Severe graft rejection, increased immunosuppression, and active CMV infection in renal transplantation

Adverse Effects of Immunosuppression: Infections

Immunosuppressive therapies are currently indicated for a wide range of diseases. As new agents emerge and indications evolve the landscape grows increasingly complex. Therapies can target pathologic immune system over-activation in rheumatologic or autoimmune disease, or conditioning and graft versus host disease (GVHD) prophylactic regimens may eliminate or inhibit host immune function to improve graft survival and risk of complication in solid organ transplantation (SOT) or hematopoietic stem cell transplantation (HSCT). With immunosuppressive therapy, infections occur. Complex disease states, host factors, and concomitant therapies contribute to a "net state" of immunosuppression that must be considered and may confound perceived increased infection risks in patients receiving treatment.

Cytomegalovirus disease in renal transplant recipients: a single-center experience

Cytomegalovirus (CMV) is the most common viral infection following kidney transplant, has been recognized as a major factor for graft loss and increased incidence of acute rejection. Different studies have reported a variable incidence of CMV disease with the use of Mycophenolate mofetil (MMF). We retrospectively analyzed our renal transplant recipients to review the results of CMV disease and to compare CMV disease in patient on Azathioprine and MMF for this purpose we retrospectively reviewed 521 live related kidney transplant recipients at our institute. 74 (14.2 %) live related allograft recipients developed CMV disease after a median interval of 7.18 ± 4.35 months from transplantation. The mean age was 36.15 ± 10.7 years. 63 of the patients were male. Malaise, fever and diarrhea were among most common symptoms. 20 (27.02 %) of the 74 recipients developed transaminitis, 13 (17.2 %) developed CMV gastritis, 5 (9.13 %) recipients developed pneumonia, and 3 (4.05 %) patient developed colitis. 59 (80 %) patients had leucopenia and 41 (56.5 %) developed thrombocytopenia. Mean serum creatinine level was 1.5 ± 0.4 (0.9-2.4) mg/dl before the disease, 1.9 ± 0.6 (1.3-3.6) mg/dl at the time of the diagnosis, and 1.7 ± 0.06 (0.8-4.2) mg/dl at the end of the treatment. CMV disease developed in 9 (36 %) of recipients who received basiliximab as induction therapy and 13 (30.24 %) of recipients who received ATG (p > 0.05). The incidence of CMV disease was similar in cyclosporine based regimen (13.2 %) and Tacrolimus based regimen 27 (16.16 %) (p = 0.137) and was also similar in Azathioprine 41 (9.5 %) and MMF group 33 (14.3 %) (p = 0.163). There was no significant difference in severity of CMV disease in both groups, except a higher incidence of leucopenia in Azathioprine group (86 vs. 74 %, p < 0.05) as compared to MMF group. 51 (68.91 %) patient developed graft dysfunction during CMV disease. In conclusion we report a low incidence (14.2 %) and milder form of cytomegalovirus disease at our center. Use of universal cytomegalovirus prophylaxis was associated with a low incidence and milder form of the disease. Incidence of CMV disease was similar between Azathioprine and MMF groups.

Dynamics of cell-mediated immune responses to cytomegalovirus in pediatric transplantation recipients

CMI responses, combined with quantification of CMV DNA (DNAemia), may identify transplantation recipients at risk for invasive disease. PBMC were collected in pediatric transplantation candidates at one, three, and six months post-transplant in 10 subjects (six renal, three cardiac, one stem cell) and at single time points in eight HC and 14 children greater than one yr post-transplant (LTTx). Cells were stimulated with anti-CD3mAb or CMV pp65 peptide pools and responses assessed by IFNG enzyme-linked immunosorbent spot assay and cytokine secretion. IFNG responses to anti-CD3mAb were significantly lower pretransplant relative to HC and were further decreased at one and three months post-transplant, but recovered to levels comparable to HC by six months. Responses to pp65 among CMV-seropositive recipients followed a similar pattern but recovered by three months. CMV-seropositive LTTx and HC showed a Th1 cytokine response to pp65 stimulation. Three LTTx subjects developed CMV DNAemia; two demonstrated decreased responses to anti-CD3mAB (and pp65 in the CMV seropositive subject) at the onset of DNAemia, which recovered as DNAemia resolved. Monitoring CMI in children is feasible and may provide an adjunct biomarker to predict CMV progression and recovery.

Probabilistic modeling of cytomegalovirus infection under consensus clinical management guidelines

BACKGROUND

Cytomegalovirus (CMV) is the most common viral pathogen after renal transplantation and remains a major therapeutic challenge with important clinical and economic implications from both direct and indirect consequences of infection.

METHODS

This 5-year study modeled the relationship between CMV infection and biopsy-proven graft rejection, graft loss, or death after renal transplantation in an inception cohort using Canadian consensus guidelines for CMV management as a component of a detailed cost-analysis of viral infection.

RESULTS

Probabilities of CMV viremia and syndrome/disease among 270 sequential graft recipients were 0.27 and 0.09, respectively; 91% of cases occurred in the first 6 months. Probability of CMV infection as the first event was 0.29, with a probability of subsequent biopsy-proven acute rejection (BPAR) of 0.05 (mean: 62+/-26 days, range: 32-85 days), whereas the probability of BPAR as the first event was 0.18, with a probability of subsequent CMV infection of 0.38 (mean: 63+/-31, range: 27-119 days). Probability of freedom from both CMV infection and BPAR throughout the period of observation was 0.53. Time-dependent Cox analysis showed that neither donor/recipient CMV risk stratum nor CMV infection influenced the risks of BPAR (P=0.24; P=0.74) or of graft loss or death (P=0.26; P=0.34). In contrast, BPAR significantly increased the risk of both subsequent CMV infection (hazard ratio=1.77, P=0.03) and of graft loss or death (hazard ratio=8.31, P<0.0001).

CONCLUSIONS

Although current antiviral therapy seems to mitigate the reported deleterious effects of CMV infection on BPAR or graft survival, BPAR remains a significantly risk factor for both CMV infection and functional graft survival.

Generation of potent neutralizing human monoclonal antibodies against cytomegalovirus infection from immune B cells

Background

Human monoclonal antibodies (mAbs) generated as a result of the immune response are likely to be the most effective therapeutic antibodies, particularly in the case of infectious diseases against which the immune response is protective.

Human cytomegalovirus (HCMV) is an ubiquitous opportunistic virus that is the most serious pathogenic agent in transplant patients. The available therapeutic armamentarium (e.g. HCMV hyperimmune globulins or antivirals) is associated with severe side effects and the emergence of drug-resistant strains; therefore, neutralizing human mAb may be a decisive alternative in the prevention of primary and re-activated HCMV infections in these patients.

Results

The purpose of this study was to generate neutralizing mAb against HCMV from the immunological repertoire of immune donors. To this aim, we designed an efficient technology relying on two discrete and sequential steps: first, human B-lymphocytes are stimulated with TLR9-agonists and IL-2; second, after both additives are removed, the cells are infected with EBV. Using this strategy we obtained 29 clones secreting IgG neutralizing the HCMV infectivity; four among these were further characterized. All of the mAbs neutralize the infection in different combinations of HCMV strains and target cells, with a potency ~20 fold higher than that of the HCMV hyperimmune globulins, currently used in transplant recipients. Recombinant human monoclonal IgG1 suitable as a prophylactic or therapeutic tool in clinical applications has been generated.

Conclusion

The technology described has proven to be more reproducible, efficient and rapid than previously reported techniques, and can be adopted at low overall costs by any cell biology laboratory for the development of fully human mAbs for immunotherapeutic uses.

Cytomegalovirus Disease Amongst Renal Transplant Recipients in Australia and New Zealand

Cytomegalovirus (CMV) is a significant pathogen causing disease in renal transplant patients. The highest incidence of CMV disease occurs during the first 3 months post-transplant and is most problematic in CMV-naïve transplant recipients. In this study, we conducted a retrospective review of two databases, the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) and the National Hospital Morbidity Database, from the Australian Institute of Health and Welfare (AIHW), to examine CMV in renal transplant recipients. The first source looked at CMV serostatus at the time of transplantation and the second recorded hospital admissions for recipients with invasive CMV disease.

From the ANZDATA registry, we obtained information from 13,530 renal transplants recipients from 1980 to 2004. Of these recipients, 7808 had a known CMV serostatus, of which 65.7% (5134/7808) had a positive sero antibody status and 34.2% (2674/7808) had a negative sero antibody status. In univariate analysis, factors significantly associated with renal rejection were being male, recipient age <50 years, being diabetic, being diagnosed with cancer at some point and having a positive EBV status. Positive CMV serostatus was not a contributing factor. Between 1993 and 2001 there were 1445 renal transplant recipients hospitalized in Australia with a diagnosis of CMV disease, of which 38% (554/1445) had CMV disease as a principal diagnoses. The average annual rate of admissions with any diagnosis was 3871 episodes per 100,000 people living with a functioning graft.

Preventative strategies for CMV in renal transplant recipients should be a priority. New vaccines for CMV may soon be available and renal transplant recipients would be a suitable target group for vaccination.

Human cytomegalovirus infection and antiviral immunity in septic patients without canonical immunosuppression

The human cytomegalovirus (HCMV) is a relevant pathogen in patients with immunosuppressive therapy; however, reactivation and subsequent recurrence occurs also in individuals without canonical immunosuppression as e.g., in patients with septic shock. Analyzing the impact of NK- and T-cell immunity on the natural course of HCMV infection in patients with septic shock, it became clear that the presence of HCMV reactive T-helper cells did not prevent the development of reactivation but, the control of active infection was achieved mostly by specific T-cells. NK-cells seemed to be dispensable for clearance of active infection in this patient group with long-lasting NK-cell anergy.