Immunophenotypic predictors of influenza vaccine immunogenicity in pediatric hematopoietic cell transplant recipients

ABSTRACT

Pediatric hematopoietic cell transplant (HCT) recipients exhibit poor serologic responses to influenza vaccination early after transplant. To facilitate the optimization of influenza vaccination timing, we sought to identify B- and T-cell subpopulations associated with influenza vaccine immunogenicity in this population. We used mass cytometry to phenotype peripheral blood mononuclear cells collected from pediatric HCT recipients enrolled in a multicenter influenza vaccine trial comparing high- and standard-dose formulations over 3 influenza seasons (2016-2019). We fit linear regression models to estimate relationships between immune cell subpopulation numbers before vaccination and prevaccination to postvaccination geometric mean fold rises in antigen-specific (A/H3N2, A/H1N1, and B/Victoria) serum hemagglutination inhibition antibody titers (28-42 days, and ∼6 months after 2 doses). For cell subpopulations identified as predictive of a response to all 3 antigens, we conducted a sensitivity analysis including time after transplant as an additional covariate. Among 156 HCT recipients, we identified 33 distinct immune cell subpopulations; 7 significantly predicted responses to all 3 antigens 28 to 42 days after a 2-dose vaccine series, irrespective of vaccine dose. We also found evidence that baseline absolute numbers of naïve B cells, naïve CD4+ T cells, and circulating T follicular helper cells predicted peak and sustained vaccine-induced titers irrespective of dose or timing of posttransplant vaccine administration. In conclusion, several B- and T-cell subpopulations predicted influenza vaccine immunogenicity in pediatric HCT recipients. This study provides insights into the immune determinants of vaccine responses and may help guide the development of tailored vaccination strategies for this vulnerable population.

The Durability of Antibody Responses of Two Doses of High-Dose Relative to Two Doses of Standard-Dose Inactivated Influenza Vaccine in Pediatric Hematopoietic Cell Transplant Recipients: A Multi-Center Randomized Controlled Trial

BACKGROUND

Our previous study established a 2-dose regimen of high-dose trivalent influenza vaccine (HD-TIV) to be immunogenically superior compared to a 2-dose regimen of standard-dose quadrivalent influenza vaccine (SD-QIV) in pediatric allogeneic hematopoietic cell transplant (HCT) recipients. However, the durability of immunogenicity and the role of time post-HCT at immunization as an effect modifier are unknown.

METHODS

This phase II, multi-center, double-blinded, randomized controlled trial compared HD-TIV to SD-QIV in children 3-17 years old who were 3-35 months post-allogeneic HCT, with each formulation administered twice, 28-42 days apart. Hemagglutination inhibition (HAI) titers were measured at baseline, 28-42 days following each dose, and 138-222 days after the second dose. Using linear mixed effects models, we estimated adjusted geometric mean HAI titer ratios (aGMR: HD-TIV/SD-QIV) to influenza antigens. Early and late periods were defined as 3-5 and 6-35 months post-HCT, respectively.

RESULTS

During 3 influenza seasons (2016-2019), 170 participants were randomized to receive HD-TIV (n = 85) or SD-QIV (n = 85). HAI titers maintained significant elevations above baseline for both vaccine formulations, although the relative immunogenic benefit of HD-TIV to SD-QIV waned during the study. A 2-dose series of HD-TIV administered late post-HCT was associated with higher GMTs compared to the early post-HCT period (late group: A/H1N1 aGMR = 2.16, 95% confidence interval [CI] = [1.14-4.08]; A/H3N2 aGMR = 3.20, 95% CI = [1.60-6.39]; B/Victoria aGMR = 1.91, 95% CI = [1.01-3.60]; early group: A/H1N1 aGMR = 1.03, 95% CI = [0.59-1.80]; A/H3N2 aGMR = 1.23, 95% CI = [0.68-2.25]; B/Victoria aGMR = 1.06, 95% CI = [0.56-2.03]).

CONCLUSIONS

Two doses of HD-TIV were more immunogenic than SD-QIV, especially when administered ≥6 months post-HCT. Both groups maintained higher titers compared to baseline throughout the season.

CLINICAL TRIALS REGISTRATION

NCT02860039.

Acute liver failure and unique challenges of pediatric liver transplantation amidst a worldwide cluster of adenovirus-associated hepatitis

Investigation into a recent cluster of acute hepatitis in children from the southeastern United States identified human adenovirus (HAdV) DNAemia in all 9 cases. Molecular genotyping in 5 of 9 (56%) children identified HAdV type 41 in all cases (100%). Importantly, 2 children from this cluster progressed rapidly to pediatric acute liver failure (PALF) and required liver transplantation. HAdV type 41, a known cause of self-limited gastroenteritis, has not previously been associated with severe cholestatic hepatitis and liver failure in healthy children. Adenovirus polymerase chain reaction assay and sequencing of amplicons performed on DNA extracted from formalin-fixed, paraffin-embedded liver tissue also identified adenovirus species F (HAdV type 40 or 41) in these 2 children with PALF. Transplant considerations and successful liver transplantation in such situations remain scarce. In this report, we describe the clinical course, laboratory results, liver pathology, and treatment of 2 children with PALF associated with HAdV type 41, one of whom developed secondary hemophagocytic lymphohistiocytosis. Their successful posttransplant outcomes demonstrate the importance of early multidisciplinary medical management and the feasibility of liver transplantation in some children with PALF and HAdV DNAemia.

1096. Riding the Waves: Infection by SARS-CoV-2 Variants in Solid Organ Transplant Recipients at Texas Children’s Hospital

Background

Texas Children’s Hospital is the largest pediatric solid organ transplant (SOT) program in the US, performing heart, kidney, liver, and lung transplants. Limited data exist about SARS-CoV-2 infection (COVID-19) in the pediatric SOT population. We evaluated the impact of different SARS-CoV-2 variants in a cohort of PCR positive SOT recipients.

Methods

SOT recipients with a positive SARS-CoV-2 PCR test from 3/1/2020 to 2/28/2022 were included in the cohort. The study period was divided into 3 eras based on the predominant circulating variant of SARS-CoV-2: 3/20-6/21 original strain/Alpha, 7/21-11/21 Delta, and 12/21-2/22 Omicron variants. Retrospective medical record review was performed; Chi-squared and Fischer exact test were used to compare groups.

Results

A total of 269 of 1031 (26%) SOT recipients tested positive for SARS-CoV-2 during the study period. By organ, 87/335 (26%) heart, 57/224 (25%) kidney, 92/405 (23%) liver, and 25/67 (37%) lung recipients had COVID-19 infection. By era, there were 99 (37%) original strain/ Alpha, 65 (24%) Delta, and 105 (39%) Omicron. The patients’ median age was 12.72 years (IQR 6.6, 15.1) with a minority of recipients being female (42%). Common comorbidities included hypertension (50%), obesity (13%), diabetes (10%), and chronic kidney disease (10%); 34% had no comorbidities aside from chronic immunosuppression post-transplant. Overall, 80% of recipients were symptomatic (Figure 1), and 50 (19%) required hospitalization. Hospitalization rates were highest (29%) during Delta, compared with 18% for original/Alpha and 13% for Omicron (p=0.02) eras. Need for respiratory support, ICU admission, and all-cause mortality did not vary by era (Table 1). Three SOT recipients (2 original/Alpha and 1 Delta) were diagnosed with multi-inflammatory syndrome in children (MIS-C).

Conclusion

Our study suggests that pediatric SOT recipients have a high risk for hospitalization and short-term complications with COVID-19; Omicron appears to cause less severe disease, including MIS-C. Additional studies are needed to understand long-term complications of COVID-19 in SOT recipients.

Disclosures

Elizabeth A. Moulton, MD, PhD, Pfizer: Grant/Research Support Flor M. Munoz, MD, MSc, Gilead: Grant/Research Support|Moderna: DSMB|Pfizer: DSMB.

1588. Epidemiology of Chronic High Level (CHL) Epstein-Barr virus (EBV) DNAemia in Pediatric Solid Organ Transplant Recipients (SOTR) at Texas Children’s Hospital (TCH)

Background

EBV infections cause significant morbidity and mortality in pediatric SOTR and can be complicated by post-transplant lymphoproliferative disorder (PTLD). Contemporary data on CHL EBV DNAemia and the development of PTLD are limited.

Methods

A retrospective cohort study of patients ≤ 21 years of age who received heart, lung, liver, kidney, or multi-organ transplants at TCH between 2011–2018 was conducted. Primary outcome was CHL EBV DNAemia, defined as peripheral blood lymphocyte EBV values ≥ 500 copies/ug or whole blood EBV values ≥ 10,000 IU/mL for ≥ 6 months. Associations with CHL EBV DNAemia were measured using chi-squared or Fisher exact test and multivariate logistic regression. Time to CHL EBV DNAemia was assessed using Kaplan-Meier method.

Results

Among 687 SOTR (152 heart, 87 lung, 259 liver, 175 kidney, 14 multi-organ), 87 (13%) developed CHL EBV DNAemia; this included 15 (9%) heart, 9 (10%) lung, 59 (22%) liver, 2 (1%) kidney, and 2 (14%) multi-organ recipients. Receiving a heart [OR 2.1, 95% CI (2.1 – 62.4)], lung [7.7, 95% CI (1.5 – 39.3)], liver [OR 31.8, 95% CI (4.9 – 208.7)], or multi-organ [OR 18.3, 95% CI (2.0 – 170)] transplant and being 1–5 years of age [OR 4.0, 95% CI (1.6 – 9.8)] were associated with CHL EBV DNAemia. SOTR transplanted from 2015–2018 were less likely to develop CHL EBV DNAemia than those transplanted from 2011–2014 [OR 0.5, 95% CI (0.3 – 0.8)]. EBV risk status, CMV risk status, gender, and induction therapy were not associated with developing CHL EBV DNAemia.

The median maximum peripheral blood lymphocyte and whole blood EBV values for those with CHL EBV DNAemia were 9475 (993 – 258151) copies/ug and 22093 (564 – 550000) IU/mL, respectively. Organ transplanted (p< 0.01), age (p< 0.01), and EBV risk status (p< 0.01) were associated with time to CHL EBV DNAemia (Figure 1). PTLD occurred in 28 (4%) of SOTR; 14 (50%) had preceding CHL EBV DNAemia (p< 0.01).

Figure 1 Time to CHL EBV DNAemia.

Conclusion

This cohort of pediatric SOTR demonstrates a low prevalence of CHL EBV DNAemia and PTLD. Receiving a heart, lung, liver, or multi-organ transplant and being 1–5 years of age were associated with developing CHL EBV DNAemia. SOTR who developed CHL EBV DNAemia were more likely to develop PTLD, suggesting that further interventions targeting this group may be warranted.

Disclosures

Flor M. Munoz, MD, MSc, Gilead: Grant/Research Support Elizabeth A. Moulton, MD, PhD, Pfizer: Co-investigator for SARS-CoV-2 pediatric vaccine trials.

A Case Series of Children with Acute Hepatitis and Human Adenovirus Infection

BACKGROUND

Human adenoviruses typically cause self-limited respiratory, gastrointestinal, and conjunctival infections in healthy children. In late 2021 and early 2022, several previously healthy children were identified with acute hepatitis and human adenovirus viremia.

METHODS

We used International Classification of Diseases, 10th Revision, codes to identify all children (<18 years of age) with hepatitis who were admitted to Children's of Alabama hospital between October 1, 2021, and February 28, 2022; those with acute hepatitis who also tested positive for human adenovirus by whole-blood quantitative polymerase chain reaction (PCR) were included in our case series. Demographic, clinical, laboratory, and treatment data were obtained from medical records. Residual blood specimens were sent for diagnostic confirmation and human adenovirus typing.

RESULTS

A total of 15 children were identified with acute hepatitis - 6 (40%) who had hepatitis with an identified cause and 9 (60%) who had hepatitis without a known cause. Eight (89%) of the patients with hepatitis of unknown cause tested positive for human adenovirus. These 8 patients plus 1 additional patient referred to this facility for follow-up were included in this case series (median age, 2 years 11 months; age range, 1 year 1 month to 6 years 5 months). Liver biopsies indicated mild-to-moderate active hepatitis in 6 children, some with and some without cholestasis, but did not show evidence of human adenovirus on immunohistochemical examination or electron microscopy. PCR testing of liver tissue for human adenovirus was positive in 3 children (50%). Sequencing of specimens from 5 children showed three distinct human adenovirus type 41 hexon variants. Two children underwent liver transplantation; all the others recovered with supportive care.

CONCLUSIONS

Human adenovirus viremia was present in the majority of children with acute hepatitis of unknown cause admitted to Children's of Alabama from October 1, 2021, to February 28, 2022, but whether human adenovirus was causative remains unclear. Sequencing results suggest that if human adenovirus was causative, this was not an outbreak driven by a single strain. (Funded in part by the Centers for Disease Control and Prevention.).

Epidemiology and long-term outcomes of cytomegalovirus DNAemia and disease in pediatric solid organ transplant recipients

Despite prevention strategies, cytomegalovirus (CMV) remains a common infection in pediatric solid organ transplant recipients (SOTR). We sought to determine the frequency, associations with, and long-term outcomes of CMV DNAemia in pediatric SOTR. We performed a single-center retrospective cohort study, including 687 first time SOTR ≤21 years receiving universal prophylaxis from 2011 to 2018. Overall, 159 (23%) developed CMV DNAemia, the majority occurring after completing primary prophylaxis. CMV disease occurred in 33 (5%) SOTR, 25 (4%) with CMV syndrome and 10 (1%) with proven/probable tissue-invasive disease. CMV contributed to the death of three (0.4%) patients (all lung). High-risk (OR 6.86 [95% CI, 3.6-12.9]) and intermediate-risk (4.36 [2.3-8.2]) CMV status and lung transplantation (4.63 [2.33-9.2]) were associated with DNAemia on multivariable analysis. DNAemia was associated with rejection in liver transplant recipients (p < .01). DNAemia was not associated with an increase in graft failure, all-cause mortality, or other organ-specific poor outcomes. We report one of the lowest rates of CMV disease after SOTR, showing that universal prophylaxis is effective and should be continued. However, we observed CMV morbidity and mortality in a subset of patients, highlighting the need for research on optimal prevention strategies. This study was IRB approved.

276. SARS-CoV-2 Infection in Solid Organ Transplant Candidates and Recipients at Texas Children’s Hospital: A Retrospective Review

Background

Texas Children’s Hospital (TCH) is the largest pediatric solid organ transplant (SOT) program in the US, performing heart, kidney, liver, and lung transplants. Limited data exists about SARS-CoV-2 infection (COVID-19) in the pediatric SOT populations. We evaluated the impact of COVID-19 in a cohort of PCR positive SOT candidates and recipients. We hypothesized that COVID-19 would more severely impact SOT recipients compared to transplant candidates.

Methods

Patients with SOT or transplant candidates at TCH with a positive SARS-CoV-2 RT-PCR test since March 1, 2020 to April 12, 2021 were included in the cohort. Retrospective medical record review was performed, and descriptive statistics were used.

Results

A total of 103 SOT patients were identified, 13 candidates and 90 recipients. Of the SOT candidates, there were 1 heart, 3 kidney, and 9 liver transplant candidates. The SOT recipient cohort included 33 heart, 6 lung, 20 kidney, 33 liver and 2 multi-visceral recipients. A significant difference in age was observed between candidates and recipients with candidates being younger with median age of 4.5 years as opposed to recipient’s median age of 12.8 years (p=0.0003). The majority of patients, 70 of 101 (69%), were symptomatic. Most common symptoms reported were fever in 34/70 (49%), cough in 31/70 (44%), and headache in 19/70 (27%). A higher percentage of candidates (31%, 4 of 13) were hospitalized for acute COVID-19 infection compared to (17%, 15 of 90) of recipients. A transplant candidate who ultimately died from underlying illness and COVID-19 was the only patient in the cohort who required mechanical ventilation. More deaths (2/13, 15%) occurred in transplant candidates with COVID-19 compared to transplant recipients with COVID-19 (1/90, 1%, p=0.04); however, 2 of the deaths occurred after recovery from acute COVID-19 illness.

Conclusion

Our study suggests that pediatric candidates who are actively listed for transplant with underlying conditions have more severe acute COVID-19 illness than pediatric SOT recipients despite their immunosuppression based on the higher mortality observed in the transplant candidates. Prospective studies are needed to better understand which specific patients are at increased risk for mortality from COVID-19.

Disclosures

Leanne Petters, MSN, APRN, CPNP-AC, Pfizer (Scientific Research Study Investigator) Flor M. Munoz, MD, Biocryst (Scientific Research Study Investigator)Gilead (Scientific Research Study Investigator)Meissa (Other Financial or Material Support, DSMB)Moderna (Scientific Research Study Investigator, Other Financial or Material Support, DSMB)Pfizer (Scientific Research Study Investigator, Other Financial or Material Support, DSMB)Virometix (Other Financial or Material Support, DSMB) Elizabeth A. Moulton, MD, PhD, Pfizer (Scientific Research Study Investigator)

A eulogy for Dr Francisco Miguel Marty Forero

As some of those who were lucky enough to have been mentored by Dr Francisco Marty in transplant infectious diseases, we stand with the larger medical community in mourning his untimely death and in commemorating him as a uniquely exceptional and talented physician, investigator, teacher, mentor, friend, artist, and human being.

1084. Epidemiology and Long-term Outcomes of Cytomegalovirus (CMV) in Pediatric Liver Transplant Recipients (PLTR) at Texas Children’s Hospital (TCH)

Background

Despite widespread use of prevention strategies, CMV DNAemia remains common in PLTR. Contemporary data, however, is limited. We sought to determine the frequency of, risk factors for, and long term outcomes of CMV DNAemia in a large, single center cohort of PLTR.

Methods

A retrospective cohort study of PLTR < 22 yrs of age transplanted from 2011-2018 was completed. Per protocol, CMV prophylaxis with ganciclovir/valganciclovir was universally implemented; high risk (HR)(D+/R-) and intermediate risk (IR)(R+) patients received 6 months while low risk (LR)(D-/R-) patients received 3 months. Primary outcomes included any CMV DNAemia, CMV DNAemia >1000 IU/mL and long term outcomes including rejection, graft failure, hepatic steatosis (HS), and de novo autoimmune hepatitis (AIH). Associations with CMV DNAemia were measured using Fisher exact and multivariate regression. Survival analysis, time to CMV infection, and time to PLTR long term outcomes were assessed using Kaplan-Meier plots.

Results

Among 270 PLTR, 81 (30%) had quantifiable CMV DNAemia; 36 (13%) had CMV DNAemia >1000 IU/mL. Fifty (19%) developed CMV DNAemia while on prophylaxis. Median time (range) to CMV DNAemia was 162 days (5-2213). HR (OR 4.18; 95% CI 1.84-9.49, p< 0.01) status was associated with CMV DNAemia and time to CMV DNAemia. CMV DNAemia was not associated with age at transplantation or cold ischemic time.

Eight PLTR (3%) developed CMV syndrome (4 HR, 3 IR, 1 LR), the median peak (range) DNAemia was 2133 IU/mL (202-58000) for these patients. No PLTR developed CMV tissue invasive disease.

CMV DNAemia was not associated with rejection (15% vs. 33%, p=0.62), graft failure (7% vs. 13%, p=0.17), HS (8% vs. 12%, p=0.32), or AIH (10% vs. 8%, p= 0.68). CMV DNAemia was associated with a longer time to rejection (p=0.02). Time to development of graft failure, HS, and AIH were not associated with CMV DNAemia (Figure 1). Finally, there was no difference in survival during the study follow-up period (1 – 9 yrs) for PLTR with vs. without CMV DNAemia (p=0.58).

Figure 1

Conclusion

This large cohort of PLTR demonstrates high rates of CMV DNAemia but low rates of CMV disease. HR status remains associated with CMV DNAemia. CMV DNAemia did not increase the risk of long term adverse outcomes such as rejection, graft failure, HS, and AIH.

Disclosures

All Authors: No reported disclosures

Coronavirus Disease 2019 in Children Cared for at Texas Children's Hospital: Initial Clinical Characteristics and Outcomes

We describe the clinical course of 57 children with coronavirus disease 2019 (COVID-19) cared for through a single hospital system. Most children were mildly symptomatic, and only a few patients with underlying medical conditions required hospitalization. Systemwide patient evaluation processes allowed for prompt identification and management of patients with COVID-19.

1750. Epidemiology of Cytomegalovirus DNAemia in Pediatric Solid-Organ Transplant Patients

Background

Despite the widespread use of prevention strategies, CMV remains a common opportunistic infection in SOTR. Contemporary data regarding CMV in pediatric SOTR is limited. We sought to determine the frequency of and risk factors for CMV infection and disease in a large single-center cohort of pediatric SOTR.

Methods

A retrospective cohort study of patients <22 yr of age who received lung, heart, liver, kidney, or multi-organ transplants at TCH between 2014 and 2018 was completed. Universal CMV prophylaxis was used based on risk status (Figure 1). Primary outcome was CMV DNAemia (plasma level ≥ 1,000 IU/mL). Associations with CMV DNAemia were measured using Fisher exact, Kruskal–Wallis, and multivariate logistic regression. Survival analysis and time to CMV infection were assessed using Kaplan–Meier plots.

Results

Among 465 SOTR, 57 (12%) had CMV DNAemia ≥ 1,000 IU/mL; this included 9/52 (17%) lung, 22/155 (14%) liver, 16/125 (13%) heart, 1/9 (11%) multi-organ, and 9/124 (7%) kidney recipients. 6 (10%) SOTR had early-onset CMV reactivation while on antiviral prophylaxis. Post-prophylaxis, 48 (85%) SOTR had CMV reactivation and 3 (5%) had primary infection. Median time to DNAemia > 1,000 IU/mL was 366 days post-transplant for lung, 115 for liver, 185 for heart, and 290 for kidney (P = 0.04), reflecting differences in prophylaxis strategies. High-risk CMV status (D+/R- for heart, liver, kidney and D+ and/or R+ for lung) was associated with CMV DNAemia (P < 0.01, Figure 2). DNAemia was not associated with age at transplantation, type of organ, or induction immunosuppression. There was no difference in survival during the study follow-up period (1 – 5 years) for SOTR with vs. without DNAemia. Overall, 18/465 (4%) SOTR had CMV disease: 2 (4%) lung, 3 (2%) liver, 5 (4%) heart, 1 (11%) multi-organ, and 7 (6%) kidney recipients. 16 had CMV syndrome and 2 had tissue-invasive disease. Median (range) maximum viral loads were 35,768 IU/mL (3,239–4,807,992) for SOTR with vs. 2,605 IU/mL (1,000–112,000) for SOTR without CMV disease (P < 0.01)

Conclusion

This large contemporary cohort of pediatric SOTR on universal prophylaxis demonstrates low overall rates of CMV DNAemia and CMV disease. High-risk CMV status remains associated with CMV DNAemia, suggesting that further interventions targeting this group may be warranted.

Disclosures

Flor M. Munoz, MD, Biocryst: Grant/Research Support; CDC: Research Grant; Moderna: Other Financial or Material Support, Safety Monitoring Board Member/Chair; NIH: Research Grant; Novavax: Research Grant; UP to Date: Author and Editor - Royalties, Other Financial or Material Support.

1564. Lower Rates of Epstein–Barr Virus (EBV) Viremia in Pediatric Solid Organ Transplant (SOT) Recipients Who Received Valganciclovir Prophylaxis

Background

Antiviral prophylaxis to prevent PTLD remains controversial, but some data suggest that valganciclovir or ganciclovir ([val]ganciclovir) use in EBV high-risk pediatric renal transplants reduces EBV viremia. We evaluated the impact of [val]ganciclovir on EBV viremia and post-transplant lymphoproliferative disease (PTLD) in pediatric nonrenal SOT recipients.

Methods

Retrospective study of 100 patients who underwent a first heart, liver, lung, intestine, or multivisceral SOT between November 2013 and November 2016 at Boston Children’s Hospital who survived without re-transplantation for at least 30 days. Data collected included EBV donor/recipient serostatus, donor’s age >2 years-old (to avoid misclassification of EBV risk due to maternal antibody), antiviral use ([val]ganciclovir or acyclovir), time to EBV viremia (>1,000 copies/mL by whole blood PCR), and time to development of PTLD. EBV high-risk patients were those with donor EBV positive [D+]/recipient EBV negative [R–] serologies; intermediate-risk were EBV R+; low risk were EBV D–/R–. Time-to-event analysis using the Kaplan–Meier method was performed and significance (P = 0.05) was evaluated using the log-rank test.

Results

High (n = 45) or intermediate (n = 27) EBV risk was associated with increased EBV viremia (P = 0.007, table). EBV viremia was significantly decreased in the subgroup of high-risk patients with donors >2 years old who received [val]ganciclovir vs. those who received no antiviral (n = 23, n = 4, P = 0.03, Figure 1). Most PTLD cases (8/9) occurred in the high-risk group (P = 0.03, Figure 2). Overall, patients who received [val]ganciclovir had less PTLD than those who did not (P = 0.03), but this was not significant in the high-risk subgroup (P = 0.14, Figure 3).

Conclusion

Lower rates of EBV viremia occurred in high EBV risk transplant recipients who received [val]ganciclovir, possibly by preventing primary EBV infection. Recipients with high EBV risk have the highest rate of PTLD.

Disclosures

F. M. Marty, Merck: Consultant and Investigator, Consulting fee, Research support and Speaker honorarium; Astellas: Consultant and Investigator, Consulting fee and Research support; Chimerix: Consultant and Investigator, Consulting fee and Research support; Fate Therapeutics: Consultant, Consulting fee; GlaxoSmithKline: Consultant, Consulting fee; LFB: Consultant, Consulting fee; Roche Molecular Diagnostics: Consultant, Consulting fee; Shire: Consultant and Investigator, Consulting fee and Research support.

CNS Measures of Pain Responses Pre- and Post-Anesthetic Ketamine in a Patient with Complex Regional Pain Syndrome

BACKGROUND

Previous reports have indicated that ketamine anesthesia may produce significant improvement if not complete recovery of patients with complex regional pain syndrome (CRPS).

AIMS

Here we report on a patient who had CRPS affecting mainly the right side of her body who underwent functional magnetic resonance imaging (fMRI) scans prior to and in the months following apparent successful treatment with anesthetic doses of ketamine.

MATERIALS AND METHODS

The patient underwent two imaging sessions: one during her pain state (CRPS+) and 1 month after her ketamine treatment in her pain-free state (CRPS-). Both spontaneous and evoked (brush, cold, and heat) pain scores decreased from 7–9/10 on a visual analog scale prior to the treatment to 0–1 immediately following and for months after the treatment. For each imaging session, the identical mechanical (brush) and thermal (cold and heat) stimuli were applied to the same location (the skin of the dorsum of the right hand).

RESULTS

Comparison of CRPS+ vs CRPS- for the three stimuli showed significant changes throughout the cerebral cortex (frontal, parietal, temporal, cingulate, and hippocampus), in subcortical regions such as caudate nucleus, and in the cerebellum. In addition, resting state network analysis showed a reversal of brain network state, and the recovered state paralleled specific default networks in healthy volunteers.

DISCUSSION

The observed changes in brain response to evoked stimuli provide a readout for the subjective response.

CONCLUSION

Future studies of brain function in these patients may provide novel insight into brain plasticity in response to this treatment for chronic pain.

Mapping pain activation and connectivity of the human habenula

The habenula, located in the posterior thalamus, is implicated in a wide array of functions. Animal anatomical studies have indicated that the structure receives inputs from a number of brain regions (e.g., frontal areas, hypothalamic, basal ganglia) and sends efferent connections predominantly to the brain stem (e.g., periaqueductal gray, raphe, interpeduncular nucleus). The role of the habenula in pain and its anatomical connectivity are well-documented in animals but not in humans. In this study, for the first time, we show how high-field magnetic resonance imaging can be used to detect habenula activation to noxious heat. Functional maps revealed significant, localized, and bilateral habenula responses. During pain processing, functional connectivity analysis demonstrated significant functional correlations between the habenula and the periaqueductal gray and putamen. Probabilistic tractography was used to assess connectivity of afferent (e.g., putamen) and efferent (e.g., periaqueductal gray) pathways previously reported in animals. We believe that this study is the first report of habenula activation by experimental pain in humans. Since the habenula connects forebrain structures with brain stem structures, we suggest that the findings have important implications for understanding sensory and emotional processing in the brain during both acute and chronic pain.

Painful heat reveals hyperexcitability of the temporal pole in interictal and ictal migraine States

During migraine attacks, alterations in sensation accompanying headache may manifest as allodynia and enhanced sensitivity to light, sound, and odors. Our objective was to identify physiological changes in cortical regions in migraine patients using painful heat and functional magnetic resonance imaging (fMRI) and the structural basis for such changes using diffusion tensor imaging (DTI). In 11 interictal patients, painful heat threshold + 1°C was applied unilaterally to the forehead during fMRI scanning. Significantly greater activation was identified in the medial temporal lobe in patients relative to healthy subjects, specifically in the anterior temporal pole (TP). In patients, TP showed significantly increased functional connectivity in several brain regions relative to controls, suggesting that TP hyperexcitability may contribute to functional abnormalities in migraine. In 9 healthy subjects, DTI identified white matter connectivity between TP and pulvinar nucleus, which has been related to migraine. In 8 patients, fMRI activation in TP with painful heat was exacerbated during migraine, suggesting that repeated migraines may sensitize TP. This article investigates a nonclassical role of TP in migraineurs. Observed temporal lobe abnormalities may provide a basis for many of the perceptual changes in migraineurs and may serve as a potential interictal biomarker for drug efficacy.

Ectromelia virus inhibitor of complement enzymes protects intracellular mature virus and infected cells from mouse complement

Poxviruses produce complement regulatory proteins to subvert the host's immune response. Similar to the human pathogen variola virus, ectromelia virus has a limited host range and provides a mouse model where the virus and the host's immune response have coevolved. We previously demonstrated that multiple components (C3, C4, and factor B) of the classical and alternative pathways are required to survive ectromelia virus infection. Complement's role in the innate and adaptive immune responses likely drove the evolution of a virus-encoded virulence factor that regulates complement activation. In this study, we characterized the ectromelia virus inhibitor of complement enzymes (EMICE). Recombinant EMICE regulated complement activation on the surface of CHO cells, and it protected complement-sensitive intracellular mature virions (IMV) from neutralization in vitro. It accomplished this by serving as a cofactor for the inactivation of C3b and C4b and by dissociating the catalytic domain of the classical pathway C3 convertase. Infected murine cells initiated synthesis of EMICE within 4 to 6 h postinoculation. The levels were sufficient in the supernatant to protect the IMV, upon release, from complement-mediated neutralization. EMICE on the surface of infected murine cells also reduced complement activation by the alternative pathway. In contrast, classical pathway activation by high-titer antibody overwhelmed EMICE's regulatory capacity. These results suggest that EMICE's role is early during infection when it counteracts the innate immune response. In summary, ectromelia virus produced EMICE within a few hours of an infection, and EMICE in turn decreased complement activation on IMV and infected cells.

An fMRI case report of photophobia: activation of the trigeminal nociceptive pathway

Photophobia, or painful oversensitivity to light, occurs in a number of clinical conditions, which range from superficial eye irritation to meningitis. In this case study, a healthy subject with transient photophobia (induced by the overuse of contact lenses) was examined using functional magnetic resonance imaging (fMRI). While being scanned in a darkened environment, the subject was presented with intermittent 6-s blocks of bright light. The subject was scanned twice, once during his photophobic state and once after recovery. The subject reported that the visual stimuli produced pain (pain intensity=3/10 and unpleasantness=7/10) only during the photophobic state. During photophobia, specific activation patterns in the trigeminal system were seen at the level of the trigeminal ganglion, trigeminal nucleus caudalis, and ventroposteromedial thalamus. The anterior cingulate cortex, a brain structure associated with unpleasantness, was also active during photophobia. After recovery from photophobia, no significant activations were detected in these areas. This study may contribute to a better understanding of the pathways involved in photophobia in the human condition.

Hemolytic uremic syndrome: an example of insufficient complement regulation on self-tissue

Hemolytic uremic syndrome (HUS) is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. HUS is classified as either diarrhea associated, most commonly caused by infection with Escherichia coli O157, or the less common atypical HUS (aHUS), which may be familial or sporadic. Approximately 50% of patients with aHUS have mutations in one of the complement control proteins: factor H, factor I, or membrane cofactor protein (MCP). These proteins regulate complement activation through cofactor activity, the inactivation of C3b by limited proteolytic cleavage, a desirable event in the fluid phase (no target) or on healthy self-tissue (wrong target). Complement activation follows the endothelial cell injury that characterizes HUS. This disease represents a model of what takes place when inappropriate complement activation occurs on self-tissues due to the presence of mutated complement regulatory proteins. Screening for mutations in factor H, factor I, or MCP is expensive and time consuming. One approach is to perform antigenic screening for factor H and factor I deficiency and to look for low levels of MCP (CD46) expression by flow cytometry. Complement regulatory protein deficiency impacts treatment decisions as patients with aHUS have a recurrence rate in renal transplants of approximately 50%, whereas those with factor H mutations have an even higher risk (approximately 80%). By contrast, MCP deficiency can be corrected in part by a renal allograft. However, caution in the use of live-related donations is needed because of the high rates of incomplete penetrance of the described mutations.

Genetic and functional analyses of membrane cofactor protein (CD46) mutations in atypical hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is characterized by the triad of thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. The non-Shiga toxin-associated HUS (atypical HUS [aHUS]) has been shown to be a disease of complement dysregulation. Mutations in the plasma complement regulators factor H and factor I and the widely expressed membrane cofactor protein (MCP; CD46) have been described recently. This study looked for MCP mutations in a panel of 120 patients with aHUS. In this cohort, approximately 10% of patients with aHUS (11 patients; nine pedigrees) have mutations in MCP. The onset typically was in early childhood. Unlike patients with factor I or factor H mutations, most of the patients do not develop end-stage renal failure after aHUS. The majority of patients have a mutation that causes reduced MCP surface expression. A small proportion expressed normal levels of a dysfunctional protein. As in other studies, incomplete penetrance is shown, suggesting that MCP is a predisposing factor rather than a direct causal factor. The low level of recurrence of aHUS in transplantation in patients with MCP mutations is confirmed, and the first MCP null individuals are described. This study confirms the association between MCP deficiency and aHUS and further establishes that a deficiency in complement regulation, specifically cofactor activity, predisposes to severe thrombotic microangiopathy in the renal vasculature.

Regional intensive and temporal patterns of functional MRI activation distinguishing noxious and innocuous contact heat

Cortical responses to painful and nonpainful heat were measured using functional magnetic resonance imaging (fMRI) region of interest analysis (ROI) of primary somatosensory cortex (S1), secondary somatosensory cortex (S2), anterior cingulate (ACC), supplementary motor area (SMA), insula, and inferior frontal gyrus (IFG). Previous studies indicated that innocuous and noxious stimuli of different modalities produce responses with different time courses in S1 and S2. The aim of this study was to 1) determine whether temporally distinct nociceptive blood oxygen level-dependent (BOLD) responses are evoked in multiple somatosensory processing cortical areas and 2) whether these responses discriminate small noxious stimulus intensity differences. Thirty-three subjects underwent fMRI scanning while receiving three intensities of thermal stimuli, ranging from innocuous warm (41 degrees C) to 1 degrees C below tolerance, applied to the dorsum of the left foot. Innocuous and noxious responses were distinguishable in contralateral S1, the mid-ACC, and SMA. The peak of the nociceptive response was temporally delayed from the innocuous response peak by 6-8 s. Responses to noxious but not to innocuous stimuli were observed in contralateral posterior insula. Responses to innocuous and noxious stimuli were not statistically different in contralateral S2. In contralateral S1 only, the nociceptive response could differentiate heat stimuli separated by 1 degrees C. These results show that 1) multiple cortical areas have temporally distinguishable innocuous and noxious responses evoked by a painfully hot thermode, 2) the nociceptive processing properties vary across cortical regions, and 3) nociceptive responses in S1 discriminate between painful temperatures at a level unmatched in other cortical areas.

Transcript signatures in experimental asthma: identification of STAT6-dependent and -independent pathways

The analysis of polygenic diseases such as asthma poses a challenging problem. In an effort to provide unbiased insight into disease pathogenesis, we took an empirical approach involving transcript expression profiling of lung tissue from mice with experimental asthma. Asthmatic responses were found to involve sequential induction of 4.7% of the tested genome; notably, there was ectopic expression of a series of genes not previously implicated in allergic or pulmonary responses. Genes were widely distributed throughout all chromosomes, but preferentially included genes involved in immunity, development, and homeostasis. When asthma was induced by two independent experimental regimens, unique gene transcript profiles were found depending upon the mode of disease induction. However, the majority of genes were common to both models representing an asthma signature genome. Analysis of STAT6-deficient mice revealed that an unexpectedly large segment of the asthma genes were STAT6 independent; this correlated with sustained inflammatory events in these mice. Notably, induction of asthma in STAT6-deficient mice resulted in gene induction not seen in wild-type mice. These results raise concern that therapeutic blockade of STAT6 in the asthmatic setting may reprogram the genetic signature, resulting in alternative lung pathology, which we indeed observed in STAT6-deficient mice. These results provide unprecedented insight into the complex steps involved in the pathogenesis of allergic airway responses; as such, these results have significant therapeutic and clinical implications.

An iceberg in Springfield: using the humanities to explore and challenge the attitudes of general practice (GP) educators towards the management of GP registrars with substance abuse problems

INTRODUCTION

Some general practice registrars (GPRs) have substance abuse problems, and course organisers and trainers need to be vigilant to this possibility. We describe a critical incident involving this type of problem, and how the learning was shared with other GP educators. By using the humanities, we attempted to generate an emotional as well as an intellectual response, with the aim of achieving deeper learning.

METHODS

We gave a presentation to a group of GP educators, using a variety of material from the creative arts (visual, auditory and creative writing) to raise awareness of the issues. The presentation was designed to enable participants to experience some of the feelings of surprise and lack of preparedness that we had experienced ourselves.

RESULTS

The presentation stimulated an in-depth discussion about the challenges faced by educators when they discover that their learners may have substance abuse problems. Early and late evaluation indicated that awareness of the problem had been raised and attitudes challenged and changed. Participation in the presentation had stimulated educators to consider including this area within their teaching, to be more vigilant to the possibility of registrars with substance abuse problems and to think about developing systems to manage such registrars.

CONCLUSION

Diverse educational methods can be effective when teaching within difficult and complex areas that challenge attitudes.

Analysis of the CC chemokine receptor 3 gene reveals a complex 5' exon organization, a functional role for untranslated exon 1, and a broadly active promoter with eosinophil-selective elements

To understand the regulation of CC chemokine receptor 3 (CCR3) expression, its gene structure and promoter have been characterized. The CCR3 gene contains 4 exons that give rise to multiple messenger RNA (mRNA) species by alternative splicing. Exon 1 is present in all transcripts, whereas exon 2 or 3 is present at low frequency (< 10%). Exon 4 contains the open reading frame and 11 bp of the 5' untranslated region. Northern analysis revealed 4 species of CCR3 mRNA. Direct sequencing revealed that the first 1 kb of the promoter and exon 1 contained only one mutation in 19 individuals, indicating that the CCR3 promoter and exon 1 are conserved between individuals. The first 1.6 kb of the 5' flanking region of exon 1 contained promoter elements including a TATA box and motifs for myeloid transcription factors and had strong promoter activity in eosinophilic, lymphoid, myeloid, and respiratory epithelial cell lines. Deletion analysis revealed differential regulation of the CCR3 promoter in eosinophilic and epithelial cells suggesting the presence of lineage-specific elements. Interestingly, exon 1 enhanced the activity of the promoter and this effect was especially prominent in eosinophilic cells. Thus, the human CCR3 gene has a complex 5' exon structure, a conserved promoter with strong activity in multiple cell types, and a functional 5' untranslated exon.