Cyclophilin A (CypA/Ppia) is a peptidyl-prolyl isomerase (PPIase) that binds the immunosuppressive drug cyclosporine. The resulting complex blocks T cell function by inhibiting the calcium-dependent phosphatase calcineurin. To identify the native function of CypA, long suspected of regulating signal transduction, we generated mice lacking the Ppia gene. These animals develop allergic disease, with elevated IgE and tissue infiltration by mast cells and eosinophils, that is driven by CD4+ T helper type II (Th2) cytokines. Ppia(-/-) Th2 cells were hypersensitive to TCR stimulation, a phenotype consistent with increased activity of Itk, a Tec family tyrosine kinase crucial for Th2 responses. CypA bound Itk via the PPIase active site. Mutation of a conformationally heterogeneous proline in the SH2 domain of Itk disrupted interaction with CypA and specifically increased Th2 cytokine production from wild-type CD4+ T cells. Thus, CypA inhibits CD4+ T cell signal transduction in the absence of cyclosporine via a regulatory proline residue in Itk.

Upon cerebral hypoxia-ischemia (HI), apoptosis-inducing factor (AIF) can move from mitochondria to nuclei, participate in chromatinolysis, and contribute to the execution of cell death. Previous work (Cande, C., N. Vahsen, I. Kouranti, E. Schmitt, E. Daugas, C. Spahr, J. Luban, R.T. Kroemer, F. Giordanetto, C. Garrido, et al. 2004. Oncogene. 23:1514–1521) performed in vitro suggests that AIF must interact with cyclophilin A (CypA) to form a proapoptotic DNA degradation complex. We addressed the question as to whether elimination of CypA may afford neuroprotection in vivo. 9-d-old wild-type (WT), CypA+/−, or CypA−/− mice were subjected to unilateral cerebral HI. The infarct volume after HI was reduced by 47% (P = 0.0089) in CypA−/− mice compared with their WT littermates. Importantly, CypA−/− neurons failed to manifest the HI-induced nuclear translocation of AIF that was observed in WT neurons. Conversely, CypA accumulated within the nuclei of damaged neurons after HI, and this nuclear translocation of CypA was suppressed in AIF-deficient harlequin mice. Immunoprecipitation of AIF revealed coprecipitation of CypA, but only in injured, ischemic tissue. Surface plasmon resonance revealed direct molecular interactions between recombinant AIF and CypA. These data indicate that the lethal translocation of AIF to the nucleus requires interaction with CypA, suggesting a model in which two proteins that normally reside in separate cytoplasmic compartments acquire novel properties when moving together to the nucleus.

New World monkeys of the genus Aotus synthesize a fusion protein (AoT5Cyp) containing tripartite motif-containing 5 (TRIM5) and cyclophilin A (CypA) that potently blocks HIV-1 infection. We attempted to generate a human HIV-1 inhibitor modeled after AoT5Cyp, by fusing human CypA to human TRIM5 (hT5Cyp). Of 13 constructs, 3 showed substantial HIV-1-inhibitory activity when expressed in human cell lines. This activity required capsid binding by CypA and correlated with CypA linkage to the TRIM5a capsid-specificity determinant and the ability to form cytoplasmic bodies. CXCR4- and CCR5-tropic HIV-1 clones and primary isolates were inhibited from infecting multiple human macrophage and T cell lines and primary cells by hT5Cyp, as were HIV-2ROD, SIVAGMtan, FIVPET, and a circulating HIV-1 isolate previously reported to be AoT5Cyp resistant. The anti-HIV-1 activity of hT5Cyp was surprisingly more effective than that of the well-characterized rhesus TRIM5alpha, especially in T cells. hT5Cyp also blocked HIV-1 infection of primary CD4+ T cells and macrophages and conferred a survival advantage to these cells without disrupting their function. Extensive attempts to elicit HIV-1 resistance to hT5Cyp were unsuccessful. Finally, Rag2-/-gammac-/- mice were engrafted with human CD4+ T cells that had been transduced by optimized lentiviral vectors bearing hT5Cyp. Upon challenge with HIV-1, these mice showed decreased viremia and productive infection in lymphoid organs and preserved numbers of human CD4+ T cells. We conclude that hT5Cyp is an extraordinarily robust inhibitor of HIV-1 replication and a promising anti-HIV-1 gene therapy candidate.

Glioblastoma, the most common malignant primary brain tumor in adults is a devastating diagnosis with an average survival of 14–16 months using the current standard of care treatment. The determination of treatment response and clinical decision making is based on the accuracy of radiographic assessment. Notwithstanding, challenges exist in the neuroimaging evaluation of patients undergoing treatment for malignant glioma. Differentiating treatment response from tumor progression is problematic and currently combines long-term follow-up using standard magnetic resonance imaging (MRI), with clinical status and corticosteroid-dependency assessments. In the clinical trial setting, treatment with gene therapy, vaccines, immunotherapy, and targeted biologicals similarly produces MRI changes mimicking disease progression. A neuroimaging method to clearly distinguish between pseudoprogression and tumor progression has unfortunately not been found to date. With the incorporation of antiangiogenic therapies, a further pitfall in imaging interpretation is pseudoresponse. The Macdonald criteria that correlate tumor burden with contrast-enhanced imaging proved insufficient and misleading in the context of rapid blood–brain barrier normalization following antiangiogenic treatment that is not accompanied by expected survival benefit. Even improved criteria, such as the RANO criteria, which incorporate non-enhancing disease, clinical status, and need for corticosteroid use, fall short of definitively distinguishing tumor progression, pseudoresponse, and pseudoprogression. This review focuses on advanced imaging techniques including perfusion MRI, diffusion MRI, MR spectroscopy, and new positron emission tomography imaging tracers. The relevant image analysis algorithms and interpretation methods of these promising techniques are discussed in the context of determining response and progression during treatment of glioblastoma both in the standard of care and in clinical trial context.

Here we provide the first report of protection against a vaginal challenge with a highly virulent simian immunodeficiency virus (SIV) by using a vaccine vector. New poliovirus vectors based on Sabin 1 and 2 vaccine strain viruses were constructed, and these vectors were used to generate a series of new viruses containing SIV gag, pol, env, nef, and tat in overlapping fragments. Two cocktails of 20 transgenic polioviruses (SabRV1-SIV and SabRV2-SIV) were inoculated into seven cynomolgus macaques. All monkeys produced substantial anti-SIV serum and mucosal antibody responses. SIV-specific cytotoxic T-lymphocyte responses were detected in three of seven monkeys after vaccination. All 7 vaccinated macaques, as well as 12 control macaques, were challenged vaginally with pathogenic SIVmac251. Strikingly, four of the seven vaccinated animals exhibited substantial protection against the vaginal SIV challenge. All 12 control monkeys became SIV positive. In two of the seven SabRV-SIV-vaccinated monkeys we found no virological evidence of infection following challenge, indicating that these two monkeys were completely protected. Two additional SabRV-SIV-vaccinated monkeys exhibited a pronounced reduction in postacute viremia to <10 3 copies/ml, suggesting that the vaccine elicited an effective cellular immune response. Three of six control animals developed clinical AIDS by 48 weeks postchallenge. In contrast, all seven vaccinated monkeys remained healthy as judged by all clinical parameters. These results demonstrate the efficacy of SabRV as a potential human vaccine vector, and they show that the use of a vaccine vector cocktail expressing an array of defined antigenic sequences can be an effective vaccination strategy in an outbred population.