold and 5-fold higher than that of the marketed Poloxamer 407 gel, respectively. Meanwhile, in vivo imaging confirmed that the retention time of BBLG in the colon lumen was more than 8 h after rectal administration. In vivo animal studies showed that BBLG also greatly enhanced the therapeutic impact of LAQ on TNBS-treated rats with ulcerative colitis, as evidenced by reduced disease activity index (DAI) scores and weight loss. Moreover, the colonic inflammation was significantly alleviated and the goblet cells were obliviously restored after treatment. Importantly, the gut mucosa barrier was largely repaired without any formation of fibrosis remodeling. Conclusively, in situ liquid gel may be a potential delivery system of hydrophobic medicines for ulcerative colitis.

Halofuginone ameliorates systemic lupus erythematosus by targeting Blk in myeloid-derived suppressor cells

Systemic lupus erythematosus (SLE) is a multisystemic, inflammatory autoimmune disease. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells participated in the pathogenesis of SLE. MDSCs has been considered a potential therapeutic target for lupus. As traditional Chinese medicine, Halofuginone (HF) has the extensive immunomodulatory effects on some autoimmune disorders. Our research was dedicated to discovering therapeutic efficacy of HF for lupus to explore novel mechanisms on MDSCs. We found that HF prominently alleviated the systemic symptoms especially nephritis in Imiquimod-induced lupus mice, and simultaneously repaired the immune system, reflected in the alteration of autoantibodies. HF diminished the quantity of MDSCs in lupus mice, and induced apoptosis of MDSCs. Through RNA sequencing performed on the sorted MDSC from lupus mice and HF-treated lupus mice, B lymphoid tyrosine kinase (Blk, a non-receptor cytoplasmic tyrosine kinase) was screened as the target molecule of HF. It's proven that HF had two independent effects on Blk. On the one hand, HF increased the mRNA expression of Blk in MDSCs by inhibiting the nuclear translocation of p65/p50 heterodimer. On the other hand, HF enhanced the kinase activity of Blk in MDSCs through direct molecular binding. We further investigated that Blk suppressed the phosphorylation of downstream ERK signaling pathway to increase the apoptosis of MDSCs. In conclusion, our study illustrated that HF alleviated the disease progression of lupus mice by targeting Blk to promote the apoptosis of MDSCs, which indicated the immunotherapeutic potential of HF to treat lupus.

The emerging role of regulatory cell-based therapy in autoimmune disease

Autoimmune disease, caused by unwanted immune responses to self-antigens, affects millions of people each year and poses a great social and economic burden to individuals and communities. In the course of autoimmune disorders, including rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and multiple sclerosis, disturbances in the balance between the immune response against harmful agents and tolerance towards self-antigens lead to an immune response against self-tissues. In recent years, various regulatory immune cells have been identified. Disruptions in the quality, quantity, and function of these cells have been implicated in autoimmune disease development. Therefore, targeting or engineering these cells is a promising therapeutic for different autoimmune diseases. Regulatory T cells, regulatory B cells, regulatory dendritic cells, myeloid suppressor cells, and some subsets of innate lymphoid cells are arising as important players among this class of cells. Here, we review the roles of each suppressive cell type in the immune system during homeostasis and in the development of autoimmunity. Moreover, we discuss the current and future therapeutic potential of each one of these cell types for autoimmune diseases.

Aryl Hydrocarbon Receptor Mechanisms Affecting Chronic Kidney Disease

The aryl hydrocarbon receptor (AHR) is a basic helix-loop-helix transcription factor that binds diverse endogenous and xenobiotic ligands, which regulate AHR stability, transcriptional activity, and cell signaling. AHR activity is strongly implicated throughout the course of chronic kidney disease (CKD). Many diverse organic molecules bind and activate AHR and these ligands are reported to either promote glomerular and tubular damage or protect against kidney injury. AHR crosstalk with estrogen, peroxisome proliferator-activated receptor-γ, and NF-κB pathways may contribute to the diversity of AHR responses during the various forms and stages of CKD. The roles of AHR in kidney fibrosis, metabolism and the renin angiotensin system are described to offer insight into CKD pathogenesis and therapies.

Role of Myeloid-derived suppressor cell (MDSC) in autoimmunity and its potential as a therapeutic target

Myeloid suppressor cells (MDSCs) are an important class of immune-regulating cells that can suppress T cell function. Most of our knowledge about the function of MDSC comes from studies of cancer models. Recent studies, however, have greatly contributed to the description of MDSC involvement in autoimmune diseases. They are known as a cell population that may negatively affect immune responses by regulating the function of CD4⁺ and CD8⁺ cells, which makes them an attractive target for autoimmune diseases therapy. However, many questions about MDSC activation, differentiation, and inhibitory functions remain unanswered. In this study, we have summarized the role of MDSCs in various autoimmune diseases, and the potential of targeting them for therapeutic benefits has been discussed.

IRF-8/miR-451a regulates M-MDSC differentiation via the AMPK/mTOR signal pathway during lupus development

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease. Myeloid-derived suppressor cells (MDSCs) have been found to be involved in the regulation of SLE development. However, little is known about the association between MDSC subsets and the factors that draw MDSCs into abnormal expansion. This study found that the percentage of M-MDSCs increased in mice with pristane-induced lupus. Toll-like receptor (TLR)7 signal activation and high interferon-α (IFN-α) level promoted M-MDSC differentiation in vitro. Moreover, both AMP-activated protein kinase (AMPK) agonist metformin and two mammalian targets of rapamycin (mTOR) inhibitors (INK128 and rapamycin) inhibited the percentage of M-MDSCs in lupus mice as well as in the TLR7- and IFN-α-induced bone marrow (BM) differentiation into MDSCs in vitro. In terms of mechanism, whole-genome transcriptome profiling was performed by RNA sequencing, revealing that the expression of the transcription factor IRF-8 was higher in M-MDSCs isolated from pristane-induced lupus mice, compared with control mice. IRF-8 was identified to be crucial for TLR7- and IFN-α-induced BM differentiation into MDSCs in vitro. Furthermore, interferon (IFN) regulatory factor8 (IRF-8) was targeted by miR-451a in M-MDSC differentiation. Of note, metformin-modified M-MDSCs could relieve lupus symptoms in pristane-induced lupus mice. The findings revealed a novel mechanism linking IRF-8/miR-451a to M-MDSC differentiation via the AMPK/mTOR signal pathway during lupus development. This study might provide an important reference for SLE therapy by targeting M-MDSCs.

Myeloid-derived suppressor cells: Important communicators in systemic lupus erythematosus pathogenesis and its potential therapeutic significance

Systemic lupus erythematosus (SLE) is a recognized chronic condition associated with immune system disorders that affect women nine times more commonly than men. SLE is characterized by over-secretion and release of autoantibodies in response to different cellular compartments and self-tolerance breaks to its own antigens. The detailed immunological dysregulation as an associated event that elicits the onset of clinical manifestations of SLE has not been clarified yet. Though, research using several animal models in the last two decades has indicated the role of the immune system in the pathogenesis of this disease. Myeloid-derived suppressor cells (MDSCs) as heterogeneous myeloid cells, are responsible for severe pathological conditions, including infection, autoimmunity, and cancer, by exerting considerable immunosuppressive effects on T-cells responses. It has been reported that these cells are involved in the regulation process of the immune response in several autoimmune diseases, particularly SLE. The function of MDSC is deleterious in infection and cancer diseases, though their role is more complicated in autoimmune diseases. In this review, we summarized the role and function of MDSCs in the pathogenesis and progression of SLE and its possible therapeutic approach.

Chylomicrons-Simulating Sustained Drug Release in Mesenteric Lymphatics for the Treatment of Crohn's-Like Colitis

BACKGROUND AND AIMS

Alteration to both the structures and functions of mesenteric lymphatic vessels is a typical hallmark of Crohn's disease [CD]. Dysfunctional lymphatics was observed in patients with both CD and experimental colitis, suggesting mesenteric lymphatics could be potential therapeutic targets. This study aimed to develop a nano-delivery system which can enhance drug delivery in mesenteric lymphatic tissue [MLT] and evaluate the therapeutic effects in Crohn's colitis.

METHODS

We designed a mesoporous silica nanoparticle [MSN] conjugated with long-chain fatty acid [LMSN] and covered with enteric coating [ELMSN] which can be specifically transported via the mesenteric lymphatic system. The therapeutic efficacy of laquinimod-loaded nanoparticles [LAQ@ELMSN] was evaluated in the well-established interleukin [IL]-10-/- spontaneous experimental colitis.

RESULTS

ELMSNs induced sustainable drug release that markedly increased drug concentration in MLT. In experimental colitis, the lymphatics-targeting drug delivery system suppressed lymphangitis and promoted lymphatic drainage. The downregulation of pro-inflammatory cytokines and the downstream NF-κB-related proteins efficiently inhibited lymphangiogenesis and restored tight junctions of mesenteric lymphatic vessels [MLVs]. LAQ@ELMSN showed a superior therapeutic effect in ameliorating intestinal inflammation compared with free drug administration. Alteration of gut microbiota and metabolites in experimental colitis was also reversed by LAQ@ELMSN.

CONCLUSION

Our study demonstrates a convenient, orally administered drug delivery system which enhances drug release in MLT. The results confirm the contribution of the mesenteric lymphatic system to the pathogenesis of gut inflammation and shed light on the application of lymphatics-targeting drug delivery therapy as a potential therapeutic strategy for CD treatment.

Myeloid-derived suppressor cells as cellular immunotherapy in transplantation and autoimmune diseases

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells, which have been characterized for their immunosuppressive capacity through multiple mechanisms. These cells have been extensively studied in the field of tumor immunity. Emerging evidence has highlighted its essential role in maintaining immune tolerance in transplantation and autoimmunity. Because of their robust immune inhibitory activities, there has been growing interest in MDSC-based cellular therapy. Various pre-clinical studies have demonstrated that the adoptive transfer of MDCS represented a promising therapeutic strategy for immune-related disorders. In this review, we summarize relevant studies of MDSC-based cell therapy in transplantation and autoimmune diseases and discuss the challenges and future directions for clinical application of MDSC-based cell therapy.

Laquinimod Inhibits Inflammation-Induced Angiogenesis in the Cornea

Background: Inflammation-induced angiogenesis plays a critical role in many eye diseases, and abnormal angiogenesis inhibition is regarded as a therapeutic approach. Here, we examined the effects of laquinimod on inflammatory corneal angiogenesis.

Methods: Mouse model of corneal neovascularization was induced by NaOH. Laquinimod or control vehicle were topically applied to alkali-treated eyes twice a day for 10 days. Corneal neovascularization, infiltrating inflammatory cells, and the levels of chemokines, pro-inflammatory cytokines were assessed. RAW cells and human umbilical vein endothelial cells were used in vitro to further explore the underlying mechanisms of the effects of laquinimod on inflammation-induced angiogenesis.

Results: Topical administration of laquinimod to the injured corneas dramatically inhibited alkali-induced corneal neovascularization and decreased inflammatory cell (such as macrophage) infiltration in a corneal injury mouse model. Laquinimod significantly downregulated the expression of chemokines (monocyte chemotactic protein-1 and macrophage inflammatory protein-1), pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-alpha), vascular endothelial growth factor, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 and apoptosis-associated speck-like protein containing C-terminal caspase-recruitment domain adaptor protein in both injured corneas and RAW cells. In vitro, laquinimod also dramatically inhibited the proliferation, migration and tube formation of human umbilical vein endothelial cells.

Conclusion: Laquinimod inhibits inflammation-induced angiogenesis in the cornea. These results suggest that laquinimod is a potential new therapeutic option for corneal neovascularization and other angiogenesis-associated diseases.

Myeloid-derived suppressor cells expand after transplantation and their augmentation increases graft survival

Myeloid-derived suppressor cells (MDSCs) expand in an inflammatory microenvironment such as cancer and autoimmunity. To study if transplantation induces MDSCs and these cells regulate allograft survival, C57BL/6 donor hearts were transplanted into BALB/c recipients and endogenous MDSCs were characterized. The effects of adoptive transfer of transplant (tx), tumor (tm), and granulocyte-colony stimulating factor (g-csf)-expanded MDSCs or depletion of MDSC were assessed. MDSCs expanded after transplantation (1.7-4.6-fold) in the absence of immunosuppression, homed to allografts, and suppressed proliferation of CD4 T cells in vitro. Tx-MDSCs differed phenotypically from tm-MDSCs and g-csf-MDSCs. Among various surface markers, Rae-1 expression was notably low and TGF-β receptor II was high in tx-MDSCs when compared to tm-MDSCs and g-csf-MDSCs. Adoptive transfer of these three MDSCs led to differential graft survival: control (6 days), tx-MDSCs (7.5 days), tm-MDSCs (9.5 days), and g-csf-MDSCs (19.5 days). In combination with anti-CD154 mAb, MDSCs synergistically extended graft survival from 40 days (anti-CD154 alone) to 86 days with tm-MDSCs and 132 days with g-csf-MDSCs. Early MDSC depletion (day 0 or 20), however, abrogated graft survival, but late depletion (day 25) did not. In conclusion, MDSCs expanded following transplantation, migrated to cardiac allografts, prolonged graft survival, and were synergistic with anti-CD154 mAb.

Myeloid-Derived Suppressor Cells: Ductile Targets in Disease

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells with major regulatory functions and rise during pathological conditions, including cancer, infections and autoimmune conditions. MDSC expansion is generally linked to inflammatory processes that emerge in response to stable immunological stress, which alter both magnitude and quality of the myelopoietic output. Inability to reinstate physiological myelopoiesis would fall in an “emergency state” that perpetually reprograms myeloid cells toward suppressive functions. While differentiation and reprogramming of myeloid cells toward an immunosuppressive phenotype can be considered the result of a multistep process that originates in the bone marrow and culminates in the tumor microenvironment, the identification of its driving events may offer potential therapeutic approaches in different pathologies. Indeed, whereas expansion of MDSCs, in both murine and human tumor bearers, results in reduced immune surveillance and antitumor cytotoxicity, placing an obstacle to the effectiveness of anticancer therapies, adoptive transfer of MDSCs has shown therapeutic benefits in autoimmune disorders. Here, we describe relevant mechanisms of myeloid cell reprogramming leading to generation of suppressive MDSCs and discuss their therapeutic ductility in disease.

Baicalein ameliorates pristane-induced lupus nephritis via activating Nrf2/HO-1 in myeloid-derived suppressor cells

INTRODUCTION

Lupus nephritis (LN) is a representative manifestation in systemic lupus erythematosus (SLE). Some studies have shown that myeloid-derived suppressor cells (MDSCs) play a vital role in the regulation of the SLE process. MDSC infiltration in the kidney as well as inflammation and oxidative stress provokes the acceleration and deterioration of LN. Nuclear factor E2-related factor 2 (Nrf2) is thought to be a major regulator of the antioxidant response. Baicalein is a flavonoid with known anti-inflammatory effects and antioxidant response. However, the effects of baicalein on MDSCs, inflammation, and oxidative stress are not evaluated in the development of pristane-induced LN in mice.

METHODS

The renoprotective effect of baicalein was detected in a pristane-induced lupus mice model. NLRP3 inflammasome activation and NF-κB phosphorylation as well as reactive oxygen species (ROS) production and Nrf2 activation were examined. The percentages and function changes of MDSCs were measured. The possible mechanisms of the underlying effects of baicalein on ROS production and signaling pathways of Nrf2/heme-oxygenase (HO)-1, NLRP3 inflammasome, and NF-κB phosphorylation in lipopolysaccharide (LPS)-primed MDSCs were analyzed.

RESULTS

Baicalein reduced proteinuria and attenuated renal function impairment and renal histopathology including intrinsic cell proliferation, cellular crescents, and podocyte injury as well as glomerulonephritis activity in lupus mice. Moreover, baicalein downregulated the activation of NLRP3 inflammasome and levels of ROS or NF-κB phosphorylation, and it enhanced Nrf2 activation. Of note, baicalein inhibited the expansion of MDSCs and improved the function of MDSCs in lupus mice. Through analyzing LPS-primed MDSCs in vitro, baicalein was found to exhibit cytoprotective effects coincident with the induction of Nrf2/HO-1 signaling and the suppression of the NLRP3 inflammasome.

CONCLUSION

The data show that baicalein alleviates the symptoms of pristane-induced LN and suggest that the alleviation may be attributed to inhibition of MDSC expansion and regulation of the balance of the Nrf2/HO-1 signal and NLRP3 expression in MDSCs.

mTOR inhibitor INK128 attenuates systemic lupus erythematosus by regulating inflammation-induced CD11b+Gr1+ cells

Systemic lupus erythematosus (SLE) is an autoimmune disease, characterized by systemic chronic inflammation that can affect multiple major organ systems. Although the etiology of SLE is known to involve a variety of factors such as the environment, random factors and genetic susceptibility, the exact role of CD11b⁺Gr1⁺ myeloid cells in lupus progression is not fully understood. Myeloid-derived CD11b⁺Gr1⁺ cells are thought to be a heterogeneous group of immature myeloid cells with immune function. Some studies have reported that CD11b⁺Gr1⁺ cells and the activation of mTOR pathway are involved in the pathogenesis of systemic lupus erythematosus (SLE). However, it is still not clarified about the mechanism of influence of lupus microenvironment and mTOR signaling on CD11b⁺Gr1⁺ cells. In the present study, we found that the percentage of CD11b⁺Gr1⁺ cells increased prior to the abnormal changes of Th17, Treg, T and B cells during lupus development. TLR7 and IFN-α signaling synergized to promote CD11b⁺Gr1⁺ cell accumulation in an mTOR-dependent manner. Moreover, compared to a traditional mTOR inhibitor, INK128 inhibited more effectively the disease activity via regulating CD11b⁺Gr1⁺ cell expansion and functions. Furthermore, TLR7/IFN-α-modified CD11b⁺Gr1⁺ cells promoted unbalance of Th17/Tregs and were inclined to differentiate into macrophages via the mTOR pathway. In conclusion, CD11b⁺Gr1⁺ cells increased in the early stages of the lupus progression and mTOR pathway was critical for CD11b⁺Gr1⁺ cells in lupus development, suggesting the changes of inflammation-induced CD11b⁺Gr1⁺ cells initate lupus development. We also provide evidence for the first time that INK128, a second generation mTOR inhibitor, has a good therapeutic action on lupus development by regulating CD11b⁺Gr1⁺ cells.

Therapy for Proliferative Lupus Nephritis

Proliferative lupus nephritis requires prompt diagnosis and treatment with immunosuppressive therapy. Cyclophosphamide is the longest studied agent, but mycophenolate mofetil has recently emerged as an efficacious induction and maintenance treatment that does not impart the risk of infertility. However, overall remission rates remain suboptimal and there is a need for improved therapeutic options. To this end, ongoing clinical studies are focusing on agents that target key molecules and pathways implicated in the pathogenesis of lupus nephritis based on previous animal and human studies. This article reviews key findings of trials supporting established induction and maintenance treatment regimens along with novel therapeutic investigations.

Myeloid-Derived Suppressor Cells Induce Podocyte Injury Through Increasing Reactive Oxygen Species in Lupus Nephritis

The expansion of myeloid-derived suppressor cells (MDSCs) has been documented in murine models and patients with lupus nephritis (LN), but the exact role of MDSCs in this process remains largely unknown. In this study, we investigated whether MDSCs are involved in the process of podocyte injury in the development of LN. In toll-like receptor-7 (TLR-7) agonist imiquimod-induced lupus mice, we found the severe podocyte injury in glomeruli of lupus mice and significant expansion of MDSCs in spleens and kidneys of lupus mice. The function of TLR-7 activated MDSCs was enhanced including the increased generation of reactive oxygen species (ROS) in vivo and in vitro. Moreover, the ROS production of MDSCs induced podocyte injury through activating the p-38MAPK and NF-kB signaling. Furthermore, we verified that podocyte injury was indeed correlated with expansion of MDSCs and their ROS secretion in LN of pristane-induced lupus mice. These findings first indicate that the podocyte injury in LN was associated with the increased MDSCs in kidney and MDSCs may be a promising therapeutic target of LN in the future.

The 2018 pipeline of targeted therapies under clinical development for Systemic Lupus Erythematosus: a systematic review of trials

Currently, Systemic Lupus Erythematosus (SLE) therapies range from antimalarials to glucocorticoids, in addition to immunosupressive agents or biologics such as rituximab or belimumab, when needed. Several unmet needs remain in the treatment SLE and more targeted drugs with improved safety profiles are expected. Based on recent advances in the understanding of the complex pathogenesis of SLE, several targeted treatments are currently assessed in clinical trials. In this study, we performed a systematic review of all targeted therapies under clinical development in SLE in 17 online registries of clinical trials. The search yielded a total of 1140 trials, from which we identified 74 targeted therapies for SLE. Those treatments target inflammatory cytokines, chemokines, or their receptors (n = 17), B cells or plasma cells (n = 17), intracellular signalling pathways (n = 10), T/B cells costimulation molecules (n = 8), interferons (n = 7), plasmacytoid dendritic cells (pDC) (n = 3), as well as various other targets (n = 12). Not all these candidate drugs will reach phase III, but the broad spectrum of drugs being investigated may satisfy the urgent need for improved lupus medications. The identification of biomarkers that would allow adequate prediction of response-to-therapy remains high, but when solved will allow a more rationale selection of the optimal pharmacological agent at the patient level.

The comparative immunogenicity of biologic therapy and its clinical relevance in psoriatic arthritis: a systematic review of the literature

INTRODUCTION

Biologic agents have demonstrated efficacy in treating patients with psoriatic arthritis (PsA). Biologic agents also have an intrinsic capacity to induce an immune response in patients that could result in unwanted adverse events and/or treatment failure.

AREAS COVERED

In this systematic literature review, the authors document the incidence of immune responses, primarily anti-drug antibodies (ADA), to the biologic therapeutic agents currently in clinical practice for the treatment of PsA. The authors discuss the importance of these responses with respect to clinical practice.

EXPERT OPINION

Our evaluation of the published literature shows that the immune responses to the various biologic therapeutic agents currently being used to treat PsA are similar to those observed for these agents in other rheumatic diseases. Moreover, similar to observations in other rheumatic diseases, the incidence of ADA formation to biologic agents in patients with PsA is often decreased when patients are given concomitant treatment with disease-modifying anti-rheumatic drugs. These data strongly suggest that the immune response is a characteristic of the biologic agent. Using therapeutic drug monitoring may be an approach to assess the immune response to the agent and to mitigate the potential impact on efficacy and safety, and consequently optimize treatment.

Laquinimod attenuates inflammation by modulating macrophage functions in traumatic brain injury mouse model

Background

Traumatic brain injury (TBI) is a critical public health and socio-economic problem worldwide. A growing body of evidence supports the involvement of inflammatory events in TBI. It has been reported that resident microglia and infiltrating monocytes promote an inflammatory reaction that leads to neuronal death and eventually behavioral and cognitive impairment. Currently, there is no effective treatment for TBI and the development of new therapeutic strategies is a scientific goal of highest priority. Laquinimod, an orally administered neuroimmunomodulator initially developed for the treatment of multiple sclerosis, might be a promising neuroprotective therapy for TBI. Herein, we aim to investigate the hypothesis that laquinimod will reduce the central nervous system (CNS) damage caused by TBI.

Methods

To test our hypothesis, Ccr2^rfp/+Cx3cr1^gfp/+ mice were submitted to a moderate TBI induced by fluid percussion. Sham controls were submitted only to craniotomy. Mice were treated daily by oral gavage with laquinimod (25 mg/kg) 7 days before and 3 days after TBI. The brains of mice treated or not treated with laquinimod were collected at 3 and 120 days post injury, and brain morphological changes, axonal injury, and neurogenesis were evaluated by microscopy analysis. We also isolated microglia from infiltrating monocytes, and the expression of immune gene mRNAs were analyzed by employing a quantitative NanoString nCounter technique.

Results

Laquinimod prevented ventricle enlargement caused by TBI in the long term. Immunohistochemical analyses revealed decreased axonal damage and restored neurogenesis in the laquinimod-treated TBI group at early stage (3 days post injury). Notably, laquinimod inhibited the monocytes infiltration to the brain. Hierarchial clustering demonstrated that the microglial gene expression from the TBI group treated with laquinimod resembles the sham group more than the TBI-water control group.

Conclusions

Administration of laquinimod reduced lesion volume and axonal damage and restored neurogenesis after TBI. Laquinimod might be a potential therapy strategy to improve TBI long-term prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1075-y) contains supplementary material, which is available to authorized users.

Update on Biologic Therapies for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystemic autoimmune disease driven by genetic, hormonal, and environmental factors. Despite the advances in diagnostic and therapeutic approaches in the last decades, SLE still leads to significant morbidity and increased mortality. Although a cure for SLE is still unknown, treatment is required to control acute disease exacerbation episodes (flares), decrease the frequency and severity of subsequent lupus flares, address comorbidities, and prevent end-organ damage. While conventional SLE pharmacotherapy may exhibit suboptimal efficacy and substantial toxicity, a growing knowledge of the disease pathogenesis enabled the research on novel therapeutic agents directed at specific disease-related targets. In this paper, we review the recent progress in the clinical investigation of biologic agents targeting B cells, T cells, cytokines, innate immunity, and other immunologic or inflammatory pathways. Although many investigational agents exhibited insufficient efficacy or inadequate safety in clinical trials, one of them, belimumab, fulfilled the efficacy and safety regulatory requirements and was approved for the treatment of SLE in Europe and the USA, which confirms that, despite all difficulties, advances in this field are possible.

Novel Treatments in Lupus

PURPOSE OF REVIEW

The treatment of systemic lupus erythematosus (SLE) still depends on non-specific immunosuppression. Herein, we review promising targeted therapies that have the potential to change this therapeutic paradigm.

RECENT FINDINGS

Besides the FDA-approved B lymphocyte stimulator (BLyS) inhibitor, belimumab, interferon-α represents a promising treatment target, albeit with modest effectiveness primarily in non-renal SLE. Preclinical and early-phase clinical trials using biologics and small molecules targeting B and T cell activation as well as the cross-talk between these cells also show promise. BLyS and interferon targeting show the most promising results in challenging the current treatment status in non-renal SLE.

Update on Lupus Nephritis

SLE is a chronic inflammatory disease that affects the kidneys in about 50% of patients. Lupus nephritis is a major risk factor for overall morbidity and mortality in SLE, and despite potent anti-inflammatory and immunosuppressive therapies still ends in CKD or ESRD for too many patients. This review highlights recent updates in our understanding of disease epidemiology, genetics, pathogenesis, and treatment in an effort to establish a framework for lupus nephritis management that is patient-specific and oriented toward maintaining long-term kidney function in patients with lupus.

T-cell-directed therapies in systemic lupus erythematosus

Drug development for the treatment of systemic lupus erythematosus (SLE) has largely focused on B-cell therapies. A greater understanding of the immunopathogenesis of SLE coupled with advanced bioengineering has allowed for clinical trials centered on other targets for SLE therapy. The authors discuss the benefits and shortcomings of focusing on T-cell-directed therapies in SLE and lupus nephritis clinical trials.

Laquinimod arrests experimental autoimmune encephalomyelitis by activating the aryl hydrocarbon receptor

Laquinimod is an oral drug currently being evaluated for the treatment of relapsing, remitting, and primary progressive multiple sclerosis and Huntington's disease. Laquinimod exerts beneficial activities on both the peripheral immune system and the CNS with distinctive changes in CNS resident cell populations, especially astrocytes and microglia. Analysis of genome-wide expression data revealed activation of the aryl hydrocarbon receptor (AhR) pathway in laquinimod-treated mice. The AhR pathway modulates the differentiation and function of several cell populations, many of which play an important role in neuroinflammation. We therefore tested the consequences of AhR activation in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) using AhR knockout mice. We demonstrate that the pronounced effect of laquinimod on clinical score, CNS inflammation, and demyelination in EAE was abolished in AhR^-/- mice. Furthermore, using bone marrow chimeras we show that deletion of AhR in the immune system fully abrogates, whereas deletion within the CNS partially abrogates the effect of laquinimod in EAE. These data strongly support the idea that AhR is necessary for the efficacy of laquinimod in EAE and that laquinimod may represent a first-in-class drug targeting AhR for the treatment of multiple sclerosis and other neurodegenerative diseases.

Laquinimod rescues striatal, cortical and white matter pathology and results in modest behavioural improvements in the YAC128 model of Huntington disease

Increasing evidence supports a role for abnormal immune activation and inflammatory responses in Huntington disease (HD). In this study, we evaluated the therapeutic potential of laquinimod (1 and 10 mg/kg), a novel immunomodulatory agent shown to be protective in a number of neuroinflammatory conditions, in the YAC128 mouse model of HD. Treatment with laquinimod for 6 months rescued atrophy in the striatum, in certain cortical regions, and in the corpus callosum of YAC128 HD mice. Diffusion tensor imaging showed that white matter microstructural abnormalities in the posterior corpus callosum were improved following treatment with low dose (1 mg/kg) laquinimod, and were paralleled by reduced levels of interleukin-6 in the periphery of YAC128 HD mice. Functionally, treatment with laquinimod (1 and 10 mg/kg) led to modest improvements in motor function and in depressive-like behaviour. Taken together, these results suggest that laquinimod may improve some features of pathology in HD, and provides support for the role of immune activation in the pathogenesis of HD.

A pathophysiology-based approach to the diagnosis and treatment of lupus nephritis

Lupus is no longer an unknown chameleon of medicine. Significant progress has been made on unraveling the pathogenesis of lupus and lupus nephritis, and how to treat the disease. Here we provide an update on the pathophysiology of lupus and its related kidney disease, consider areas of controversy in disease management, and discuss the unmet needs of lupus nephritis and how to address these needs. We focus on rethinking how innovative therapies for lupus nephritis should be evaluated and evolving strategies to more efficiently mitigate irreversible nephron loss in patients with lupus nephritis.

Myeloid-derived suppressor cells contribute to systemic lupus erythaematosus by regulating differentiation of Th17 cells and Tregs

Although major advancements have made in investigating the aetiology of SLE (systemic lupus erythaematosus), the role of MDSCs (myeloid-derived suppressor cells) in SLE progression remains confused. Recently, some studies have revealed that MDSCs play an important role in lupus mice. However, the proportion and function of MDSCs in lupus mice and SLE patients are still poorly understood. In the present study, we investigated the proportion and function of MDSCs using different stages of MRL/lpr lupus mice and specimens from SLE patients with different activity. Results showed that splenic granulocytic (G-)MDSCs were significantly expanded by increasing the expression of CCR1 (CC chemokine receptor 1) in diseased MRL/lpr lupus mice and in high-disease-activity SLE patients. However, the proportion of monocytic (M-)MDSCs remains similar in MRL/lpr lupus mice and SLE patients. G-MDSCs produce high levels of ROS (reactive oxygen species) through increasing gp91(phox) expression, and activated TLR2 (Toll-like receptor 2) and AIM2 (absent in melanoma 2) inflammasome in M-MDSCs lead to IL-1β (interleukin 1β) expression in diseased MRL/lpr mice and high-disease-activity SLE patients. Previous study has revealed that MDSCs could alter the plasticity of Th17 (T helper 17) cells and Tregs (regulatory T-cells) via ROS and IL-1β. Co-culture experiments showed that G-MDSCs impaired Treg differentiation via ROS and M-MDSCs promoted Th17 cell polarization by IL-1β in vitro Furthermore, adoptive transfer or antibody depletion of MDSCs in MRL/lpr mice confirmed that MDSCs influenced the imbalance of Tregs and Th17 cells in vivo Our results indicate that MDSCs with the capacity to regulate Th17 cell/Treg balance may be a critical pathogenic factor in SLE.

A benzenediamine derivate FC-99 attenuates lupus nephritis in MRL/lpr mice via inhibiting myeloid dendritic cell-secreted BAFF

Myeloid dendritic cells (DCs) can produce B-cell-activating factor (BAFF) that modulates survival and differentiation of B cells and plays a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE). Toll-like receptor 4 (TLR4) signaling has important functions in the process of BAFF production. Our previous study showed that a benzenediamine derivate FC-99 possesses anti-inflammation activity and directly interacts with interleukin-1 receptor-associated kinase 4 (IRAK4), which was a pivotal molecule in TLR4 signaling. In this study, we demonstrated that FC-99 attenuated lupus nephritis in the MRL/lpr mice. FC-99 also decreased the levels of total immunoglobulin G (IgG), total IgG2a and IgM in sera, as well as the activation of B cells in the spleens of MRL/lpr mice. Moreover, FC-99 inhibited abnormal activation of myeloid DCs in spleens and reduced the levels of BAFF in sera, spleens, and kidneys of MRL/lpr mice. Furthermore, upon TLR4 stimulation with lipopolysaccharide in vitro, FC-99 inhibited IRAK4 phosphorylation, as well as the activation and BAFF production in murine bone marrow-derived DCs. These data indicate that FC-99 attenuates lupus nephritis in MRL/lpr mice via inhibiting DC-secreted BAFF, suggesting that FC-99 may be a potential therapeutic candidate for the treatment of SLE.

Hurdles to the introduction of new therapies for immune-mediated kidney diseases

Innovative immunotherapies continue to markedly benefit many disciplines in clinical medicine but disappointingly, these benefits have not translated to the treatment of kidney diseases despite encouraging findings from preclinical models of kidney dysfunction. This lack of progress in nephrology might relate to the unique biology of the kidney. More likely, this lack of progress relates to conceptual hurdles in the application of newer therapies to renal disease. In this Review we discuss seven hurdles that must be addressed in order to appropriately assess and introduce immunologic therapies for immune-mediated kidney disease: the use of appropriate criteria to define disease categories; issues relating to the heterogeneity of kidney diseases and how this heterogeneity affects approaches to treatment; issues related to the rarity of most kidney diseases; the paucity of good animal models of human kidney disease; issues relating to trial design; problems with current approaches to the identification and use of appropriate and feasible study end points; and a lack of adequate biomarkers of intrarenal inflammation and parenchymal injury. We suggest that overcoming these hurdles, in addition to searching for better therapeutic targets, will be necessary to progress the treatment of immune-mediated kidney disease into a new age of drug therapy.

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.

Epidermal injury promotes nephritis flare in lupus-prone mice

Systemic lupus erythematosus is clinically characterized by episodes of flare and remission. In patients, cutaneous exposure to ultraviolet light has been proposed as a flare trigger. However, induction of flare secondary to cutaneous exposure has been difficult to emulate in many murine lupus models. Here, we describe a system in which epidermal injury is able to trigger the development of a lupus nephritis flare in New Zealand Mixed (NZM) 2328 mice. 20-week old NZM2328 female mice underwent removal of the stratum corneum via duct tape, which resulted in rapid onset of proteinuria and death when compared to sham-stripped littermate control NZM2328 mice. This was coupled with a drop in serum C3 concentrations and dsDNA antibody levels and enhanced immune complex deposition in the glomeruli. Recruitment of CD11b(+)CD11c(+)F4/80(high) macrophages and CD11b(+)CD11c(+)F4/80(low) dendritic cells was noted prior to the onset of proteinuria in injured mice. Transcriptional changes within the kidney suggest a burst of type I IFN-mediated and inflammatory signaling which is followed by upregulation of CXCL13 following epidermal injury. Thus, we propose that tape stripping of lupus-prone NZM2328 mice is a novel model of lupus flare induction that will allow for the study of the role of cutaneous inflammation in lupus development and how crosstalk between dermal and systemic immune systems can lead to lupus flare.

The Role and Potential Therapeutic Application of Myeloid-Derived Suppressor Cells in Allo- and Autoimmunity

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that consists of myeloid progenitor cells and immature myeloid cells. They have been identified as a cell population that may affect the activation of CD4(+) and CD8(+) T-cells to regulate the immune response negatively, which makes them attractive targets for the treatment of transplantation and autoimmune diseases. Several studies have suggested the potential suppressive effect of MDSCs on allo- and autoimmune responses. Conversely, MDSCs have also been found at various stages of differentiation, accumulating during pathological situations, not only during tumor development but also in a variety of inflammatory immune responses, bone marrow transplantation, and some autoimmune diseases. These findings appear to be contradictory. In this review, we summarize the roles of MDSCs in different transplantation and autoimmune diseases models as well as the potential to target these cells for therapeutic benefit.

Cytokines: Names and Numbers You Should Care About

Cytokines play an important role in host defense against microorganisms. They orchestrate innate immunity by inducing protective local inflammation and systemic acute phase responses. Cytokines are important in initiating, amplifying, directing, mediating, and regulating adaptive immunity. Unfortunately, they may also direct tissue damage if excessive responses occur or if they are involved in directing and mediating autoimmunity. Under these circumstances, cytokines are potential therapeutic targets. Over the last 20 years, we have seen the successful development and clinical implementation of biologic strategies that target key cytokines in specific inflammatory diseases with efficacy, specificity, and toxicity profiles challenging conventional drug therapies. These therapies are finding new applications and many new agents show promise. Unfortunately, these new cytokine-based therapies have had little effect on renal disease. This review provides evidence that common renal diseases, including those causing AKI and the autoimmune proliferative and crescentic forms of GN, have cytokine mediation profiles that suggest they would be susceptible to cytokine-targeting therapeutic strategies.

Immune parameters of patients treated with laquinimod, a novel oral therapy for the treatment of multiple sclerosis: results from a double-blind placebo-controlled study

Laquinimod is a novel orally administered drug for the treatment of relapsing remitting multiple sclerosis (RRMS). In this immunological substudy of the phase III Assessment of Oral Laquinimod in Preventing Progression of MS (ALLEGRO) trial, we performed an ex vivo and in vitro analysis of effects exerted by laquinimod on peripheral blood immune cell populations from RRMS patients with a special focus on monocyte phenotype and function. Approximately 100 patients were enrolled following a standardized protocol. Half of the patients received laquinimod and the other half received placebo. Peripheral blood samples were collected prior to commencement of therapy and after 1, 3, 6, 12, and 24 months of continuous therapy. Main lymphocytic and antigen presenting cell fractions were analyzed in peripheral blood mononuclear cells (PBMCs) ex vivo by flow cytometry. The proliferative response of PBMCs to mitogen or recall antigen was assessed in culture experiments. Untouched monocytes were sorted magnetically and cultured under pro-inflammatory conditions. PBMC analysis showed no significant differences of investigated lymphocytic and antigen presenting cell populations over time within each group, or between the two groups. However, the detailed in vitro analysis of monocytes demonstrated a lower level of CD86 expression on monocytes stimulated with LPS in laquinimod patients beginning from the 1st month of treatment. Upon pro-inflammatory stimulation, monocytes obtained from laquinimod treated patients tended to secrete lower levels of the proinflammatory chemokines CCL2 or CCL5. Taken together, in this prospective study, we demonstrate immune modulation but no immunosuppressive biological activity of laquinimod in a large group of MS patients.

Piperlongumine alleviates lupus nephritis in MRL-Fas(lpr) mice by regulating the frequency of Th17 and regulatory T cells

Recent data have shown that piperlongumine (PL), an important component of Piper longum fruits, is known to possess anti-inflammatory and vascular-protective activities. This study aimed to examine the therapeutic effects and underlying mechanisms of PL on lupus-prone MRL-Fas(lpr) mice. Female MRL-Fas(lpr) mice were intraperitoneally treated with PL (2.4 mg kg(-1) d(-1)) for 10 weeks, and the proteinuria level was biweekly monitored. After the mice were euthanized, serum biochemical parameters and renal damage were determined. Splenocytes of MRL-Fas(lpr) mice were isolated for in vitro study. Treatment of the mice with PL significantly attenuated the progression of proteinuria and glomerulonephritis. The improvement was accompanied by decreased serum levels of nephritogenic anti-dsDNA antibodies, IL-6, IL-17, IL-23 and TNF-α. Treatment of the mice with PL suppressed the frequency of Th17 cells and increased the regulatory T cells (Tregs). In vitro, the levels of IL-6, IL-17, IL-23 and TNF-α were significantly decreased in the cultures of splenocytes from PL-treated mice compared with those from vehicle-treated mice. In addition, PL treatment impeded activation of the JAK/STAT3 signaling in splenocytes. Of great important, the survival of MRL-Fas(lpr) mice were improved by PL treatment. In summary, PL effectively ameliorates lupus syndrome in MRL-Fas(lpr) mice by suppressing the pathogenic Th17 cells and increasing the Tregs as well as inhibiting activation of the JAK/STAT3 signaling pathway. This study sheds new light on the immune-modulatory role of PL.