Luis E. Morales-Buenrostro

Natural Human Leukocyte Antigen Antibodies Found in Nonalloimmunized Healthy Males

Background. Human leukocyte antigen (HLA) antibodies were normally not found in subjects who have not been immunized by pregnancies, transfusions, or transplants. But with new methodology, we now see that HLA antibodies are often found in nonalloimmunized males. Methods. The sera of 424 healthy male donors were tested with single antigen Luminex beads. Results. Human leukocyte antigen antibodies were detected in 63% of 424 male blood donors when a fluorescent value of more than 1000 was used as the cutoff. Antibodies to class I was found in 42%, class II in 11% and both in 12%. Five males who were tested eight times over a 6-month period consistently had the same specificity at similar strength levels at each testing. The antibodies reacted with specificities that are rare in the general population: 18.9% had antibodies to A*3002; more than 10% had antibodies to A*3101, B76, B*8201, and Cw*1701. About half of the donors with antibodies had one or two specificities; the other half had three or more specificities. Among those with class II specificities, 20.5% had antibodies to DPA1*0201/DPB1*0101, and 10.8% to DQA1*0503/DQB1*0301. Because the above data were obtained by testing sera of 424 Mexican donors, as a check, 29 males in Los Angeles were tested and shown to have similar specificities at roughly similar frequencies. Conclusions. Normal males were found to have HLA antibodies to infrequent HLA specificities. It is likely that these HLA antibodies are produced to cross-reactive epitopes found in microorganisms, ingested proteins and allergens—making them natural antibodies.

Epitopes of human leukocyte antigen class I antibodies found in sera of normal healthy males and cord blood

This study defines 96 epitopes targeted by human leukocyte antigen (HLA) antibodies reported in the sera of normal healthy males with no history of deliberate alloimmunizations and in cord blood. These epitopes are accessible for antibody binding on either the intact or the dissociated forms of recombinant HLA class I single antigens. Sixty percent of the epitopes are accessible on dissociated antigens, are defined mostly by hidden amino acids, and are designated as cryptic epitopes. All 96 epitopes are located exclusively on A-, B-, or C-locus antigens except for one interlocus epitope. All sera in this study were tested in parallel, using single antigen beads that bear either intact or dissociated HLA antigens and antibodies with nearly identical specificities were identified in all tested sera. Because the specificities of these naturally occurring antibodies are unavoidably detected when testing for specificities of alloantibodies, it may be necessary to clearly differentiate the two forms of antibody. To date, the relevance of these antibodies in transplantation is unknown, but even if they are determined to be irrelevant to graft rejection, awareness of the newly identified epitopes could prove useful in avoiding the unnecessary exclusion of potential transplant donors.

Antibodies to HLA-E in Nonalloimmunized Males: Pattern of HLA-Ia Reactivity of Anti–HLA-E–Positive Sera

Natural anti-HLA Abs found in sera of healthy nonalloimmunized males recognize HLA-Ia alleles parallel to those recognized by anti–HLA-E mAbs (MEM-E/02/06/07). Therefore, some of the HLA-Ia Abs seen in healthy males could be due to anti–HLA-E Abs cross-reacting with HLA-Ia. If anti–HLA-E Abs occur in healthy nonalloimmunized males, it can be assessed whether they evoke HLA-Ia reactivity as do mouse HLA-E mAbs. IgG and IgM Abs to HLA-E and HLA-Ia alleles are identified in sera of healthy males using microbeads coated with recombinant denatured HLA-E or a panel of rHLA-Ia alleles. The pattern of allelic recognition is comparable to that of anti–HLA-E mAbs. Sixty-six percent of the sera with HLA-E IgG have a high level of HLA-Ia IgG, whereas 70% of those with no anti–HLA-E Abs have no HLA-Ia Abs. HLA-E IgM/IgG ratios of sera are divided into four groups: IgMLow/IgGLow, IgMHigh/IgGLow, IgMHigh/IgGHigh, and IgMLow/IgGHigh. These groups correspond to anti–HLA-Ia IgM/IgG ratio groups. When HLA-E IgM and IgG are absent or present in males, the IgM or IgG of HLA-Ia are similarly absent or present. The mean fluorescent intensity of HLA-Ia Abs correlates with that of anti–HLA-E Abs. Most importantly, HLA-E and HLA-Ia reactivities of the sera are inhibited by the shared, but cryptic, peptide sequences 117AYDGKDY123 and 137DTAAQIS143. Therefore, Abs to the H chain of HLA-E may be responsible for some of the HLA-Ia allele reactivity of the natural HLA-Ia Ab in human sera. Absence of any anti–HLA-Ia Abs in 112 nonvegans and the presence of the same in vegans suggest that dietary meat proteins might not have induced the natural allo-HLA Abs.

Hsp72 is an early and sensitive biomarker to detect acute kidney injury

This study was designed to assess whether heat shock protein Hsp72 is an early and sensitive biomarker of acute kidney injury (AKI) as well as to monitor a renoprotective strategy. Seventy‐two Wistar rats were divided into six groups: sham‐operated and rats subjected to 10, 20, 30, 45 and 60 min of bilateral ischemia (I) and 24 h of reperfusion (R). Different times of reperfusion (3, 6, 9, 12, 18, 24, 48, 72, 96 and 120 h) were also evaluated in 30 other rats subjected to 30 min of ischemia. Hsp72 messenger RNA (mRNA) and protein levels were determined in both kidney and urine. Hsp72‐specificity as a biomarker to assess the success of a renoprotective intervention was evaluated in rats treated with different doses of spironolactone before I/R. Renal Hsp72 mRNA and protein, as well as urinary Hsp72 levels, gradually increased relative to the extent of renal injury induced by different periods of ischemia quantified by histomorphometry as a benchmark of kidney damage. Urinary Hsp72 increased significantly after 3 h and continued rising until 18 h, followed by restoration after 120 h of reperfusion in accord with histopathological findings. Spironolactone renoprotection was associated with normalization of urinary Hsp72 levels. Accordingly, urinary Hsp72 was significantly increased in patients with clinical AKI before serum creatinine elevation. Our results show that urinary Hsp72 is a useful biomarker for early detection and stratification of AKI. In addition, urinary Hsp72 levels are sensitive enough to monitor therapeutic interventions and the degree of tubular recovery following an I/R insult.

Time-zero renal biopsy in living kidney transplantation: a valuable opportunity to correlate predonation clinical data with histological abnormalities.

Background. Living kidney donation is increasing as a partial solution for wait-listed patients. Despite properly followed guideline criteria for donor selection, current reports identify unsuspected renal pathology at preimplantation or time-zero biopsy (T0-RBx). Methods. T0-RBx was evaluated for following: interstitial fibrosis (IF), tubular atrophy (TA), arteriolar hyalinosis (AH), mesangial increase (MI), and glomerulosclerosis (GS). Predonation data were demography, body weight, body mass index (BMI), systolic/diastolic blood pressure (BP), serum creatinine (SCr), estimated glomerular filtration rate (eGFR), and proteinuria. Results. Two hundred nineteen T0-RBx were analyzed. Of these 54.4% had abnormal findings, namely, IF in 29%, TA in 13%, MI in 12%, AH in 10%, and GS in 10%. Mean clinical data were as follows: age 35.4±10 years, weight 66.27±10.14 kg, BMI 25.53±2.99, systolic BP 115±9 mm Hg, diastolic BP 74±7 mm Hg, SCr 0.91±0.25 mg/dL, eGFR 96±16.65 mL/min, and proteinuria 70.25±62.8 mg/24 hr. A total of 56.7% were women. IF correlated to age (r=0.22, P=0.001) and SCr (r=0.19, P=0.005); TA to diastolic BP (r=0.15, P=0.03) and proteinuria (r=0.20, P=0.009); AH to SCr (r=0.15, P=0.02) and eGFR (r=−0.16, P=0.018); MI to BMI (r=0.13, P=0.047). Multivariate analysis failed to sustain the significant associations found on bivariate analysis, most likely due to a low event/parameter relation and sample size. Conclusions. A significant correlation was established between T0-RBx findings and clinical predonation parameters. Whether these mild histologic findings at the time of kidney donation represent a higher risk for the remaining kidney ought to be evaluated during follow-up. In an era, when living kidney donation is increasing, we advise closer donor surveillance to modify risk factors that participate in kidney damage progression.

Análisis del factor de impacto de las revistas científicas latinoamericanas

Few Latin-American journalsare included in the Thomson ISI data base. The mean impact factor was 0.76 (0.23-3.2) foreight Mexican journals, 0.66 (0.10-2.1) for eight Chilean journals, 0.39 (0.06-0.7) for fiveArgentinian journals and 0.41 (0.09-1.1) for 16 Brazilian journals. The mean impact factorfor 11 journals written in English was 0.74 (0.12-2.1), 0.53 (0.09-3.2) for 18 bilingual journalsand 0.28 (0.06-0.56) for eight journals written in native language. The differences betweencountries and languages were not statistically significant.

CYP3A5 polymorphism in Mexican renal transplant recipients and its association with tacrolimus dosing.

BACKGROUND AND AIMS Variability in CYP3A5 expression associated with differences in tacrolimus bioavailability has been documented. The wild-type allele CYP3A5*1 expresses the functional protein, whereas the CYP3A5*3 allele is a splice variant with a premature stop codon and encodes a truncated nonfunctional protein. The aim of the study was to determine the frequency of CYP3A5*1 and CYP3A5*3 in 291 (124 adults, 167 pediatric) Mexican renal transplant recipients, evaluate the tacrolimus dose requirements by genotype and compare genotype frequency data with that of other populations. METHODS We carried out a multicenter study. Patients were recruited from three institutions located in Mexico City. Genotyping of the CYP3A5*1 and CYP3A5*3 alleles was performed by direct DNA sequencing. RESULTS Eighteen patients (6.2%) were CYP3A5*1*1 homozygous carriers or functional protein expresser homozygous, 121 patients (41.6 %) were CYP3A5*1*3 were heterozygous carriers or heterozygous expressers, and 152 patients (52.2%) were CYP3A5*3*3 homozygous carriers or homozygous nonexpressers. There was a statistically significant difference in frequency of the functional and nonfunctional expresser phenotypes from those reported for Black and Caucasian, but not for South Asian populations. The CYP3A5 phenotype had a significant impact in tacrolimus bioavailability, as wild-type carriers required higher dosing compared to mutated carriers to achieve similar drug trough levels. Patients with CYP3A5*1*1 genotype had a median dose requirement of 0.16 mg/kg/day, CYP3A5*1*3 patients had a median tacrolimus dose of 0.13 mg/kg/day and CYP3A5*3*3 had a median dose of 0.07 mg/kg/day (Kruskal-Wallis, p <0.0001). CONCLUSIONS Of the Mexican transplant recipients, 52.2% were CYP3A5*3*3 and required significantly lower tacrolimus dose than those with CYP3A5*1 allele.

Mineralocorticoid Receptor Blockade Reduced Oxidative Stress in Renal Transplant Recipients: A Double-Blind, Randomized Pilot Study

Background: Previous experimental studies from our laboratory have demonstrated that aldosterone plays a central role in renal ischemic processes. This study was designed to evaluate the effect of mineralocorticoid receptor blockade in renal transplant recipients from living donors. Methods: 20 adult kidney transplant recipients from living donors were included in a double-blind, randomized, placebo-controlled clinical pilot study that compared spironolactone and placebo. Placebo or spironolactone (25 mg) was administered 1 day before and 3 days posttransplantation. Renal function and urinary kidney injury molecule-1, interleukin-18, and heat shock protein 72 as well as urinary hydrogen peroxide (H2O2) levels were quantified. Results: No significant differences were seen between the groups studied regarding age, gender, indication for kidney transplantation, residual renal function, renal replacement therapy, or warm and cold ischemia periods. In contrast, spironolactone administration significantly reduced the oxidative stress assessed by the urinary H2O2 excretion, in spite of no differences in renal function or reduction in tubular injury biomarkers. Conclusions: The findings of this exploratory study strongly suggest that aldosterone promotes oxidative stress and that the administration of spironolactone reduces the production of urinary H2O2 as a result of lesser formation of surrogate reactive oxygen species secondary to the ischemia-reperfusion phenomenon.

Neurocognitive Profile of an Adult Sample With Chronic Kidney Disease

Chronic kidney disease (CKD) is a common and debilitating illness that impacts neurocognitive function. However, the majority of previous studies varied in methodologic design and rigor, thus minimizing definitive conclusions. The present study was designed to determine the impact of CKD on neurocognitive function through specific examination of CKD factors and therapeutic interventions. We evaluated 120 CKD outpatients and 41 healthy donors (controls) in terms of neurocognitive function, anxiety, and depressive symptomatology, and somnolence. Information regarding medical and treatment history was recorded. Twenty-three percent of CKD patients presented with cognitive impairment. Stage 5 patients had lower scores (p < .05) compared with controls and patients in stage 3 and 4 on measures of global cognitive function. No differences in global cognitive function were found between stage 3 and 4 patients and controls. A greater proportion of patients undergoing hemodialysis relative to those treated with peritoneal dialysis showed impairment on measures of memory functions. Results suggest that stage 5 CKD patients may present with impaired cognitive functions. Anemia appeared to be a key variable that may explain the memory impairment in this sample. Future longitudinal investigations of CKD are warranted to determine the trajectory of cognitive impairment.

Probability of deceased donor kidney transplantation based on % PRA

UNLABELLED Sensitization to HLA antigens creates an obstacle for the accessibility and success of kidney transplantation (KT). Highly sensitized patients have longer waiting times and some may never receive a KT. AIM To determine the probability of patients on the deceased donor (DD) waiting list to receive a KT based on the panel reactive antibody percentage (% PRA) in our center. METHODS The DD waiting list from our institution was analyzed from 01/05 to 08/12 documenting the clinical variables from donor and potential recipients (ABO blood group), lymphocyte cross-match [CxM (CDC-AHG)] results, highest % PRA determination, and time on the waiting list. The patients were classified into 4 groups based on the % PRA: 0%, 1-19%, 20-79% and 80-100%. The data was analyzed using odds ratio and logistic regression (significant p<0.05). RESULTS 58 DD (F:M 34:24, ABO group O=35, A=13, B=10) and 179 potential recipients were analyzed (F:M 98:81, ABO group O=127, A=33, B=19, participating 4.2 ± 3.8 times with different donors to receive KT). The mean PRA for the whole group was 22 ± 32%, median [md] 0 (0-98). A total of 100 patients received KT (mean waiting time 2.2 ± 1.7 years, 12 days-7 years) and their mean % PRA was 11.6 ± 24, md 0 (0-94) vs. 31.4 ± 37 md 8.5 (0-98) in those who have not received a KT. An association between the % PRA group and KT (p<0.003) was observed. The probability of receiving KT with a 0% PRA vs. >0% was higher (OR 2.12, 1.17-3.84). There was no difference between the 0% vs. 1-19% group (OR 1); differences were observed between 0% vs. 20-79% (OR 2.5, 1.18-5.3) and 0% vs. 80-100% (OR 5, 1.67-14.9). For every percent increase in the PRA above 20%, the risk of not receiving a KT increased by 5% (1-9, p<0.01). CONCLUSIONS The probability of receiving a DD kidney transplant is inversely related to the % PRA although a higher risk for not receiving a KT becomes evident with a PRA >20%.