Rosiglitazone decreases blood pressure and renal injury in a female mouse model of systemic lupus erythematosus

A cellular overview of immunometabolism in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease, characterized by a breakdown of immune tolerance and the development of autoantibodies against nucleic self-antigens. Immunometabolism is a rapidly expanding scientific field investigating the metabolic programming of cells of the immune system. During the normal immune response, extensive reprogramming of cellular metabolism occurs, both to generate adenosine triphosphate and facilitate protein synthesis, and also to manage cellular stress. Major pathways upregulated include glycolysis, oxidative phosphorylation, the tricarboxylic acid cycle and the pentose phosphate pathway, among others. Metabolic reprogramming also occurs to aid resolution of inflammation. Immune cells of both patients with SLE and lupus-prone mice are characterized by metabolic abnormalities resulting in an altered functional and inflammatory state. Recent studies have described how metabolic reprogramming occurs in many cell populations in SLE, particularly CD4+ T cells, e.g. favouring a glycolytic profile by overactivation of the mechanistic target of rapamycin pathway. These advances have led to an increased understanding of the metabolic changes affecting the inflammatory profile of T and B cells, monocytes, dendritic cells and neutrophils, and how they contribute to autoimmunity and SLE pathogenesis. In the current review, we aim to summarize recent advances in the field of immunometabolism involved in SLE and how these could potentially lead to new therapeutic strategies in the future.

Androgen-Induced Cardiovascular Risk in Polycystic Ovary Syndrome: The Role of T Lymphocytes

An estimated 15-20% of reproductive-age women are affected by polycystic ovary syndrome (PCOS). PCOS is associated with substantial metabolic and cardiovascular long-term consequences. In young women with PCOS, several cardiovascular risk factors may be found, including chronic inflammation, high blood pressure, and elevated leukocytes. These women are at an increased risk of cardiovascular diseases (CVD), not only during the reproductive years, but also with aging and menopause; therefore, the early prevention and treatment of future cardiovascular adverse effects are necessary. The fundamental characteristic of PCOS is hyperandrogenemia, which is associated with increased pro-inflammatory cytokines and T lymphocytes. Whether these factors play a role in the pathophysiology of hypertension, a risk factor of CVD, due to PCOS is not well established. This review will briefly discuss how a modest increase in androgens in females is linked to the development of hypertension through pro-inflammatory cytokines and T lymphocyte subsets and the promotion of renal injury. Moreover, it reveals a few existing research gaps in this area, including the lack of specific therapy directed at androgen-induced inflammation and immune activation, thus emphasizing the necessity to explore the systemic inflammation in women with PCOS to halt the inevitable inflammatory process targeting the underlying abnormalities of CVD.

Renal TLR-7/TNF-α pathway as a potential female-specific mechanism in the pathogenesis of autoimmune-induced hypertension

Hypertension is prevalent in patients with systemic lupus erythematosus (SLE). The goal of the current study is to track the pathogenesis of hypertension and renal injury in SLE, identify contributory mechanisms, and highlight differences in disease development among sexes. Mean arterial pressure was measured in conscious male and female SLE (NZBWF1) and control (NZW) mice at 34-35 wk of age using indwelling arterial catheters. Measures of renal injury, renal inflammation, and renal hemodynamics were used to monitor the potential contributors to latent sex differences. Both male and female SLE mice were hypertensive at 35 wk of age, and the hypertension was linked to renal injury in females, but not in males. A known contributor of renal pathology in SLE, Toll-like receptor (TLR)-7, and its downstream effector, the proinflammatory cytokine tumor necrosis factor (TNF)-α, were lower in male SLE mice than in females. Male SLE mice also had higher glomerular filtration rate (GFR) and lower renal vascular resistance (RVR) than females. Our data suggest that although hypertension in female SLE mice is associated with renal mechanisms, hypertension in male SLE mice may develop independent of renal changes. Future studies will continue to dissect sex-specific factors that should be considered when treating patients with hypertension with underlying chronic inflammation and/or autoimmunity.NEW & NOTEWORTHY There is a high prevalence of hypertension in male and female SLE; however, male SLE mice are hypertensive without renal involvement. The development of hypertension in female SLE mice is renocentric and strongly associated with injurious renal mechanisms like the TLR-7→TNF-α pathway. This clear difference in the pathogenesis among the sexes could have a significant impact on how we treat patients with hypertension with underlying chronic autoimmune/inflammatory diseases.

Peroxisome proliferator activated receptor-γ agonist pioglitazone improves vascular and metabolic dysfunction in systemic lupus erythematosus

OBJECTIVES

Premature cardiovascular events in systemic lupus erythematosus (SLE) contribute to morbidity and mortality, with no effective preventive strategies described to date. Immune dysregulation and metabolic disturbances appear to play prominent roles in the induction of vascular disease in SLE. The peroxisome proliferator activated receptor-gamma agonist pioglitazone (PGZ suppresses vascular damage and immune dysregulation in murine lupus and improves endothelial dysfunction in other inflammatory diseases. We hypothesised that PGZ could improve vascular dysfunction and cardiometabolic parameters in SLE.

METHODS

Eighty SLE subjects with mild to severe disease activity were randomised to a sequence of PGZ followed by placebo for 3 months, or vice versa, in a double-blind, cross-over design with a 2-month wash-out period. Primary endpoints were parameters of endothelial function and arterial inflammation, measured by multimodal assessments. Additional outcome measures of disease activity, neutrophil dysregulation, metabolic disturbances and gene expression studies were performed.

RESULTS

Seventy-two subjects completed the study. PGZ was associated with a significant reduction in Cardio-Ankle Vascular Index (a measure of arterial stiffness) compared with placebo. Various metabolic parameters improved with PGZ, including insulin resistance and lipoprotein profiles. Circulating neutrophil extracellular trap levels also significantly decreased with PGZ compared with placebo. Most adverse events experienced while on PGZ were mild and resolved with reduction in PGZ dose.

CONCLUSION

PGZ was well tolerated and induced significant improvement in vascular stiffness and cardiometabolic parameters in SLE. The results suggest that PGZ should be further explored as a modulator of cardiovascular disease risk in SLE.

TRIAL REGISTRATION NUMBER

NCT02338999.

Should Renal Inflammation Be Targeted While Treating Hypertension?

Despite extensive research and a plethora of therapeutic options, hypertension continues to be a global burden. Understanding of the pathological roles of known and underexplored cellular and molecular pathways in the development and maintenance of hypertension is critical to advance the field. Immune system overactivation and inflammation in the kidneys are proposed alternative mechanisms of hypertension, and resistant hypertension. Consideration of the pathophysiology of hypertension in chronic inflammatory conditions such as autoimmune diseases, in which patients present with autoimmune-mediated kidney inflammation as well as hypertension, may reveal possible contributors and novel therapeutic targets. In this review, we 1) summarize current therapies used to control blood pressure and their known effects on inflammation; 2) provide evidence on the need to target renal inflammation, specifically, and especially when first-line and combinatory treatment efforts fail; and 3) discuss the efficacy of therapies used to treat autoimmune diseases with a hypertension/renal component. We aim to elucidate the potential of targeting renal inflammation in certain subsets of patients resistant to current therapies.

Autoimmune-mediated renal disease and hypertension

Hypertension is a major risk factor for cardiovascular disease, chronic kidney disease (CKD), and mortality. Troublingly, hypertension is highly prevalent in patients with autoimmune renal disease and hastens renal functional decline. Although progress has been made over the past two decades in understanding the inflammatory contributions to essential hypertension more broadly, the mechanisms active in autoimmune-mediated renal diseases remain grossly understudied. This Review provides an overview of the pathogenesis of each of the major autoimmune diseases affecting the kidney that are associated with hypertension, and describes the current state of knowledge regarding hypertension in these diseases and their management. Specifically, discussion focuses on Systemic Lupus Erythematosus (SLE) and Lupus Nephritis (LN), Immunoglobulin A (IgA) Nephropathy, Idiopathic Membranous Nephropathy (IMN), Anti-Neutrophil Cytoplasmic Antibody (ANCA)-associated glomerulonephritis, and Thrombotic Thrombocytopenic Purpura (TTP). A summary of disease-specific animal models found to exhibit hypertension is also included to highlight opportunities for much needed further investigation of underlying mechanisms and novel therapeutic approaches.

Role of the Peroxisome Proliferator Activated Receptors in Hypertension

Nuclear receptors represent a large family of ligand-activated transcription factors which sense the physiological environment and make long-term adaptations by mediating changes in gene expression. In this review, we will first discuss the fundamental mechanisms by which nuclear receptors mediate their transcriptional responses. We will focus on the PPAR (peroxisome proliferator-activated receptor) family of adopted orphan receptors paying special attention to PPARγ, the isoform with the most compelling evidence as an important regulator of arterial blood pressure. We will review genetic data showing that rare mutations in PPARγ cause severe hypertension and clinical trial data which show that PPARγ activators have beneficial effects on blood pressure. We will detail the tissue- and cell-specific molecular mechanisms by which PPARs in the brain, kidney, vasculature, and immune system modulate blood pressure and related phenotypes, such as endothelial function. Finally, we will discuss the role of placental PPARs in preeclampsia, a life threatening form of hypertension during pregnancy. We will close with a viewpoint on future research directions and implications for developing novel therapies.

Increased Expression of PPAR-γ Modulates Monocytes Into a M2-Like Phenotype in SLE Patients: An Implicative Protective Mechanism and Potential Therapeutic Strategy of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a spectrum of autoimmune disorders characterized by continuous inflammation and the production of autoantibodies. Monocytes, as precursors of dendritic cells and macrophages, are involved in the pathogenesis of SLE, particularly in the inflammatory reactions. Previous studies have proved that Pam3CSK4, as a synthetic ligand of TLR2, could stimulate monocytes to differentiated into a M2-like phenotype which presented immunosuppressive functions. However, the underlying mechanisms remain to be further studied. Here, we reported an increased expression of PPAR-γ in the CD14⁺ monocytes from SLE patients, particularly in the treated group of SLE patients and the group with positive anti-dsDNA antibodies. Additionally, PPAR-γ expression decreased in the SLE patients with skin lesion. Furthermore, we demonstrated that Pam3CSK4 stimulation can decrease the expression of CCR7, CD80, IL-1β, IL-6, IL-12, and NF-κB which were related to the M1-like subset of monocytes and increased the expression of ARG1 which was related to the M2-like subset through upregulated PPAR-γ expression and consequently downregulated NF-κB expression in the CD14⁺ monocytes in a time-dependent manner. ChIP-qPCR results further demonstrated that Pam3CSK4 pretreatment could modulate PPAR-γ expression by regulating histone modification through the inhibition of Sirt1 binding to the PPAR-γ promoter. Taken together, our study indicated a protective role of TLR2/Sirt1/PPAR-γ pathway in the pathogenesis of SLE which provided potential therapeutic strategies.

Blood pressure and albuminuria in a female mouse model of systemic lupus erythematosus: impact of long-term high salt consumption

Hypertension and kidney involvement are common in patients with autoimmune disease. Sodium intake is linked to hypertension in both human and animal studies. Evidence suggests that dietary salt may be an important environmental factor that promotes autoimmune activity. Therefore, we hypothesized that a long-term high-salt diet would accelerate the progression of autoimmunity, hypertension, and albuminuria during systemic lupus erythematosus (SLE), an autoimmune disease that predominantly affects young women and has a high prevalence of hypertension and renal disease. To test this hypothesis, an established experimental model of SLE (female NZBWF1 mice) that develops hypertension and renal disease was used. SLE mice were fed a high-salt (4% NaCl) or normal (0.4% NaCl) diet for 24 wk beginning at 10 wk of age and ending at 34 wk of age, a time by which female NZBWF1 mice typically have hypertension and exhibit signs of renal disease. Plasma anti-dsDNA autoantibodies were measured as an indicator of active SLE disease, and urinary albumin was monitored longitudinally as a marker of renal disease. Arterial pressure was measured in conscious, freely moving mice at 34 wk of age. Urinary endothelin-1 (ET-1) excretion, renal endothelin A and B receptor protein expression, and renal mRNA expression of NOS1, NOS2, NOX2, MCP-1, TNF-α, serum- and glucocorticoid-regulated kinase 1, and interleukin-2 (IL-2) were assessed to determine the impact on gene products commonly altered by a high-salt diet. SLE mice fed a high-salt diet had increased circulating autoantibodies, but the high-salt diet did not significantly affect albuminuria or arterial pressure. Urinary ET-1 excretion was increased, whereas renal endothelin A receptor and IL-2 expression were decreased in response to a high-salt diet. These data suggest that a chronic high-salt diet may not accelerate cardiovascular and renal consequences commonly associated with SLE.

Curcumin attenuates autoimmunity and renal injury in an experimental model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder with prevalent hypertension and renal disease. To avoid side effects of immunosuppressive drugs, alternative therapies are needed. Curcumin has been used in Eastern medicine for its anti‐inflammatory and antioxidant properties. This study tested whether oral curcumin administration attenuates autoimmunity and renal injury during SLE. Female NZBWF1 (model of SLE) and NZW/LacJ (control) mice were administered curcumin (500 mg kg^‐1 day^‐1, oral gavage) for 14 days in two separate groups beginning at either 26 or 32 weeks of age. Body weight and composition were monitored throughout the study. Immune activity was assessed by spleen weight, circulating dsDNA autoantibodies, and B lymphocytes. Renal injury (albumin excretion, glomerulosclerosis, blood urea nitrogen (BUN)) was measured as a hemodynamic function (glomerular filtration rate (GFR), mean arterial pressure (MAP)) in conscious mice. Body weight and composition were maintained in curcumin‐treated SLE mice, but decreased in vehicle‐treated SLE mice. Curcumin‐treated SLE mice had lower spleen weight and renal injury (glomerulosclerosis) compared to vehicle‐treated SLE mice when treatment started at 26 weeks of age. When curcumin treatment started at 32 weeks of age, renal injury (glomerulosclerosis, BUN) was reduced in SLE mice compared to vehicle‐treated SLE mice. GFR was reduced, and MAP was increased in vehicle‐treated SLE mice compared to controls; however, these were not improved with curcumin. No significant changes were observed in curcumin‐treated control mice. These data suggest that curcumin modulates autoimmune activity and may lessen renal injury in female mice with SLE.

Regulation of the germinal center response by nuclear receptors and implications for autoimmune diseases

The immune system plays an essential role in protecting the host from infectious diseases and cancer. Notably, B and T lymphocytes from the adaptive arm of the immune system can co-operate to form long-lived antibody responses and are therefore the main target in vaccination approaches. Nevertheless, protective immune responses must be tightly regulated to avoid hyper-responsiveness and responses against self that can result in autoimmunity. Nuclear receptors (NRs) are perfectly adapted to rapidly alter transcriptional cellular responses to altered environmental settings. Their functional role is associated with both immune deficiencies and autoimmunity. Despite extensive linking of nuclear receptor function with specific CD4 T helper subsets, research on the functional roles and mechanisms of specific NRs in CD4 follicular T helper cells (Tfh) and germinal center (GC) B cells during the germinal center reaction is just emerging. We review recent advances in our understanding of NR regulation in specific cell types of the GC response and discuss their implications for autoimmune diseases such as systemic lupus erythematosus (SLE).

Coptisine Alleviates Pristane-Induced Lupus-Like Disease and Associated Kidney and Cardiovascular Complications in Mice

Systemic lupus erythaematosus (SLE) is a chronic multi-system autoimmune disease with a high prevalence of kidney and cardiovascular complications. Considering that Rho-associated coiled-coil-containing protein kinases (ROCKs) play important roles in SLE, inflammation, and cardiovascular disease, we hypothesized that coptisine, which has been found to inhibit ROCKs, may have an effect on SLE. The effect of coptisine was assessed in female BALB/c mice intraperitoneally injected with 0.5 mL of pristane. Serum autoantibodies were tested every month, blood pressure was measured every 2 months, and serum inflammatory markers, spleen pathologic characteristics, renal injury and vascular function were observed at 6 months. The results showed that coptisine decreased the levels of serum autoantibodies and serum inflammatory markers in the SLE mice, improved the pathologic characteristics of the spleen, and simultaneously improved renal injury, decreased inflammatory responses in the kidneys, reduced blood pressure, and improved vascular endothelial function. Western blot assays revealed that inhibiting the activation of the NF-κB and Rho/ROCK signalling pathways and downstream signalling molecules might be the potential mechanisms of the effects of coptisine. Our findings suggest that therapy with coptisine may be a strategy for preventing SLE and ameliorating associated kidney and cardiovascular complications.

Temporal hemodynamic changes in a female mouse model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease characterized by circulating autoantibodies, prevalent hypertension, renal injury, and cardiovascular disease. Onset of the disease often occurs in young women of childbearing age. Although kidney involvement is common to patients with SLE, little is known about temporal changes in renal hemodynamic function and its relationship to the pathogenesis of hypertension during autoimmune diseases. We hypothesized that the loss of immunological tolerance and subsequent production of autoantibodies in SLE leads to impaired renal hemodynamic function that precedes the development hypertension. Female NZBWF1 (SLE) mice and female NZW/LacJ (control) mice were instrumented with carotid artery and jugular vein catheters to determine mean arterial pressure (MAP) and glomerular filtration rate, respectively, at ages of 15, 20, 24, 28, 31, and 34 wk. In addition, urinary albumin excretion, blood urea nitrogen, circulating autoantibodies, and glomerulosclerosis were assessed at each age. Levels of circulating autoantibodies are increased between 24 and 28 wk of age in NZBWF1 mice and were significantly greater than in control mice. Glomerular filtration rate was significantly increased at 28 wk of age in NZBWF1 mice followed by a sharp decline at 34 wk of age. NZBWF1 mice had an increase in MAP that occurred by 34 wk of age. These data show that changes in circulating autoantibodies, renal hemodynamic function, and glomerular injury occur in NZBWF1 mice before changes in MAP, suggesting an important mechanistic role for autoimmunity to directly impair renal hemodynamic function and promote the development of hypertension.

Renal cyst growth is attenuated by a combination treatment of tolvaptan and pioglitazone, while pioglitazone treatment alone is not effective

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is one of the most common monogenic disorders, characterized by the progressive formation of fluid-filled cysts. Tolvaptan is an approved drug for ADPKD patients, but is also associated with multiple side effects. The peroxisome proliferator-activator receptor gamma (PPARγ) agonist pioglitazone slows disease progression in the PCK rat model for PKD. Here, we tested whether a combination treatment of relevant doses of tolvaptan and pioglitazone leads to improved efficacy in an adult-onset PKD mouse model. Tolvaptan indeed slowed PKD progression, but the combination treatment was not more effective than tolvaptan alone. In addition, although pioglitazone raised plasma levels of its surrogate drug marker adiponectin, the drug unexpectedly failed to slow PKD progression. The pioglitazone target PPARγ was expressed at surprisingly low levels in mouse, rat and human kidneys. Other pioglitazone targets were more abundantly expressed, but this pattern was comparable across various species. The data suggest that several potential pharmacokinetic and pharmacodynamic (PK/PD) differences between different species may underlie whether or not pioglitazone is able to slow PKD progression. The ongoing phase II clinical trial with low-dose pioglitazone treatment (NCT02697617) will show whether pioglitazone is a suitable drug candidate for ADPKD treatment.

Pioglitazone Modulates the Vascular Contractility in Hypertension by Interference with ET-1 Pathway

Endothelin-1 (ET-1) is an important modulator of the vascular tone and a proinflammatory molecule that contributes to the vascular damage observed in hypertension. Peroxisome-proliferator activated receptors-γ (PPARγ) agonists show cardioprotective properties by decreasing inflammatory molecules such as COX-2 and reactive oxygen species (ROS), among others. We investigated the possible modulatory effect of PPARγ activation on the vascular effects of ET-1 in hypertension. In spontaneously hypertensive rats (SHR), but not in normotensive rats, ET-1 enhanced phenylephrine-induced contraction through ET_A by a mechanism dependent on activation of TP receptors by COX-2-derived prostacyclin and reduction in NO bioavailability due to enhanced ROS production. In SHR, the PPARγ agonist pioglitazone (2.5 mg/Kg·day, 28 days) reduced the increased ET_A levels and increased those of ET_B. After pioglitazone treatment of SHR, ET-1 through ET_B decreased ROS levels that resulted in increased NO bioavailability and diminished phenylephrine contraction. In vascular smooth muscle cells from SHR, ET-1 increased ROS production through AP-1 and NFκB activation, leading to enhanced COX-2 expression. These effects were blocked by pioglitazone. In summary, in hypertension, pioglitazone shifts the vascular ET_A/ET_B ratio, reduces ROS/COX-2 activation and increases NO availability; these changes explain the effect of ET-1 decreasing phenylephrine-induced contraction.

Human recombinant relaxin-2 does not attenuate hypertension or renal injury but exacerbates vascular dysfunction in a female mouse model of SLE

Systemic lupus erythematosus (SLE) is an autoimmune disease that disproportionately affects women of reproductive age and increases their risk for developing hypertension, vascular, and renal disease. Relaxin has potential beneficial therapeutic effects in cardiovascular disease through direct actions on the vasculature. The potential therapeutic benefit of relaxin on SLE-associated cardiovascular and renal risk factors like hypertension has not previously been tested. We hypothesized that relaxin would attenuate hypertension, renal injury, and vascular dysfunction in an established female mouse model of SLE (NZBWF1 mice). Serelaxin (human recombinant relaxin-2, 0.5 mg·kg^-1·day^-1) or vehicle was administered via osmotic mini-pump for 4 wk in female control (NZW) or SLE mice between 28 and 31 wk of age. Serelaxin treatment increased uterine weights in both groups, suggesting that the Serelaxin was bioactive. Mean arterial pressure, measured by carotid artery catheter, was significantly increased in vehicle-treated SLE mice compared with vehicle-treated controls, but was not changed by Serelaxin treatment. Albumin excretion rate, measured by ELISA, was similar between vehicle- and Serelaxin-treated SLE mice and between vehicle- and Serelaxin-treated control mice. Wire myography was performed using isolated carotid arteries to assess endothelial-independent and -dependent vasodilation, and data confirm that SLE mice have impaired endothelium-independent and -dependent relaxation compared with control mice. Serelaxin treatment did not affect endothelium-independent vasodilation, but exacerbated the endothelium-dependent dysfunction. These data suggest that, contrary to our hypothesis, Serelaxin infusion does not attenuate hypertension, renal injury, or vascular dysfunction in SLE, but worsens underlying vascular endothelial dysfunction in this experimental model of SLE. These data do not support the use of human recombinant relaxin-2 as an antihypertensive in the SLE patient population. NEW & NOTEWORTHY Relaxin is a peptide hormone commonly known for its role in pregnancy and for its use in recent clinical trials for the treatment of heart failure. Evidence suggests that relaxin has immunomodulatory effects; however, the potential therapeutic impact of relaxin in chronic immune mediated disease is unclear. This study tests whether recombinant human relaxin (Serelaxin) attenuates the progression of autoimmunity, and the associated cardiovascular consequences, in an experimental model of systemic lupus erythematosus.

Lactobacillus fermentum CECT5716: a novel alternative for the prevention of vascular disorders in a mouse model of systemic lupus erythematosus

The aim of the present study was to examine whether the immune-modulatory bacteria Lactobacillus fermentum CECT5716 (LC40) ameliorates disease activity and cardiovascular complications in a female mouse model of lupus. Eighteen-week-old NZBWF1 [systemic lupus erythematosus (SLE)] and NZW/LacJ (control) mice were treated with vehicle or LC40 (5 × 10⁸ colony-forming units/d) for 15 wk. LC40 treatment reduced lupus disease activity, blood pressure, cardiac and renal hypertrophy, and splenomegaly in SLE mice. LC40 reduced the elevated T, B, regulatory T cells (T_reg), and T helper (T_h)-1 cells in mesenteric lymph nodes of lupus mice. LC40 lowered the higher plasma concentration of proinflammatory cytokines observed in lupus mice. Aortas from SLE mice showed reduced endothelium-dependent vasodilator responses to acetylcholine. Endothelial dysfunction found in SLE is related to an increase of both NADPH oxidase-driven superoxide production and eNOS phosphorylation at the inhibitory Thr⁴⁹⁵. These activities returned to normal values after a treatment with LC40. Probiotic administration to SLE mice reduced plasma LPS levels, which might be related to an improvement of the gut barrier integrity. LC40 treatment increases the Bifidobacterium count in gut microbiota of SLE mice. In conclusion, our findings identify the gut microbiota manipulation with LC40 as an alternative approach to the prevention of SLE and its associated vascular damage.-Toral, M., Robles-Vera, I., Romero, M., de la Visitación, N., Sánchez, M., O'Valle, F., Rodriguez-Nogales, A., Gálvez, J., Duarte, J., Jiménez, R. Lactobacillus fermentum CECT5716: a novel alternative for the prevention of vascular disorders in a mouse model of systemic lupus erythematosus.

Cyclophosphamide treatment for hypertension and renal injury in an experimental model of systemic lupus erythematosus

Cardiovascular disease is the major cause of mortality among patients with the autoimmune disorder systemic lupus erythematosus (SLE). Our laboratory previously reported that immunosuppression with mycophenolate mofetil, a common therapy in patients with SLE, attenuates the development of hypertension in an experimental model of SLE. Cyclophosphamide (CYC) is another common therapy for patients with SLE that has contributed to improved disease management; however, its impact on the development of hypertension associated with SLE is not clear. We tested whether treatment with CYC (25 mg/kg, once/week, IP injection) for 4 weeks would attenuate hypertension in an established female mouse model of SLE with hypertension (30-week-old NZBWF1 females). Plasma anti-dsDNA IgG levels, pathogenic for the disease, were lower in CYC-treated SLE mice compared to vehicle-treated SLE mice, suggesting efficacy of the therapy to suppress aberrant immune system function. Mean arterial pressure (MAP) was assessed by carotid artery catheters in conscious mice. Treatment did not attenuate the development of hypertension when compared to vehicle-treated SLE mice; however, urinary albumin excretion was lower in CYC-treated animals. Corresponding with the reduction in autoantibodies, data suggest that CYC treatment lowered circulating CD45R+ B cells. Paradoxically, circulating CD11b+ Ly6G+ neutrophils were increased in CYC-treated SLE mice compared to vehicle treated. Estrus cycling data also suggest that CYC treatment had an impact on ovarian function that may be consistent with reduced circulating estrogen levels. Taken together, these data suggest that CYC treatment attenuates autoantibody production and renal disease during SLE, but that the potential to affect MAP may be blunted by the increase in circulating neutrophils and CYC's impact on ovarian function.

Virgin olive oil and its phenol fraction modulate monocyte/macrophage functionality: a potential therapeutic strategy in the treatment of systemic lupus erythematosus

Monocytes and macrophages are critical effectors and regulators of inflammation and innate immune response, which appear altered in different autoimmune diseases such as systemic lupus erythematosus (SLE). Recent studies suggested that virgin olive oil (VOO) and particularly its phenol compounds might possess preventive effects on different immune-inflammatory diseases, including SLE. Here, we evaluated the effects of VOO (and sunflower oil) on lipopolysaccharide (LPS)-activated peritoneal macrophages from a model of pristane-induced SLE in BALB/c mice, as well as those of the phenol fraction (PF) from VOO on the immune-inflammatory activity and plasticity in monocytes and monocyte-derived macrophages from healthy volunteers. The release of nitrite and inflammatory cytokines was lower in LPS-treated peritoneal macrophages from pristane-SLE mice fed the VOO diet when compared with the sunflower oil diet. PF from VOO similarly decreased the secretion of nitrite and inflammatory cytokines and expression of inducible nitric oxide, PPARγ and Toll-like receptor 4 in LPS-treated human monocytes. PF from VOO also prevented the deregulation of human monocyte subset distribution by LPS and blocked the genetic signature of M1 macrophages while favouring the phenotype of M2 macrophages upon canonical polarisation of naïve human macrophages. For the first time, our study provides several lines of in vivo and in vitro evidence that VOO and PF from VOO target and counteract inflammatory pathways in the monocyte–macrophage lineage of mice with pristane-induced SLE and of healthy subjects, which is a meaningful foundation for further development and application in preclinical and clinical use of PF from VOO in patients with SLE.

Role of the Immune System in Hypertension

High blood pressure is present in more than one billion adults worldwide and is the most important modifiable risk factor of death resulting from cardiovascular disease. While many factors contribute to the pathogenesis of hypertension, a role of the immune system has been firmly established by a large number of investigations from many laboratories around the world. Immunosuppressive drugs and inhibition of individual cytokines prevent or ameliorate experimental hypertension, and studies in genetically-modified mouse strains have demonstrated that lymphocytes are necessary participants in the development of hypertension and in hypertensive organ injury. Furthermore, immune reactivity may be the driving force of hypertension in autoimmune diseases. Infiltration of immune cells, oxidative stress, and stimulation of the intrarenal angiotensin system are induced by activation of the innate and adaptive immunity. High blood pressure results from the combined effects of inflammation-induced impairment in the pressure natriuresis relationship, dysfunctional vascular relaxation, and overactivity of the sympathetic nervous system. Imbalances between proinflammatory effector responses and anti-inflammatory responses of regulatory T cells to a large extent determine the severity of inflammation. Experimental and human studies have uncovered autoantigens (isoketal-modified proteins and heat shock protein 70) of potential clinical relevance. Further investigations on the immune reactivity in hypertension may result in the identification of new strategies for the treatment of the disease.

Anti-CD3 antibody therapy attenuates the progression of hypertension in female mice with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disorder with prevalent hypertension that significantly contributes to the mortality in this patient population. Pre-clinical and clinical evidence suggests that anti-CD3 antibody therapy may attenuate the development of autoimmune diseases like SLE. However, it is unclear whether this treatment impacts the development of the prevalent hypertension associated with SLE. The present study was designed to determine whether anti-CD3 antibody treatment attenuates the progression of hypertension in female SLE mice with already established renal disease (albuminuria ≥100mg/dL). Female SLE (NZBWF1) and control (NZW) mice were administered either an antibody to CD3ε, a component of the T cell receptor complex expressed on all T cells, or IgG antibody (isotype control) for up to 4 weeks (intranasal; 25μg/week). Spleen weight was lower in SLE mice treated with anti-CD3 antibody than in IgG-treated SLE mice, suggesting that immune system hyperactivity is decreased. Circulating anti-dsDNA autoantibodies were increased in SLE mice compared to controls and were blunted in the anti-CD3-treated SLE mice. The development of hypertension was attenuated in anti-CD3 treated mice with SLE independently of changes in renal injury (assessed by urinary albumin). These data suggest anti-CD3 therapy during autoimmune disease may have added clinical benefit to attenuate cardiovascular risk factors like hypertension.

Immunometabolism in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease mediated by pathogenic autoantibodies directed against nucleoprotein complexes. Beyond the activation of autoreactive B cells, this process involves dysregulation in many other types of immune cells, including CD4⁺ T cells, dendritic cells, macrophages and neutrophils. Metabolic substrate utilization and integration of cues from energy sensors are critical checkpoints of effector functions in the immune system, with common as well as cell-specific programmes. Patients with SLE and lupus-prone mice present with activated metabolism of CD4⁺ T cells, and the use of metabolic inhibitors to normalize these features is associated with therapeutic effects. Far less is known about the metabolic requirements of B cells and myeloid cells in SLE. This article reviews current knowledge of the alterations in metabolism of immune cells in patients with SLE and mouse models of lupus in the context of what is known about the metabolic regulation of these cells during normal immune responses. How these alterations might contribute to lupus pathogenesis and how they can be targeted therapeutically are also discussed.

Immunosuppression With Mycophenolate Mofetil Attenuates Hypertension in an Experimental Model of Autoimmune Disease

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that predominantly affects women and is associated with prevalent hypertension, renal injury, and cardiovascular disease. Immune system dysfunction is recognized as an important factor in the pathogenesis of hypertension. We recently showed that preventing autoimmunity prevents the development of hypertension in an experimental model of SLE (female NZBWF1 mice). The present study tests the hypothesis that mycophenolate mofetil (MMF), an immunosuppressive therapy used clinically to treat SLE by depleting proliferating B and T lymphocytes, can improve blood pressure control.

Methods and Results

Female SLE and control (NZW/LacJ) mice were treated daily for 8 weeks with 60 mg/kg MMF. Circulating CD45R⁺ B cells were lower in MMF‐treated SLE mice after 4 weeks of treatment, but neither CD4⁺ nor CD8⁺ T cells were reduced by MMF. Plasma anti–double‐stranded DNA IgG autoantibodies, a marker of SLE disease activity, were higher in SLE mice compared with controls and were lower in SLE mice after 8 weeks of MMF. Mean arterial pressure was elevated in SLE mice compared with controls and lower in SLE mice treated with MMF compared with vehicle‐treated SLE mice. MMF also reduced both renal injury (urinary albumin excretion and glomerulosclerosis) and the infiltration of CD45R⁺ B cells and CD3⁺CD4⁺ T cells in kidneys from mice with SLE.

Conclusions

These data suggest that MMF selectively depleted CD45R⁺ B cells and lowered subsequent autoantibody production, furthering the concept that autoantibodies mechanistically contribute to the pathogenesis of hypertension.

Activation of Peroxisome Proliferator Activator Receptor β/δ Improves Endothelial Dysfunction and Protects Kidney in Murine Lupus

Women with systemic lupus erythematosus exhibit a high prevalence of hypertension, endothelial dysfunction, and renal injury. We tested whether GW0742, a peroxisome proliferator activator receptor β/δ (PPARβ/δ) agonist, ameliorates disease activity and cardiovascular complications in a female mouse model of lupus. Thirty-week-old NZBWF1 (lupus) and NZW/LacJ (control) mice were treated with GW0742 or with the PPARβ/δ antagonist GSK0660 plus GW0742 for 5 weeks. Blood pressure, plasma double-stranded DNA autoantibodies and cytokines, nephritis, hepatic opsonins, spleen lymphocyte populations, endothelial function, and vascular oxidative stress were compared in treated and untreated mice. GW0742 treatment reduced lupus disease activity, blood pressure, cardiac and renal hypertrophy, splenomegaly, albuminuria, and renal injury in lupus mice, but not in control. GW0742 increased hepatic opsonins mRNA levels in lupus mice and reduced the elevated T, B, Treg, and Th1 cells in spleens from lupus mice. GW0742 lowered the higher plasma concentration of proinflammatory cytokines observed in lupus mice. Aortae from lupus mice showed reduced endothelium-dependent vasodilator responses to acetylcholine and increased nicotinamide adenine dinucleotide phosphate oxidase-driven vascular reactive oxygen species production, which were normalized by GW0742 treatment. All these effects of GW0742 were inhibited by PPARβ/δ blockade with GSK0660. Pharmacological activation of PPARβ/δ reduced hypertension, endothelial dysfunction, and organ damage in severe lupus mice, which was associated with reduced plasma antidouble-stranded DNA autoantibodies and anti-inflammatory and antioxidant effects in target tissues. Our findings identify PPARβ/δ as a promising target for an alternative approach in the treatment of systemic lupus erythematosus and its associated vascular damage.

Nephropathy in Pparg-null mice highlights PPARγ systemic activities in metabolism and in the immune system

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor involved in many aspects of metabolism, immune response, and development. Total-body deletion of the two Pparg alleles provoked generalized lipoatrophy along with severe type 2 diabetes. Herein, we explore the appearance and development of structural and functional alterations of the kidney, comparing Pparg null-mice to their littermate controls (carrying Pparg floxed alleles). We show that renal hypertrophy and functional alterations with increased glucosuria and albuminuria are already present in 3 weeks-old Pparg null-mice. Renal insufficiency with decreased creatinine clearance progress at 7 weeks of age, with the advance of the type 2 diabetes. At 52 weeks of age, these alterations are accompanied by signs of fibrosis and mesangial expansion. More intriguingly, aged Pparg null-mice concomitantly present an anti-phospholipid syndrome (APS), characterized by the late appearance of microthrombi and a mesangioproliferative pattern of glomerular injury, associated with significant plasmatic levels of anti-β2- glycoprotein1 antibodies and renal deposition of IgG, IgM, and C3. Thus, in line with the role of PPARγ in metabolic homeostasis, Pparg null-mice first represent a potent model for studying the initiation and the development of diabetic nephropathy. Second, and in relation with the important PPARγ activity in inflammation and in immune system, these mice also highlight a new role for PPARγ signaling in the promotion of APS, a syndrome whose pathogenesis is poorly known and whose current treatment is limited to prevention of thrombosis events.

Preclinical lupus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is often preceded by immune dysregulation and clinical manifestations below the threshold for SLE classification. This review discusses current and evolving concepts about the preclassification period of SLE, including clinical and mechanistic observations, and potential avenues for early identification and intervention.

RECENT FINDINGS

Although incomplete lupus erythematosus (ILE) involves fewer clinical manifestations than SLE, ILE patients can suffer organ damage and early mortality. Common clinical features in ILE include antinuclear antibody seropositivity, polyarthritis, immunologic manifestations, and hematological disorders. Despite having lower disease activity and damage scores than SLE patients, ILE patients may develop pulmonary arterial hypertension, or renal, neurological, or peripheral vascular damage. The recently proposed Systemic Lupus International Collaborating Clinics SLE classification criteria could shift the period considered 'preclinical SLE'. Murine studies suggest that the balance of T-helper/T-regulatory cells, peroxisome proliferator-activated receptor γ activity, and plasmacytoid dendritic cell pathways may be valuable targets for early intervention.

SUMMARY

Advances in our understanding of early SLE, including stages before clinical features are fully developed, will improve our ability to identify individuals at high risk of classification for potential prevention trials, provide necessary information to improve diagnostic testing, and perhaps identify novel targets for directed therapeutics in clinical SLE.

Understanding mechanisms of hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that predominately affects women of reproductive age. Hypertension is an important cardiovascular risk factor that is prevalent in this patient population. Despite the high incidence of hypertension in women with SLE, the pathophysiological mechanisms underlying the development of hypertension remain poorly understood. This review will focus on disease-related factors, including inflammation, autoantibodies, and sex hormones that may contribute to hypertension in patients with SLE. In addition, we will highlight studies performed by our laboratory using the female NZBWF1 (F1 hybrid of New Zealand Black and New Zealand White strains) mouse model, a spontaneous model of SLE that mimics human disease and develops hypertension and renal injury. Specifically, using female NZBWF1 mice, we have demonstrated that multiple factors contribute to the pathogenesis of hypertension, including the inflammatory cytokine, tumor necrosis factor (TNF)-α, oxidative stress, as well as B-cell hyperactivity and autoantibody production.

PPARγ and the Innate Immune System Mediate the Resolution of Inflammation

The resolution of inflammation is an active and dynamic process, mediated in large part by the innate immune system. Resolution represents not only an increase in anti-inflammatory actions, but also a paradigm shift in immune cell function to restore homeostasis. PPARγ, a ligand activated transcription factor, has long been studied for its anti-inflammatory actions, but an emerging body of literature is investigating the role of PPARγ and its ligands (including thiazolidinediones, prostaglandins, and oleanolic acids) in all phases of resolution. PPARγ can shift production from pro- to anti-inflammatory mediators by neutrophils, platelets, and macrophages. PPARγ and its ligands further modulate platelet and neutrophil function, decreasing trafficking, promoting neutrophil apoptosis, and preventing platelet-leukocyte interactions. PPARγ alters macrophage trafficking, increases efferocytosis and phagocytosis, and promotes alternative M2 macrophage activation. There are also roles for this receptor in the adaptive immune response, particularly regarding B cells. These effects contribute towards the attenuation of multiple disease states, including COPD, colitis, Alzheimer's disease, and obesity in animal models. Finally, novel specialized proresolving mediators-eicosanoids with critical roles in resolution-may act through PPARγ modulation to promote resolution, providing another exciting area of therapeutic potential for this receptor.

The PPAR-γ antagonist GW9662 elicits differentiation of M2c-like cells and upregulation of the MerTK/Gas6 axis: a key role for PPAR-γ in human macrophage polarization

Background

The nuclear receptors PPAR-γ and LXRs regulate macrophage lipid metabolism and macrophage mediated inflammation. We examined the influence of these molecules on macrophage alternative activation, with particular focus on differentiation of “M2c” anti-inflammatory cells.

Methods

We cultured human monocytes in M0, M1, M2a or M2c macrophage differentiating conditions, in the presence or absence of PPAR-γ and LXR ligands. Flow cytometry was used to analyze membrane expression of phenotypic markers. Basal and LPS-stimulated production of soluble mediators was measured by ELISA. Efferocytosis assays were performed by coincubating monocytes/macrophages with apoptotic neutrophils.

Results

We found that PPAR-γ inhibition, using the PPAR-γ antagonist GW9662, elicits differentiation of M2c-like (CD206⁺ CD163⁺ CD16⁺) cells and upregulation of the MerTK/Gas6 axis. Exposure of differentiating macrophages to IFN-γ, GM-CSF or LPS (M1 conditions), however, hampers GW9662 induction of MerTK and Gas6. When macrophages are differentiated with IL-4 (M2a conditions), addition of GW9662 results into an M2a (CD206⁺ CD209⁺ CD163⁻ MerTK⁻) to M2c (CD206^high CD209⁻ CD163⁺ MerTK⁺) polarization shift. Conversely, in the presence of dexamethasone (M2c conditions), the PPAR-γ agonist rosiglitazone attenuates CD163 and MerTK upregulation. The LXR agonist T0901317 induces MerTK independently of M2c polarization; indeed, CD206, CD163 and CD16 are downregulated. GW9662-differentiated M2c-like cells secrete high levels of Gas6 and low amounts of TNF-α and IL-10, mimicking dexamethasone effects in vitro. However, unlike conventional M2c cells, GW9662-differentiated cells do not show enhanced efferocytic ability.

Conclusions

Our results provide new insights into the role of PPAR-γ and LXR receptors in human macrophage activation and reveal the existence of different patterns regulating MerTK expression. Unexpectedly, PPAR-γ appears to negatively control the expansion of a discrete subset of M2c-like anti-inflammatory macrophages.

Inhibitory effects of peroxisome proliferator-activated receptor γ agonists on collagen IV production in podocytes

Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have beneficial effects on the kidney diseases through preventing microalbuminuria and glomerulosclerosis. However, the mechanisms underlying these effects remain to be fully understood. In this study, we investigate the effects of PPAR-γ agonist, rosiglitazone (Rosi) and pioglitazone (Pio), on collagen IV production in mouse podocytes. The endogenous expression of PPAR-γ was found in the primary podocytes and can be upregulated by Rosi and Pio, respectively, detected by RT-PCR and Western blot. PPAR-γ agonist markedly blunted the increasing of collagen IV expression and extraction in podocytes induced by TGF-β. In contrast, adding PPAR-γ antagonist, GW9662, to podocytes largely prevented the inhibition of collagen IV expression from Pio treatment. Our data also showed that phosphorylation of Smad2/3 enhanced by TGF-β in a time-dependent manner was significantly attenuated by adding Pio. The promoter region of collagen IV gene contains one putative consensus sequence of Smad-binding element (SBE) by promoter analysis, Rosi and Pio significantly ameliorated TGF-β-induced SBE4-luciferase activity. In conclusion, PPAR-γ activation by its agonist, Rosi or Pio, in vitro directly inhibits collagen IV expression and synthesis in primary mouse podocytes. The suppression of collagen IV production was related to the inhibition of TGF-β-driven phosphorylation of Smad2/3 and decreased response activity of SBEs of collagen IV in PPAR-γ agonist-treated mouse podocytes. This represents a novel mechanistic support regarding PPAR-γ agonists as podocyte protective agents.

The immunological basis of hypertension

A large number of investigations have demonstrated the participation of the immune system in the pathogenesis of hypertension. Studies focusing on macrophages and Toll-like receptors have documented involvement of the innate immunity. The requirements of antigen presentation and co-stimulation, the critical importance of T cell-driven inflammation, and the demonstration, in specific conditions, of agonistic antibodies directed to angiotensin II type 1 receptors and adrenergic receptors support the role of acquired immunity. Experimental findings support the concept that the balance between T cell-induced inflammation and T cell suppressor responses is critical for the regulation of blood pressure levels. Expression of neoantigens in response to inflammation, as well as surfacing of intracellular immunogenic proteins, such as heat shock proteins, could be responsible for autoimmune reactivity in the kidney, arteries, and central nervous system. Persisting, low-grade inflammation in these target organs may lead to impaired pressure natriuresis, an increase in sympathetic activity, and vascular endothelial dysfunction that may be the cause of chronic elevation of blood pressure in essential hypertension.

Peroxisome proliferator-activated receptor gamma agonists in the prevention and treatment of murine systemic lupus erythematosus

Peroxisome proliferator-activated receptor gamma (PPARγ) agonists are known to have many immunomodulatory effects. We have previously shown that the PPARγ agonist rosiglitazone is beneficial when used early in prevention of disease in murine models of systemic lupus erythematosus (SLE) and SLE-related atherosclerosis. In this report, we demonstrate that another PPARγ agonist, pioglitazone is also beneficial as a treatment for early murine lupus, indicating that this is a class effect and not agent-specific. We further attempt to define the ability of PPARγ agonists to ameliorate established or severe autoimmune disease using two mouse models: the MRL.lpr SLE model and the gld.apoE(-/-) model of accelerated atherosclerosis and SLE. We demonstrate that, in contrast to the marked amelioration of disease seen when PPARγ agonist treatment was started before disease onset, treatment with rosiglitazone after disease onset in MRL.lpr or gld.apoE(-/-) mice had minimal beneficial effect on the development of the autoimmune phenotype; however, rosiglitazone treatment remained highly effective at reducing lupus-associated atherosclerosis in gld.apoE(-/-) mice after disease onset or when mice were maintained on a high cholesterol Western diet. These results suggest that beneficial effects of PPARγ agonists on the development of autoimmunity might be limited to the early stages of disease, but that atherosclerosis, a major cause of death in SLE patients, may be ameliorated even in established or severe disease.

Estrogen in cardiovascular disease during systemic lupus erythematosus

PURPOSE

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease that disproportionately affects women during their childbearing years. Cardiovascular disease is the leading cause of mortality in this patient population at an age when women often have low cardiovascular risk. Hypertension is a major cardiovascular disease risk factor, and its prevalence is markedly increased in women with SLE. Estrogen has traditionally been implicated in SLE disease progression because of the prevalence of the disease in women; however, its role in cardiovascular risk factors such as hypertension is unclear. The objective of this review is to discuss evidence for the role of estrogen in both human and murine SLE with emphasis on the effect of estrogen on cardiovascular risk factors, including hypertension.

METHODS

PubMed was used to search for articles with terms related to estradiol and SLE. The references of retrieved publications were also reviewed.

FINDINGS

The potential permissive role of estrogen in SLE development is supported by studies from experimental animal models of lupus in which early removal of estrogen or its effects leads to attenuation of SLE disease parameters, including autoantibody production and renal injury. However, data about the role of estrogens in human SLE are much less clear, with most studies not reaching firm conclusions about positive or negative outcomes after hormonal manipulations involving estrogen during SLE (ie, oral contraceptives, hormone therapy). Significant gaps in knowledge remain about the effect of estrogen on cardiovascular risk factors during SLE. Studies in women with SLE were not designed to determine the effect of estrogen or hormone therapy on blood pressure even though hypertension is highly prevalent, and risk of premature ovarian failure could necessitate use of hormone therapy in women with SLE. Recent evidence from an experimental animal model of lupus found that estrogen may protect against cardiovascular risk factors in adulthood. In addition, increasing evidence suggests that estrogen may have distinct temporal effects on cardiovascular risk factors during SLE.

IMPLICATIONS

Data from experimental models of lupus suggest that estrogens may have an important permissive role for developing SLE early in life. However, their role in adulthood remains unclear, particularly for the effect on cardiovascular disease and its risk factors. Additional work is needed to understand the effect of estrogens in human SLE, and preclinical studies in experimental models of SLE may contribute important mechanistic insight to further advance the field.

Impact of early life ovariectomy on blood pressure and body composition in a female mouse model of systemic lupus erythematosus

Because of the preponderance of women affected by the chronic autoimmune disease systemic lupus erythematosus (SLE), estrogen is thought to contribute to SLE disease progression. This is supported by evidence from experimental animal models of SLE showing that removal of estrogen in young female mice delays autoantibody production and renal injury and lengthens survival. Blood pressure and changes in body composition are important cardiovascular risk factors that can be regulated by estrogens. Because cardiovascular disease is the leading cause of death in patients with SLE, we used an established female mouse model of SLE (NZBWF1) to test whether early life removal of estrogen impacts the development of hypertension and changes in body composition commonly associated with SLE. Eight-week-old female SLE and control mice (NZW/LacJ) underwent either a sham operation or ovariectomy. Body weight, body composition (fat and lean masses), and renal injury (albuminuria) were monitored until mice reached 34 wk of age, at which time mean arterial pressure was assessed in conscious animals by a carotid catheter. Early life removal of the ovaries delayed the onset of autoantibody production and albuminuria while causing an increase in body weight and fat mass. Blood pressure in the adult was not altered by early life removal of the ovaries. These data suggest that estrogens may have a permissive role for the development of SLE while helping to maintain normal body weight and composition, which is associated with reduced cardiovascular risk.

Preventing autoimmunity protects against the development of hypertension and renal injury

Several studies suggest a link between autoimmunity and essential hypertension in humans. However, whether autoimmunity can drive the development of hypertension remains unclear. The autoimmune disease systemic lupus erythematosus is characterized by autoantibody production, and the prevalence of hypertension is increased markedly in this patient population compared with normal healthy women. We hypothesized that preventing the development of autoimmunity would prevent the development of hypertension in a mouse model of lupus. Female lupus (NZBWF1) and control mice (NZW) were treated weekly with anti-CD20 or immunoglobulin G antibodies (both 10 mg/kg, IV) starting at 20 weeks of age for 14 weeks. Anti-CD20 therapy markedly attenuated lupus disease progression as evidenced by reduced CD45R+ B cells and lower double-stranded DNA autoantibody activity. In addition, renal injury in the form of urinary albumin, glomerulosclerosis, and tubulointerstitial fibrosis, as well as tubular injury (indicated by renal cortical expression of neutrophil gelatinase-associated lipocalin) was prevented by anti-CD20 therapy in lupus mice. Finally, lupus mice treated with anti-CD20 antibody did not develop hypertension. The protection against the development of hypertension was associated with lower renal cortical tumor necrosis factor-α expression, a cytokine that has been previously reported by us to contribute to the hypertension in this model, as well as renal cortical monocyte chemoattractant protein-1 expression and circulating T cells. These data suggest that the development of autoimmunity and the resultant increase in renal inflammation are an important underlying factor in the prevalent hypertension that occurs during systemic lupus erythematosus.

Cardiovascular disease in lupus: insights and updates

PURPOSE OF REVIEW

With improved management of the classical disease manifestations of systemic lupus erythematosus (SLE), cardiovascular disease (CVD) has emerged as one of the most important causes of morbidity and mortality. This review in particular focuses on progress over the past year in clinical and basic aspects of SLE-driven accelerated atherosclerosis.

RECENT FINDINGS

Both subclinical CVD and CV events continue to be recognized at increased frequency in previously unstudied lupus cohorts and populations. Novel associations have been identified between lupus CVD and cognitive impairment, depression, and low-income status. In terms of pathogenesis, there is an ever-increasing focus on the innate immune system and, in particular, type I interferons (IFNs). Recent studies have drawn connections in both human and murine models between neutrophils, plasmacytoid dendritic cells, type I IFNs, and endothelial dysfunction. Whether treatments such as mycophenolate mofetil or statins have a role in prevention of lupus CVD is an area of intensive study.

SUMMARY

CVD is a major complication of lupus and is now a leading cause of death among people living with this disease. As such, additional studies are needed in order to identify the most effective preventive strategies and most predictive vascular risk biomarkers. Type I IFNs may play a critical role in lupus CVD pathogenesis, and it is recommended that vascular outcomes be included in ongoing trials testing the efficacy of anti-IFN biologics.

Peroxisome proliferator-activated receptor agonists in a battle against the aging kidney

As aging is a complex phenomenon characterized by intraindividual and interindividual diversities in the maintenance of the homeostatic condition of cells and tissues, changes in renal function are not uniform and depend on associated diseases and environmental factors. Multiple studies have investigated the possible underlying mechanisms of age-related decline in kidney function. Evolutionary, molecular, cellular and systemic theories have been postulated to explain the primary disease independent age-related changes and adaptive responses. As peroxisome proliferator-activated receptors (PPARs) are involved in a broad spectrum of biological processes, PPAR activation might have an effect on the prevention of cell senescence. In this review, we will focus on the experimental and clinical evidence of PPAR agonists in a battle against the aging kidney.

17β-Estradiol protects against the progression of hypertension during adulthood in a mouse model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disorder with a high prevalence of hypertension and cardiovascular disease. Because SLE predominantly affects women, estrogen is commonly implicated as a contributor to SLE disease progression. Using an established mouse model of SLE (female NZBWF1), we tested whether estrogen has a causal role in the development of hypertension in adulthood. Thirty-week-old SLE and control mice (NZW/LacJ) underwent either a sham or ovariectomy (OVX) procedure. 17β-Estradiol (E2; 5 μg/mouse, twice/week, subcutaneously) was administered to a subset of OVX mice. Mean arterial pressure (in mm Hg) was increased in SLE mice (134±4 versus 119±3 in controls). Contrary to our hypothesis, OVX exacerbated the hypertension in female SLE mice (153±3; P<0.05 versus SLE sham), and repletion of E2 prevented the OVX-induced increase in blood pressure (132±2). The prevalence of albuminuria was increased in SLE mice compared with controls (37% versus 0%). OVX increased the prevalence in SLE mice (70% versus 37% in SLE shams). Repletion of E2 completely prevented albuminuria in OVX SLE mice. Renal cortical tumor necrosis factor α was increased in SLE mice compared with controls and was further increased in OVX SLE. The OVX-induced increase in renal tumor necrosis factor α expression was prevented by repletion of E2. Treatment of OVX SLE mice with the tumor necrosis factor α inhibitor, etanercept, blunted the OVX-induced increase in blood pressure (140±2) and prevalence of albuminuria (22%). These data suggest that 17β-estradiol protects against the progression of hypertension during adulthood in SLE, in part, by reducing tumor necrosis factor α.

The role of lipid-activated nuclear receptors in shaping macrophage and dendritic cell function: From physiology to pathology

Nuclear receptors are ligand-activated transcription factors linking lipid signaling to the expression of the genome. There is increasing appreciation of the involvement of this receptor network in the metabolic programming of macrophages and dendritic cells (DCs), essential members of the innate immune system. In this review we focus on the role of retinoid X receptor, retinoic acid receptor, peroxisome proliferator-associated receptor γ, liver X receptor, and vitamin D receptor in shaping the immune and metabolic functions of macrophages and DCs. We also provide an overview of the contribution of macrophage- and DC-expressed nuclear receptors to various immunopathologic conditions, such as rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, asthma, and some others. We suggest that systematic analyses of the roles of these receptors and their activating lipid ligands in immunopathologies combined with complementary and focused translational and clinical research will be crucial for the development of new therapies using the many molecules available to target nuclear receptors.

The peroxisome-proliferator activated receptor-γ agonist pioglitazone modulates aberrant T cell responses in systemic lupus erythematosus

PPAR-γ agonists can suppress autoimmune responses and renal inflammation in murine lupus but the mechanisms implicated in this process remain unclear. We tested the effect of the PPAR-γ agonist pioglitazone in human lupus and control PBMCs with regard to gene regulation and various functional assays. By Affymetrix microarray analysis, several T cell-related pathways were significantly highlighted in pathway analysis in lupus PBMCs. Transcriptional network analysis showed IFN-γ as an important regulatory node, with pioglitazone treatment inducing transcriptional repression of various genes implicated in T cell responses. Confirmation of these suppressive effects was observed specifically in purified CD4+ T cells. Pioglitazone downregulated lupus CD4+ T cell effector proliferation and activation, while it significantly increased proliferation and function of lupus T regulatory cells. We conclude that PPAR-γ agonists selectively modulate CD4+ T cell function in SLE supporting the concept that pioglitazone and related,-agents should be explored as potential therapies in this disease.

Hypertension in an experimental model of systemic lupus erythematosus occurs independently of the renal nerves

Systemic lupus erythematosus (SLE) is a chronic inflammatory disorder with prevalent hypertension and renal injury. In this study, we tested whether the renal nerves contribute to the development of hypertension in an established mouse model of SLE (NZBWF1). Female SLE and control (NZW/LacJ) mice were subjected to either bilateral renal denervation or a sham procedure at 32 wk of age. Two weeks later, blood pressure was assessed in conscious mice using carotid artery catheters. Blood pressure was higher in SLE mice compared with controls, as previously reported; however, blood pressure was not altered in the denervated SLE or control mice. The development of albuminuria was markedly blunted in denervated SLE mice; however, glomerulosclerosis was increased. Renal denervation reduced renal cortical expression of monocyte-chemoattractant protein in SLE mice but did not significantly alter renal monocyte/macrophage infiltration. Renal cortical TNF-α expression was also increased in sham SLE mice, but this was not impacted by denervation. This study suggests that the renal nerves do not have a significant role in the pathogenesis of hypertension, but have a complex effect on the associated renal inflammation and renal injury.

Differential expression of functional Fc-receptors and additional immune complex receptors on mouse kidney cells

The precise mechanisms by which circulating immune complexes accumulate in the kidney to form deposits in glomerulonephritis are not well understood. In particular, the role of resident cells within glomeruli of the kidney has been widely debated. Immune complexes have been shown to bind one glomerular cell type (mesangial cells) leading to functional responses such as pro-inflammatory cytokine production. To further assess the presence of functional immunoreceptors on resident glomerular cells, cultured mouse renal epithelial, endothelial, and mesangial cells were treated with heat-aggregated mouse IgG or preformed murine immune complexes. Mesangial and renal endothelial cells were found to bind IgG complexes, whereas glomerular epithelial cell binding was minimal. A blocking antibody for Fc-gamma receptors reduced binding to mesangial cells but not renal endothelial cells, suggesting differential immunoreceptor utilization. RT-PCR and immunostaining based screening of cultured renal endothelial cells showed limited low-level expression of known Fc-receptors and Ig binding proteins. The interaction between mesangial cells and renal endothelial cells and immune complexes resulted in distinct, cell-specific patterns of chemokine and cytokine production. This novel pathway involving renal endothelial cells likely contributes to the predilection of circulating immune complex accumulation within the kidney and to the inflammatory responses that drive kidney injury.

Cardiovascular risk in rheumatoid arthritis and systemic autoimmune rheumatic disorders: a suggested model of preventive strategy

The pathogenesis of accelerated cardiovascular damage commonly characterizing patients affected by systemic chronic inflammatory and autoimmune rheumatic disorders is quite complex and still not fully clarified. However, it is well accepted that a strong relationship between multiple factors, including both traditional cardiovascular risk factors and disease-related inflammatory and autoimmune mechanisms, may in part explain the precocious atherosclerotic vessel damage and the increased incidence of cardiovascular events. Nevertheless, although several recent studies focused their attention on the investigation of these complex mechanisms, data regarding possible preventive strategies aimed to reduce long-term cardiovascular risk in these subjects are still lacking and not conclusive. In this setting, the early introduction of evidence-based preventive measures for the correct management of patients with systemic autoimmune disorders would be of extreme importance to reduce subclinical atherosclerosis incidence and possible major cardiovascular events.

Immune and inflammatory role in renal disease

Chronic and acute renal diseases, irrespective of the initiating cause, have inflammation and immune system activation as a common underlying mechanism. The purpose of this review is to provide a broad overview of immune cells and inflammatory proteins that contribute to the pathogenesis of renal disease, and to discuss some of the physiological changes that occur in the kidney as a result of immune system activation. An overview of common forms of acute and chronic renal disease is provided, followed by a discussion of common therapies that have anti-inflammatory or immunosuppressive effects in the treatment of renal disease.

Pioglitazone, a peroxisome proliferator activated receptor γ agonist, decreases renal crystal deposition, oxidative stress and inflammation in hyperoxaluric rats

PURPOSE

Kidney stone disease has characteristics similar to those of metabolic syndrome, including inflammation and oxidative stress. The peroxisome proliferator activated receptor γ agonist pioglitazone (AK Scientific, Union, California) is used to treat type 2 diabetes mellitus with an adjunctive effect that improves glycemic control and has anti-inflammatory and antioxidative effects. We investigated the preventive effects of pioglitazone for stone formation in a hyperoxaluric rat model.

MATERIALS AND METHODS

We divided Sprague-Dawley® rats into a control group, a 1% ethylene glycol group and a 1% ethylene glycol plus 10 mg/kg pioglitazone group. Blood and 24-hour urine samples, and kidney sections were collected on days 7, 14 and 28. We examined crystal formation using Pizzolato staining and polarized light optical microscopy. We also evaluated cell injury, apoptosis and oxidative stress with N-acetyl-β-glucosaminidase, 8-hydroxydeoxyguanosine and TUNEL assay. Expression of crystal and inflammation related genes was examined by immunohistochemistry and quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Kidney crystal formation was significantly less in the ethylene glycol plus pioglitazone group than in the ethylene glycol group. Cell injury, apoptosis and oxidative stress markedly decreased after pioglitazone administration. Expression of osteopontin and ED1 for proinflammatory macrophages was lower in the ethylene glycol plus pioglitazone group than in the ethylene glycol group while that of ED2 for anti-inflammatory macrophages was the same in the 2 groups. Linear regression analysis showed a significant change in the correlation coefficient with pioglitazone treatment between Spp1 and Sod1 expression, and the amount of crystals.

CONCLUSIONS

Pioglitazone suppressed kidney crystal formation through renal tubular cell protection, and antioxidative and anti-inflammatory effects in hyperoxaluric rats.

Oxidative stress promotes hypertension and albuminuria during the autoimmune disease systemic lupus erythematosus

Several lines of evidence suggest that essential hypertension originates from an autoimmune-mediated mechanism. One consequence of chronic immune activation is the generation of oxygen-derived free radicals, resulting in oxidative stress. Renal oxidative stress has direct prohypertensive actions on renal microvascular and tubular function. Whether oxidative stress contributes to the prevalent hypertension associated with autoimmune disease is not clear. We showed previously that female NZBWF1 mice, an established model of the autoimmune disease systemic lupus erythematosus (SLE), develop hypertension associated with renal oxidative stress. In the present study we tested the hypothesis that oxidative stress contributes to autoimmune-mediated hypertension by treating SLE and control (NZW/LacJ) mice with tempol (2.0 mmol/L) and apocynin (1.5 mmol/L) in the drinking water for 4 weeks. Although the treatment did not alter SLE disease activity (assessed by plasma double-stranded DNA autoantibodies), blood pressure and renal injury (urinary albumin) were reduced in the treated SLE mice. Tempol plus apocynin-treated SLE mice had reduced expression of nitrosylated proteins in the renal cortex, as well as reduced urinary and renal cortical hydrogen peroxide, suggesting that treatment reduced renal markers of oxidative stress. These data suggest that renal oxidative stress plays an important mechanistic role in the development of autoimmune-mediated hypertension.

Blood pressure in a hypertensive mouse model of SLE is not salt-sensitive

Systemic lupus erythematosus (SLE) is a risk factor for hypertension. Previously, we demonstrated that an established mouse model of SLE (female NZBWF1 mice) develops hypertension with renal inflammation and oxidative stress, both characteristics known as contributing mechanisms to the development of salt-sensitive hypertension. On the basis of this model, we hypothesized that blood pressure in SLE mice would be salt-sensitive. Thirty-week-old female SLE and control mice (NZW/LacJ) were fed 8% high-salt (HS) diet or normal diet (0.4% salt) for 4 wk. Plasma levels of double-stranded DNA (dsDNA) autoantibodies, a marker of SLE disease activity, were increased in SLE mice compared with controls (472 ± 148 vs. 57 ± 17 U/ml × 1,000, P < 0.001). HS did not alter dsDNA autoantibody levels in SLE or control mice. Mean arterial pressure was increased in SLE mice compared with controls (132 ± 3 vs. 118 ± 2 mmHg, P < 0.001) and was not significantly altered by the HS diet in either group. Similarly, albuminuria was higher in SLE mice compared with controls (10.7 ± 9.0 vs. 0.3 ± 0.1 mg/day) but was not significantly increased in SLE or control mice fed a HS diet. In summary, blood pressure during SLE is not salt-sensitive, and the HS diet did not adversely affect SLE disease activity or significantly augment albuminuria. These data suggest that renal inflammation and oxidative stress, characteristics common to both SLE and models of salt-sensitive hypertension, may have diverging mechanistic roles in the development of hypertension.

Blood pressure and renal hemodynamic responses to acute angiotensin II infusion are enhanced in a female mouse model of systemic lupus erythematosus

Inflammation and immune system dysfunction contributes to the development of cardiovascular and renal disease. Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disorder that carries a high risk for both renal and cardiovascular disease. While hemodynamic changes that may contribute to increased cardiovascular risk have been reported in humans and animal models of SLE, renal hemodynamics have not been widely studied. The renin-angiotensin system (RAS) plays a central role in renal hemodynamic control, and although RAS blockade is a common therapeutic strategy, the role of RAS in hemodynamic function during SLE is not clear. This study tested whether mean arterial pressure (MAP) and renal hemodynamic responses to acute infusions of ANG II in anesthetized animals were enhanced in an established female mouse model of SLE (NZBWF1). Baseline MAP was not different between anesthetized SLE and control (NZWLacJ) mice, while renal blood flow (RBF) was significantly lower in mice with SLE. SLE mice exhibited an enhanced pressor response and greater reduction in RBF after ANG II infusion. An acute infusion of the ANG II receptor blocker losartan increased RBF in control mice but not in mice with SLE. Renin and ANG II type 1 receptor expression was significantly lower, and ANG II type 2 receptor expression was increased in the renal cortex from SLE mice compared with controls. These data suggest that there are fewer ANG II receptors in the kidneys from mice with SLE but that the existing receptors exhibit an enhanced sensitivity to ANG II.