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Crescentic glomerulonephritis (CGN), which frequently results in acute and chronic kidney disease, is characterized by and dependent on glomerular infiltration by macrophages. The mannose receptor (MR) is a pattern recognition receptor implicated in the uptake of endogenous and microbial ligands by macrophages, mesangial cells (MCs), and selected endothelial cells. It is upregulated on alternatively activated macrophages (i.e., macrophages associated with tissue repair and humoral immunity) and involved in antigen presentation to T cells. We used the mouse model of nephrotoxic nephritis to investigate the role of MR in CGN. Our results demonstrate what we believe to be a novel role for MR in the promotion of CGN that is independent of adaptive immune responses. MR-deficient ([Mr.sup.[-/-]]) mice were protected from CGN despite generating humoral and T cell responses similar to those of WT mice, but they demonstrated diminished macrophage and MC Fc receptor-mediated (FcR-mediated) functions, including phagocytosis and Fc-mediated oxygen burst activity. [Mr.sup.[-/-]] MCs demonstrated augmented apoptosis compared with WT cells, and this was associated with diminished Akt phosphorylation. Macrophage interaction with apoptotic MCs induced a noninflammatory phenotype that was more marked in [Mr.sup.[-/-]]macrophages than in WT macrophages. Our results demonstrate that MR augments Fc-mediated function and promotes MC survival. We suggest that targeting MR may provide an alternative therapeutic approach in CGN while minimizing the impact on adaptive immune responses, which are affected by conventional immunosuppressive approaches., Introduction Crescentic glomerulonephritis (CGN), in association with primary systemic vasculitis or SLE, frequently results in end-stage kidney disease despite immunosuppressive therapy (1), (2). Although numerous immune effectors, including antibodies, complement, [...]

We recently described the effect of the constitutively expressed chaperone, Hsc70 protein, on αSynuclein aggregation, a phenomenon associated with Parkinson disease. In vitro, Hsc70 binds to soluble αSyn and slows down its assembly into fibrils. Hsc70 also binds fibrillar αSyn, 5-fold tighter than soluble αSyn. This interaction reduces the cytotoxicity associated with naked αSyn fibrils. Herein, we discuss the feasibility of engineering a "minichaperone" which could be used against αSyn assembly propagation in Parkinson disease: taking what is necessary and sufficient within Hsc70 to protect against the damaging repercussions of high molecular weight αSyn species' passage from one neuron to another in the brain. [ABSTRACT FROM AUTHOR]

The aggregation of α-synuclein (α-Syn), the primary component of Lewy bodies, into high molecular weight assemblies is strongly associated with Parkinson disease. This event is believed to result from a conformational change within native α-Syn. Molecular chaperones exert critical housekeeping functions in vivo including refolding, maintaining in a soluble state, and/or pacifying protein aggregates. The influence of the stress-induced heat shock protein 70 (Hsp70) on α-Syn aggregation has been notably investigated. The constitutively expressed chaperone Hsc70 acts as an antiaggregation barrier before cells are overwhelmed with α-Syn aggregates and Hsp70 expression induced. Here, we investigate the interaction between Hsc70 and α-Syn, the consequences of this interaction, and the role of nucleotides and co-chaperones Hdj1 and Hdj2 as modulators. We show that Hsc70 sequesters soluble α-Syn in an assembly incompetent complex in the absence of ATP. The affinity of Hsc70 for soluble α-Syn diminishes upon addition of ATP alone or together with its co-chaperones Hdj1 or Hdj2 allowing faster binding and release of client proteins thus abolishing α-Syn assembly inhibition by Hsc70. We show that Hsc70 binds α-Syn fibrils with a 5-fold tighter affinity compared with soluble α-Syn. This suggests that Hsc70 preferentially interacts with high molecular weight α-Syn assemblies in vivo. Hsc70 binding certainly has an impact on the physicochemical properties of α-Syn assemblies. We show a reduced cellular toxicity of α-Syn fibrils coated with Hsc70 compared with "naked" fibrils. Hsc70 may therefore significantly affect the cellular propagation of α-Syn aggregates and their spread throughout the central nervous system in Parkinson disease.