Objective Diffuse alveolar hemorrhage (DAH) in lupus patients is >50% fatal. The cause is unknown. The pathogenesis of DAH in C57BL/6 mice with pristane-induced lupus, a model of human lupus-associated DAH, was examined. Methods Clinical/pathological and immunological manifestations DAH in pristane-lupus were compared with human DAH. Tissue distribution of pristane was examined by mass spectrometry. Cell types responsible for disease were determined by in vivo depletion using clodronate liposomes (CloLip) and anti-neutrophil monoclonal antibodies (GR1). The effect of complement depletion with cobra venom factor (CVF) was examined. Results After i.p. injection, pristane migrated to the lung, causing cell death, small vessel vasculitis, and alveolar hemorrhage similar to human DAH. B-cell-deficient mice were resistant to induction of DAH, but susceptibility was restored by infusing IgM. C3-deficient and CD18-deficient mice also were resistant and DAH was prevented in wild-type mice by CVF. Induction of DAH was independent of TLRs, inflammasomes, and inducible nitric oxide (iNOS). Mortality was increased in IL-10-deficient mice and pristane treatment decreased IL-10 receptor expression in monocytes and Stat3 phosphorylation in lung macrophages. In vivo neutrophil depletion was not protective, whereas treatment with CloLip prevented DAH, suggesting that macrophage activation is central to DAH pathogenesis. Conclusion The pathogenesis of DAH involves opsonization of dead cells by natural IgM and complement followed by complement receptor-mediated lung inflammation. The disease is macrophage-dependent and IL-10 is protective. Complement inhibition and/or macrophage-targeted therapies may reduce mortality in lupus-associated DAH.

Autoantibodies against a panoply of self-antigens are seen in systemic lupus erythematosus, but only a few (anti-Sm/RNP, anti-Ro/La, anti-dsDNA) are common. The common lupus autoantigens are nucleic acid complexes and levels of autoantibodies can be extraordinarily high. We explore why that is the case. Lupus is associated with impaired central or peripheral B-cell tolerance and increased circulating autoreactive B cells. However, terminal differentiation is necessary for autoantibody production. Nucleic acid components of the major lupus autoantigens are immunostimulatory ligands for toll-like receptor (TLR)7 or TLR9 that promote plasma cell differentiation. We show that the levels of autoantibodies against the U1A protein (part of a ribonucleoprotein) are markedly higher than autoantibodies against other antigens, including dsDNA and the non-nucleic acid-associated autoantigens insulin and thyroglobulin. In addition to driving autoantibody production, TLR7 engagement is likely to contribute to the pathogenesis of inflammatory disease in lupus.

Dead cells accumulating in the tissues may contribute to chronic inflammation. We examined the cause of impaired apoptotic cell clearance human and murine lupus. Dead cells accumulated in bone marrow from lupus patients but not from non-autoimmune patients undergoing myeloablation, where they were efficiently removed by macrophages. Impaired apoptotic cell uptake by macrophages also was seen in mice treated i.p. with pristane (develop lupus) but not mineral oil (MO, do not develop lupus). The inflammatory response to both pristane and MO rapidly depleted resident (Tim4+) large peritoneal macrophages (LPM). The peritoneal exudate of pristane-treated mice contained mainly Ly6Chi inflammatory monocytes, whereas in MO-treated mice, it consisted predominantly of a novel subset of highly phagocytic macrophages resembling small peritoneal macrophages (SPM) that expressed CD138+ and the scavenger receptor Marco. Treatment with anti-Marco neutralizing antibodies and the class A scavenger receptor antagonist polyinosinic acid inhibited phagocytosis of apoptotic cells by CD138+ macrophages. CD138+ macrophages expressed IL-10 receptor, CD206, and CCR2 but little TNFα or CX3CR1. They also expressed high levels of activated CREB, a transcription factor implicated in generating alternatively activated macrophages. Similar cells were identified in the spleen and lung of MO-treated mice and also were induced by lipopolysaccharide. We conclude that highly phagocytic, CD138+ SPM-like cells with an anti-inflammatory phenotype may promote the resolution of inflammation in lupus and infectious diseases. These SPM-like cells are not restricted to the peritoneum, and may help clear apoptotic cells from tissues such as the lung, helping to prevent chronic inflammation.

The generation of CD138+ phagocytic macrophages with an alternative (M2) phenotype that clear apoptotic cells from tissues is defective in lupus. Liver X receptor-alpha (LXRα) is an oxysterol-regulated transcription factor that promotes reverse cholesterol transport and alternative (M2) macrophage activation. Conversely, hypoxia-inducible factor 1-α (HIF1α) promotes classical (M1) macrophage activation. The objective of this study was to see if lupus can be treated by enhancing the generation of M2-like macrophages using LXR agonists. Peritoneal macrophages from pristane-treated mice had an M1 phenotype, high HIFα-regulated phosphofructokinase and TNFα expression (quantitative PCR, flow cytometry), and low expression of the LXRα-regulated gene ATP binding cassette subfamily A member 1 (Abca1) and Il10 vs. mice treated with mineral oil, a control inflammatory oil that does not cause lupus. Glycolytic metabolism (extracellular flux assays) and Hif1a expression were higher in pristane-treated mice (M1-like) whereas oxidative metabolism and LXRα expression were higher in mineral oil-treated mice (M2-like). Similarly, lupus patients’ monocytes exhibited low LXRα/ABCA1 and high HIF1α vs. controls. The LXR agonist T0901317 inhibited type I interferon and increased ABCA1 in lupus patients’ monocytes and in murine peritoneal macrophages. In vivo, T0901317 induced M2-like macrophage polarization and protected mice from diffuse alveolar hemorrhage (DAH), an often fatal complication of lupus. We conclude that end-organ damage (DAH) in murine lupus can be prevented using an LXR agonist to correct a macrophage differentiation abnormality characteristic of lupus. LXR agonists also decrease inflammatory cytokine production by human lupus monocytes, suggesting that these agents may be have a role in the pharmacotherapy of lupus.

Drug targeting is an active area of research and nano-scaled drug delivery systems hold tremendous potential for the treatment of neoplasms. In this study, a novel cyclodextrin (CD)-based nanoparticle drug delivery system has been assembled and characterized for the therapy of folate receptor-positive [FR(+)] cancer. Water-soluble folic acid (FA)-conjugated CD carriers (FACDs) were successfully synthesized and their structures were confirmed by 1D/2D nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF-MS), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and circular dichroism. Drug complexes of adamatane (Ada) and cytotoxic doxorubicin (Dox) with FACD were readily obtained by mixed solvent precipitation. The average size of FACD-Ada-Dox was 1.5–2.5 nm. The host-guest association constant K a was 1,639 M−1 as determined by induced circular dichroism and the hydrophilicity of the FACDs was greatly enhanced compared to unmodified CD. Cellular uptake and FR binding competitive experiments demonstrated an efficient and preferentially targeted delivery of Dox into FR-positive tumor cells and a sustained drug release profile was seen in vitro. The delivery of Dox into FR(+) cancer cells via endocytosis was observed by confocal microscopy and drug uptake of the targeted nanoparticles was 8-fold greater than that of non-targeted drug complexes. Our docking results suggest that FA, FACD and FACD-Ada-Dox could bind human hedgehog interacting protein that contains a FR domain. Mouse cardiomyocytes as well as fibroblast treated with FACD-Ada-Dox had significantly lower levels of reactive oxygen species, with increased content of glutathione and glutathione peroxidase activity, indicating a reduced potential for Dox-induced cardiotoxicity. These results indicate that the targeted drug complex possesses high drug association and sustained drug release properties with good biocompatibility and physiological stability. The novel FA-conjugated β-CD based drug complex might be promising as an anti-tumor treatment for FR(+) cancer.