Necrosome-positive granulovacuolar degeneration is associated with TDP-43 pathological lesions in the hippocampus of ALS/FTLD cases.

AIM: Granulovacuolar degeneration (GVD) in Alzheimer's disease (AD) involves the necrosome, which is a protein complex consisting of phosphorylated receptor-interacting protein kinase 1 (pRIPK1), pRIPK3 and phosphorylated mixed lineage kinase domain-like protein (pMLKL). Necrosome-positive GVD was associated with neuron loss in AD. GVD was recently linked to the C9ORF72 mutation in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with transactive response DNA-binding protein (TDP-43) pathology (FTLD-TDP). Therefore, we investigated whether GVD in cases of the ALS-FTLD-TDP spectrum (ALS/FTLD) shows a similar involvement of the necrosome as in AD, and whether it correlates with diagnosis, presence of protein aggregates and cell death in ALS/FTLD. METHODS: We analysed the presence and distribution of the necrosome in post-mortem brain and spinal cord of ALS and FTLD-TDP patients (n = 30) with and without the C9ORF72 mutation, and controls (n = 22). We investigated the association of the necrosome with diagnosis, the presence of pathological protein aggregates and neuronal loss. RESULTS: Necrosome-positive GVD was primarily observed in hippocampal regions of ALS/FTLD cases and was associated with hippocampal TDP-43 inclusions as the main predictor of the pMLKL-GVD stage, as well as with the Braak stage of neurofibrillary tangle pathology. The central cortex and spinal cord, showing motor neuron loss in ALS, were devoid of any accumulation of pRIPK1, pRIPK3 or pMLKL. CONCLUSIONS: Our findings suggest a role for hippocampal TDP-43 pathology as a contributor to necrosome-positive GVD in ALS/FTLD. The absence of necroptosis-related proteins in motor neurons in ALS argues against a role for necroptosis in ALS-related motor neuron death.

Minimal modulation of the host immune response to SIS matrix implants by mesenchymal stem cells from the amniotic fluid.

PURPOSE: Surgical restoration of soft tissue defects often requires implantable devices. The clinical outcome of the surgery is determined by the properties inherent to the used matrix. Mesenchymal stem cells (MSC) modulate the immune processes after in vivo transplantation and their addition to matrices is associated with constructive remodeling. Herein we evaluate the potential of MSC derived from the amniotic fluid (AF-MSC), an interesting MSC source for cell therapeutic applications in the perinatal period, for immune modulation when added to a biomaterial. METHODS: We implant cell free small intestinal submucosa (SIS) or SIS seeded with AF-MSC at a density of 1 × 105/cm2 subcutaneously at the abdominal wall in immune competent rats. The host immune response is evaluated at 3, 7 and 14 days postoperatively. RESULTS: The matrix-specific or cellular characteristics are not altered after 24 h of in vitro co-culture of SIS with AF-MSC. The host immune response was not different between animals implanted with cell free or AF-MSC-seeded SIS in terms of cellular infiltration, vascularity, macrophage polarization or scaffold replacement. Profiling the mRNA expression level of inflammatory cytokines at the matrix interface shows a significant reduction in the expression of the pro-inflammatory marker Tnf-α and a trend towards lower iNos expression upon AF-MSC-seeding of the SIS matrix. Anti-inflammatory marker expression does not alter upon cell seeding of matrix implants. CONCLUSION: We conclude that SIS is a suitable substrate for in vitro culture of AF-MSC and fibroblasts. AF-MSC addition to SIS does not significantly modulate the host immune response after subcutaneous implantation in rats.