Association of CMV-specific T-cell immunity and risk of CMV infection in lung transplant recipients

CMV management of patients with leukopenia after CMV high-risk kidney transplantation

BACKGROUND

For CMV high-risk constellations, guidelines recommend 3-6 months of prophylaxis with valganciclovir (VGCV). Management in preventing CMV primary infection in patients developing VGCV-associated leukopenia remains challenging.

METHODS

We retrospectively analyzed the development of leukopenia during VGCV prophylaxis in 57 seronegative kidney recipients of a CMV-seropositive donor between 2008 and 2021. We analyzed CMV risk and development of CMV-specific T cells in the first post-transplant year depending on leukopenia during VGCV prophylaxis and management with CMV-IVIg.

RESULTS

Leukopenia developed in 19/57 patients, with a significant difference in leukocyte counts occurring after 10 weeks of VGCV prophylaxis compared to patients without leukopenia (p = 0.0003). VGCV discontinuation led to leukocyte reconstitution, which tended to be faster in patients receiving additional prophylaxis with CMV-IVIg after VGCV discontinuation (n = 11, p = 0.083). In the first post-transplant year, patients with leukopenia had no higher risk for severe CMV events. Interestingly, patients receiving CMV-IVIg prophylaxis showed a significantly lower peak CMV-load during primary infection (p = 0.040), with no difference in CMV-specific T-cell levels compared to patients without leukopenia or patients with additional CMV-IVIg prophylaxis (p = 0.972). Patients developing adequate CMV-specific T-cell responses less frequently underwent CMV reactivation 50 days following primary infection.

CONCLUSION

Leukopenia developed late during VGCV prophylaxis and did not result in an increased risk for CMV primary infections or severe disease. Leukopenic patients receiving CMV-IVIg tended to have a faster leukocyte reconstitution and had lower peak DNAemia, which did not adversely affect CMV-specific T-cell induction. CMV-IVIg may therefore be considered as an alternative prophylactic strategy in patients with VGCV-associated leukopenia.

CMV Infection Risk Factors and Viral Dynamics After Valganciclovir Prophylaxis: 10 Years of Experience in Lung Transplant Recipients

(1) The prevention of cytomegalovirus (CMV) in lung transplant recipients (LTx) is based on the administration of VGC for a period of 6-12 months, but there is little information on the premature discontinuation of the drug. Our objective was to evaluate the reasons for early cessation of VGC and the dynamics of CMV replication after discontinuation. (2) We carried out a retrospective study of LTx on VGC prophylaxis according to guidelines, with an outpatient follow-up period of >90 days. The detection of any level of CMV-DNA in the plasma (Cobas, Roche Diagnostics®) during a period of 18 months after the discontinuation of VGC was considered positive. (3) We included 312 patients (64% male, mean age 53.50 ± 12.27; 71% D+R+, 15% D-R+, and 14% D+R-) in our study. The prescribed prophylaxis was completed by 179 patients (57.05%). The mean duration of prophylaxis was 7.17 ± 1.08 months. The recorded reasons for VGC discontinuation in 133 patients (43%) were myelotoxicity (n = 55), impaired renal function (n = 32), and gastrointestinal disturbances (n = 11). The reason for discontinuation was not recorded for 29 patients. CMV-DNA was detected in 79% (n = 246) of cases, and D+R+ and D+R- recipients showed a high risk of detection (p < 0.001). The median times to onset of CMV-DNA detection were 35 days in D+R-, 73 days in D+R+, and 96 days in D-R+ (p < 0.001). (4) Adverse effects of VGC are frequent in LTx. CMV-DNA detection is very common after the discontinuation of VGC and is related to the CMV donor and recipient serostatus.

The changing landscape of infections in the lung transplant recipient

PURPOSE OF REVIEW

Infections in lung transplant recipients remain a major challenge and can affect lung allograft function and cause significant morbidity and mortality. New strategies for the prevention and treatment of infection in lung transplantation have emerged and are reviewed.

RECENT FINDINGS

For important vaccine preventable infections (VPIs), guidance has been updated for at risk solid organ transplant (SOT) recipients. However, data on the efficacy of newer vaccines in lung transplant, including the respiratory syncytial virus (RSV) vaccine, are limited. Studies demonstrate improved vaccination rate with Infectious Diseases consultation during pretransplant evaluation. Two new antiviral agents for the treatment and prevention of cytomegalovirus (CMV) in SOT, letermovir and maribavir, are being incorporated into clinical care. CMV-specific cell-mediated immune function assays are more widely available. Antibiotics for the management of multidrug resistant pathogens and Burkholderia cepacia complex have been described in case series and case reports in lung transplant.

SUMMARY

Although new vaccines and novel therapies for preventing and treating infections are available, larger studies evaluating efficacy in lung transplant recipients are needed.

A call for cytomegalovirus stewardship initiatives in cardiothoracic transplant

Despite the availability of potent antiviral therapy and increasingly long prophylaxis courses, cytomegalovirus (CMV) infection continues to negatively affect outcomes after cardiothoracic transplant (CT). CMV antiviral stewardship (AVS) represents an opportunity to implement organ-specific prophylaxis, treatment, and monitoring algorithms while optimizing care of the allograft and patient. Within the nuanced context of heart and lung transplant recipients, CMV prophylaxis, monitoring, and treatment strategies are reviewed for efficacy and safety. These insights highlight opportunities for CMV AVS programs to combine organ- and patient-specific data while implementing CMV guidelines, appropriately adopted to local context by local experts, with concurrent and retrospective evaluation for each patient and the transplant program. By applying concepts of CMV AVS currently practiced in abdominal transplant, CT programs can work to improve graft and patient outcomes related to CMV, including ongoing challenges such as atherosclerosis and impaired endothelial function in heart transplant recipients and chronic lung allograft dysfunction in lung transplant recipients. While implementation of CMV AVS is not without challenges, it also represents an opportunity for multidisciplinary teams to foster the development of CMV-specific cell-mediated immunity and improve long-term outcomes.

In Vitro Profiling of Commonly Used Post-transplant Immunosuppressants Reveals Distinct Impact on Antiviral T-cell Immunity Towards CMV

Infectious complications, including widespread human cytomegalovirus (CMV) disease, frequently occur after hematopoietic stem cell and solid organ transplantation due to immunosuppressive treatment causing impairment of T-cell immunity. Therefore, in-depth analysis of the impact of immunosuppressants on antiviral T cells is needed. We analyzed the impact of mTOR inhibitors sirolimus (SIR/S) and everolimus (EVR/E), calcineurin inhibitor tacrolimus (TAC/T), purine synthesis inhibitor mycophenolic acid (MPA/M), glucocorticoid prednisolone (PRE/P) and common double (T+S/E/M/P) and triple (T+S/E/M+P) combinations on antiviral T-cell functionality. T-cell activation and effector molecule production upon antigenic stimulation was impaired in presence of T+P and triple combinations. SIR, EVR and MPA exclusively inhibited T-cell proliferation, TAC inhibited activation and cytokine production and PRE inhibited various aspects of T-cell functionality including cytotoxicity. This was reflected in an in vitro infection model, where elimination of CMV-infected human fibroblasts by CMV-specific T cells was reduced in presence of PRE and all triple combinations. CMV-specific memory T cells were inhibited by TAC and PRE, which was also reflected with double (T+P) and triple combinations. EBV- and SARS-CoV-2-specific T cells were similarly affected. These results highlight the need to optimize immune monitoring to identify patients who may benefit from individually tailored immunosuppression.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Prevention and Management of Infections in Lung Transplant Recipients

Anti-rejection medications are essential in preventing organ rejection amongst solid organ transplant recipients; however, these agents also cause profound immunosuppression, predisposing lung transplant recipients (LTRs) to infectious complications. The timely management including prevention, diagnosis, and treatment of such infectious complications is vital to prevent significant morbidity and mortality in solid organ transplant recipients and allograft dysfunction. LTRs are inundated with microbes that may be recognized as commensals in hosts with intact immune systems. Bacterial infections are the most common ones, followed by viral pathogens. Indications of a brewing infectious process may be subtle. Hence, the importance of adapting vigilance around isolated hints through symptomatology and signs is pivotal. Signals to suggest an infectious process, such as fever and leukocytosis, may be dampened by immunosuppressive agents. One must also be vigilant about drug interactions of antibiotics and immunosuppressive agents. Treatment of infections can become challenging, as antimicrobials can interact with immunosuppressive agents, and antimicrobial resistance can surge under antimicrobial pressure. Transplant infectious disease physicians work in concert with transplant teams to obtain specimens for diagnostic testing and follow through with source control when possible. This heavily impacts medical decisions and fosters a multidisciplinary approach in management. Furthermore, the reduction of immunosuppression, although it augments the risk of allograft rejection, is as crucial as the initiation of appropriate antimicrobials when it comes to the management of infections.