The beneficial effects of treatment with all-trans-retinoic acid plus corticosteroid on autoimmune nephritis in NZB/WF mice

The Network of Inflammatory Mechanisms in Lupus Nephritis

Several signaling pathways are involved in the progression of kidney disease in humans and in animal models, and kidney disease is usually due to the sustained activation of these pathways. Some of the best understood pathways are specific proinflammatory cytokine and protein kinase pathways (e.g., protein kinase C and mitogen-activated kinase pathways, which cause cell proliferation and fibrosis and are associated with angiotensin II) and transforming growth factor-beta (TGF-β) signaling pathways (e.g., the TGF-β signaling pathway, which leads to increased fibrosis and kidney scarring. It is thus necessary to continue to advance our knowledge of the pathogenesis and molecular biology of kidney disease and to develop new treatments. This review provides an update of important findings about kidney diseases (including diabetic nephropathy, lupus nephritis, and vasculitis, i.e., vasculitis with antineutrophilic cytoplasmic antibodies). New disease targets, potential pathological pathways, and promising therapeutic approaches from basic science to clinical practice are presented, and the blocking of JAK/STAT and TIM-1/TIM-4 signaling pathways as potential novel therapeutic agents in lupus nephritis is discussed.

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).

Expansion of regulatory T cells using low-dose interleukin-2 attenuates hypertension in an experimental model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disorder that is characterized by prevalent hypertension, renal injury, and cardiovascular disease. Numerous studies have reported a low prevalence and/or impaired function of regulatory T (T_REG) cells in both patients with SLE and murine models of the disease. Evidence suggests that T_REG cell dysfunction in SLE results from a deficiency in IL-2. Recent studies have reported that low-dose IL-2 therapy expands T_REG cells in mouse models of SLE, but whether expanding T_REG cells protects against hypertension and renal injury during SLE is unclear. To examine this question, female SLE (NZBWF1) and control (NZW) mice were injected with vehicle or recombinant mouse IL-2 three times in 24 h followed by single maintenance doses every 5 days for 4 wk. Treatment with IL-2 effectively expanded T_REG cell populations in the peripheral blood, spleen, and kidneys. Circulating levels of anti-dsDNA IgG autoantibodies, a marker of SLE disease activity, were higher in SLE mice compared with control mice but were unaffected by IL-2 treatment. As previously reported by our laboratory, mean arterial pressure, measured in conscious mice by a carotid catheter, was higher in SLE mice than in control mice. Mean arterial pressure was significantly lower in IL-2-treated SLE mice compared with vehicle-treated SLE mice, suggesting that expanding T_REG cells using low-dose IL-2 attenuates the development of hypertension. While the mechanism for the protection against hypertension is unclear, it does not appear to be related to the delay of SLE disease progression.

A Liposome-Based Adjuvant Containing Two Delivery Systems with the Ability to Induce Mucosal Immunoglobulin A Following a Parenteral Immunization

Worldwide, enteric infections rank third among all causes of disease burdens, and vaccines able to induce a strong and long-lasting intestinal immune responses are needed. Parenteral immunization generally do not generate intestinal IgA. Recently, however, injections of retinoic acid (RA) dissolved in oil, administered multiple times before vaccination to precondition the vaccine-draining lymph nodes, enabled a parenteral vaccine strategy to induce intestinal IgA. As multiple injections of RA before vaccination is not an attractive strategy for clinical practice, we aimed to develop a "one injection" vaccine formulation that upon parenteral administration induced intestinal IgA. Our vaccine formulation contained two liposomal delivery systems. One delivery system, based on 1,2-distearoyl- sn-glycero-3-phosphocholine stabilized with PEG, was designed to exhibit fast drainage of RA to local lymph nodes to precondition these for a mucosal immune response before being subjected to the vaccine antigen. The other delivery system, based on the cationic liposomal adjuvant CAF01 stabilized with cholesterol, was optimized for prolonged delivery of the antigen by migratory antigen-presenting cells to the preconditioned lymph node. Combined we call the adjuvant CAF23. We show that CAF23, administered by the subcutaneous route induces an antigen specific intestinal IgA response, making it a promising candidate adjuvant for vaccines against enteric diseases.

All-Trans Retinoic Acid Induces CD4+CD25+FOXP3+ Regulatory T Cells by Increasing FOXP3 Demethylation in Systemic Sclerosis CD4+ T Cells

Background

Retinoic acid (RA) is an active metabolite of vitamin A and has been reported to improve the clinical symptoms of patients with systemic sclerosis (SSc). However, the mechanism of RA in the prevention of SSc remains unclear. Regulatory T cells (Tregs) are a subpopulation of T cells with immunosuppressive activity. The quantitative and functional defects of Tregs may mediate the immune dysfunction in SSc. The addition of all-trans retinoic acid (ATRA) to human naïve CD4+ cells could promote the maturation of Tregs and increase the stable expression of Foxp3. In this study, we explored the role of RA on Tregs in SSc CD4+ T cells and its possible epigenetic mechanisms, so as to further understand the mechanisms of RA on SSc.

Methods

CD4+ T cells were isolated from peripheral blood of SSc and treated with or without ATRA and/or transforming growth factor-β (TGF-β). The percentage of CD4+CD25+FOXP3+ Tregs was counted by flow cytometry. FOXP3 mRNA and protein levels were measured by quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting, respectively. Bisulfite sequencing was performed to determine the methylation status of the FOXP3 proximal promoter sequences.

Results

The expression of Tregs and FOXP3 in CD4+ T cells from patients with SSc increased in response to ATRA. Moreover, combined stimulation with ATRA and TGF-β resulted in the enhancement of these effects. Further studies revealed that stimulation with ATRA increased the expression of FOXP3 in SSc CD4+ T cells by downregulating FOXP3 promoter methylation levels.

Conclusions

ATRA acts as an inducer of Treg response in SSc CD4+ T cells via demethylation of the FOXP3 promoter and activation of FOXP3 expression. This may be one of the molecular mechanisms for ATRA, and therefore, RA can be used for the treatment of SSc.

Lipopolysaccharide-Induced Acute Kidney Injury Is Dependent on an IL-18 Receptor Signaling Pathway

The proinflammatory cytokine interleukin (IL)-18 is an important mediator of the organ failure induced by endotoxemia. IL-18 (known as an interferon-gamma (IFN-γ) inducing factor), and other inflammatory cytokines have important roles in lipopolysaccharide (LPS)-induced acute kidney injury (AKI). We investigated the effect of inflammatory cytokines and Toll-like receptor 4 (TLR4) expression, an event that is accompanied by an influx of monocytes, including CD4⁺ T cells and antigen-presenting cells (APCs) in IL-18Rα knockout (KO) mice and wild-type (WT) mice after LPS injection. In the acute advanced phase, the IL-18Rα KO mice showed a higher survival rate and a suppressed increase of blood urea nitrogen, increased levels of proinflammatory cytokines such as IFN-γ and IL-18, the infiltration of CD4⁺ T cells and the expression of kidney injury molecule-1 as an AKI marker. In that phase, the renal mRNA expression of the M1 macrophage phenotype and C-C chemokine receptor type 7 as the maturation marker of dendritic cells (DCs) was also significantly decreased in the IL-18Rα KO mice, although there were small numbers of F4/80⁺ cells and DCs in the kidney. Conversely, there were no significant differences in the expressions of mRNA and protein TLR4 after LPS injection between the WT and IL-18Rα KO groups. Our results demonstrated that the IL-18Rα-mediated signaling pathway plays critical roles in CD4⁺ T cells and APCs and responded more quickly to IFN-γ and IL-18 than TLR4 stimulation in the pathogenesis of LPS-induced AKI.

Oral all-trans retinoic acid plus danazol versus danazol as second-line treatment in adults with primary immune thrombocytopenia: a multicentre, randomised, open-label, phase 2 trial

BACKGROUND

Primary immune thrombocytopenia is a severe bleeding disorder. About 50-85% of patients achieve initial remission from first-line therapies, but optimal second-line treatment remains a challenge. All-trans retinoic acid (ATRA) has an immunomodulatory effect on haemopoiesis, making it a possible treatment option. We aimed to evaluate the efficacy and safety of ATRA plus danazol versus danazol in non-splenectomised patients with corticosteroid-resistant or relapsed primary immune thrombocytopenia.

METHODS

We did a multicentre, randomised, open-label, phase 2 study of adult patients (≥18 years) with primary immune thrombocytopenia from five different tertiary medical centres in China. Those eligible were non-splenectomised, resistant to corticosteroid treatment or relapsed, and had a platelet count less than 30 × 10⁹ per L. Masked statisticians used simple randomisation to assign patients (1:1) to receive oral ATRA (10 mg twice daily) plus oral danazol (200 mg twice daily) or oral danazol monotherapy (200 mg twice daily) for 16 weeks. Neither clinicians nor patients were masked to group assignments. All patients were assessed every week during the first 8 weeks of treatment, and at 2-week intervals thereafter. The primary endpoint was 12-month sustained response defined as platelet count of 30 × 10⁹ per L or more and at least a doubling of baseline platelet count (partial response), or a platelet count of 100 × 10⁹ per L or more (complete response) and the absence of bleeding without rescue medication at the 12-month follow-up. All randomly allocated patients, except for those who withdrew consent, were included in the modified intention-to-treat population and efficacy assessment, and all patients who received at least one dose of the study agents were included in the safety analysis. Study enrolment was stopped early because the trial results crossed the interim analysis efficacy boundary for sustained response. This trial is registered with ClinicalTrials.gov, number NCT01667263.

FINDINGS

From June 1, 2012, to July 1, 2016, we screened 130 patients for eligibility; 34 were excluded and 96 were randomly assigned. 93 patients were included in the modified intention-to-treat analysis: 45 in the ATRA plus danazol group and 48 in the danazol group. At the 12-month follow-up, sustained response was achieved more frequently in patients receiving ATRA plus danazol than in those receiving danazol monotherapy (28 [62%] of 45 vs 12 [25%] of 48; odds ratio 4·94, 95% CI 2·03-12·02, p=0·00037). Only two grade 3 adverse events were reported: one (2%) patient receiving ATRA plus danazol with dry skin, and one (2%) patient receiving danazol monotherapy with liver injury. There was no grade 4 or worse adverse event or treatment-related death in either group.

INTERPRETATION

Patients with primary immune thrombocytopenia given ATRA plus danazol had a rapid and sustained response compared with danazol monotherapy. This finding suggests that ATRA represents a promising candidate for patients with corticosteroid-resistant or relapsed primary immune thrombocytopenia.

FUNDING

National Natural Science Foundation of China, Beijing Natural Science Foundation, Beijing Municipal Science and Technology Commission, and the National Key Research and Development Program of China.

Regulatory T Cells in SLE: Biology and Use in Treatment

T regulatory cells (Tregs) represent a phenotypically and functionally heterogeneous group of lymphocytes that exert immunosuppressive activities on effector immune responses. Tregs play a key role in maintaining immune tolerance and homeostasis through diverse mechanisms which involve interactions with components of both the innate and adaptive immune systems. As in many autoimmune diseases, Tregs have been proposed to play a relevant role in the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease characterized by a progressive breakdown of tolerance to self-antigens and the presence of concomitant hyperactive immune responses. Here, we review how Tregs dysfunction in SLE has been manipulated experimentally and preclinically in the attempt to restore, at last in part, the immune disturbances in the disease.

Pin1-Targeted Therapy for Systemic Lupus Erythematosus

OBJECTIVE

Systemic lupus erythematosus (SLE) is a debilitating autoimmune disease affecting multiple organs in the body, but therapeutic options are still very limited and often come with adverse effects. Increasing evidence has underlined an important role of the Toll-like receptor 7 (TLR-7)/TLR-9/interleukin-1 receptor-associated kinase 1 (IRAK-1)/interferon regulatory factor 7 (IRF-7) pathway in the development and progression of SLE. Notably, the prolyl isomerase Pin1 is an essential regulator of IRAK-1 in TLR-7/TLR-9 signaling, but its role in SLE is unknown. We undertook this study to determine whether Pin1 is activated and plays any role in the development and treatment of SLE.

METHODS

Activation of Pin1 and TLR-7/TLR-9/IRAK-1/IRF-7 signaling was determined in various cell types among peripheral blood mononuclear cells from healthy controls and SLE patients. The effects of Pin1 and TLR signaling on SLE development were determined using validated Pin1 short hairpin RNA (shRNA), Pin1 genetic knockout, and the small-molecule Pin1 inhibitor all-trans-retinoic acid (ATRA) in immune cells and in several strains of lupus-prone mice.

RESULTS

We found abnormal activation of Pin1 and its downstream targets IRAK-1 and IRF-7 in SLE patients. Furthermore, inhibition of Pin1 using either validated Pin1 shRNA or ATRA blocked TLR-7-induced activation of IRAK-1 and IRF-7 in SLE patient-derived immune cells. Moreover, in multiple lupus-prone animals, both Pin1 knockout and ATRA strikingly attenuated the expression of autoimmunity, including skin lesions, lymphadenopathy, splenomegaly, glomerulonephritis, proteinuria, and production of anti-double-stranded DNA antibodies and CD4-CD8- T cells, and also prolonged overall survival in MRL/lpr and B6.lpr mice.

CONCLUSION

Pin1 plays a critical role in the development of SLE, and Pin1-targeted therapy offers a promising new strategy for treating SLE.

An update on diet and nutritional factors in systemic lupus erythematosus management

Systemic lupus erythematosus (SLE) is a chronic inflammatory and autoimmune disease characterised by multiple organ involvement and a large number of complications. SLE management remains complicated owing to the biological heterogeneity between patients and the lack of safe and specific targeted therapies. There is evidence that dietary factors can contribute to the geoepidemiology of autoimmune diseases such as SLE. Thus, diet therapy could be a promising approach in SLE owing to both its potential prophylactic effects, without the side effects of classical pharmacology, and its contribution to reducing co-morbidities and improving quality of life in patients with SLE. However, the question arises as to whether nutrients could ameliorate or exacerbate SLE and how they could modulate inflammation and immune function at a molecular level. The present review summarises preclinical and clinical experiences to provide the reader with an update of the positive and negative aspects of macro- and micronutrients and other nutritional factors, including dietary phenols, on SLE, focusing on the mechanisms of action involved.

All- Trans-Retinoic Acid Augments the Histopathological Outcome of Neuroinflammation and Neurodegeneration in Lupus-Prone MRL/lpr Mice

Recently, we demonstrated that treatment with all- trans-retinoic acid (tRA) induced a paradoxical effect on immune activation during the development of autoimmune lupus. Here, we further describe its negative effects on mediating neuroinflammation and neurodegeneration. Female MRL/lpr mice were orally administered tRA or VARA (retinol mixed with 10% tRA) from 6 to 14 weeks of age. Both treatments had a significant effect on brain weight, which correlated with histopathological evidence of focal astrogliosis, meningitis, and ventriculitis. Infiltration of CD138- and Iba1-positve immune cells was observed in the third ventricle and meninges of treated mice that co-labeled with ICAM-1, indicating their inflammatory nature. Increased numbers of circulating plasma cells, autoantibodies, and total IgG were also apparent. IgG and C3 complement deposition in these brain regions were also prominent as was focal astrogliosis surrounding the ventricular lining and meninges. Using Fluoro-Jade staining, we further demonstrate that neuroinflammation was accompanied by neurodegeneration in the cortex of treated mice compared with vehicle controls. These findings indicate that vitamin A exposure exacerbates the immunogenic environment of the brain during the onset of systemic autoimmune disease. Vitamin A may therefore compromise the immuno-privileged nature of the central nervous system under a predisposed immunogenic environment.

Impact of CD200-Fc on dendritic cells in lupus-prone NZB/WF1 mice

Abnormal expression of CD200/CD200R1 may contribute to the immunologic abnormalities in patients with systemic lupus erythematosus (SLE). This study aimed to assess the function of CD200/CD200R1and impact of CD200-Fc on dendritic cells in lupus-prone NZB/WF1 mice. Female NZB/WF1 mice were treated with CD200-Fc or control for 4 weeks. Plasma samples were collected to measure autoantibody levels. The expression levels of CD200/CD200R1 in peripheral blood mononuclear cells (PBMCs) and splenocytes were examined. The percentage of CD200/CD200R1-positive cells in splenocytes from NZB/WF1 mice was lower than that of C57BL/6 mice (p < 0.05). The plasma level of anti-dsDNA was significantly higher in NZB/WF1 mice than C57BL/6 mice (p < 0.001). However, the anti-dsDNA levels decreased (p = 0.047) after CD200-Fc treatment. Finally, CD200-Fc reduced the levels of IL-6 (p = 0.017) and IL-10 (p = 0.03) in the dendritic cell culture supernatant. This study suggests that the immunosuppressive CD200/CD200R1 signaling pathway might be involved in the immunopathology of NZB/WF1 mice; the present results merit further exploration of agents that can modulate the CD200/CD200FR1 pathway as a therapy for human lupus.

The safety of isotretinoin in patients with lupus nephritis: a comprehensive review

Oral isotretinoin (13-cis-retinoinc acid) is a derivative of vitamin A and belongs to the first generation of retinoids, which act as synthetic isomers of retinoic acid (RA). It is a very effective agent in a treatment of acne vulgaris; however, multiple side effects related to therapy with retinoids preclude the use of isotretinoin in less severe acne vulgaris. A significant limitation for the administration of isotretinoin appears in case of concomitant kidney disease with a special attention regarding the safety of the agent in patients with lupus nephritis (LN). The aim of this review is an assessment of the safety of isotretinoin for the treatment of acne vulgaris in patients with LN. We searched both MEDLINE and SCOPUS databases, as well as several dermatological textbooks, to present all limitations and benefits of therapy with isotretinoin or its isomer (ATRA) for patients with kidney diseases. Several mouse models of SLE revealed a significant modulatory influence of retinoids on autoimmune injury of the glomerular unit. Retinoids were demonstrated to affect mononuclear cell infiltrations of renal tissue allowing for a reduction in the overall glomerular damage. Presumptively, they can affect a synthesis of autoantibodies significantly limiting their deposition in the glomerular unit. Moreover, retinoids were also shown to affect the synthesis of different cytokines specific both for lymphocytes Th1 (IL-2, IL-12, INFγ) ant Th2 (IL-4, IL-10). The influence of retinoids on the course of LN seems to be more multidimensional than only restricted to immune aspects and these synthetic RA isomers manifest also antiproteinuric activity in comparable extent to steroidal agents. The agents were demonstrated to counteract a loss of podocytes after the injury of the glomerular unit. They can promote a differentiation of renal progenitor cells (RPCs) within the Bowman capsule into mature podocytes leading to regeneration of podocyte number. Additionally, retinoids can probably protect podocytes from injury limiting their apoptosis, as well as reducing foot process effacement. Although, an endogenous production of RA isomers increases after the injury of the glomerular unit aiming to the restoration of podocyte number, it can be significantly impaired by a loss of albumins into urine. RA isomers are progressively sequestered by albumin within the Bowman's space and therefore, they are quickly eliminated with urine. It was demonstrated that the administration of exogenous RA isomers (retinoids) can bypass the activity of albumins enhancing the regeneration of podocytes. Finally, retinoids can regulate the production of vasoactive substances influencing on different vascular functions in the kidney. They can beneficially change a balance of angiotensin metabolites through by down-regulation of angiotensin-converting enzyme type 1 and the enhancement of an expression of angiotensin-converting enzyme type 2. Another studies revealed that retinoids could also alter the activity of renal endothelin pathway; however, the significance of this effect requires further elucidation. Taken all these presented effects of retinoids in the kidney into consideration, we can conclude that isotretinoin can be the safe treatment option of acne vulgaris in patients with LN.

The SOD1 transgene expressed in erythroid cells alleviates fatal phenotype in congenic NZB/NZW-F1 mice

Oxidative stress due to a superoxide dismutase 1 (SOD1) deficiency causes anemia and autoimmune responses, which are phenotypically similar to autoimmune hemolytic anemia (AIHA) and systemic lupus erythematosus (SLE) in C57BL/6 mice and aggravates AIHA pathogenesis in New Zealand black (NZB) mice. We report herein on an evaluation of the role of reactive oxygen species (ROS) in a model mouse with inherited SLE, that is, F1 mice of the NZB × New Zealand white (NZW) strain. The ROS levels within red blood cells (RBCs) of the F1 mice were similar to the NZW mice but lower compared to the NZB mice throughout adult period. Regarding SLE pathogenesis, we examined the effects of an SOD1 deficiency or the overexpression of human SOD1 in erythroid cells by establishing corresponding congenic F1 mice. A SOD1 deficiency caused an elevation in ROS production, methemoglobin content, and hyperoxidation of peroxiredoxin in RBC of the F1 mice, which were all consistent with elevated oxidative stress. However, while the overexpression of human SOD1 in erythroid cells extended the life span of the congenic F1 mice, the SOD1 deficiency had no effect on life span compared to wild-type F1 mice. It is generally recognized that NZW mice possess a larval defect in the immune system and that NZB mice trigger an autoimmune reaction in the F1 mice. Our results suggest that the oxidative insult originated from the NZB mouse background has a functional role in triggering an aberrant immune reaction, leading to fatal responses in F1 mice.

The potential protective role of hepatitis B virus infection in pristane-induced lupus in mice

OBJECTIVE

The objective of this study was to investigate whether hepatitis B virus (HBV) infection plays a role in the regulation of autoimmunity for systemic lupus erythematosus (SLE).

METHOD

A total of 21 female BALB/c mice and 21 female HBV transgenic BALB/c mice aged two months were randomly divided into four groups: BALB/c mice, HBV(Tg) mice, pristane-injected BALB/c mice, and pristane-injected HBV(Tg) mice. BALB/c mice and HBV(Tg) mice were given an intraperitoneal injection of 0.5 ml normal saline, and the mice in the other two groups were given an intraperitoneal injection of 0.5 ml pristane. ANA and anti-dsDNA levels in serum were detected by indirect immunofluorescence. Interleukin 2 (IL-2), IL-4, IL-6, IL-17, and TNF-α were measured by Luminex technology. The serum BAFF level was measured using an Elisa kit. Twenty-four weeks after pristane administration, kidneys were removed, dissected, and stained with hematoxylin and eosin and periodic-acid Schiff.

RESULT

At six months after injecting, the ANA titers in pristane-injected HBV(Tg) mice were significantly lower than pristane-injected BALB/c mice. IL-17, TNF-α, and BAFF levels were significantly higher in pristane-injected BALB/c mice than BALB/c mice and pristane-injected HBV(Tg) mice. IL-2, IL-4, and IL-6 levels were much higher in pristane-injected HBV(Tg) mice than pristane-injected BALB/c mice. In pristane-injected HBV(Tg) mice and HBV(Tg) mice, fewer glomerulonephritis changes were found in the kidneys.

CONCLUSIONS

Our results showed that the incidence of SLE was much lower in HBV(Tg) mice, and that HBV infection helped the SLE mice survive high levels of inflammatory cytokines and severe renal damage. All these findings demonstrated the protective role of HBV in SLE patients via the immunoregulatory networks of the cytokines.

SLE: Another Autoimmune Disorder Influenced by Microbes and Diet?

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease. Despite years of study, the etiology of SLE is still unclear. Both genetic and environmental factors have been implicated in the disease mechanisms. In the past decade, a growing body of evidence has indicated an important role of gut microbes in the development of autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. However, such knowledge on SLE is little, though we have already known that environmental factors can trigger the development of lupus. Several recent studies have suggested that alterations of the gut microbial composition may be correlated with SLE disease manifestations, while the exact roles of either symbiotic or pathogenic microbes in this disease remain to be explored. Elucidation of the roles of gut microbes - as well as the roles of diet that can modulate the composition of gut microbes - in SLE will shed light on how this autoimmune disorder develops, and provide opportunities for improved biomarkers of the disease and the potential to probe new therapies. In this review, we aim to compile the available evidence on the contributions of diet and gut microbes to SLE occurrence and pathogenesis.

Remission of systemic lupus erythematosus disease activity with regulatory cytokine interleukin (IL)-35 in Murphy Roths Large (MRL)/lpr mice

The immunological mechanisms mediated by regulatory cytokine interleukin (IL)-35 are unclear in systemic lupus erythematosus (SLE). We investigated the frequency of CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) regulatory T (Treg ) and IL-10(+) regulatory B (Breg ) cells and related immunoregulatory mechanisms in a female Murphy Roths Large (MRL)/lpr mouse model of spontaneous lupus-like disease, with or without IL-35 treatment. A remission of histopathology characteristics of lupus flare and nephritis was observed in the MRL/lpr mice upon IL-35 treatment. Accordingly, IL-35 and IL-35 receptor subunits (gp130 and IL-12Rβ2) and cytokines of MRL/lpr and BALB/c mice (normal controls) were measured. The increased anti-inflammatory cytokines and decreased proinflammatory cytokines were possibly associated with the restoration of Treg and Breg frequency in MRL/lpr mice with IL-35 treatment, compared to phosphate-buffered saline (PBS) treatment. mRNA expressions of Treg -related FoxP3, IL-35 subunit (p35 and EBI3) and soluble IL-35 receptor subunit (gp130 and IL12Rβ2) in splenic cells were up-regulated significantly in IL-35-treated mice. Compared with the PBS treatment group, IL-35-treated MRL/lpr mice showed an up-regulation of Treg -related genes and the activation of IL-35-related intracellular Janus kinase/signal transducer and activator of transcription signal pathways, thereby indicating the immunoregulatory role of IL-35 in SLE. These in vivo findings may provide a biochemical basis for further investigation of the regulatory mechanisms of IL-35 for the treatment of autoimmune-mediated inflammation.

MicroRNAs in lupus

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by the production of an array of pathogenic autoantibodies, including high-affinity anti-dsDNA IgG antibodies, which play an important role in disease development and progression. Lupus preferentially affects women during their reproductive years. The pathogenesis of lupus is contributed by both genetic factors and epigenetic modifications that arise from exposure to the environment. Epigenetic marks, including DNA methylation, histone post-translational modifications and microRNAs (miRNAs), interact with genetic programs to regulate immune responses. Epigenetic modifications influence gene expression and modulate B cell functions, such as class-switch DNA recombination, somatic hypermutation and plasma cell differentiation, thereby informing the antibody response. Epigenetic dysregulation can result in aberrant antibody responses to exogenous antigens or self-antigens, such as chromatin, histones and dsDNA in lupus. miRNAs play key roles in the post-transcriptional regulation of most gene-regulatory pathways and regulate both the innate and adaptive immune responses. In mice, dysregulation of miRNAs leads to aberrant immune responses and development of systemic autoimmunity. Altered miRNA expression has been reported in human autoimmune diseases, including lupus. The dysregulation of miRNAs in lupus could be the result of multiple environmental factors, such as sex hormones and viral or bacterial infection. Modulation of miRNA is a potential therapeutic strategy for lupus.

Potential role of nuclear receptor ligand all-trans retinoic acids in the treatment of fungal keratitis

Fungal keratitis (FK) is a worldwide visual impairment disease. This infectious fungus initiates the primary innate immune response and, later the adaptive immune response. The inflammatory process is related to a variety of immune cells, including macrophages, helper T cells, neutrophils, dendritic cells, and Treg cells, and is associated with proinflammatory, chemotactic and regulatory cytokines. All-trans retinoic acids (ATRA) have diverse immunomodulatory actions in a number of inflammatory and autoimmune conditions. These retinoids regulate the transcriptional levels of target genes through the activation of nuclear receptors. Retinoic acid receptor α (RAR α), retinoic acid receptor γ (RAR γ), and retinoid X receptor α (RXR α) are expressed in the cornea and immune cells. This paper summarizes new findings regarding ATRA in immune and inflammatory diseases and analyzes the perspective application of ATRA in FK.

Paradoxical effects of all-trans-retinoic acid on lupus-like disease in the MRL/lpr mouse model

Roles of all-trans-retinoic acid (tRA), a metabolite of vitamin A (VA), in both tolerogenic and immunogenic responses are documented. However, how tRA affects the development of systemic autoimmunity is poorly understood. Here we demonstrate that tRA have paradoxical effects on the development of autoimmune lupus in the MRL/lpr mouse model. We administered, orally, tRA or VA mixed with 10% of tRA (referred to as VARA) to female mice starting from 6 weeks of age. At this age, the mice do not exhibit overt clinical signs of lupus. However, the immunogenic environment preceding disease onset has been established as evidenced by an increase of total IgM/IgG in the plasma and expansion of lymphocytes and dendritic cells in secondary lymphoid organs. After 8 weeks of tRA, but not VARA treatment, significantly higher pathological scores in the skin, brain and lung were observed. These were accompanied by a marked increase in B-cell responses that included autoantibody production and enhanced expression of plasma cell-promoting cytokines. Paradoxically, the number of lymphocytes in the mesenteric lymph node decreased with tRA that led to significantly reduced lymphadenopathy. In addition, tRA differentially affected renal pathology, increasing leukocyte infiltration of renal tubulointerstitium while restoring the size of glomeruli in the kidney cortex. In contrast, minimal induction of inflammation with tRA in the absence of an immunogenic environment in the control mice was observed. Altogether, our results suggest that under a predisposed immunogenic environment in autoimmune lupus, tRA may decrease inflammation in some organs while generating more severe disease in others.

Development of a nanoparticulate formulation of retinoic acid that suppresses Th17 cells and upregulates regulatory T cells

Retinoic acid (RA) is a small molecule capable of shunting developing T cells away from the Th17 lineage and towards the Treg phenotype, making it a potentially useful therapeutic for autoimmune and inflammatory diseases. However, therapy can be complicated by systemic toxicity and unpredictable bioavailability, making a targeted drug delivery vehicle for local therapy desirable. A promising approach is the use of nanoparticles, which have been demonstrated to increase potency and decrease toxicity of therapies in a variety of disease models including Th17 mediated diseases. Nanoparticles can also be targeted to specific cell types via surface modification, further increasing the potential specificity of this approach. We therefore constructed a nanoparticulate drug delivery platform from poly(lactic-co-glycolic acid) (PLGA) capable of encapsulating and releasing RA. Here we report the fabrication, characterization, and in vitro bioactivity of this platform. We demonstrate that RA containing PLGA nanoparticles suppress IL-17 production and ROR-γ(t) expression in T cells polarized towards the Th17 phenotype in vitro with similar potency to that of free drug. Furthermore, we show that these particles enhance TGF-β dependent Foxp3 expression and IL-10 production of T cells in vitro with similar potency to free RA. Finally, we demonstrate that T cells polarized towards the Th17 phenotype in the presence of free and nanoparticulate RA have similarly suppressed ability to induce IL-6 production by fibroblasts. Our findings demonstrate the feasibility of RA delivery via biodegradable nanoparticles and represent an exciting technology for the treatment of autoimmune and inflammatory diseases.

Dynamics of gut microbiota in autoimmune lupus

Gut microbiota has been recognized as an important environmental factor in health, as well as in metabolic and immunological diseases, in which perturbation of the host gut microbiota is often observed in the diseased state. However, little is known on the role of gut microbiota in systemic lupus erythematosus. We investigated the effects of host genetics, sex, age, and dietary intervention on the gut microbiome in a murine lupus model. In young, female lupus-prone mice resembling women at childbearing age, a population with the highest risk for lupus, we found marked depletion of lactobacilli, and increases in Lachnospiraceae and overall diversity compared to age-matched healthy controls. The predicted metagenomic profile in lupus-prone mice showed a significant enrichment of bacterial motility- and sporulation-related pathways. Retinoic acid as a dietary intervention restored lactobacilli that were downregulated in lupus-prone mice, and this correlated with improved symptoms. The predicted metagenomes also showed that retinoic acid reversed many lupus-associated changes in microbial functions that deviated from the control. In addition, gut microbiota of lupus-prone mice were different between sexes, and an overrepresentation of Lachnospiraceae in females was associated with an earlier onset of and/or more severe lupus symptoms. Clostridiaceae and Lachnospiraceae, both harboring butyrate-producing genera, were more abundant in the gut of lupus-prone mice at specific time points during lupus progression. Together, our results demonstrate the dynamics of gut microbiota in murine lupus and provide evidence to suggest the use of probiotic lactobacilli and retinoic acid as dietary supplements to relieve inflammatory flares in lupus patients.

Epigenetics in the treatment of systemic lupus erythematosus: potential clinical application

The current treatments of systemic lupus erythematosus (SLE) have been based on the use of immunosuppressive drugs which are linked to serious side effects. The more effective therapeutic approaches with minimal or no side effects for SLE patients are hard to develop, mainly due to the complexity of the disease. The discovery of pharmacoepigenetics provides a new way to solve this problem. Epigenetic modifications can influence drug efficacy by altering gene expression via changing chromatin structure. Although still in early development, epigenetic studies in SLE are expected to reveal novel therapeutic targets and disease biomarkers in autoimmunity. For example, miRNAs, which have been identified to govern many genes including drug targets, are altered in disease development and after drug administration. This review aims to present an overview of current epigenetic mechanisms involved in the pathogenesis of SLE, and discuss their potential roles in clinical and pharmacological applications.

Could retinoids be a potential treatment for rheumatic diseases?

Retinoid, a derivative of vitamin A, is a general term used to describe compounds that bind to and activate retinoic acid receptors [RARs (RARα, RARβ, and RARγ)] and/or retinoid X receptors [RXRs (RXRα, RXRβ, and RXRγ)]. They have been shown to surpress the differentiation of Th1/Th17 cells and induce the development of Th1/regulatory T cells. They also affect the proliferation of B cells as both an inducer and suppressor. Furthermore, retinoids may induce the maturation of dendritic cells and production of interleukin-10 from monocytes/macrophages. We recently demonstrated that retinoids suppressed the production of reactive oxygen species, the release of elastase from neutrophils by inhibiting mitogen-activated protein kinase signals, and both the migration speed and chemotaxis directionality of neutrophils. Retinoids, such as all-trans retinoic acid and tamibarotene, were previously shown to have positive effects on animal models of several rheumatic diseases, including arthritis, myositis, and vasculitis in vivo. Moreover, retinoids have been used in a pilot study to effectively treat patients with lupus nephritis and systemic sclerosis. We herein reviewed the effects of retinoids on immune cells, animal models of rheumatic diseases, and rheumatic patients.

Effects of all-trans retinoic acid on signal pathway of cyclooxygenase-2 and Smad3 in transforming growth factor-β-stimulated glomerular mesangial cells

All-trans retinoic acid (ATRA) has been used for the treatment of acute promyelocytic leukemia. It remains unclear, however, whether ATRA affects cyclooxygenase-2 (COX-2; an enzyme involved in prostaglandin production), PGE2, and thromboxane A2 (TXA2) (metabolic products of COX-2) by a transforming growth factor-β/Smad-signaling pathway, which plays important roles in mesangial-cell proliferation and renal fibrosis. In this study, the mRNA and protein of Smad3, Smad7, and COX-2 were detected by reverse transcription-polymerase chain reaction and Western blot, respectively, in mesangial cells stimulated by transforming growth factor-β (TGF-β) and treated with ATRA at various concentrations and times. The protein level of PGE2 and TXA2 was also measured by enzyme-linked immunosorbent assay. The localization of Smad3 and Smand7 was observed by confocal microscope. Cell proliferation was detected by MTT assay, while apoptosis was determined using Hoechest staining. The expression of Smad3, Smad7, and COX-2 mRNA and protein was increased by exogenous TGF-β, but inhibited by pretreatment of ATRA, in dose and time-dependent manners. In addition, the expression of Smad3 and Smad7 was significantly reduced not only by staurosporine, an inhibitor of threonine/serine protein kinases as well as smad, but also by NS-398, an inhibitor of COX-2. PGE2 and TXA2 were raised by TGF-β, but also decreased by ATRA, staurosporine, and NS-398. Moreover, ATRA reversed the translocation of Smad3 and Smad7 induced by TGF-β. Compared with the control, TGF-β also significantly enhanced proliferation and inhibited apoptosis of mesangial cells. ATRA dose-dependently inhibited TGF-β-induced cell proliferation, but had no significant effect on apoptosis in rat mesangial cells. Therefore, ATRA repressed COX-2, PGE2, and TXA2 via the TGF-β/Smad-signaling pathway and inhibited mesangial-cell proliferation, which might subsequently prevent renal fibrosis.

Sialoadhesin deficiency does not influence the severity of lupus nephritis in New Zealand black x New Zealand white F1 mice

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic inflammatory condition with multisystem involvement. One of the key features of the disease is the upregulation of type I interferons, resulting in the so-called "interferon signature". Recent flow cytometric and transcriptomic studies identified Sialoadhesin (Sn, CD169) as an important interferon-induced blood monocyte biomarker in diseased patients. To investigate a potential causative role of Sn in SLE, we generated NZBWF1 (New Zealand Black x New Zealand White F1) mice lacking Sn and compared onset and progression of disease with NZBWF1 expressing normal levels of Sn.

METHODS

Sn expression in renal tissues of pre-diseased and diseased NZBWF1 mice was evaluated by Quantitative real time PCR (QPCR) and immunohistochemistry. Sn-/- NZBWF1 mice were generated by speed congenics. Disease severity of Sn+/+ and Sn-/- NZBWF1 mice was assessed by serum immunoassays, flow cytometry, light microscopy and immunohistochemistry.

RESULTS

Renal tissues from proteinuric NZBWF1 mice exhibited a significant upregulation of Sn mRNA and protein expression following disease onset. Further immunohistochemical analysis showed that Sn+ macrophages assumed a distinct periglomerular distribution and, unlike CD68+ macrophages, were not present within the glomeruli. Analysis of disease severity in Sn-/- and Sn+/+ NZBWF1 mice revealed no significant differences in the disease progression between the two groups although Sn-deficient mice showed a more rapid onset of proteinuria.

CONCLUSIONS

These data confirm a positive correlation of Sn with disease activity. However, Sn deficiency does not have a significant effect on the severity and progression of lupus nephritis in the NZBWF1 mouse model.

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.

Retinoids: novel immunomodulators and tumour-suppressive agents?

Retinoids play important roles in the transcriptional activity of normal, degenerative and tumour cells. Retinoid analogues may be promising therapeutic agents for the treatment of immune disorders as different as type I diabetes and systemic lupus erythematosus. In addition, the use of retinoids in cancer treatment has progressed significantly in the last two decades; thus, numerous retinoid compounds have been synthesized and tested. In this paper, the actual or potential use of retinoids as immunomodulators or tumour-suppressive agents is discussed.

Retinoids augment the expression of podocyte proteins by glomerular parietal epithelial cells in experimental glomerular disease

BACKGROUND/AIMS

A decrease in glomerular podocyte number in membranous nephropathy and focal segmental glomerulosclerosis (FSGS) ultimately underlines glomerulosclerosis and the decrease in kidney function. Recent studies have shown that in these diseases, glomerular parietal epithelial cells begin to express proteins considered unique to podocytes, and that these glomerular epithelial transition cells might serve as podocyte progenitors. Because retinoids improve many forms of experimental glomerular disease characterized by podocyte injury and loss, we asked if all-trans retinoic acid (ATRA) induces parietal epithelial cells to express podocyte proteins.

METHODS

ATRA or vehicle was administered to rats with experimental membranous nephropathy (passive Heymann nephritis model) and mice with experimental FSGS (anti-glomerular antibody model) following the onset of proteinuria. Immunohistochemistry staining of PAX2 (parietal epithelial cell marker), WT-1 (podocyte cell marker), and Ki-67 (proliferation marker) were performed on kidney tissues.

RESULTS

Compared to diseased animals receiving vehicle, ATRA statistically significantly increased the number of glomerular transition cells, defined as cells double-staining for PAX2 and WT-1, in membranous nephropathy at weeks 2, 5 and 16, and in FSGS at weeks 1 and 2. This was accompanied by an increase in the number of podocytes compared to diseased controls receiving vehicle.

CONCLUSION

ATRA increases the number of glomerular epithelial transition cells in experimental proteinuric glomerular diseases. Thus, ATRA may provide a useful pharmacologic approach to decipher the mechanisms underlying the possible progenitor role of parietal epithelial cells.

[Therapeutic effect of retinoic acid in lupus nephritis]

Lupus nephritis is a major cause of morbidity and mortality among patients with systemic lupus erythematosus (SLE). In these patients, treatment with immunosuppressive agents can significantly improve the outcome of lupus nephritis. However, these agents have severe adverse reactions and some patients are refractory to those therapies. Retinoids, a group of natural and synthetic derivatives of vitamin A, play important regulatory roles of cellular proliferation, differentiation and apoptosis. They have been used for the treatment of acute promyelocytic leukemia and inflammatory disorders such as psoriasis and acne. It has also been shown that retinoids have therapeutic effects in various animal models of kidney disease, including lupus nephritis. Based on these findings, retinoids are a promising agent for the treatment of lupus nephritis. We studied the clinical effects of retinoid therapy in patients with lupus nephritis. In open clinical trial, 7 patients with active lupus nephritis that was refractory to steroid therapy were studied. In all these patients, retinoid was added to the immunosuppressive therapy and its therapeutic effects were evaluated. As a result, 4 out of 7 patients showed improvement of the clinical symptoms and laboratory findings, including urinary protein and anti-dsDNA antibody levels. No important adverse effects of ATRA therapy were observed in all patients. Thus, retinoids might be indicated in cases of lupus nephritis that are refractory to conventional immunosuppressive therapy.

Dietary factors regulate cytokines in murine models of systemic lupus erythematosus

Cytokines play the active roles in the pathogenesis of systemic lupus erythematosus (SLE) and contribute significantly to the immune imbalance in this disease. Conservative therapeutic approaches, such as dietary modifications have been shown to have some beneficial impact on the disease activity of the SLE. Over the past years, accumulating evidences have supported a major role for specific dietary factors, including calorie restriction, n-3/n-6 fatty acids, vitamin A, vitamin D, vitamin E, phytoestrogens or herbal medicine in the regulation of cytokines involved in SLE development. Although there are many reviews that discuss the issue of nutrition and immunity, there are relatively few articles that focus on the regulation of cytokines by dietary factors. This concise review will summarize those animal studies that investigated not only the outcome of autoantibody production and proteinuria, but also cytokines production. However, the field of dietary factors in the immunomodulation of SLE is still in its infancy. More clinical studies are needed to confirm the preliminary results and advance the knowledge in this field. Lifestyle modification and adjustments in diet are important and encouraged to be suggested as an adjuvant therapy for SLE.

Therapeutic effect of retinoic acid on unilateral ureteral obstruction model

BACKGROUND

Retinoic acids, a group of natural and synthetic vitamin A derivatives, have potent anti-proliferative, anti-inflammatory and anti-fibrotic properties. We investigated the therapeutic effect of all-trans-retinoic acid (ATRA) on unilateral ureteral obstruction (UUO) model mice.

METHODS

First, to evaluate the prophylactic effect, we administered 0.5 mg of ATRA for 3 days before UUO (UUO ATRA). Then, to evaluate the therapeutic effects, we administered 0.5 mg of ATRA 3 days after UUO (Day 3 ATRA). We compared the histological changes and immunostaining of macrophages, α-smooth muscle actin (α-SMA) and collagen I, and mRNA expression of monocyte chemotactic protein-1 (MCP-1), transforming growth factor (TGF)-β(1) and TGF-β R-II by RT-PCR 7 days after UUO.

RESULTS

In the UUO ATRA and Day 3 ATRA groups, we observed a significant improvement in histological and immunological findings, including macrophage infiltration and improved expression of MCP-1, TGF-β(1), α-SMA and collagen I compared with the UUO Day 7 group.

CONCLUSION

ATRA treatment is not only an effective prophylactic strategy, but also a therapeutic strategy for the treatment of progressive renal fibrosis in diseased kidneys.

The immunoregulatory role of vitamins A, D and E in patients with primary Sjogren's syndrome

OBJECTIVE

The aim of the present study was to investigate the immunomodulating role of fat-soluble vitamins in 25 patients with primary SS (pSS) and 15 healthy individuals.

METHODS

Plasma levels of vitamins A, D and E were determined by HPLC. Peripheral NK, NK T cells, T-cell subsets, B cells, IL-10 producing Tr1 cells, CD4(+)CD25(+) Treg cells and Th17 were determined by flow cytometry. Various Th1- and Th2-soluble cytokines were assessed by ELISA, whereas intracytoplasmic cytokines (IFN-gamma, IL-4, -10 and -17) were measured by flow cytometry. Correlation was assessed between vitamin levels and immunological and clinical parameters.

RESULTS

Vitamin A levels did not differ between patients and controls, yet in patients with extraglandular manifestations (EGMs) a significant decrease in vitamin A levels was apparent compared with pSS patients without EGMs (P = 0.005). Vitamin E levels were increased in patients compared with controls (P = 0.004), whereas vitamin D levels were similar in pSS and control subjects. In patients, vitamin A showed a positive correlation with both NK cell (P = 0.038) and Th17 cell (P = 0.025), and a negative correlation with Schirmer's test values (P = 0.035). Positive correlation was found between vitamin E and NK cells (P = 0.043), Th1 cells (P = 0.049) and the Th1/Th2 ratio (P = 0.043). In the control group, we found correlation between vitamin E and serum IL-10 levels (P = 0.003).

CONCLUSIONS

Our data suggest that fat-soluble vitamins may be important in immunoregulatory processes in patients with pSS.

Successful treatment with retinoids in patients with lupus nephritis

Lupus nephritis is a major manifestation of systemic lupus erythematosus. Treatment with such immunosuppressive agents as corticosteroids or cyclophosphamide can decrease the progression of lupus nephritis; however, these agents have potentially severe adverse reactions. Therefore, the development of new drugs with fewer side effects is needed. Here, we report 2 patients with lupus that were treated successfully with retinoids. Initially, both patients were treated with 60 mg/d of prednisolone. However, nephrotic syndrome was not improved. Subsequently, treatment with 10 mg/d of all-trans-retinoic acid was started orally and elicited a good response, showing a decrease in proteinuria. Although additional controlled clinical studies are needed to confirm these findings, we suggest that therapy using retinoids may represent a novel approach to the treatment of patients with lupus nephritis.

Augmentation of antibody responses by retinoic acid and costimulatory molecules

Antibody production is crucial for a successful vaccine response. Beyond the ability of vitamin A (VA) and its active metabolite, all-trans-retinoic acid (RA) to restore growth in VA-deficient animals, supplementation with VA and/or treatment with RA can augment antibody responses in both VA-deficient and VA-adequate animals. RA alone, and in combination with stimuli that are ligands for the Toll-like receptor family, can augment the adaptive immune response leading to a heightened primary antibody response, and a stronger recall response upon restimulation. Mechanisms may include regulation of cell populations, type 1/type 2 cytokines, and B cell-related transcription factors, leading to accelerated B cell maturation.

Beneficial effects of suplatast tosilate (IPD-1151T) in a rat cystitis model induced by intravesical hydrochloric acid

OBJECTIVE

To examine the effects of suplatast tosilate (IPD-1151T), a Th2 cytokine inhibitor recently recognized to improve the symptoms in patients with interstitial cystitis (IC), in a rat model of HCl-induced chronic cystitis, to elucidate the possible mechanisms by which the drug improves the symptoms of IC.

MATERIALS AND METHODS

Chronic cystitis was induced by intravesical instillation of 0.2 mL of 0.4 m HCl in female adult rats. After a once-daily oral administration of IPD-1151T (0.1-100 mg/kg) or prednisolone (5 mg/kg) for 7 days, cystometry was performed under urethane anaesthesia. The bladder from HCl-induced cystitis rats was also assessed histopathologically.

RESULTS

On cystometrography there was frequent voiding in cystitis rats. Administration of IPD-1151T for 7 days after intravesical HCl instillation dose-dependently increased the micturition volume and intercontraction intervals. Treatment with prednisolone had similar therapeutic effects. Histological analyses in the bladder from cystitis rats revealed oedema and infiltration of inflammatory cells such as mast cells and eosinophils in the lamina propria and the transitional epithelial thickening. These histological changes and the number of mast cells and eosinophils were reduced by administration of IPD-1151T or prednisolone.

CONCLUSION

The present results indicate that IPD-1151T improves bladder function and pathological changes in HCl-induced cystitis rats, as previously observed in patients with IC. The rat cystitis model induced by HCl could provide useful information for studying proposed therapies for IC which might involve T cell-dependent inflammatory responses as one of its potential pathophysiologies.

Effects of estrogen receptor subtype-selective agonists on autoimmune disease in lupus-prone NZB/NZW F1 mouse model

The specific roles of estrogen receptor (ER) subtypes alpha and beta in mediating estrogen's influences on lupus autoimmunity are unknown. Herein we found that ovariectomized NZB/NZW F1 mice treated with propyl pyrazole triol (ERalpha-selective agonist) had significantly shorter survival, earlier development of albuminuria, higher serum concentrations of total IgG and prolactin, increased serum levels of anti-DNA IgG3, IgG2a and IgG2b and decreased anti-DNA IgG1 level compared to vehicle controls. In contrast, diarylpropionitrile (ERbeta-selective agonist) administration significantly decreased serum anti-DNA IgG2b level but did not significantly affect serum levels of other anti-DNA IgG subclasses, serum total IgG or prolactin concentration, mortality or the occurrence of albuminuria. These findings suggest that ERalpha activation plays the predominant and immunostimulatory role in estrogen-mediated modulation of lupus while ERbeta activation appears to have a slightly immunosuppressive effect on this disease. ERalpha activation coincidentally increased serum prolactin concentrations and may accelerate lupus disease activity also through this mechanism.

Direct and indirect effects of retinoic acid on human Th2 cytokine and chemokine expression by human T lymphocytes

BACKGROUND

Vitamin A (VA) deficiency induces a type 1 cytokine response and exogenously provided retinoids can induce a type 2 cytokine response both in vitro and in vivo. The precise mechanism(s) involved in this phenotypic switch are inconsistent and have been poorly characterized in humans. In an effort to determine if retinoids are capable of inducing Th2 cytokine responses in human T cell cultures, we stimulated human PBMCs with immobilized anti-CD3 mAb in the presence or absence of all-trans retinoic acid (ATRA) or 9-cis-RA.

RESULTS

Stimulation of human PBMCs and purified T cells with ATRA and 9-cis-RA increased mRNA and protein levels of IL-4, IL-5, and IL-13 and decreased levels of IFN-gamma, IL-2, IL-12p70 and TNF-alpha upon activation with anti-CD3 and/or anti-CD28 mAbs. These effects were dose-dependent and evident as early as 12 hr post stimulation. Real time RT-PCR analysis revealed a dampened expression of the Th1-associated gene, T-bet, and a time-dependent increase in the mRNA for the Th2-associated genes, GATA-3, c-MAF and STAT6, upon treatment with ATRA. Besides Th1 and Th2 cytokines, a number of additional proinflammatory and regulatory cytokines including several chemokines were also differentially regulated by ATRA treatment.

CONCLUSION

These data provide strong evidence for multiple inductive roles for retinoids in the development of human type-2 cytokine responses.

[Retinoid therapy for autoimmune diseases]

Retinoid is a collective term for compounds which bind to and activate retinoic acid receptors (RARalpha, beta, gamma and RXRalpha, beta, gamma), members of nuclear hormone receptor superfamily. The most important endogeneous retinoid is all-trans-retinoic acid (ATRA) which is an RARalpha, beta and gamma ligand. ATRA and its mimics have been in clinical use for treatment of acute promyelocytic leukemia (APL) and some skin diseases. Many synthetic retinoids have been developed and attempts to improve their medicinal properties have been made. Among them, tamibarotene (Am80) is an RARalpha- and RARbeta-specific (but RARgamma- and RXRs-nonbinding) synthetic retinoid that is effective in the treatment of psoriasis patients and relapsed APL. Experimentally, this compound is also active in animal models of rheumatoid arthritis and experimental autoimmune encephalomyelitis. On this background, possible application of retinoids for the treatment of autoimmune diseases was discussed. In particular, Th1 dominant autoimmune diseases may be the targets of the retinoids.

Anti-inflammatory effect of all-trans-retinoic acid in inflammatory arthritis

OBJECTIVE

To determine whether all-trans-retinoic acid (ATRA) improves the destruction of joints and the effect of cytokines on DBA/1J mice with collagen-induced arthritis (CIA).

METHODS

Starting from the time of type II collagen injection, DBA/1J mice were injected intraperitoneally with PBS or 0.5 mg of ATRA 3 times per week for 35 days. The effects of treatment were monitored by determining arthritis and histological scores and measuring cellular proliferation, production of cytokines (IL-2, IL-10, IL-12, IL-6, IFN-gamma, and TNF-alpha) and IgG, and the expression of mRNAs for inducible nitric oxide synthase (iNOS), monocyte chemoattractant protein-1 (MCP-1), and CXCR3.

RESULTS

The arthritis score and incidence of arthritis were lower in the mice treated with ATRA than in those treated with PBS. Histopathologic evidence of joint damage was 34% lower, and the infiltrations of macrophages were reduced in the mice treated with ATRA compared with those treated with PBS. Type II collagen- and ConA-stimulated proliferation of spleen cells, the production of cytokines (IL-6, IL-12, and TNF-alpha), the serum levels of total IgG and IgG1 anti-collagen antibodies, and the expression of mRNAs for MCP-1 were significantly reduced in the mice treated with ATRA than in those treated with PBS.

CONCLUSION

ATRA improved the clinical course and reduced the production of inflammatory cytokines, immunoglobulin, and chemokines in murine CIA. These data suggest that ATRA might be also effective for the treatment of inflammatory arthritis like human rheumatoid arthritis.