The IFN-γ-induced immunoproteasome is suppressed in highly pathogenic porcine reproductive and respiratory syndrome virus-infected alveolar macrophages.

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) evades cytotoxic T lymphocyte (CTL) responses through interactions between viral Nsp1α and Nsp4 and ß2 M heavy and light chains, respectively, of swine leukocyte antigen class (SLA)-I. However, whether the immunoproteasome (i-proteasome) complex, which is an important component of the antigen delivery pathway that functions by mediating peptide production, is also affected by viral infection is unknown. In this study, we investigated the effects of HP-PRRSV (HuN4-F5) infection on IFN-γ-induced i-proteasome expression using a cell culture system (alveolar macrophages, AMs). We found that this virus inhibited the expression of IFN-γ-induced i-proteasome subunits LMP2, LMP7, and MECL-1 at the mRNA and protein level. In addition, expression levels of the i-proteasome regulatory subunits PSME1 and PSME2 in the HP-PRRSV HuN4-F5-infected group were also significantly decreased compared to those in the uninfected group. However, there was no significant difference in the expression of proteasome subunits PSMB5, PSMB6, and PSMB7 between HP-PRRSV HuN4-F5-infected and uninfected groups. This study provides insight into the mechanisms underlying immune regulation by HP-PRRSV; specifically, this virus affects the antigen-processing machinery by suppressing IFN-γ-induced i-proteasome expression in infected AMs.

Outcomes of patients with multiple myeloma refractory to CD38-targeted monoclonal antibody therapy.

The introduction of CD38-targeting monoclonal antibodies (CD38 MoABs), daratumumab and isatuximab, has significantly impacted the management of patients with multiple myeloma (MM). Outcomes of patients with MM refractory to CD38 MoABs have not been described. We analyzed outcomes of 275 MM patients at 14 academic centers with disease refractory to CD38 MoABs. Median interval between MM diagnosis and refractoriness to CD38 MoAB (T0) was 50.1 months. The median overall survival (OS) from T0 for the entire cohort was 8.6 [95% C.I. 7.5-9.9] months, ranging from 11.2 months for patients not simultaneously refractory to an immunomodulatory (IMiD) agent and a proteasome inhibitor (PI) to 5.6 months for "penta-refractory" patients (refractory to CD38 MoAB, 2 PIs and 2 IMiDs). At least one subsequent treatment regimen was employed after T0 in 249 (90%) patients. Overall response rate to first regimen after T0 was 31% with median progression-free survival (PFS) and OS of 3.4 and 9.3 months, respectively. PFS was best achieved with combinations of carfilzomib and alkylator (median 5.7 months), and daratumumab and IMiD (median 4.5 months). Patients with MM refractory to CD38 MoAB have poor prognosis and this study provides benchmark for new therapies to be tested in this population.

The immunoproteasome-specific inhibitor ONX 0914 reverses susceptibility to acute viral myocarditis.

Severe heart pathology upon virus infection is closely associated with the immunological equipment of the host. Since there is no specific treatment available, current research focuses on identifying new drug targets to positively modulate predisposing immune factors. Utilizing a murine model with high susceptibility to coxsackievirus B3-induced myocarditis, this study describes ONX 0914-an immunoproteasome-specific inhibitor-as highly protective during severe heart disease. Represented by reduced heart infiltration of monocytes/macrophages and diminished organ damage, ONX 0914 treatment reversed fulminant pathology. Virus-induced immune response features like overwhelming pro-inflammatory cytokine and chemokine production as well as a progressive loss of lymphocytes all being reminiscent of a sepsis-like disease course were prevented by ONX 0914. Although the viral burden was only minimally affected in highly susceptible mice, resulting maintenance of immune homeostasis improved the cardiac output, and saved animals from severe illness as well as high mortality. Altogether, this could make ONX 0914 a potent drug for the treatment of severe virus-mediated inflammation of the heart and might rank immunoproteasome inhibitors among drugs for preventing pathogen-induced immunopathology.

Blockade of the malignant phenotype by ß-subunit selective noncovalent inhibition of immuno- and constitutive proteasomes.

A structure-based virtual screening of over 400,000 small molecules against the constitutive proteasome activity followed by in vitro assays led to the discovery of a family of proteasome inhibitors with a sulfonyl piperazine scaffold. Some members of this family of small non-peptidic inhibitors were found to act selectively on the ß2 trypsin-like catalytic site with a preference for the immunoproteasome ß2i over the constitutive proteasome ß2c, while some act on the ß5 site and post-acid site ß1 of both, the immunoproteasome and the constitutive proteasome. Anti-proliferative and anti-invasive effects on tumor cells were investigated and observed for two compounds. We report novel chemical inhibitors able to interfere with the three types of active centers of both, the immuno- and constitutive proteasomes. Identifying and analyzing a novel scaffold with decorations able to shift the binders' active site selectivity is essential to design a future generation of proteasome inhibitors able to distinguish the immunoproteasome from the constitutive proteasome.

Proteasome inhibitors as immunosuppressants: biological rationale and clinical experience.

Accumulating evidence supports the potential of proteasome inhibitors as immunosuppressants. Proteasome inhibitors interfere with antigen processing and presentation, as well as with the signaling cascades involved in immune cell function and survival. Both myeloma and healthy plasma cells appear to be highly susceptible to proteasome inhibitors due to impaired proteasomal activity in both cell types. As a consequence, these agents can be used to reduce antibody production and thus prevent antibody-induced tissue damage. Several clinical studies have explored the potential of bortezomib, a peptide boronate proteasome inhibitor, for treating immune disorders, such as antibody-mediated organ rejection and graft-versus-host disease (GVHD), with encouraging results. Here, we discuss the biological rationale for the use of proteasome inhibitors as immunosuppressive agents and review the clinical experience with bortezomib in immune-mediated diseases.

Molecular biology of cervical cancer

Cervical cancer is a virus-induced disease that is caused by the integration of high-risk infecting human papillomaviruses (HPV) in the host genome. For this reason, the carcinogenesis process of cervical cancer is associated to the expression of the viral oncogenic proteins E6 and E7. These proteins are capable of inactivating p53 and pRb, which induces a continuous cell proliferation with the increasing risk of accumulation of DNA damage that eventually leads to cancer. Moreover, cervical cancer can be prevented by prophylactic HPV vaccines; their molecular characteristics and mechanism of action are reviewed. Ultimately, new molecular targets for cervical cancer like proteasome, the EGFR family and IGF family are exposed (AU)