The role of Calprotectin (S100A8/A9) in the pathogenesis of glomerulonephritis and ANCA-associated vasculitis.

Glomerulonephritis is a common cause of end-stage renal failure and a feature of ANCA-associated vasculitis (AAV). AAV is an example of a small vessel vasculitis, characterised by inflammation of the endothelium and glomeruli in which the interaction between leukocytes and endothelial cells play a crucial role. Macrophages have been demonstrated to have a critical role during the initiation and progression of glomerulonephritis. Calprotectin (also termed S100A8/A9, mrp8/14), is a complex of 2 small calcium binding proteins that is abundantly expressed in neutrophils and monocytes as well as early infiltrating macrophages and is a ligand of Toll-like receptor 4 (TLR4) and the receptor for advanced glycation end-products (RAGE). There is growing evidence in animal models and patients with autoimmune diseases, of calprotectin being involved in the inflammatory response, as well as being a marker of activation of innate immunity. I have initially characterised the presence of calprotectin-positive cells in renal biopsies of patients with focal and crescentic AAV glomerulonephritis, therefore linking the presence of these cells with renal outcome. Patients with active AAV have elevated serum calprotectin levels, as well as significant expression on neutrophils and monocytes, which although decrease during remission, does not normalise. I have demonstrated that mrp14-/- mice are protected from nephrotoxic nephritis, which is abrogated by use of LPS during disease progression. Bone-marrow derived macrophages (BMDMs) release pro-inflammatory cytokines following stimulation with calprotectin; mediated by TLR4. Mrp14-/- BMDMs do not respond to the pro-inflammatory stimulus of S100A8/A9. The co-culture of endothelial cells (EC) and wild-type BMDMs is pro-inflammatory unlike that of mrp14-/- BMDM and ECs. Mrp14-/- mesangial cells also have a decreased pro-inflammatory response. This work demonstrates that calprotectin has a role in experimental glomerulonephritis as well as AAV patients. This may improve our understanding of the inflammatory response and identify a new novel treatment targets

Sirolimus use in patients with subglottic stenosis in the context of granulomatosis with polyangiitis (GPA), suspected GPA, and immunoglobulin G4-related disease

OBJECTIVE: Subglottic stenosis (SGS) is a severe, life-threatening disease found in immune-mediated diseases such as granulomatosis with polyangiitis (GPA) and in rare cases of immunoglobulin G4 (IgG4)-related disease. It can result in persistent airway compromise due to the fibrotic response following inflammation. Standard management involves repeated endoscopic interventions to dilate the airway, and tracheostomy is occasionally required. In addition, immunosuppression remains a cornerstone of therapy aimed at controlling the underlying inflammatory disease; however, cumulative dosing leads to significant adverse effects. We present five cases of predominantly anti-neutrophil cytoplasmic antibody-negative GPA and a case of IgG4-related disease with SGS, in whom we evaluated the long-term utility of sirolimus, which has beneficial anti-proliferative and fibrotic effects, in the management of their disease. METHOD: We conducted a retrospective review of a cohort of patients with SGS at a tertiary vasculitis unit. These patients were treated with sirolimus, in addition to conventional medical and endoscopic treatment. Clinical symptoms, frequency and time to endoscopic intervention pre- and post-treatment, additional rescue therapy, and any adverse effects were recorded and analysed. RESULTS: Six patients were treated with sirolimus and followed for up to 9 years; two discontinued the drug owing to adverse effects, early on. In the remaining four patients, glucocorticoids were withdrawn, and the frequency of endoscopic intervention was reduced. One patient on sirolimus required rituximab therapy for disease flare. CONCLUSION: Sirolimus may be a therapeutic option for some patients with severe SGS, allowing steroid withdrawal and resulting in a positive adverse effect profile

Warfarin-induced skin necrosis in HIV-1-infected patients with tuberculosis and venous thrombosis

Background. At the turn of the century, only 300 cases of warfarin-induced skin necrosis (WISN) had been reported. WISN is a rare but potentially fatal complication of warfarin therapy. There are no published reports of WISN occurring in patients with HIV-1 infection or tuberculosis (TB).Methods. We retrospectively reviewed cases of WISN presenting from April 2005 to July 2008 at a referral hospital in Cape Town, South Africa.Results. Six cases of WISN occurred in 973 patients receiving warfarin therapy for venous thrombosis (0.62%, 95% CI 0.25 - 1.37%). All 6 cases occurred in HIV-1-infected women (median age 30 years, range 27 - 42) with microbiologically confirmed TB and venous thrombosis. All were profoundly immunosuppressed (median CD4+ count at TB diagnosis49 cells/μl, interquartile range 23 - 170). Of the 3 patients receiving combination antiretroviral therapy, 2 had TB-IRIS (immune reconstitution inflammatory syndrome). The median interval from initiation of antituberculosis treatment to venous thrombosis was 37 days (range 0 - 150). The median duration of parallel heparin and warfarin therapy was 2days (range 1 - 6). WISN manifested 6 days (range 4 - 8) after initiation of warfarin therapy. The international normalised ratio (INR) at WISN onset was supra-therapeutic, median 5.6 (range 3.8 - 6.6). Sites of WISN included breasts, buttocks and thighs. Four of 6 WISN sites were secondarily infected with drug-resistant nosocomial bacteria (methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter, extendedspectrumβ-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae) 17 - 37 days after WISN onset. In 4 patients, the median interval from WISN onset to death was 43 days (range 25 - 45). One of the 2 patients who survived underwent bilateral mastectomies and extensive skin graftingat a specialist centre. Conclusion. This is one of the largest case series of WISN. We report a novel clinical entity: WISN in HIV-1 infected patients with TB and venous thrombosis. The occurrence of 6 WISN cases in a 40-month period may be attributed to (i) hypercoagulability, secondary to HIV-1 and TB; (ii) shortconcurrent heparin and warfarin therapy; and (iii) high loading doses of warfarin. Active prevention and appropriate management of WISN are likely to improve the dire morbidity and mortality of this unusual condition.S Afr Med J 2010; 100: 372-377

Neutrophil-Associated Central Nervous System Inflammation in Tuberculous Meningitis Immune Reconstitution Inflammatory Syndrome.

Background. The immunopathogenesis of tuberculosis-associated immune reconstitution inflammatory syndrome (IRIS) remains incompletely understood, and we know of only 1 disease site-specific study of the underlying immunology; we recently showed that Mycobacterium tuberculosis culture positivity and increased neutrophils in the cerebrospinal fluid (CSF) of patients with tuberculous meningitis (TBM) are associated with TBM-IRIS. In this study we investigated inflammatory mediators at the disease site in patients with TBM-IRIS. Methods. We performed lumbar puncture at 3–5 time points in human immunodeficiency virus (HIV)–infected patients with TBM (n = 34), including at TBM diagnosis, at initiation of antiretroviral therapy (ART) (day 14), 14 days after ART initiation, at presentation of TBM-IRIS, and 14 days thereafter. We determined the concentrations of 40 mediators in CSF (33 paired with blood) with Luminex or enzyme-linked immunosorbent assays. Findings were compared between patients who developed TBM-IRIS (n = 16) and those who did not (TBM-non-IRIS; n = 18). Results. At TBM diagnosis and 2 weeks after ART initiation, TBM-IRIS was associated with severe, compartmentalized inflammation in the CSF, with elevated concentrations of cytokines, chemokines, neutrophil-associated mediators, and matrix metalloproteinases, compared with TBM-non-IRIS. Patients with TBM-non-IRIS whose CSF cultures were positive for M. tuberculosis at TBM diagnosis (n = 6) showed inflammatory responses similar to those seen in patients with TBM-IRIS at both time points. However, at 2 weeks after ART initiation, S100A8/A9 was significantly increased in patients with TBM-IRIS, compared with patients with TBM-non-IRIS whose cultures were positive at baseline. Conclusions. A high baseline M. tuberculosis antigen load drives an inflammatory response that manifests clinically as TBM-IRIS in most, but not all, patients with TBM. Neutrophils and their mediators, especially S100A8/A9, are closely associated with the central nervous system inflammation that characterizes TBM-IRIS

Disulfiram overcomes bortezomib and cytarabine resistance in Down-syndrome-associated acute myeloid leukemia cells

Background Children with Down syndrome (DS) have increased risk for developing AML (DS-AMKL), and they usually experience severe therapy-related toxicities compared to non DS-AMKL. Refractory/relapsed disease has very poor outcome, and patients would benefit from novel, less toxic, therapeutic strategies that overcome resistance. Relapse/resistance are linked to cancer stem cells with high aldehyde dehydrogenase (ALDH) activity. The purpose of the present work was to study less toxic alternative therapeutic agents for relapsed/refractory DS-AMKL. Methods Fourteen AML cell lines including the DS-AMKL CMY and CMK from relapsed/refractory AML were used. Cytarabine (Ara-C), bortezomib (BTZ), disulfiram/copper (DSF/Cu2+) were evaluated for cytotoxicity, depletion of ALDH-positive cells, and resistance. BTZ-resistant CMY and CMK variants were generated by continuous BTZ treatment. Cell viability was assessed using CellTiter-Glo®, ALDH activity by ALDELUORTM, and proteasome inhibition by western blot of ubiquitinated proteins and the Proteasome-Glo™ Chymotrypsin-Like (CT-like) assay, apoptosis by Annexin V Fluos/Propidium iodide staining, and mutations were detected using PCR, cloning and sequencing. Results Ara-C-resistant AML cell lines were sensitive to BTZ and DSF/Cu2+. The Ara-C-resistant DS-AMKL CMY cells had a high percentage of ALDHbright “stem-like” populations that may underlie Ara-C resistance. One percent of these cells were still resistant to BTZ but sensitive to DSF/Cu2+. To understand the mechanism of BTZ resistance, BTZ resistant (CMY-BR) and (CMK-BR) were generated. A novel mutation PSMB5 Q62P underlied BTZ resistance, and was associated with an overexpression of the β5 proteasome subunit. BTZ-resistance conferred increased resistance to Ara-C due to G1 arrest in the CMY-BR cells, which protected the cells from S-phase damage by Ara-C. CMY-BR and CMK-BR cells were cross-resistant to CFZ and MG-132 but sensitive to DSF/Cu2+. In this setting, DSF/Cu2+ induced apoptosis and proteasome inhibition independent of CT-like activity inhibition. Conclusions We provide evidence that DSF/Cu2+ overcomes Ara-C and BTZ resistance in cell lines from DS-AMKL patients. A novel mutation underlying BTZ resistance was detected that may identify BTZ-resistant patients, who may not benefit from treatment with CFZ or Ara-C, but may be responsive to DSF/Cu2+. Our findings support the clinical development of DSF/Cu2+ as a less toxic efficacious treatment approach in patients with relapsed/refractory DS-AMKL

Single-electron population and depopulation of an isolated quantum dot using a surface-acoustic-wave pulse

We use a pulse of surface acoustic waves (SAWs) to control the electron population and depopulation of a quantum dot. The barriers between the dot and reservoirs are set high to isolate the dot. Within a time scale of similar to 100 s the dot can be set to a nonequilibrium charge state, where an empty (occupied) level stays below (above) the Fermi energy. A pulse containing a fixed number of SAW periods is sent through the dot, controllably changing the potential, and hence the tunneling probability, to add (remove) an electron to (from) the dot

Membranous nephropathy: a retrospective observational study of membranous nephropathy in north east and central London

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Work on this study was supported in part by grants from the European Union, FP7 (EURenOmics grant agreement 2012-305608)

Regulatory B cells are numerically but not functionally deficient in anti-neutrophil cytoplasm antibody-associated vasculitis

Objectives: B cells are central to the pathology of ANCA-associated vasculitis (AAV), a disease characterized by autoantibodies and effectively treated by rituximab. In addition to promoting inflammation, a subset of B cells act to suppress harmful autoimmune responses (Breg). The balance of effector and regulatory B cell subsets in AAV is not known. This study was conducted to assess the relative frequency of these subsets during different states of disease activity. / Methods: B memory (Bmem), naive (Bnaive) and regulatory (Breg) subsets were defined by their relative expression of CD24 and CD38. Function was assessed by cytokine production and suppressive action on CD4(+) Th1 activation evaluated in a co-culture system. / Results: Compared with healthy controls, the frequency of Breg (CD24(hi)CD38(hi)) was significantly reduced during disease remission in both proteinase 3 (PR3)- and MPO-ANCA patients and during acute disease in PR3-ANCA patients, while the frequency of memory cells (CD24(hi)CD38(lo)) was reduced during active disease and restored during remission. Breg cell frequency showed a positive correlation, while Bmem had an inverse correlation with IL-10 production in vitro. B and T cell co-cultures revealed that memory and naive B cell subsets augmented Th1 activation in vitro, which was prevented by Breg, and this pattern did not differ between remission AAV patients and controls. / Conclusion: In remission there is a numerical, but not functional, deficiency in Breg and preservation of Bmem associated with reduced IL-10 production and increased Th1 activation in vitro. This imbalance may contribute to the high rate of relapse observed in AAV, especially in PR3-ANCA patients

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.G.M.K. is supported by the Royal Society as a Royal Society University Research Fellow. J.E.R. is supported as a Future Faculty Leaders Fellow at the Harvard-Smithsonian Center for Astrophysics. M.C.W. acknowledges support from the European Union through ERC grant no. 279973. Early work on KELT-North was supported by NASA grant no. NNG04GO70G