Metformin Inhibits the Type 1 IFN Response in Human CD4+ T Cells.

In systemic lupus erythematosus, defective clearance of apoptotic debris and activation of innate cells result in a chronically activated type 1 IFN response, which can be measured in PBMCs of most patients. Metformin, a widely used prescription drug for Type 2 diabetes, has a therapeutic effect in several mouse models of lupus through mechanisms involving inhibition of oxidative phosphorylation and a decrease in CD4+ T cell activation. In this study, we report that in CD4+ T cells from human healthy controls and human systemic lupus erythematosus patients, metformin inhibits the transcription of IFN-stimulated genes (ISGs) after IFN-α treatment. Accordingly, metformin inhibited the phosphorylation of pSTAT1 (Y701) and its binding to IFN-stimulated response elements that control ISG expression. These effects were independent of AMPK activation or mTORC1 inhibition but were replicated using inhibitors of the electron transport chain respiratory complexes I, III, and IV. This indicates that mitochondrial respiration is required for ISG expression in CD4+ T cells and provides a novel mechanism by which metformin may exert a therapeutic effect in autoimmune diseases.

Immunophenotyping reveals distinct subgroups of lupus patients based on their activated T cell subsets.

OBJECTIVE: This study performed an integrated analysis of the cellular and transcriptional differences in peripheral immune cells between patients with Systemic Lupus Erythematosus (SLE) and healthy controls (HC). METHODS: Peripheral blood was analyzed using standardized flow cytometry panels. Transcriptional analysis of CD4+ T cells was performed by microarrays and Nanostring assays. RESULTS: SLE CD4+ T cells showed an increased expression of oxidative phosphorylation and immunoregulatory genes. SLE patients presented higher frequencies of activated CD38+HLA-DR+ T cells than HC. Hierarchical clustering identified a group of SLE patients among which African Americans were overrepresented, with highly activated T cells, and higher frequencies of Th1, Tfh, and plasmablast cells. T cell activation was positively correlated with metabolic gene expression in SLE patients but not in HC. CONCLUSIONS: SLE subjects presenting with activated T cells and a hyperactive metabolic signature may represent an opportunity to correct aberrant immune activation through targeted metabolic inhibitors.

Positive correlation of STAT1 and miR-146a with anemia in patients with systemic lupus erythematosus.

PURPOSE: Anemia is one of the most common hematological manifestations in SLE patients, occurring in about 50% of active cases. STAT1 is a critical signaling molecule required for the production of type-1 interferon (I-IFN), CCL2, and CXCL10, all of which are upregulated in SLE. Overexpression of STAT1 has been described to be involved in anemia in animal models. The aim of this study is to analyze how these components are involved in SLE-associated anemia. METHODS: Blood samples were collected from 39 healthy donors and 101 SLE patients fulfilling ACR criteria. Samples were collected from a total of 180 visits (58 patients had 2 or more visits) of which 52 visits included a diagnosis of anemia. Healthy donors had only single visit. Total RNA, isolated from leukocytes, was analyzed by Taqman qPCR. Relative expression levels of I-IFN signature genes, chemokines, and miR-146a were determined by the ΔΔCT method. Results were correlated with clinical data and analyzed by the Wilcoxon/Kruskal-Wallis test and Fisher's exact test. RESULTS: Significant increases in IFN score (p < 0.0001), STAT1 (p < 0.0001), miR-146a (p < 0.0005), CCL2 (p = 0.0047), and CXCL10 (p = 0.017), as well as a significant decrease in pri-miR-146a (p = 0.0002), were detected in the anemic SLE patient visits (n = 52) compared to non-anemic SLE visits (n = 128). Regardless of disease activity, lupus nephritis, or race, anemic SLE patients displayed significantly elevated levels of STAT1 and miR-146a compared to non-anemic SLE patients. CONCLUSIONS: STAT1 and miR-146a may be upregulated during inflammation and via proinflammatory cytokines and chemokines in SLE. Prolonged upregulation of STAT1 and miR-146a appears to play an important role in anemia in SLE patients.

Pre-B cell leukemia homeobox 1 is associated with lupus susceptibility in mice and humans.

Sle1a.1 is part of the Sle1 susceptibility locus, which has the strongest association with lupus nephritis in the NZM2410 mouse model. In this study, we show that Sle1a.1 results in the production of activated and autoreactive CD4(+) T cells. Additionally, Sle1a.1 expression reduces the peripheral regulatory T cell pool, as well as induces a defective response of CD4(+) T cells to the retinoic acid expansion of TGF-ß-induced regulatory T cells. At the molecular level, Sle1a.1 corresponds to an increased expression of a novel splice isoform of Pbx1, Pbx1-d. Pbx1-d overexpression is sufficient to induce an activated/inflammatory phenotype in Jurkat T cells and to decrease their apoptotic response to retinoic acid. PBX1-d is expressed more frequently in the CD4(+) T cells from lupus patients than from healthy controls, and its presence correlates with an increased central memory T cell population. These findings indicate that Pbx1 is a novel lupus susceptibility gene that regulates T cell activation and tolerance.

Lupus susceptibility gene Pbx1 controls the development, stability, and function of regulatory T cells via Rtkn2 expression.

The maintenance of regulatory T (Treg) cells critically prevents autoimmunity. Pre-B cell leukemia transcription factor 1 (Pbx1) variants are associated with lupus susceptibility, particularly through the expression of a dominant negative isoform Pbx1-d in CD4+ T cells. Pbx1-d overexpression impaired Treg cell homeostasis and promoted inflammatory CD4+ T cells. Here, we showed a high expression of Pbx1 in human and murine Treg cells, which is decreased in lupus patients and mice. Pbx1 deficiency or Pbx1-d overexpression reduced the number, stability, and suppressive activity of Treg cells, which increased murine responses to immunization and autoimmune induction. Mechanistically, Pbx1 deficiency altered the expression of genes implicated in cell cycle and apoptosis in Treg cells. Intriguingly, Rtkn2, a Rho-GTPase previously associated with Treg homeostasis, was directly transactivated by Pbx1. Our results suggest that the maintenance of Treg cell homeostasis and stability by Pbx1 through cell cycle progression prevent the expansion of inflammatory T cells that otherwise exacerbates lupus progression in the hosts.

IL-1α modulates neutrophil recruitment in chronic inflammation induced by hydrocarbon oil.

Exposure to naturally occurring hydrocarbon oils is associated with the development of chronic inflammation and a wide spectrum of pathological findings in humans and animal models. The mechanism underlying the unremitting inflammatory response to hydrocarbons remains largely unclear. The medium-length alkane 2,6,10,14 tetramethylpentadecane (also known as pristane) is a hydrocarbon that potently elicits chronic peritonitis characterized by persistent infiltration of neutrophils and monocytes. In this study, we reveal the essential role of IL-1α in sustaining the chronic recruitment of neutrophils following 2,6,10,14 tetramethylpentadecane treatment. IL-1α and IL-1R signaling promote the migration of neutrophils to the peritoneal cavity in a CXCR2-dependent manner. This mechanism is at least partially dependent on the production of the neutrophil chemoattractant CXCL5. Moreover, although chronic infiltration of inflammatory monocytes is dependent on a different pathway requiring TLR-7, type I IFN receptor, and CCR2, the adaptor molecules MyD88, IL-1R-associated kinase (IRAK)-4, IRAK-1, and IRAK-2 are shared in regulating the recruitment of both monocytes and neutrophils. Taken together, our findings uncover an IL-1α-dependent mechanism of neutrophil recruitment in hydrocarbon-induced peritonitis and illustrate the interactions of innate immune pathways in chronic inflammation.

Autoantibodies to survival of motor neuron complex in patients with polymyositis: immunoprecipitation of D, E, F, and G proteins without other components of small nuclear ribonucleoproteins.

OBJECTIVE: Autoantibodies in the systemic rheumatic diseases are clinically useful biomarkers of the diagnosis or of certain clinical characteristics. An unusual pattern of immunoprecipitation, in which the D, E, F, and G proteins of small nuclear RNPs (snRNP) but without other components of the snRNP, was noticed at the autoantibody screening. The purpose of this study was to examine the target antigens and clinical manifestations associated with this specificity. METHODS: Autoantibodies in sera from 1,966 American patients (including 434 with systemic lupus erythematosus, 121 with scleroderma, 86 with polymyositis/dermatomyositis [PM/DM]) and 248 Italian patients with autoimmune diseases were screened by immunoprecipitation of (35) S-methionine-labeled cell extracts. Sera with which D, E, F, and G proteins of snRNP was immunoprecipitated, but without the other snRNP proteins, were further examined by analysis of RNA components by immunoprecipitation (silver staining), Western blotting using survival of motor neuron (SMN) complex, and immunofluorescence. RESULTS: Three sera that immunoprecipitated D, E, F, and G proteins without other components (U1-70K, A, B'/B, C) of the snRNP were found. Four additional proteins (130 kd, 120 kd, 38 kd, and 33 kd) were also commonly immunoprecipitated. The target antigen was identified as SMN complex (Gemin 3, Gemin 4, SMN, and Gemin 2, respectively), which plays a critical role in the assembly of snRNP. In immunofluorescence analyses, all 3 sera showed nuclear dots (Cajal bodies) and cytoplasmic staining. Only 1 serum was weakly positive on Western blotting of SMN, suggesting that these sera mainly recognize native molecule or quaternary structure. All 3 patients were white women with PM, an interesting finding, since deletion or mutation of SMN is known to cause spinal muscular atrophy. CONCLUSION: SMN complex was identified as a new Cajal body autoantigen recognized by sera from white patients with PM. The biologic and clinical significance of anti-SMN autoantibodies will need to be clarified.

Pathogenic role of B cells in the development of diffuse alveolar hemorrhage induced by pristane.

Diffuse alveolar hemorrhage is an uncommon, yet often fatal, complication of systemic lupus erythematosus (SLE). Advances in the treatment of alveolar hemorrhage have been hampered because of the heterogeneity of clinical findings and the lack of suitable animal models. A single intraperitoneal injection of pristane induces a lupus-like syndrome characterized by lupus-related autoantibodies and glomerulonephritis in non-autoimmune-prone strains of mice. In addition, C57BL/6 (B6) mice frequently develop alveolar hemorrhage within a few weeks of pristane injection. Immunopathogenesis of pristane-induced alveolar hemorrhage was investigated in the present study. Early (2-4 weeks after injection) mortality due to hemorrhage was unique to C57BL/6 and C57BL/10 strains of mice. Recruitment of the macrophages and neutrophils preceded the hemorrhage by several days, and hemorrhage started 3-7 days after pristane injection in some mice, peaked at 2 weeks (84% in B6) and then resolved by 4 weeks in a majority of mice. Alveolar hemorrhage was independent of MyD88 (myeloid differentiation factor 88), or TLR7 pathways, in contrast to autoantibody production and glomerulonephritis, and was also independent of FcγR or Fas. Rag1(-/-) mice had a reduced prevalence of alveolar hemorrhage compared with B6 (P=0.01) congenics. However, T-cell receptor-deficient mice developed alveolar hemorrhage at a rate comparable to wild-type controls, whereas B6 Igµ(-/-) mice surprisingly had a strikingly reduced prevalence (7% vs 84% in B6, P<0.0001). Reconstitution of B6 Igµ(-/-) mice with wild-type B cells increased the prevalence to 50% (P=0.028). Pristane-induced alveolar hemorrhage is a useful model to study the pathogenesis and develop new therapy for this underappreciated and often life-threatening complication of SLE.

First assessment of three-dimensional quantitative photoacoustic tomography for in vivo detection of osteoarthritis in the finger joints.

PURPOSE: The purpose of this pilot clinical study is to assess three-dimensional (3-D) quantitative photoacoustic tomography (qPAT) for in vivo detection of osteoarthritis (OA) in the finger joints. METHODS: All subject data were handled in compliance with the rules and regulations concerning the privacy and security of protected health information under HIPAA. Seven female subjects (two OA patients and five healthy controls) entered the study and their distal interphalangeal (DIP) joints were examined by a 3-D photoacoustic scanner. 3-D optical absorption coefficient images of all the photoacoustically examined joints were recovered using a 3-D qPAT reconstruction algorithm. RESULTS: The recovered quantitative photoacoustic images revealed obvious difference in the optical absorption coefficient of the joint cavity (cartilage and synovial fluid) between the OA and healthy joints. Quantitative analysis of the joints also indicated an apparent difference in the recovered joint spacing between the OA and healthy subjects. CONCLUSION: This initial clinical evaluation suggests that it is feasible to detect osteoarthritis in the finger joints with our 3-D qPAT approach, which has paved the way to further statistically evaluate the diagnostic performance of the 3-D qPAT approach in comparison with radiography or magnetic resonance imaging (MRI) on a sample of hand osteoarthritis.

Computer-aided classification of optical images for diagnosis of osteoarthritis in the finger joints.

This study presents a computer-aided classification method to distinguish osteoarthritis finger joints from healthy ones based on the functional images captured by x-ray guided diffuse optical tomography. Three imaging features, joint space width, optical absorption, and scattering coefficients, are employed to train a Least Squares Support Vector Machine (LS-SVM) classifier for osteoarthritis classification. The 10-fold validation results show that all osteoarthritis joints are clearly identified and all healthy joints are ruled out by the LS-SVM classifier. The best sensitivity, specificity, and overall accuracy of the classification by experienced technicians based on manual calculation of optical properties and visual examination of optical images are only 85%, 93%, and 90%, respectively. Therefore, our LS-SVM based computer-aided classification is a considerably improved method for osteoarthritis diagnosis.

Type I interferon modulates monocyte recruitment and maturation in chronic inflammation.

Chronic inflammation is characterized by continuous recruitment and activation of immune cells such as monocytes in response to a persistent stimulus. Production of proinflammatory mediators by monocytes leads to tissue damage and perpetuates the inflammatory response. However, the mechanism(s) responsible for the sustained influx of monocytes in chronic inflammation are not well defined. In chronic peritonitis induced by pristane, the persistent recruitment of Ly6C(hi) inflammatory monocytes into the peritoneum was abolished in type I interferon (IFN-I) receptor-deficient mice but was unaffected by the absence of IFN-gamma, tumor necrosis factor-alpha, interleukin-6, or interleukin-1. IFN-I signaling stimulated the production of chemokines (CCL2, CCL7, and CCL12) that recruited Ly6C(hi) monocytes via interactions with the chemokine receptor CCR2. Interestingly, after 2,6,10,14-tetramethylpentadecane treatment, the rapid turnover of inflammatory monocytes in the inflamed peritoneum was associated with a lack of differentiation into Ly6C(lo) monocytes/macrophages, a more mature subset with enhanced phagocytic capacity. In contrast, Ly6C(hi) monocytes differentiated normally into Ly6C(lo) cells in IFN-I receptor-deficient mice. The effects of IFN-I were specific for monocytes as granulocyte migration was unaffected in the absence of IFN-I signaling. Taken together, our findings reveal a novel role of IFN-I in promoting the recruitment of inflammatory monocytes via the chemokine receptor CCR2. Continuous monocyte recruitment and the lack of terminal differentiation induced by IFN-I may help sustain the chronic inflammatory response.

Quantitative two-dimensional photoacoustic tomography of osteoarthritis in the finger joints.

We present for the first time in vivo experimental evidence that quantitative photoacoustic tomography (qPAT) has the potential to detect osteoarthritis (OA) in the finger joints. In this pilot study, 2 OA patients and 4 healthy volunteers were enrolled, and their distal interphalangeal (DIP) joints were examined photoacoustically by a PAT scanner. Tissue absorption coefficient images of all the examined joints, which were unavailable from the conventional PAT, were recovered using our finite element based qPAT approach. The recovered quantitative photoacoustic images revealed significant differences in the tissue absorption coefficient of the joint cavity (cartilage and synovial fluid) between the OA and normal joints.

High-resolution x-ray guided three-dimensional diffuse optical tomography of joint tissues in hand osteoarthritis: morphological and functional assessments.

PURPOSE: The aim of this study was to investigate the potential use of multimodality functional imaging techniques to identify the quantitative optical findings that can be used to distinguish between osteoarthritic and normal finger joints. METHODS: Between 2006 and 2009, the distal interphalangeal finger joints from 40 female subjects including 22 patients and 18 healthy controls were examined clinically and scanned by a hybrid imaging system. This system integrated x-ray tomosynthetic setup with a diffuse optical imaging system. Optical absorption and scattering images were recovered based on a regularization-based hybrid reconstruction algorithm. A receiver operating characteristic curve was used to calculate the statistical significance of specific optical features obtained from osteoarthritic and healthy joints groups. RESULTS: The three-dimensional optical and x-ray images captured made it possible to quantify optical properties and joint space width of finger joints. Based on the recovered optical absorption and scattering parameters, the authors observed statistically significant differences between healthy and osteoarthritis finger joints. CONCLUSIONS: The statistical results revealed that sensitivity and specificity values up to 92% and 100%, respectively, can be achieved when optical properties of joint tissues were used as classifiers. This suggests that these optical imaging parameters are possible indicators for diagnosing osteoarthritis and monitoring its progression.

Autoimmune inner ear disease: A systematic review of management.

OBJECTIVES: The study systematically reviewed the existing literature on the management of autoimmune inner ear disease (AIED). STUDY DESIGN: Systematic review. METHODS: We performed a literature search of Embase, NCBI, Cochrane, and Web of Science databases from April 1990 to April 2020. Inclusion criteria included studies that were retrospective or prospective in nature evaluating the treatment of AIED with audiometric data measuring hearing outcomes during treatment. Hearing improvement was the primary study outcome and improvement in vestibular symptoms was the secondary study outcome. RESULTS: Sixteen of 412 candidate articles were included in our study. Systemic steroid treatment is most commonly described. Alternative treatment modalities included intratympanic steroid treatment, methotrexate, cyclophosphamide, azathioprine, infliximab, etanercept, adalimumab, golimumab, methylprednisolone, rituximab, and anakinra. CONCLUSION: Systemic corticosteroids are the first line treatment of AIED. Intratympanic steroids are a potential adjuvant or alternative treatment for patients who cannot tolerate or become refractory to steroid treatment. Steroid nonresponders may benefit from biologic therapy. Alternative treatment modalities including nonsteroidal immunosuppressants and biologics have been studied in small cohorts of patients with varying results. Prospective studies investigating the efficacy of biologic and nonsteroidal therapy are warranted. LEVEL OF EVIDENCE: 2.

Intrafollicular location of marginal zone/CD1d(hi) B cells is associated with autoimmune pathology in a mouse model of lupus.

Marginal zone (MZ) B cells contain a large number of autoreactive clones and the expansion of this compartment has been associated with autoimmunity. MZ B cells also efficiently transport blood-borne antigen to the follicles where they activate T cells and differentiate into plasma cells. Using the B6.NZM2410.Sle1.Sle2.Sle3 (B6.TC) model of lupus, we show that the IgM+ CD1d(hi)/MZ B-cell compartment is expanded, and a large number of them reside inside the follicles. Contrary to the peripheral B-cell subset distribution and their activation status, the intrafollicular location of B6.TC IgM+ CD1d(hi)/MZ B cells depends on both bone marrow- and stromal-derived factors. Among the factors responsible for this intrafollicular location, we have identified an increased response to CXCL13 by B6.TC MZ B cells and a decreased expression of VCAM-1 on stromal cells in the B6.TC MZ. However, the reduced number of MZ macrophages observed in B6.TC MZs was independent of the IgM+ CD1d(hi)/B-cell location. B7-2 but not B7-1 deficiency restored IgM+ CD1d(hi)/MZ B-cell follicular exclusion in B6.TC mice, and it correlated with tolerance to dsDNA and a significant reduction of autoimmune pathology. These results suggest that follicular exclusion of IgM+ CD1d(hi)/MZ B cells is an important B-cell tolerance mechanism, and that B7-2 signaling is involved in breaching this tolerance checkpoint.

T cell hyperactivity in lupus as a consequence of hyperstimulatory antigen-presenting cells.

Sle3 is an NZM2410-derived lupus susceptibility locus on murine chromosome 7. Congenic recombination has resulted in a novel mouse strain, B6.Sle3, associated with serum antinuclear autoantibodies (ANAs), T cell hyperactivity, and elevated CD4/CD8 ratios. An OVA-specific TCR transgene was used as a tool to demonstrate that Sle3 facilitated heightened T cell expansion in vitro, and in vivo, following antigen challenge. Indeed, continued T cell expansion was noted even in response to a tolerogenic signal. However, these phenotypes did not appear to be T cell intrinsic but were dictated by hyperstimulatory B6.Sle3 APCs. Importantly, B6.Sle3-derived DCs and macrophages appeared to be significantly more mature/activated, less apoptotic, and more proinflammatory and were better at costimulating T cells in vitro, compared with the B6 counterparts. Finally, the adoptive transfer of B6.Sle3-derived DCs into healthy B6 recipients elicited increased CD4/CD8 ratios and serum ANAs, 2 cardinal Sle3-associated phenotypes. We posit that their heightened expression of various costimulatory molecules, including CD80, CD106, I-A, and CD40, and their elevated production of various cytokines, including IL-12 and IL-1beta, may explain why Sle3-bearing DCs may be superior at breaching self tolerance. These studies provide mechanistic evidence indicating that intrinsic abnormalities in DCs and possibly other myeloid cells may dictate several of the phenotypes associated with systemic lupus, including ANA formation and T cell hyperactivity.

Tomographic x-ray-guided three-dimensional diffuse optical tomography of osteoarthritis in the finger joints.

We describe a multimodality imaging approach that combines x-ray tomosynthesis with near-infrared diffuse optical tomography (DOT) for high-resolution imaging of osteoarthritis in the finger joints. In this approach, we take advantage of high resolution x-ray imaging particularly of the bones and incorporate the fine structural maps obtained from x ray as a priori information into DOT reconstructions. To realize this multi-modality approach, we constructed a hybrid imaging platform that integrated a C-arm-based x-ray tomosynthetic system with a multichannel optic-fiber-based DOT system. We also implemented improved hybrid regularization-based reconstruction algorithms that have shown to be especially effective for high-resolution modality-guided DOT. Initial evaluation of our x-ray-guided DOT reconstruction approach in the finger joints shows that spatial resolution of DOT can be enhanced dramatically when the three-dimensional geometry of bones is known a priori. In particular, the improved quantitative capability of imaging absorption and scattering coefficients of the joint tissues allows for more accurate diagnosis of osteoarthritis over x-ray radiography or DOT alone.

Comparison of chlordecone and estradiol effects on splenic T-cells in (NZBxNZW)F(1) mice.

Previous studies have shown that treatment of ovariectomized females with 17-beta estradiol (E2) accelerates the development of autoimmunity in the (NZBxNZW)F(1) murine lupus model. Treatment with estrogenic organochlorine pesticides (OCPs) such as chlordecone produces a similar effect. Although it is reasonable to postulate that the effects of chlordecone and related OCPs on autoimmunity are due to their estrogenic effects, this has not been clearly demonstrated. The objective of this study was to compare effects of chlordecone and E2 on splenic T lymphocyte parameters plausibly related to autoimmunity; specifically, on T-cell phenotype and functions. Ovariectomized (NZBxNZW)F(1) mice were treated for 6 weeks with implanted sustained-release pellets containing chlordecone or E2 at dosing rates shown previously to significantly shorten time to onset of disease. E2, but not chlordecone, increased the percentage of activated and memory CD4 T-cells, and reduced naive CD4 T-cells. E2 also elevated CD25 and glucocorticoid-induced TNF receptor (GITR) levels in CD4 T-cells, an effect not shared by chlordecone. On the other hand, both chlordecone and E2 increased Bcl-2 expression in CD4 T-cells and reduced CD4 T-cell apoptosis without affecting their proliferation. Although both treatments increased TNF-alpha and IL-2 secretion by CD4 T-cells, only chlordecone increased secretion of IFN-gamma and GM-CSF. E2, but not chlordecone, increased IL-10 secretion. These observations indicate that although it is considered an estrogenic OCP, chlordecone exerts effects on splenic T-cells that are different in a number of ways from E2.

Acceleration of autoimmunity by organochlorine pesticides: a comparison of splenic B-cell effects of chlordecone and estradiol in (NZBxNZW)F1 mice.

The weakly estrogenic organochlorine pesticide chlordecone can accelerate the development of systemic lupus erythematosus (SLE) in ovariectomized (NZBxNZW)F1 mice, with a shortened time to appearance of autoantibodies and disease similar to that produced by treatment with the sex hormone 17beta-estradiol (E2). It is unclear whether chlordecone and E2 share the same pathways in mediating this effect. The effects of chlordecone and E2 treatment on splenic germinal center (GC) and marginal zone B cells were examined. Both chlordecone and E2 activated splenic B cells and enhanced GC reactions, as shown by upregulated protein expression of GL7, CXCR5, and CXCR4. Both treatments increased B-cell bcl-2 and shp-1 gene expression and enhanced ICAM-1 and VCAM-1 protein levels in GC B cells. Chlordecone reduced total B cell and GC B-cell apoptosis without affecting proliferation, another feature shared by E2 treatment. However, chlordecone treatment did not alter the composition of splenic B-cell subsets in marked contrast to the decrease in transitional B cells and increase in marginal zone B cells seen in E2-treated mice. The differences in effects between chlordecone and E2 indicate that chlordecone is not functioning simply as an estrogen mimic with respect to effects on the immune system. Similarities in the effects of chlordecone and E2 on specific immune functions, such as diminished apoptosis in GC B cells, may provide valuable clues regarding key events in the acceleration of autoimmunity by E2, chlordecone, and other agents.

Diminished prolactin from chlordecone treatment in ovariectomized (NZBxNZW)F(1) mice.

In murine models of systemic lupus erythematosus (SLE), administration of either prolactin or estradiol (E2) increases autoimmunity, and there is evidence that elevated prolactin in response to E2 administration may contribute substantially to E2 effects. Hormonal influence on SLE can extend to environmental agents, as demonstrated by the ability of estrogenic organochlorine pesticides such as chlordecone to accelerate the development of lupus in female (NZBxNZW)F(1) mice. In order to evaluate a potential role for prolactin in chlordecone effects on SLE, it was necessary to first determine whether treatment with chlordecone, like E2, results in elevated prolactin levels. Ovariectomized (NZBxNZW)F(1) mice were treated for 5-6 weeks with chlordecone or E2 in doses shown previously to significantly shorten the time to onset of SLE. At the end of the treatment period, serum prolactin levels were increased 10- to 20-fold in E2-treated mice compared to untreated controls, but decreased in an apparent dose-dependent manner in mice treated with chlordecone. Prolactin receptor in purified splenic B and CD4 T cells from treated animals, assessed through measurement of mRNA using quantitative real-time PCR, was increased by E2 treatment but unchanged in response to chlordecone. These observations suggest that the role of prolactin in eliciting autoimmunity in E2-treated animals is absent in the case of chlordecone, and by implication, that chlordecone possesses other actions that can replace the contribution of prolactin to development of SLE.