Safety of Repeated Administration of Xenogeneic Human Apoptotic State (Allocetra-OTS) in Sprague Dawley Rats.

Apoptotic cells possess immunomodulatory effects that can be utilized to treat imbalanced immune conditions. Information on the preclinical safety of such treatment is sparse. In this study, the safety of apoptotic cells (Allocetra-OTS) was assessed in a GLP toxicological study on Sprague Dawley rats. Three doses of Allocetra-OTS or vehicle were administered intravenously (IV) for 3 consecutive days. Animals in the main study were sacrificed on day 4, while animals from the recovery groups were kept for 14 or 28 days. Allocetra-OTS was well tolerated, and no adverse effects were observed in terms of body weight, clinical signs, food consumption, or ophthalmologic observation. Thus, the No Observed Adverse Effect Level (NOAEL) dose was determined as the highest dose administered. An observed elevation in immune cells was suspected to be due to Allocetra-OTS, similarly to other clinical chemistry parameters; however, it was resolved in the recovery phases. Splenomegaly and dose-related extramedullary hematopoiesis (EMH) in the red pulp were observed, with no adverse events, and were considered to be a normal and expected reaction following the IV administration of cell-based therapies. In conclusion, under the conditions of this study, Allocetra-OTS was concluded to be safe, further supporting its potential candidacy for clinical studies.

Development of stage-dependent glycans on the Fc domains of IgG antibodies of ALS animals.

We recently revealed a unique glycan on the Fc domain of IgG antibodies in ALS patients that mediates antibody-dependent cell cytotoxicity (ADCC). This glycan has a bi-antennary structure that lacks the core fucose and sialic acid residues but contains a bisecting GlcNAc (A2BG2). Little is known, however, about the incidence of A2BG2 expression and IgG cytotoxicity under ALS conditions within well-defined clinical stages. Here, we characterize the IgG antibodies produced in ALS Tg mice by detecting intra- and extra-cellular antigens of motor neurons that express different glycan patterns during the disease. The increased number of innate immune cells found at the disease onset was insufficient to induce an optimal systemic T-cell response. Nevertheless, IgG antibodies were produced against intracellular antigens at the pre-symptomatic stage in the secondary lymphoid organs under the conditions of a poor systemic immune response. Moreover, while the glycosyltransferases of plasma B-cells that synthesize the Fc-glycans were regulated by IL-2 or IL-4, the observed glycosyltransferase pattern did not match that found in ALS Tg mice. We further found that A2BG2 glycan is specific for ALS, its quantity increased with disease progression and that the IgG antibodies identifying extracellular motor neuron antigens were developed at the final stage of the disease. Therefore, the most effective ADCC of motor neurons was observed at the end stage of the disease. We conclude that in ALS, IgG antibodies are produced despite the poor systemic immune response and that the frequency and quantity of A2BG2 glycan expression on the Fc domain depends on the clinical stage. Therefore, A2BG2 is a potential prognostic biomarker for ALS.

Glycans in sera of amyotrophic lateral sclerosis patients and their role in killing neuronal cells.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease caused by degeneration of upper and lower motor neurons. To date, glycosylation patterns of glycoproteins in fluids of ALS patients have not been described. Moreover, the aberrant glycosylation related to the pathogenesis of other neurodegenerative diseases encouraged us to explore the glycome of ALS patient sera. We found high levels of sialylated glycans and low levels of core fucosylated glycans in serum-derived N-glycans of patients with ALS, compared to healthy volunteer sera. Based on these results, we analyzed the IgG Fc N(297)-glycans, as IgG are major serum glycoproteins affected by sialylation or core fucosylation and are found in the motor cortex of ALS patients. The analyses revealed a distinct glycan, A2BG2, in IgG derived from ALS patient sera (ALS-IgG). This glycan increases the affinity of IgG to CD16 on effector cells, consequently enhancing Antibody-Dependent Cellular Cytotoxicity (ADCC). Therefore, we explore whether the Fc-N(297)-glycans of IgG may be involved in ALS disease. Immunostaining of brain and spinal cord tissues revealed over-expression of CD16 and co-localization of intact ALS-IgG with CD16 and in brain with activated microglia of G93A-SOD1 mice. Intact ALS-IgG enhanced effector cell activation and ADCC reaction in comparison to sugar-depleted or control IgG. ALS-IgG were localized in the synapse between brain microglia and neurons of G93A-SOD1 mice, manifesting a promising in vivo ADCC reaction. Therefore, glycans of ALS-IgG may serve as a biomarker for the disease and may be involved in neuronal damage.

HSP60 is transported through the secretory pathway of 3-MCA-induced fibrosarcoma tumour cells and undergoes N-glycosylation.

There is increasing evidence localizes the mitochondrial chaperone heat shock protein (HSP)60, outside the cell, where it mediates interactions between immune cells and other body tissues. However, the mechanisms by which HSP60 is secreted into the extracellular environment are not fully understood. Recent studies have shown that HSP60 is actively released by a nonconventional secretion mechanism, the lipid raft-exosome pathway. In the present study, we show for the first time that HSP60, produced by 3-methylcholantrene-induced fibrosarcoma tumour cells, is secreted through the conventional endoplasmic reticulum-Golgi secretory pathway. Confocal microscopy using anti-TGN38 and anti-HSP60 antibodies together with monensin, a Golgi transport inhibitor, demonstrated the relocation of HSP60 to the Golgi of malignant cells but not primary fibroblast cells subjected to heat shock or fibroblast cell lines. Transmission electron microscopy, flow cytometry and cell fractionation of cell treated with brefeldin A, an inhibitor of endoplasmic reticulum to Golgi protein transport, further indicated that HSP60 is present both in the endoplasmic reticulum and the Golgi complex of malignant cells. We found a single mRNA with a mitochondrial targeting sequence encoding for HSP60 in the malignant cells but two HSP60 translation products, namely the native unmodified protein and a protein post-translationally modified by N-glycosylation. The N-glycans observed were composed of high-mannose structures and bi-, tri- and tetra-antennary complex type structures occupying sites of the three potential glycosylation sites present on HSP60. Accordingly, we propose that HSP60 in malignant cells is transported through the endoplasmic reticulum-Golgi secretion pathway, where it acquires N-glycans, and thus can affect the immunological properties of the proteins in the tumour microenvironment.