Objective We postulated that proteasome inhibition (PI) may be useful in the treatment of SLE by targeting plasmacytoid dendritic cells (pDCs) and plasma cells (PCs), both critical to disease pathogenesis. Methods Lupus prone mice were treated with the non-selective PIs carfilzomib and bortezomib, the LMP7-selective immunoproteasome inhibitor ONX 0914, or vehicle control. Tissues were harvested and analyzed by flow cytometry using standard markers. Nephritis was monitored by proteinuria and kidney harvest. Serum anti-dsDNA levels were measured by ELISA and total IgG and dsDNA antibody secreting cells (ASC) by ELIspot. Human PBMCs or mouse bone marrow cells were incubated with TLR agonists and PIs and interferon α measured by ELISA and flow cytometry. Results Early treatment of lupus prone mice with the dual targeting PIs carfilzomib or bortezomib or the immunoproteasome specific inhibitor ONX 0914 prevented disease progression, and treatment of mice with established disease dramatically abrogated nephritis. Treatment had profound effects on plasma cells with greater reductions in autoreactive than total IgG ASCs, an effect that became more pronounced with prolonged treatment, and was reflected in decreasing serum autoantibodies. Remarkably, proteasome inhibition efficiently suppressed production of interferon α by toll-like receptor activated pDCs in vitro and in vivo, an effect mediated by both an inhibition of pDC survival and function. Conclusions Inhibition of the immunoproteasome is equally efficacious to dual targeting agents in preventing lupus disease progression by targeting two critical pathways in disease pathogenesis, type I interferon activation and autoantibody production by plasma cells.

Some autoreactive T cells normally escape thymic selection and persist in the periphery. This is true of myelin-reactive CD4+ T cells, the effectors of experimental autoimmune encephalomyelitis (EAE) in laboratory animals and the presumed mediators of multiple sclerosis in humans. Nonetheless, most individuals do not succumb to autoimmune disease. There is growing evidence that while peripheral APCs stimulate immune responses against foreign Ags in the setting of tissue destruction and “danger,” they actually maintain tolerance against self Ags under steady state conditions. We hypothesized that tolerance against candidate autoantigens could be reversed by activation of APCs via CD40 or Toll-like receptor 9 signaling. Adult SJL mice injected i.p. with a peptide fragment of proteolipid protein (a candidate autoantigen in multiple sclerosis) emulsified in IFA fail to mount lymphoproliferative or cytokine responses and are protected from EAE upon subsequent challenge with the Ag combined with adjuvants. Here we report that tolerized proteolipid protein-specific lymph node cells regain the ability to divide, differentiate along a Th1 lineage, and transfer EAE when reactivated in the presence of agonistic Abs against CD40 or CpG oligonucleotides. The effects of both anti-CD40 and CpG oligonucleotides are dependent upon induction of IL-12. Our findings suggest two mechanisms to explain the well-documented association between infectious illnesses and flare-ups of multiple sclerosis. Microbial pathogens could 1) release molecules that bind Toll-like receptors, and/or 2) stimulate microbe-specific T cells to express CD40 ligand, thereby licensing APCs that bear both microbial and autoantigens to break tolerance.

Infection with the protozoan parasite Toxoplasma gondii is a major health risk owing to birth defects, its chronic nature, ability to reactivate to cause blindness and encephalitis, and high prevalence in human populations. Unlike most eukaryotes, Toxoplasma propagates in intracellular parasitophorous vacuoles, but like nearly all other eukaryotes, Toxoplasma glycosylates many cellular proteins and lipids and assembles polysaccharides. Toxoplasma glycans resemble those of other eukaryotes, but species-specific variations have prohibited deeper investigations into their roles in parasite biology and virulence. The Toxoplasma genome encodes a suite of likely glycogenes expected to assemble N-glycans, O-glycans, a C-glycan, GPI-anchors, and polysaccharides, along with their precursors and membrane transporters. To investigate the roles of specific glycans in Toxoplasma, here we coupled genetic and glycomics approaches to map the connections between 67 glycogenes, their enzyme products, the glycans to which they contribute, and cellular functions. We applied a double-CRISPR/Cas9 strategy, in which two guide RNAs promote replacement of a candidate gene with a resistance gene; adapted MS-based glycomics workflows to test for effects on glycan formation; and infected fibroblast monolayers to assess cellular effects. By editing 17 glycogenes, we discovered novel Glc 0-2-Man 6-GlcNAc 2-type N-glycans, a novel HexNAc-GalNAc-mucin-type O-glycan, and Tn-antigen; identified the glycosyltransferases for assembling novel nuclear O-Fuc-type and cell surface Glc-Fuc-type O-glycans; and showed that they are important for in vitro growth. The guide sequences, editing constructs, and mutant strains are freely available to researchers to investigate the roles of glycans in their favorite biological processes. Toxoplasma gondii is a worldwide, obligate intracellular apicomplexan parasite that can infect most nucleated cells of warm-blooded animals (1), with up to 80% of some human populations being seropositive (2). Toxoplasmosis, the disease caused by Toxoplasma, is associated with encephalitis and blindness in individuals whose parasites are reactivated, as can occur in AIDS and other immunosuppressed patients (3). In utero infections can cause mental retardation, blindness, and death (4). Toxoplasma is transmitted by digesting parasites from feline feces (as oocysts) or undercooked meat (as tissue cysts). Once in the host, parasites convert to the tachyzoite form that disseminates to peripheral tissues (e.g. brain, retina, and muscle). The resulting immune response and/or drugs can control tachyzoite replication, but the parasite survives by encysting into slowly growing bradyzoites. Sporadically, burst of cysts allows the parasites to convert to tachyzoites, whose unchecked growth results in cell and tissue damage (5, 6). Currently, no Toxoplasma vaccine exists, anti-toxoplasmosis drugs have severe side effects, and resistance is developing to these drugs (7-11). As individuals remain infected for life, new anti-Toxoplasma drugs a...

The CRISPR-Cas systems provide invader defense in a wide variety of prokaryotes, as well as technologies for many powerful applications. The Type III-A or Csm CRISPR-Cas system is one of the most widely distributed across prokaryotic phyla, and cleaves targeted DNA and RNA molecules. In this work, we have constructed modules of Csm systems from 3 bacterial species and heterologously expressed the functional modules in E. coli. The modules include a Cas6 protein and a CRISPR locus for crRNA production, and Csm effector complex proteins. The expressed modules from L. lactis, S. epidermidis and S. thermophilus specifically eliminate invading plasmids recognized by the crRNAs of the systems. Characteristically, activation of plasmid targeting activity depends on transcription of the plasmid sequence recognized by the crRNA. Activity was not observed when transcription of the crRNA target sequence was blocked, or when the opposite strand or a non-target sequence was transcribed. Moreover, the Csm module can be programmed to recognize plasmids with novel target sequences by addition of appropriate crRNA coding sequences to the module. These systems provide a platform for investigation of Type III-A CRISPR-Cas systems in E. coli, and for introduction of programmable transcription-activated DNA targeting into novel organisms.

Autoantibodies to double-stranded DNA (dsDNA), produced by auto-reactive plasma cells (PC), are a hallmark of systemic lupus erythematosus (SLE) and play a key role in disease pathogenesis. Recent data suggests that auto-reactive PC accumulate not only in lymphoid tissues but also in the inflamed kidney in lupus nephritis. We hypothesized that the variable efficacy of anti-CD20 (rituximab) mediated B cell depletion (BCD) in SLE may be related to the absence of an effect on auto-reactive PCs in the kidney. Here we report that an enrichment of auto-reactive dsDNA antibody secreting cells (ASC) in the kidney of lupus-prone mice (up to 40% of the ASCs) coincided with a progressive increase in splenic germinal centers (GC) and PCs and an increase in renal expression for PC survival factors (BAFF, APRIL and IL6) and PC attracting chemokines (CXCL12). Short-term treatment with anti-CD20 (4 weeks), neither decreased anti-dsDNA nor IgG ASCs in different anatomical locations. However, long-term treatment (12 weeks) significantly reduced both IgG- and dsDNA specific ASCs. In addition, long-term treatment substantially decreased splenic GC- and PC generation and unexpectedly reduced the expression for PC survival factors in the kidney. These results suggest that prolonged BCD may alter the PC survival niche in the kidney, regulating the accumulation and maintenance of auto-reactive PCs.