Peripheral blood antigen-presenting cells from African-Americans exhibit increased CD80 and CD86 expression

Heart transplantation in patients from socioeconomically distressed communities

BACKGROUND

Studies examining heart transplantation disparities have focused on individual factors such as race or insurance status. We characterized the impact of a composite community socioeconomic disadvantage index on heart transplantation outcomes.

METHODS

From the Scientific Registry of Transplant Recipients (SRTR), we identified 49,340 primary, isolated adult heart transplant candidates and 32,494 recipients (2005-2020). Zip code-level socioeconomic disadvantage was characterized using the Distressed Community Index (DCI: 0-most prosperous, 100-most distressed) based on education, poverty, unemployment, housing vacancies, median income, and business growth. Patients from distressed communities (DCI ≥ 80) were compared to all others.

RESULTS

Patients from distressed communities were more often non-white, less educated, and had public insurance (all p < 0.01). Distressed patients were more likely to require ventricular assist devices at listing (29.4 vs 27.1%) and before transplant (44.8 vs 42.0%, both p < 0.001), and they underwent transplants at lower-volume centers (23 vs 26 cases/year, p < 0.01). Distressed patients had higher 1-year waitlist mortality or deterioration (12.3% [95% confidence interval (CI) 11.6-13.0] vs 10.9% [95% CI 10.5-11.3]) and inferior 5-year survival (75.3% [95% CI 74.0-76.5] vs 79.5% [95% CI 79.0-80.0]) (both p < 0.001). After adjustment, living in a distressed community was independently associated with an increased risk of waitlist mortality or deterioration hazard ratio (HR 1.10, 95% CI 1.02-1.18) and post-transplant mortality (HR 1.13, 95% CI 1.06-1.20).

CONCLUSIONS

Patients from socioeconomically distressed communities have worse waitlist and post-transplant mortality. These findings should not be used to limit access to heart transplantation, but rather highlight the need for further studies to elucidate mechanisms underlying the impact of community-level socioeconomic disparity.

Immune mechanisms behind prostate cancer in men of African ancestry: A review

BACKGROUND

Men of African ancestry (AA) with prostate cancer suffer from worse outcomes. However, a recent analysis of patients treated with the dendritic cell vaccine sipuleucel-T for prostate cancer suggested that AA patients could have improved outcomes relative to whites.

METHODS

We conducted a focused literature review of Medline-indexed articles and clinical trials listed on clinicaltrials.gov.

RESULTS

We identify several studies pointing to enrichment of inflammatory cellular infiltrates and cytokine signaling among AA patients with prostate cancer. We outline potential genomic and transcriptomic alterations that may contribute to immunogenicity. Last, we investigate differences in host immunity and vaccine responsiveness that may be enhanced in AA patients.

CONCLUSIONS

AA patients with prostate cancer may be enriched for an immunogenic phenotype. Dedicated studies are needed to better understand the immune mechanisms that contribute to existing cancer disparities and test immune-based therapies in this population.

Racial differences in outcomes after receiving advanced heart failure therapies

PURPOSE OF REVIEW

Despite advances in medical and device-based therapies for advanced heart failure as well as public policy, disparities by race/ethnicity persist in heart failure clinical outcomes. The purpose of this review is to describe disparities in outcomes by race--ethnicity in patients after receipt of heart transplantation and left ventricular assist device (LVAD), and the current understanding of factors contributing to these disparities.

RECENT FINDINGS

The proportion of black and Latinx patients receiving advanced heart failure therapies continues to rise, and they have worse hemodynamic profiles at the time of referral for heart transplantation and LVAD. Black patients have lower rates of survival after heart transplantation, in part because of higher rates of cellular and humoral rejection that may be mediated through unique gene pathways, and increased risk for allosensitization and de-novo donor-specific antibodies. Factors that have previously been cited as reasons for worse outcomes in race--ethnic minorities, including psychosocial risk and lower SES, may not be as strongly correlated with outcomes after LVAD.

SUMMARY

Black and Latinx patients are sicker at the time of referral for advanced heart failure therapies. Despite higher psychosocial risk factors among race--ethnic minorities, outcomes after LVAD appear to be similar to white patients. Black patients continue to have lower posttransplant survival, because of a complex interplay of immunologic susceptibility, clinical and socioeconomic factors. No single factor accounts for the disparities in clinical outcomes for race--ethnic minorities, and thus consideration of these components together is critical in management of these patients.

Racial and ethnic disparities in outcomes after heart transplantation: A systematic review of contributing factors and future directions to close the outcomes gap

The demographics of patients undergoing heart transplantation in the United States have shifted over the last 10 years, with an increasing number of racial and ethnic minorities undergoing heart transplant. Multiple studies have shown that survival of African American patients after heart transplantation is lower compared with other ethnic groups. We review the data supporting the presence of this outcome disparity and examine the multiple mechanisms that contribute. With an increasingly diverse population in the United States, knowledge of these disparities, their mechanisms, and ways to improve outcomes is essential.

Gene expression profiling to study racial differences after heart transplantation

Background

The basis for increased mortality after heart transplantation in African Americans and other non-Caucasian racial groups is poorly defined. We hypothesized that increased risk of adverse events is driven by biological factors. To test this hypothesis in the IMAGE study, we determined whether the event rate of the primary outcome of acute rejection, graft dysfunction, death, or re-transplantation varied by race as a function of calcineurin inhibitor levels and gene expression profile (GEP) scores.

Methods

We determined the event rate of the primary outcome, comparing racial groups, stratified by time post-transplant. Logistic regression was used to compute the relative risk across racial groups and linear modeling was used to measure the dependence of CNI levels and GEP score on race.

Results

In 580 patients followed for a median of 19 months, the incidence of the primary endpoint in African Americans, other non-Caucasians, and Caucasians was 18.3%, 22.2%, and 8.5%, respectively (p<0.001). There were small but significant correlations of race and tacrolimus trough levels to GEP score. Tacrolimus levels were similar between races. Of patients receiving tacrolimus, other non-Caucasians had higher GEP scores than the other racial groups. African American recipients demonstrated a unique decrease in expression of the FLT3 gene in response to higher tacrolimus levels.

Conclusions

African Americans and other non-Caucasian heart transplant recipients were 2.5–3 times more likely than Caucasians to experience outcome events in IMAGE. The increased risk of adverse outcomes may be partly due to the biology of the alloimmune response, which is less effectively inhibited at similar tacrolimus levels in minority racial groups.

Genetics of transfusion recipient alloimmunization: can clues from susceptibility to autoimmunity pave the way?

The search for genetic determinants of alloimmunization in sickle cell disease transfusion recipients was based on two premises: i) that polymorphisms responsible for stronger immune and/or inflammatory responses and hemoglobin β(S) mutation were co-selected by malaria; and ii) that stronger responder status contributes to development of lupus. We found a marker of alloimmunization in the gene encoding for Ro52 protein, also known as Sjögren syndrome antigen 1 (SSA1) and TRIM21. Surprisingly, the nature of the association was opposite of that with lupus; the same variant of a polymorphism (rs660) that was associated with lupus incidence was also associated with induction of tolerance to red blood cell antigens during early childhood. The dual function of Ro52 can explain this apparent contradiction. We propose that other lupus/autoimmunity susceptibility loci may reveal roles of additional molecules in various aspects of alloimmunization induced by transfusion as well as during pregnancy.

Assessing immunologic risk factors in transplantation

The innate and adaptive immune systems, together, represent the largest impediment to good and long-lasting graft function. Although improved immunosuppressive agents and expanded and enhanced diagnostic tools have led to better prevention and treatment of acute rejection, chronic rejection remains a serious threat to long-term graft survival. Immunologic heterogeneity among patients, variability in treatment protocols and unforeseen events following transplantation translate into different levels of risk among patients. While one cannot predict with certainty the short- and long-term outcomes of a particular transplant, it is possible to identify immunologic risk factors that can affect outcome.

Immune factors influencing ethnic disparities in kidney transplantation outcomes

An influence of ethnicity on the outcomes of kidney transplant recipients has been recognized for several decades. Both immune and nonimmune factors have been explored as potential explanations. Most studies have focused on the inferior outcomes of African-Americans. As a group, African-Americans differ from Caucasians with respect to a number of measurable components of the alloimmune response, including the T-cell repertoire and the expression and function of costimulatory molecules and various cytokines and chemokines. In general, these differences suggest that African-Americans may be high immune responders. However, no single difference in any of these components of alloimmunity satisfactorily explains the disparities in outcomes. It seems probable that some combination of immune factors interacts with nonimmune factors, such as socioeconomic resources, to influence transplant outcomes in a complex manner.

African American kidney transplantation survival: the ability of immunosuppression to balance the inherent pre- and post-transplant risk factors

Among organ transplant recipients, the African American population historically has received special attention. This is because secondary to their disposition to certain disease states, for example hypertension, an African American patient has a propensity to reach end-stage renal disease and require renal replacement earlier than a Caucasian patient. Regardless of the initiative to replace dialysis therapy with organ transplantation, the African American patient has many barriers to kidney transplantation, thus extending their time on dialysis and waiting time on the organ transplant list. These factors are among the many negative causes of decreased kidney graft survival, realized before kidney transplantation. Unfortunately, once the African American recipient receives a kidney graft, the literature documents that many post-transplant barriers exist which limit successful outcomes. The primary post-transplant barrier relates to designing proper immunosuppression protocols. The difficulty in designing protocols revolves around (i) altered genetic metabolism/lower absorption, (ii) increased immuno-active cytokines and (iii) detrimental effects of noncompliance. Based on the literature, dosing of immunosuppression must be aggressive and requires a diligent practitioner. Research has indicated that, despite some success with proven levels of immunosuppression, the African American recipient usually requires a higher 'dose per weight' regimen. However, even with aggressive immunosuppressant dosing, African Americans still have worse outcomes than Caucasian recipients. Additionally, many of the targeted sites of action that immunosuppression exerts its effects on have been found to be amplified in the African American population. Finally, noncompliance is the most discouraging inhibitor of long-term success in organ transplantation. The consequences of noncompliance are biased by ethnicity and affect the African American population more severely. All of these factors are discussed further in this review in the hope of identifying an ideal healthcare model for caring for the African American transplant recipient, from diagnosing chronic kidney disease through to successful kidney graft outcomes. An indepth review of the literature is described and organized in a fashion that highlights all of the issues affecting success in African Americans. The compilation of the literature in this review will enable the reader to get closer to understanding the caveats of kidney transplantation in the African American patient, but falls short of delivering an actual 'equation' for post-transplant care in an African American kidney recipient.

Chronic brucellosis patients retain low frequency of CD4+ T-lymphocytes expressing CD25 and CD28 after Escherichia coli LPS stimulation of PHA-cultured PBMCs

Chronic brucellosis patients display a defective Th1 response to PHA. We have previously shown that heat-killed B. abortus (HKBA) can downregulate the PHA-induced increase of CD4+/CD25+ and CD14+/CD80+ cells of brucellosis patients. In the present study, we investigate the effect of E. coli LPS, as a potent stimulant of monocytes and autologous T-lymphocytes, on the PHA-cultured PBMCs of the same groups of patients. Thirteen acute brucellosis (AB) patients, 22 chronic brucellosis (CB) patients, 11 “cured” subjects, and 15 healthy volunteers were studied. The percentage of CD4+/CD25+ and CD4+/CD28+ T-lymphocytes as well as CD14+/CD80+ monocytes were analyzed by flow cytometry after PBMCs culture with PHA plus E. coli LPS. A significant decrease in the percentage of CD4+/CD25+ and CD4+/CD28+ T-lymphocytes was observed in CB compared to AB. In HKBA cultures, compared to E. coli LPS-cultures, there was a significant reduction of CD4+/CD25+ T-lymphocytes in all groups and CD14+/CD80+ in patients groups. We suggest that Brucella can modulate host immune response, leading to T-cell anergy and chronic infection.

Chronic immune stimulation and subsequent Waldenström macroglobulinemia

BACKGROUND

Certain autoimmune and infectious conditions are associated with increased risks of subtypes of non-Hodgkin lymphoma. A few previous studies suggest that chronic inflammation may particularly elevate risk of the distinct non-Hodgkin lymphoma subtype Waldenström macroglobulinemia (WM).

METHODS

We assessed WM risk in relation to a variety of chronic immune stimulatory conditions in 4 million US veterans. We identified 361 patients with WM with up to 27 years of follow-up. Using time-dependent Poisson regression, we estimated rate ratios (RRs) and 95% confidence intervals (CIs) for WM risk in relation to history of autoimmune diseases that typically have autoantibodies (with systemic or organ involvement) or do not have autoantibodies, infections, and allergies. All the models were adjusted for attained age, calendar year, race, number of hospital visits, and latency between study entry and exit.

RESULTS

The age-standardized incidence of WM was 0.34 per 100,000 person-years. Risk of WM was elevated in individuals with any previous autoimmune condition (RR, 2.23; 95% CI, 1.68-2.97), autoantibodies with systemic involvement (2.50; 1.55-4.02), or autoantibodies with organ involvement (2.30; 1.57-3.37). Risks of WM were also increased with hepatitis (RR, 3.39; 95% CI, 1.38-8.30), human immunodeficiency virus (12.05; 2.83-51.46), and rickettsiosis (3.35; 1.38-8.14).

CONCLUSIONS

In the largest investigation of WM risk factors to date, we found a 2- to 3-fold elevated risk of WM in persons with a personal history of autoimmune diseases with autoantibodies and notably elevated risks associated with hepatitis, human immunodeficiency virus, and rickettsiosis. These findings provide novel insights into the still unknown etiology of WM.

Prenatal, perinatal, and heritable influences on cord blood immune responses

BACKGROUND

Maternal and perinatal environmental exposures, as well as inherited factors, may influence neonatal immune responses.

OBJECTIVE

To determine relations of maternal and perinatal exposures to antigen-specific cord blood lymphoproliferative responses.

METHODS

In 427 newborns from a Boston pregnancy/birth cohort, lymphoproliferative responses in cord blood mononuclear cells to stimulation with cockroach (Bla g 2), house dust mite (Der f 1), ovalbumin, and mitogen phytohemagglutinin were measured as stimulation index (SI). We used the Wilcoxon rank sum and chi2 tests to evaluate predictors of ovalbumin SI as a continuous ranked or dichotomous outcome. We used t test and Spearman correlation for univariate testing and linear regression to evaluate predictors of natural log-transformed Bla g 2, Der f 1, and phytohemagglutinin SI. Logistic multivariate regression was applied to evaluate predictors of Bla g 2, Der f 1, and phytohemagglutinin SI dichotomized at 2 or at the median for phytohemagglutinin.

RESULTS

Maternal smoking during pregnancy, inadequate or excessive maternal weight gain during pregnancy, neonate black race/ethnicity (compared with white), and Apgar score less than 8 were each independently associated with increased cord blood mononuclear cell proliferative responses to stimulation with Bla g 2 and/or Der f 1. Maternal history of asthma was associated only with increased lymphoproliferative response to ovalbumin stimulation.

CONCLUSIONS

Distinct fetal and perinatal exposures and black race/ethnicity may be associated with increased cord blood lymphoproliferative responses. The implications of these findings for future development of allergy or asthma are, as yet, unknown.

Population frequencies of single nucleotide polymorphisms (SNPs) in immuno-modulatory genes

Inherited polymorphisms in immuno-modulatory genes may contribute to variations in immune function and genetic susceptibility for complex diseases, including cancer. We report results from a comprehensive study to discover novel single nucleotide polymorphisms (SNPs) and to estimate allelic frequency for both novel and known coding and regulatory region SNPs in genes encoding proteins that have been implicated in the immune response to tumors. We identified 12 novel nucleotide substitution variants and one deletion variant in 17 genes analyzed (TGFBETA;R, BETA;2M, IFNGAMMA;, TNFALPHA;, TNFALPHA;R, LTALPHA;, IL-6, IL-12, IL-2, IL-1ALPHA;, IL-1BETA;, IL-1RN, IL-10, CTLA4, CD40L, FAS and FASL). We determined the frequency of these novel polymorphisms, as well as 17 previously identified polymorphisms, in a control sample of 158 individuals, approximately half of which were Caucasian (n = 74) and half of which were African American (n = 84). Significant differences in allele frequencies were observed between the two racial groups for 13/17 genes tested. These allelic variations maybe associated with alterations in immune function and thus susceptibility to a number of complex disease states such as cancer.

Changing trends in pediatric transplantation: 2001 Annual Report of the North American Pediatric Renal Transplant Cooperative Study

The North American Pediatric Renal Transplant Cooperative Study has collected clinical information on children undergoing a renal transplantation since 1987. This cooperative group now includes over 150 participating medical centers in the United States, Canada, Mexico, and Costa Rica. This report covers the years from 1987 through 2001 and includes data on 7545 renal transplants in 6878 patients. This report demonstrates changing trends in many areas of pediatric transplantation including increasing numbers of African American and Hispanic children receiving transplantation, remarkable improvements in the rate of acute rejection, rejection reversal, and short- and long-term allograft survival. In the most recent cohorts of patients, we now see that 1-yr allograft survival is no different in cadaver donor compared to living donor recipients and in infants compared to all other age groups. However, this analysis also reveals areas of continued challenges including inferior outcomes in African American and adolescent populations, chronic rejection, and the adverse effects of immunosuppression.

Ethnicity greatly influences cytokine gene polymorphism distribution

Polymorphisms in the regulatory regions of cytokine genes are associated with high and low cytokine production and may modulate the magnitude of alloimmune responses following transplantation. Ethnicity influences allograft half-life and the incidence of acute and chronic rejection. We have questioned whether ethnic-based differences in renal allograft survival could be due in part to inheritance of cytokine polymorphisms. To address that question, we studied the inheritance patterns for polymorphisms in several cytokine genes (IL-2, IL-6, IL-10, TNF-alpha, TGF-beta, and IFN-gamma) within an ethnically diverse study population comprised of 216 Whites, 58 Blacks, 25 Hispanics, and 31 Asians. Polymorphisms were determined by allele-specific polymerase chain reaction and restriction fragment length analysis. We found striking differences in the distribution of cytokine polymorphisms among ethnic populations. Specifically, significant differences existed between Blacks and both Whites and Asians in the distribution of the polymorphic alleles for IL-2. Blacks, Hispanics and Asians demonstrated marked differences in the inheritance of IL-6 alleles and IL-10 genotypes that result in high expression when compared with Whites. Those of Asian descent exhibited an increase in IFN-gamma genotypes that result in low expression as compared to Whites. In contrast, we did not find significant ethnic-based differences in the inheritance of polymorphic alleles for TNF-alpha. Our results show that the inheritance of certain cytokine gene polymorphisms is strongly associated with ethnicity. These differences may contribute to the apparent influence of ethnicity on allograft outcome.

Role of gender and race mismatch and graft failure in patients undergoing liver transplantation

Previous data have suggested an increased risk of graft failure in male recipients of female livers, and in nonwhite recipients of orthotopic liver transplantation. United Network for Organ Sharing records of liver transplantations from 1992 through 2000 with at least one follow-up visit were reviewed. Analysis of these data was performed with proportional hazards regression, controlling for follow-up time, age, gender, ethnicity, number of comorbidities, functional status at time of transplant, and status 1 designation. Separate analyses comparing transplants among whites and blacks only and matched versus mismatched transplants for male and female recipients were performed. The results revealed that gender-mismatched patients (n = 13,992) had a higher likelihood of graft failure when compared with gender matched transplants (n = 18,522) (12.2% versus 11.3% respectively, P =.013). After controlling for the above potential confounders, gender-mismatched patients were found to have a 6.9% increase in likelihood of graft failure, (P =.042). Female recipients receiving male organs had no significant change in the risk of graft failure (11.5%; P =.368). A worse outcome was found in male recipients receiving female organs (12.9%; P =.0003). Graft failure rate among patients with donors matched by race (white to white or nonwhite to nonwhite; n = 21,818) was 11.6% versus 11.9%, and among unmatched patients (n = 10,697), the difference was not significant (P =.33). Multivariate regression analysis controlling for potential confounders confirmed that this difference was not significant (P =.21). Mismatch between black donors and white recipients was found to increase the risk of liver graft failure (27.4%, P = <.0001), independently of gender, number of comorbidities, and functional status at time of transplant.

Association of cytokine single nucleotide polymorphisms with B7 costimulatory molecules in kidney allograft recipients

African-American race is associated with an increased risk of allograft loss, suggesting that African-American patients may form an immunologically higher risk group. Previously, we demonstrated that immune cell costimulatory molecule expression is significantly higher in African-Americans than in Caucasians. Polymorphic variations in the genes for cytokines have been associated with a number of immunological conditions, and with transplant rejection. This study was performed to determine the distribution, in African-American and Caucasian renal transplant recipients, of single nucleotide polymorphisms (SNPs) in the following cytokine genes: tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-6, IL-10, and transforming growth factor-beta (TGF-beta). Cytokine production from blood cells was determined, and cell-surface B7 (CD80, CD86) expression was measured. There was a significant link between IL-10 genotype and acute rejection episodes, but only in African-American patients (p < 0.01). Also, African-American patients had a significantly higher probability of having the IL-6 G-allele (p < 0.0001), which is associated with a high production of IL-6 protein. Incubation of blood cells with IL-6 resulted in increased expression of surface CD80 and CD86, while IL-10 decreased CD80 expression. This study demonstrated a clear correlation of the IL-6 G-allele with increased cellular CD80 expression and the IL-10 G-allele with decreased CD80 expression. These data raise the possibility that specific genotypes are associated with local cytokine regulation of cell-surface costimulatory molecule expression. African-American patients may have a genetically determined, quantitatively different immune response than Caucasian patients, contributing to adverse transplant outcomes.

Decreased effect of immunosuppression on immunocompetence in African--Americans after kidney and liver transplantation

Several studies indicate that the poorer outcomes for African--Americans after transplantation may be due to decreased effectiveness of immunosuppressive agents. Using an in vitro test of immunocompetence (IMC), we measured the effects of immunosuppression on African-American, compared with Caucasian, kidney or liver transplantation recipients. The IMC result was the highest of three mixed lymphocyte culture responses using validated stimulator cell pools. A total of 293 tests were done in Caucasians and 144 in African--Americans. Overall, the IMC for African--Americans was 38, compared with 19 for Caucasians (p<0.01). This decreased effect of immunosuppression (higher IMC) was the same for liver as for kidney transplant recipients, occurred at the 2--3-yr interval, and was largely in patients of tacrolimus (FK506), with a strong but not significant trend in cyclosporine (CYA) recipients. The two groups were on the same nominal immunosuppression and FK506 and CYA levels were not different. We conclude that African-Americans retain more immune responsiveness on equivalent dose immunosuppression, notable particularly in years 2--3 after transplantation when earlier graft loss occurs in this group.

Increased costimulatory responses in African-American kidney allograft recipients

BACKGROUND

The issue of racial differences in immune responses has been seldom investigated, despite the increased incidence of transplant rejection and inferior allograft outcomes in African-Americans (AA). We previously reported significantly increased expression of costimulatory molecules on peripheral blood cells from healthy adult AA compared with Caucasian (CS) volunteers. This report extends the study to pediatric kidney allograft recipients.

METHODS

Surface antigen expression by peripheral blood mononuclear cells (MNC) from AA and CS transplant patients was determined by flow cytometry, after staining with specific antibodies. In vitro proliferation, in a one-way mixed lymphocyte response (MLR), was measured after stimulation with allogeneic irradiated mononuclear cells. The concentration of cyclosporine (CsA) achieving 50% inhibition (IC50) of in vitro proliferative responses to PHA and OKT3 was calculated.

RESULTS

MNC from AA patients were shown to have significantly higher expression of CD80 (CS 5.2% +/- 0.6, AA 9.6% +/- 1.2, P < 0.0001) than cells from CS patients. Additionally, the cells from AA transplant recipients proliferated significantly more in an MLR (stimulation index: CS 8 +/- S2, AA 25 +/- 8, P < 0.05), and the CsA IC50 values, during proliferation to PHA and OKT3, were significantly higher in AA compared to CS patients.

CONCLUSIONS

Although socioeconomic factors and therapeutic compliance are undoubtedly important issues in long-term allograft survival, our data suggest that AA patients mount more vigorous immune responses to antigens. The increased requirement for immunosuppression may be linked to racial variations in costimulatory molecule expression on antigen-presenting cells.