Protection against murine coxsackievirus B3 myocarditis by T cell vaccination

Immunoglobulin treatment ameliorates myocardial injury in experimental autoimmune myocarditis associated with suppression of reactive oxygen species

AIMS

We tested the hypothesis that immunoglobulin ameliorated experimental autoimmune myocarditis (EAM) in mice attributing to the suppression of reactive oxygen species (ROS)-mediated myocardial injury.

METHODS

We intraperitoneally administered intact type of human immunoglobulin (Ig) or F(ab')2 fragments of human immunoglobulin, 1g/kg/day daily for 3 weeks, to male BALB/c mice with heart failure due to EAM.

RESULTS

The results showed that intact type of Ig, but not F(ab')2 type, reduced the severity of myocarditis by comparing the heart weight/body weight and lung weight/body weight ratios, pericardial effusion score, macroscopic and microscopic scores. Tissue superoxide production was marked in untreated mice with EAM, which was suppressed by the treatment of immunoglobulins. The cytotoxic activities of lymphocytes in mice with EAM treated with Ig were reduced compared with untreated controls. The shift from Th1 toward Th2 cytokine balance was demonstrated by the treatment of immunoglobulins both in vitro and in vivo.

CONCLUSION

ROS may be involved in the development of myocarditis. Intact Ig ameliorates myocardial damage in mice with myocarditis associated with suppression of ROS and cytotoxic activity of lymphocytes.

GP120-specific exosome-targeted T cell-based vaccine capable of stimulating DC- and CD4(+) T-independent CTL responses

The limitations of highly active anti-retroviral therapy (HAART) have necessitated the development of alternative therapeutics. In this study, we generated ovalbumin (OVA)-pulsed and pcDNAgp120-transfected dendritic cell (DC)-released exosomes (EXOova and EXOgp120) and ConA-stimulated C57BL/6 CD8(+) T cells. OVA- and Gp120-Texo vaccines were generated from CD8(+) T cells with uptake of EXOova and EXOgp120, respectively. We demonstrate that OVA-Texo stimulates in vitro and in vivo OVA-specific CD4(+) and CD8(+) cytotoxic T lymphocyte (CTL) responses leading to long-term immunity against OVA-expressing BL6-10(OVA) melanoma. Interestingly, CD8(+) T cell responses are DC and CD4(+) T cell independent. Importantly, Gp120-Texo also stimulates Gp120-specific CTL responses and long-term immunity against Gp120-expressing B16 melanoma. Therefore, this novel HIV-1-specific EXO-targeted Gp120-Texo vaccine may be useful in induction of efficient CTL responses in AIDS patients with DC dysfunction and CD4(+) T cell deficiency.

Novel exosome-targeted CD4+ T cell vaccine counteracting CD4+25+ regulatory T cell-mediated immune suppression and stimulating efficient central memory CD8+ CTL responses

T cell-to-T cell Ag presentation is increasingly attracting attention. In this study, we demonstrated that active CD4+ T (aT) cells with uptake of OVA-pulsed dendritic cell-derived exosome (EXO(OVA)) express exosomal peptide/MHC class I and costimulatory molecules. These EXO(OVA)-uptaken (targeted) CD4+ aT cells can stimulate CD8+ T cell proliferation and differentiation into central memory CD8+ CTLs and induce more efficient in vivo antitumor immunity and long-term CD8+ T cell memory responses than OVA-pulsed dendritic cells. They can also counteract CD4+25+ regulatory T cell-mediated suppression of in vitro CD8+ T cell proliferation and in vivo CD8+ CTL responses and antitumor immunity. We further elucidate that the EXO(OVA)-uptaken (targeted)CD4+ aT cell's stimulatory effect is mediated via its IL-2 secretion and acquired exosomal CD80 costimulation and is specifically delivered to CD8+ T cells in vivo via acquired exosomal peptide/MHC class I complexes. Therefore, EXO-targeted active CD4+ T cell vaccine may represent a novel and highly effective vaccine strategy for inducing immune responses against not only tumors, but also other infectious diseases.

Nonspecific CD4(+) T cells with uptake of antigen-specific dendritic cell-released exosomes stimulate antigen-specific CD8(+) CTL responses and long-term T cell memory

Dendritic cell (DC) and DC-derived exosomes (EXO) have been used extensively for tumor vaccination. However, its therapeutic efficiency is limited to only production of prophylactic immunity against tumors. T cells can uptake DC-released EXO. However, the functional effect of transferred exosomal molecules on T cells is unclear. In this study, we demonstrated that OVA protein-pulsed DC-derived EXO (EXO(OVA)) can be taken up by Con A-stimulated, nonspecific CD4(+) T cells derived from wild-type C57BL/6 mice. The active EXO-uptaken CD4(+) T cells (aT(EXO)), expressing acquired exosomal MHC I/OVA I peptide (pMHC I) complexes and costimulatory CD40 and CD80 molecules, can act as APCs capable of stimulating OVA-specific CD8(+) T cell proliferation in vitro and in vivo and inducing efficient CD4(+) Th cell-independent CD8(+) CTL responses in vivo. The EXO(OVA)-uptaken CD4(+) aT(EXO) cell vaccine induces much more efficient CD8(+) T cell responses and immunity against challenge of OVA-transfected BL6-10 melanoma cells expressing OVA in wild-type C57BL/6 mice than EXO(OVA). The in vivo stimulatory effect of the CD4(+) aT(EXO) cell to CD8(+) T cell responses is mediated and targeted by its CD40 ligand signaling/acquired exosomal CD80 and pMHC I complexes, respectively. In addition, CD4(+) aT(EXO) vaccine stimulates a long-term, OVA-specific CD8(+) T cell memory. Therefore, the EXO(OVA)-uptaken CD4(+) T cells may represent a new, effective, EXO-based vaccine strategy in induction of immune responses against tumors and other infectious diseases.

Favourable clinical outcome in patients with cardiogenic shock due to fulminant myocarditis supported by percutaneous extracorporeal membrane oxygenation

AIMS

The clinical outcome of severe acute myocarditis patients with cardiogenic shock who require circulatory support devices is not well known. We studied the survival and clinical courses of patients with fulminant myocarditis supported by percutaneous extracorporeal membrane oxygenation (ECMO) and compared them with those of patients with acute non-fulminant myocarditis.

METHODS AND RESULTS

Patients with acute myocarditis were divided into the following two groups. Fourteen patients who required ECMO for cardiogenic shock were defined as having fulminant myocarditis (F group), whereas 13 patients who had an acute onset of symptoms, but did not have compromised, were defined as having acute non-fulminant myocarditis (NF group). In the F group, 10 patients were weaned successfully from percutaneous ECMO. Therefore, the overall acute survival rate was 71%. Patients who were not weaned from ECMO showed smaller left ventricular end-diastolic and end-systolic dimensions, thicker left ventricular wall, and higher creatine phosphokinase MB isoform levels than those who were weaned from ECMO. When compared with patients in the NF group, the fractional shortening in the F group was more severely decreased in the acute phase [F: 10+/-4 vs. NF: 23+/-8% (mean+/-SD), P<0.001], but recovered in the chronic phase (F: 33+/-7 vs. NF: 34+/-6%). The prevalence of adverse clinical events in both groups was similar during the follow-up period of 50 months.

CONCLUSION

In patients with fulminant myocarditis, percutaneous ECMO is a highly effective form of a haemodynamic support. Once a patient recovers from inflammatory myocardial damage, the subsequent clinical outcome is favourable, similar to that observed in patients with acute non-fulminant myocarditis.