Infections in pediatric solid-organ transplant recipients

Biomarkers from subcutaneous engineered tissues predict acute rejection of organ allografts

Invasive graft biopsies assess the efficacy of immunosuppression through lagging indicators of transplant rejection. We report on a microporous scaffold implant as a minimally invasive immunological niche to assay rejection before graft injury. Adoptive transfer of T cells into Rag2-/- mice with mismatched allografts induced acute cellular allograft rejection (ACAR), with subsequent validation in wild-type animals. Following murine heart or skin transplantation, scaffold implants accumulate predominantly innate immune cells. The scaffold enables frequent biopsy, and gene expression analyses identified biomarkers of ACAR before clinical signs of graft injury. This gene signature distinguishes ACAR and immunodeficient respiratory infection before injury onset, indicating the specificity of the biomarkers to differentiate ACAR from other inflammatory insult. Overall, this implantable scaffold enables remote evaluation of the early risk of rejection, which could potentially be used to reduce the frequency of routine graft biopsy, reduce toxicities by personalizing immunosuppression, and prolong transplant life.

Approach to vaccinating the pediatric solid organ transplant candidate and recipient

Solid organ transplantation (SOT) candidates and recipients are at increased risk for morbidity and mortality from vaccine-preventable infections. Children are at particular risk given that they may not have completed their primary immunization series at time of transplant or have acquired natural immunity to pathogens from community exposures. Multiple society guidelines exist for vaccination of SOT candidate and recipients, although challenges remain given limited safety and efficacy data available for pediatric SOT recipients, particularly for live-vaccines. After transplant, individual patient nuances regarding exposure risks and net state of immunosuppression will impact timing of immunizations. The purpose of this review is to provide readers with a concise, practical, expert-opinion on the approach to vaccinating the SOT candidate and recipient and to supplement existing guidelines. In addition, pediatric-specific knowledge gaps in the field and future research priorities will be highlighted.

Innate immune cell dysfunction and systemic inflammation in children with chronic liver diseases undergoing transplantation

Advanced liver diseases (ALD) can affect immune function and compromise host defense against infections. In this study, we examined the phenotypic and functional alterations in circulating monocyte and dendritic cells (DCs) in children with ALD undergoing liver transplantation (LT). Children were stratified into 2 clusters, C1 (mild) and C2 (severe), on the basis of laboratory parameters of ALD and compared with healthy pediatric controls. Children in C2 had a significant reduction in frequencies of nonclassical monocytes and myeloid DCs. Children in C2 displayed monocyte and DC dysfunction, characterized by lower human leucocyte antigen DR expression and reduced interleukin 12 production, and had an increased incidence of infections before and after LT. Children in C2 demonstrated immune dysregulation with elevations of pro- and anti-inflammatory cytokines in plasma. Alterations of innate immune cells correlated with multiple laboratory parameters of ALD, including plasma bile acids. In vitro, monocytes cultured with specific bile acids demonstrated a dose-dependent reduction in interleukin 12 production, similar to alterations in children with ALD. In conclusion, a cohort of children with ALD undergoing LT exhibited innate immune dysfunction, which may be related to the chronic elevation of serum bile acids. Identifying at-risk patients may permit personalized management pre- and post-transplant, thereby reducing the incidence of infection-related complications.

Intestinal Dominance by Multidrug-Resistant Bacteria in Pediatric Liver Transplant Patients

Pediatric liver transplantation (PLTx) is commonly associated with extensive antibiotic treatments that can produce gut microbiome alterations and open the way to dominance by multidrug-resistant organisms (MDROs). In this study, the relationship between intestinal Relative Loads (RLs) of β-lactamase genes, antibiotic consumption, microbiome disruption, and the extraintestinal dissemination of MDROs among PLTx patients is investigated. 28 PLTx patients were included, from whom 169 rectal swabs were collected. Total DNA was extracted and bla_{CTX-M-1-Family}, bla_OXA-1, bla_OXA-48, and bla_VIM were quantified via quantitative polymerase chain reaction (qPCR) and normalized to the total bacterial load (16SrRNA) through LogΔΔCt to determine the RLs. 16SrRNA sequencing was performed for 18 samples, and metagenomic sequencing was performed for 2. Patients' clinical data were retrieved from the hospital's database. At least one of the genes tested were detected in all of the patients. The RLs for bla_{CTX-M-1-Family}, bla_OXA-1, bla_OXA-48, and bla_VIM were higher than 1% of the total bacterial population in 67 (80.73%), 56 (78.87%), 57 (77.03%) and 39 (61.9%) samples, respectively. High RLs for bla_{CTX-M-1-Family}, bla_OXA-1, and/or bla_OXA-48, were positively associated with the consumption of carbapenems with trimethoprim-sulfamethoxazole and coincided with low diversity in the gut microbiome. Low RLs were associated with the consumption of noncarbapenem β-lactams with aminoglycosides (P < 0.05). Extraintestinal isolates harboring the same gene(s) as those detected intraintestinally were found in 18 samples, and the RLs of the respective swabs were high. We demonstrated a relationship between the consumption of carbapenems with trimethoprim-sulfamethoxazole, intestinal dominance by MDROs and extraintestinal spread of these organisms among PLTx patients. IMPORTANCE In this study, we track the relative intestinal loads of antibiotic resistance genes among pediatric liver transplant patients and determine the relationship between this load, antibiotic consumption, and infections caused by antibiotic-resistant organisms. We demonstrate that the consumption of broad spectrum antibiotics increase this load and decrease the gut microbial diversity among these patients. Moreover, the high loads of resistance genes were related to the extraintestinal spread of multidrug-resistant organisms. Together, our data show that the tracking of the relative intestinal loads of antibiotic resistance genes can be used as a biomarker that has the potential to stop the extraintestinal spread of antibiotic-resistant bacteria via the measurement of the intestinal dominance of these organisms, thereby allowing for the application of preventive measures.

Donor considerations in pediatric kidney transplantation

This article reviews kidney transplant donor options for children with end-stage kidney disease (ESKD). Global access to kidney transplantation is variable. Well-established national policies, organizations for organ procurement and allocation, and donor management policies may account for higher deceased donor (DD transplants) in some countries. Living donor kidney transplantation (LD) predominates in countries where organ donation has limited national priority. In addition, social, cultural, religious and medical factors play a major role in both LD and DD kidney transplant donation. Most children with ESKD receive adult-sized kidneys. The transplanted kidney has a finite survival and the expectation is that children who require renal replacement therapy from early childhood will probably have 2 or 3 kidney transplants in their lifetime. LD transplant provides better long-term graft survival and is a better option for children. When a living related donor is incompatible with the intended recipient, paired kidney exchange with a compatible unrelated donor may be considered. When the choice is a DD kidney, the decision-making process in accepting a donor offer requires careful consideration of donor history, kidney donor profile index, HLA matching, cold ischemia time, and recipient's time on the waiting list. Accepting or declining a DD offer in a timely manner can be challenging when there are undesirable facts in the donor's history which need to be balanced against prolonging dialysis in a child. An ongoing global challenge is the significant gap between organ supply and demand, which has increased the need to improve organ preservation techniques and awareness for organ donation.

Pulmonary Manifestations of Immunodeficiency and Immunosuppressive Diseases Other than Human Immunodeficiency Virus

Immune deficiencies may alter normal lung function and protective mechanisms, resulting in a myriad of pulmonary manifestations. Primary immunodeficiencies involve multiple branches of the immune system, and defects may predispose to recurrent upper and lower respiratory infections by common pathogens; opportunistic infections; and autoimmune, inflammatory, and malignant processes that may result in interstitial pneumonias. Secondary immunodeficiencies may result from neoplasms or their treatment, organ transplant and immunosuppression, and from autoimmune diseases and their treatments. Primary and secondary immunodeficiencies and their pulmonary manifestations may be difficult to diagnose and treat. A multidisciplinary approach to evaluation is essential.

Torque teno viral load reflects immunosuppression in paediatric kidney-transplanted patients-a pilot study

BACKGROUND

Chronic deterioration of kidney graft function is related to inadequate immunosuppression (IS). A novel tool to assess the individual net state of IS in transplanted patients might be the monitoring of Torque teno virus (TTV) viral load. TTV is a non-pathogen virus detectable in almost all individuals. TTV level in the peripheral blood has been linked to the immune-competence of its host and should thus reflect IS after solid organ transplantation.

METHODS

TTV plasma load was quantified monthly by RT-PCR for a period of 1 year in 45 kidney-transplanted children. Post-transplant time was at least 3 months. The relation of the virus DNA levels to IS and transplant-specific clinical and laboratory parameters was analysed longitudinally.

RESULTS

TTV DNA was detectable in 94.5% of the plasma samples. There was a significant association with the post-transplant follow-up time as well as with the type of IS regimen, with lower virus loads in patients after longer post-transplant time and mTOR inhibitor-based IS. Furthermore, a significant positive correlation with the dose of prednisolone and mycophenolate mofetil was found.

CONCLUSIONS

TTV levels show an association/correlation with the strength of IS. Further studies are needed in order to evaluate TTV measurement as a tool for IS monitoring for hard clinical outcomes such as presence of donor-specific antibodies, rejections or infections-common consequences of insufficient or too intense IS.

Care of Pediatric Solid Organ Transplant Recipients: An Overview for Primary Care Providers

As the number of living pediatric solid organ transplant (SOT) recipients continues to grow, there is an increased likelihood that primary care providers (PCPs) will encounter pediatric SOT recipients in their practices. In addition, as end-stage organ failure is replaced with chronic medical conditions in transplant recipients, there is a need for a comprehensive approach to their management. PCPs can significantly enhance the care of immunosuppressed hosts by advising parents of safety considerations and avoiding adverse drug interactions. Together with subspecialty providers, PCPs are responsible for ensuring that appropriate vaccinations are given and can play an important role in the diagnosis of infections. Through early recognition of rejection and posttransplant complications, PCPs can minimize morbidity. Growth and development can be optimized through frequent assessments and timely referrals. Adherence to immunosuppressive regimens can be greatly improved through reinforcement at every encounter, particularly among adolescents. PCPs can also improve long-term outcomes by easing the transition of pediatric SOT recipients to adult providers. Although guidelines exist for the primary care management of adult SOT recipients, comprehensive guidance is lacking for pediatric providers. In this evidence-based overview, we outline the main issues affecting pediatric SOT recipients and provide guidance for PCPs regarding their management from the first encounter after the transplant to the main challenges that arise in childhood and adolescence. Overall, PCPs can and should use their expertise and serve as an additional layer of support in conjunction with the transplant center for families that are caring for a pediatric SOT recipient.

Brincidofovir for the treatment of human adenovirus infection in pediatric solid organ transplant recipients: A case series

HAdV viremia can cause significant morbidity among pediatric recipients of SOT with variability in incidence and severity of disease based on the type of allograft. Currently, there are no US FDA-approved treatments for HAdV infections, and historically, the mainstay of treatment has been decreasing immunosuppression, with antiviral therapies reserved for those with severe disease. We describe the treatment of four pediatric SOT recipients (two kidney, one combined kidney-liver, and one liver) presenting with HAdV disease at our institution using brincidofovir. Our case series highlights the variability in presentation and the potential for severe disease in pediatric SOT recipients as we review disease presentation, disease course, complications, and treatment with brincidofovir.