Understanding and measuring human B‐cell tolerance and its breakdown in autoimmune disease

The maintenance of immunological tolerance of B lymphocytes is a complex and critical process that must be implemented as to avoid the detrimental development of autoreactivity and possible autoimmunity. Murine models have been invaluable to elucidate many of the key components in B‐cell tolerance; however, translation to human homeostatic and pathogenic immune states can be difficult to assess. Functional autoreactive, flow cytometric, and single‐cell cloning assays have proven to be critical in deciphering breaks in B‐cell tolerance within autoimmunity; however, newer approaches to assess human B‐cell tolerance may prove to be vital in the further exploration of underlying tolerance defects. In this review, we supply a comprehensive overview of human immune tolerance checkpoints with associated mechanisms of enforcement, and highlight current and future methodologies which are likely to benefit future studies into the mechanisms that become defective in human autoimmune conditions.     

Progress in prion vaccines and immunotherapies

The transmissible spongiform encephalopathies have presented a challenge to physicians and scientists attempting to develop immunologically-based treatments. Self-tolerance has been one of the major obstacles to successfully raising antibodies against the prion protein (PrP), the host-encoded protein whose misfolded form (PrPSc) is linked to the protein-only infectious agent responsible for these disorders. Recently, it has been shown that antibodies directed against the normal cellular isoform of PrP (PrPC) can reduce or eliminate PrP isoform conversion in both in vitro and in vivo model systems. Similar studies with a PrPSc-specific epitope target are in progress. There is now rational hope that this devastating group of diseases may soon be amenable to immunotherapy and immunoprophylaxis.     

Intercellular propagated misfolding of wild-type Cu/Zn superoxide dismutase occurs via exosome-dependent and -independent mechanisms

Amyotrophic lateral sclerosis (ALS) is predominantly sporadic, but associated with heritable genetic mutations in 5–10% of cases, including those in Cu/Zn superoxide dismutase (SOD1). We previously showed that misfolding of SOD1 can be transmitted to endogenous human wild-type SOD1 (HuWtSOD1) in an intracellular compartment. Using NSC-34 motor neuron-like cells, we now demonstrate that misfolded mutant and HuWtSOD1 can traverse between cells via two nonexclusive mechanisms: protein aggregates released from dying cells and taken up by macropinocytosis, and exosomes secreted from living cells. Furthermore, once HuWtSOD1 propagation has been established, misfolding of HuWtSOD1 can be efficiently and repeatedly propagated between HEK293 cell cultures via conditioned media over multiple passages, and to cultured mouse primary spinal cord cells transgenically expressing HuWtSOD1, but not to cells derived from nontransgenic littermates. Conditioned media transmission of HuWtSOD1 misfolding in HEK293 cells is blocked by HuWtSOD1 siRNA knockdown, consistent with human SOD1 being a substrate for conversion, and attenuated by ultracentrifugation or incubation with SOD1 misfolding-specific antibodies, indicating a relatively massive transmission particle which possesses antibody-accessible SOD1. Finally, misfolded and protease-sensitive HuWtSOD1 comprises up to 4% of total SOD1 in spinal cords of patients with sporadic ALS (SALS). Propagation of HuWtSOD1 misfolding, and its subsequent cell-to-cell transmission, is thus a candidate process for the molecular pathogenesis of SALS, which may provide novel treatment and biomarker targets for this devastating disease.Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular condition that afflicts as many as 1 of 350 males and 420 females over the age of 18 (1). In ALS, degeneration of upper and lower motor neurons causes progressive muscle paralysis and spasticity, affecting mobility, speech, swallowing, and respiration (2). Half of affected individuals die within 3 y, and less than 20% survive for more than 5 y (3); 90–95% of ALS cases are sporadic (SALS) in which some apparently facilitating gene mutations, such as repeat expansions in the gene that encodes ataxin-2 (4), have been identified. The remaining 5–10% of ALS cases are familial (FALS) and predominantly associated with Mendelian-inherited mutations in the genes encoding Cu/Zn superoxide dismutase (SOD1), TAR-DNA–binding protein 43 (TDP-43), fused in sarcoma/translocated in liposarcoma (FUS/TLS), C9ORF72, and other genes (reviewed in ref. 3).Despite the profusion of functionally diverse genes implicated in FALS and SALS, clinical and pathological similarities between all forms of ALS suggest the existence of a common pathogenic pathway that could be united by a single gene/protein (5). One of the mechanisms by which a mutant or wild-type (WT) protein can dominate pathogenesis of phenotypically diverse diseases is by propagated protein misfolding, such as that underpinning the prion diseases, which has been increasingly implicated in other neurodegenerative and systemic disorders (6, 7). A role for propagated protein misfolding in ALS is supported by the prion-like spatiotemporal progression of disease through the neuroaxis (8, 9). However, given the disparity in protein inclusion pathology between subtypes of ALS, a single unifying prion-like protein that could explain such a progression remains obscure.Whereas it is generally accepted SOD1 is not found in large perikaryal cytoplasmic inclusions outside of SOD1 FALS cases, misfolded SOD1 has been increasingly identified in SALS and non-SOD1 FALS (5, 10, 11). Indeed, we have reported that misfolded human wild-type SOD1 (HuWtSOD1) can be detected by spinal cord immunohistochemistry (IHC) in FALS secondary to FUS mutation, and in SALS patients with cytosolic WT TDP-43 accumulation (11). Moreover, in cell models, overexpression of WTTDP-43, or expression of mutant FUS or TDP-43, is associated with HuWtSOD1 misfolding (11). Collectively, these data are consistent with SOD1 being a molecular common denominator for all types of ALS. Furthermore, prion-like activity has been described for the cell-to-cell transmission of misfolding of mutant SOD1 (12), and we have reported that mutant SOD1 can confer its misfold on HuWtSOD1 (13). However, mutant SOD1 cannot explain propagation in SALS.To test if HuWtSOD1 participates in cell-to-cell transmission of protein misfolding, we make use of previously developed mouse mAb probes for misfolded/oxidized SOD1, recognizing either full-length human mutant or WT SOD1, generated against regions that are antibody-inaccessible in natively folded SOD1 (13–15). Misfolded SOD1 mAbs used in this work are 10E11C11 and 3H1, directed against an unstructured electrostatic loop [disease-specific epitope-2 (DSE2)], and 10C12, directed against a C-terminal dimer interface peptide in which the cysteine at position 146 is substituted by a cysteic acid residue to mimic oxidation of this residue (DSE1a) (13). The use of such antibody probes have enabled us to unambiguously determine the role of misfolded mutant G127X in the induced misfolding of HuWtSOD1, which upon misfolding acquires a marked increase in sensitivity to protease digestion, consistent with global loosening of structure (13). The finding that misfolded endogenous HuWtSOD1 was observed long after transfected G127X-SOD1 was degraded suggested that HuWtSOD1, once misfolded, is capable of triggering an intracellular propagated misfolding reaction (13). We now report for the first time that misfolded HuWtSOD1 can transit cell to cell both via exosomes, and release of protein aggregates and subsequent uptake in neuronal cells. In addition, misfolded HuWtSOD1 can sustain intercellular propagated misfolding in vitro and is detectable in the spinal cord of all ALS patients tested, regardless of the genetic etiology of the disease. Collectively, these data indicate that HuWtSOD1 is competent to participate in propagated misfolding, suggesting a common pathogenic mechanism linking FALS and SALS.     

Engraftment of NOD/SCID-beta2 microglobulin null mice with multilineage neoplastic cells from patients with myelodysplastic syndrome

The development of immunodeficient mouse xenograft models has greatly facilitated the investigation of some human hematopoietic malignancies, but application of this approach to the myelodysplastic syndromes (MDSs) has proven difficult. We now show that cells from most MDS patients (including all subtypes) repopulate nonobese diabetic-severe combined immunodeficient (scid)/scid-beta2 microglobulin null (NOD/SCID-beta2m(-/-)) mice at least transiently and produce abnormal differentiation patterns in this model. Normal marrow transplants initially produce predominantly erythroid cells and later predominantly B-lymphoid cells in these mice, whereas most MDS samples produced predominantly granulopoietic cells. In 4 of 4 MDS cases, the regenerated cells showed the same clonal markers (trisomy 8, n = 3; and 5q-, n = 1) as the original sample and, in one instance, regenerated trisomy 8(+) B-lymphoid as well as myeloid cells were identified. Interestingly, the enhanced growth of normal marrow obtained in NOD/SCID-beta2m(-/-) mice engineered to produce human interleukin-3, granulocyte-macrophage colony-stimulating factor, and Steel factor was seen only with 1 of 7 MDS samples. These findings support the concept that human MDS originates in a transplantable multilineage hematopoietic stem cell whose genetic alteration may affect patterns of differentiation and responsiveness to hematopoietic growth factors. They also demonstrate the potential of this new murine xenotransplant model for future investigations of MDS.     

A Strategic and Shared Agenda to Advance Mental Health in Schools through Family and System Partnerships

The paper reviews data on the gap between young people who need and young people who receive mental health care. The fact that need far outstrips available resources underscores the importance of moving forward a shared agenda that builds a coalition of shared values and goals among families, schools, mental health agencies and other community programs and stakeholders. The importance of a coordinated public health approach, emphasizing broad systems enhancement, early intervention, and more intensive programs and services, is emphasized, and recommendations for strategic action at local, state and national levels are presented.     

SENP5 mediates breast cancer invasion via a TGFβRI SUMOylation cascade

Identifying novel mechanisms, which are at the core of breast cancer biology, is of critical importance. Such mechanisms may explain response to treatment, reveal novel targets or drive detection assays.To uncover such novel mechanisms, we used survival analysis on gene expression datasets encompassing 1363 patients. By iterating over the compendia of genes, we screened for their significance as prognosis biomarkers and identified SUMO-specific protease 5 (SENP5) to significantly stratify patients into two survival groups across five unrelated tested datasets. According to these findings, low expression of SENP5 is associated with good prognosis among breast cancer patients.Following these findings, we analyzed SENP5 silencing and show it is followed by inhibition of anchorage-independence growth, proliferation, migration and invasion in breast cancer cell lines. We further show that these changes are conducted via regulation of TGFβRI levels. These data relate to recent reports about the SUMOylation of TGFβRI. Following TGFβRI changes in expression, we show that one of its target genes, MMP9, which plays a key role in degrading the extracellular matrix and contributes to TGFβ-induced invasion, is dramatically down regulated upon SENP5 silencing.This is the first report represents SENP5-TGFβ-MMP9 cascade and its mechanistic involvement in breast cancer.