The Impact of Pretransplant Cytomegalovirus Infection on Acute Renal Allograft Rejection

CRISPR-Cas9-Edited Tacrolimus-Resistant Antiviral T Cells for Advanced Adoptive Immunotherapy in Transplant Recipients

Viral infections, such as with cytomegalovirus (CMV), remain a major risk factor for mortality and morbidity of transplant recipients because of their requirement for lifelong immunosuppression (IS). Antiviral drugs often cause toxicity and sometimes fail to control disease. Thus, regeneration of the antiviral immune response by adoptive antiviral T cell therapy is an attractive alternative. Our recent data, however, show only short-term efficacy in some solid organ recipients, possibly because of malfunction in transferred T cells caused by ongoing IS. We developed a vector-free clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9-based good manufacturing practice (GMP)-compliant protocol that efficiently targets and knocks out the gene for the adaptor protein FK506-binding protein 12 (FKBP12), required for the immunosuppressive function of tacrolimus. This was achieved by transient delivery of ribonucleoprotein complexes into CMV-specific T cells by electroporation. We confirmed the tacrolimus resistance of our gene-edited T cell products in vitro and demonstrated performance comparable with non-tacrolimus-treated unmodified T cells. The alternative calcineurin inhibitor cyclosporine A can be administered as a safety switch to shut down tacrolimus-resistant T cell activity in case of adverse effects. Furthermore, we performed safety assessments as a prerequisite for translation to first-in-human applications.

Allografts stimulate cross-reactive virus-specific memory CD8 T cells with private specificity

Viral infections have been associated with the rejection of transplanted allografts in humans and mice, and the induction of tolerance to allogeneic tissues in mice is abrogated by an ongoing viral infection and inhibited in virus-immune mice. One proposed mechanism for this 'heterologous immunity' is the induction of alloreactive T cell responses that cross-react with virus-derived antigens. These cross-reactive CD8 T cells are generated during acute viral infection and survive into memory, but their ability to partake in the immune response to allografts in vivo is not known. We show here that cross-reactive, virus-specific memory CD8 T cells from mice infected with LCMV proliferated in response to allografts. CD8 T cells specific to several LCMV epitopes proliferated in response to alloantigens, with the magnitude and hierarchy of epitope-specific responses varying with the private specificities of the host memory T cell repertoire, as shown by adoptive transfer studies. Last, we show that purified LCMV-specific CD8 T cells rejected skin allografts in SCID mice. These findings therefore implicate a potential role for heterologous immunity in virus-induced allograft rejection.

Manifestations of human cytomegalovirus infection: proposed mechanisms of acute and chronic disease

Infections with human cytomegalovirus (HCMV) are a major cause of morbidity and mortality in humans with acquired or developmental deficits in innate and adaptive immunity. In the normal immunocompetent host, symptoms rarely accompany acute infections, although prolonged virus shedding is frequent. Virus persistence is established in all infected individuals and appears to be maintained by both a chronic productive infections as well as latency with restricted viral gene expression. The contributions of the each of these mechanisms to the persistence of this virus in the individual is unknown but frequent virus shedding into the saliva and genitourinary tract likely accounts for the near universal incidence of infection in most populations in the world. The pathogenesis of disease associated with acute HCMV infection is most readily attributable to lytic virus replication and end organ damage either secondary to virus replication and cell death or from host immunological responses that target virus-infected cells. Antiviral agents limit the severity of disease associated with acute HCMV infections, suggesting a requirement for virus replication in clinical syndromes associated with acute infection. End organ disease secondary to unchecked virus replication can be observed in infants infected in utero, allograft recipients receiving potent immunosuppressive agents, and patients with HIV infections that exhibit a loss of adaptive immune function. In contrast, diseases associated with chronic or persistent infections appear in normal individuals and in the allografts of the transplant recipient. The manifestations of these infections appear related to chronic inflammation, but it is unclear if poorly controlled virus replication is necessary for the different phenotypic expressions of disease that are reported in these patients. Although the relationship between HCMV infection and chronic allograft rejection is well known, the mechanisms that account for the role of this virus in graft loss are not well understood. However, the capacity of this virus to persist in the midst of intense inflammation suggests that its persistence could serve as a trigger for the induction of host-vs-graft responses or alternatively host responses to HCMV could contribute to the inflammatory milieu characteristic of chronic allograft rejection.

PTH regulation of the human cytomegalovirus immediate-early gene promoter

Secondary hyperparathyroidism and human cytomegalovirus (hCMV) seropositivity are highly prevalent in patients undergoing renal transplantation, and both are linked to the development of chronic allograft nephropathy (CAN). We investigated the hypothesis that parathyroid hormone (PTH) 1-84 regulates hCMV immediate-early gene (IEG) promoter activation in proximal renal tubular cells. PTH 1-84 enhanced hCMV IEG promoter (-548 to +92) activity in opossum kidney cells. Deletion analysis from the 5' end of the promoter localized the PTH 1-84 associated activity to the DNA sequence between -123 and -45. Mutation of an imperfect ATF/AP-1 DNA element within this region abrogated the PTH 1-84 effect and also strongly attenuated basal gene expression. Mobility shift analyses using this DNA element revealed that a member of the ATF-1 family was in the binding complex. In summary, we present evidence for a novel pathogenic role of PTH 1-84 in promoting hCMV immediate-early gene transcription.

Review of nonimmunological causes for deteriorated graft function and graft loss after transplantation

Various factors determine the graft- and patient survival after transplantation. HLA-matching and immunological factors are of importance for the short- and long-term survival. Apart from these obvious determinants, nonimmunological factors play an important role in defining the baseline organ quality as well as the recipients' status. The influence of these parameters on graft- and patient survival is still underestimated and is a topic of debate. On account of the increasing acceptance of marginal-donor organs these events are of increasing importance for graft survival and long-term function. We review nonimmunological causes for deteriorated graft function and graft loss after solid organ transplantation.

Association of the Outcome of Renal Transplantation with Antibody Response to Cytomegalovirus Strain--Specific Glycoprotein H Epitopes

BACKGROUND

Cytomegalovirus (CMV) is the most important pathogen affecting the outcome of renal transplantation. The combination of CMV-seronegative transplant recipients with CMV-seropositive transplant donors places recipients at the highest risk of CMV disease. In cases of congenital CMV infection, existing immunity only partially protected mothers from reinfection with a different genotypic strain. The effect of differences in infected CMV strains between CMV-seropositive transplant donors and CMV seropositive transplant recipients on the outcome of transplantation remains unclear.

METHODS

In this prospective multicenter study, the presence of antibodies against strain-specific glycoprotein H epitopes in 84 CMV-seropositive transplant donor/CMV-seropositive transplant recipient renal transplantation cases were determined, and their relationships to acute transplant rejection, CMV infection, degree of antigenemia, and CMV disease were evaluated.

RESULTS

Among the 84 donor/recipient pairs, 45 and 32 had matched and mismatched strain-specific glycoprotein H antibodies, respectively. Acute transplant rejection in the mismatched group was more frequent than it was in the matched group (63% vs. 22%; P=.005). CMV disease was also more frequently observed in the mismatched group (28% vs. 9%; P=.026). The mismatched group had a higher level of antigenemia (P=.019).

CONCLUSIONS

Our results illustrate more adverse events in the cases with a CMV-seropositive transplant donor and a CMV-seropositive transplant recipient in which the glycoprotein H antibodies are mismatched, suggesting that reinfection with a different CMV strain results in more complications.