Autoantibody-mediated diseases like myasthenia gravis, autoimmune hemolytic anemia and systemic lupus erythematosus represent a therapeutic challenge. In particular, long-lived plasma cells producing autoantibodies resist current therapeutic and experimental approaches. Recently, we showed that the sensitivity of myeloma cells toward proteasome inhibitors directly correlates with their immunoglobulin synthesis rates. Therefore, we hypothesized that normal plasma cells are also hypersensitive to proteasome inhibition owing to their extremely high amount of protein biosynthesis. Here we show that the proteasome inhibitor bortezomib, which is approved for the treatment of multiple myeloma, eliminates both short- and long-lived plasma cells by activation of the terminal unfolded protein response. Treatment with bortezomib depleted plasma cells producing antibodies to double-stranded DNA, eliminated autoantibody production, ameliorated glomerulonephritis and prolonged survival of two mouse strains with lupus-like disease, NZB/W F1 and MRL/lpr mice. Hence, the elimination of autoreactive plasma cells by proteasome inhibitors might represent a new treatment strategy for antibody-mediated diseases.

Autoantibodies against double-stranded DNA (dsDNA) and nucleosomes represent a hallmark of systemic lupus erythematosus (SLE). However, the mechanisms involved in breaking the immunological tolerance against these poorly immunogenic nuclear components are not fully understood. Impaired phagocytosis of apoptotic cells with consecutive release of nuclear antigens may contribute to the immune pathogenesis. The architectural chromosomal protein and proinflammatory mediator high mobility group box protein 1 (HMGB1) is tightly attached to the chromatin of apoptotic cells. We demonstrate that HMGB1 remains bound to nucleosomes released from late apoptotic cells in vitro. HMGB1–nucleosome complexes were also detected in plasma from SLE patients. HMGB1-containing nucleosomes from apoptotic cells induced secretion of interleukin (IL) 1β, IL-6, IL-10, and tumor necrosis factor (TNF) α and expression of costimulatory molecules in macrophages and dendritic cells (DC), respectively. Neither HMGB1-free nucleosomes from viable cells nor nucleosomes from apoptotic cells lacking HMGB1 induced cytokine production or DC activation. HMGB1-containing nucleosomes from apoptotic cells induced anti-dsDNA and antihistone IgG responses in a Toll-like receptor (TLR) 2–dependent manner, whereas nucleosomes from living cells did not. In conclusion, HMGB1–nucleosome complexes activate antigen presenting cells and, thereby, may crucially contribute to the pathogenesis of SLE via breaking the immunological tolerance against nucleosomes/dsDNA.

Multiple myeloma is an incurable plasma cell neoplasia characterized by the production of large amounts of monoclonal immunoglobulins.

The research on high hydrostatic pressure in medicine and life sciences is multifaceted. According to the used pressure head the research has to be divided into two different parts. To study physiological aspects of pressure on eukaryotic cells physiological pressure (pHHP; < 100 MPa) is used. pHHP induces morphological alterations in the cellular organelles and evokes a reversible stress response similar to the well known heat shock response. pHHP induces highly reversible alterations and normally does not affect cellular viability. The treatment of eukaryotic cells with non-physiological pressure (HHP; > or = 100 MPa) reveals different outcomes. Treatment with HHP < 150 MPa does not markedly affect viability of human cells, but induces apoptosis in murine cells. In human cells apoptosis is observed after treatment with > or = 200 MPa. Moreover, HHP treatment with > 300 MPa leads to necrosis. Therefore, HHP plays a role for the sterilisation of human transplants, of food stuff, and pharmaceuticals. Human tumour cells subjected to HHP > 300 MPa display a necrotic phenotype along with a gelificated cytoplasm, preserve their shape, and retain their immunogenicity. These observations favour the use of HHP to produce whole cell based tumour vaccines. Further experiments revealed that the increment of pressure as well as the pressure holding time influences the cell death of tumour cells. We conclude that high hydrostatic pressure offers both, an economic, easy to apply, clean, and fast technique for the generation of vaccines, and a promising tool to study physiological aspects.

Most of the classical therapies for solid tumors have limitations in achieving long-lasting anti-tumor responses. Therefore, treatment of cancer requires additional and multimodal therapeutic strategies. One option is based on the vaccination of cancer patients with autologous inactivated intact tumor cells. The master requirements of cell-based therapeutic tumor vaccines are the: (a) complete inactivation of the tumor cells; (b) preservation of their immunogenicity; and (c) need to remain in accordance with statutory provisions. Physical treatments like freeze-thawing and chemotherapeutics are currently used to inactivate tumor cells for vaccination purposes, but these techniques have methodological, therapeutic, or legal restrictions. For this reason, we have proposed the use of a high hydrostatic pressure (HHP) treatment (p >or= 100 MPa) as an alternative method for the inactivation of tumor cells. HHP is a technique that has been known for more than 100 years to successfully inactivate micro-organisms and to alter biomolecules. In the studies here, we show that the treatment of MCF7, B16-F10, and CT26 tumor cells with HHP >or= 300 MPa results in mainly necrotic tumor cell death forms displaying degraded DNA. Only CT26 cells yielded a notable amount of apoptotic cells after the application of HHP. All tumor cells treated with >or= 200 MPa lost their ability to form colonies in vitro. Furthermore, the pressure-inactivated cells retained their immunogenicity, as tested in a xenogeneic as well as syngeneic mouse models. We conclude that the complete tumor cell inactivation, the degradation of the cell's nuclei, and the retention of the immunogeneic potential of these dead tumor cells induced by HHP favor the use of this technique as a powerful and low-cost technique for the inactivation of tumor cells to be used as a vaccine.