SWI/SNF chromatin remodeling enzymes in melanocyte differentiation and melanoma

Epidermal melanocytes are pigment-producing cells derived from the neural crest that protects skin from the damaging effects of solar radiation. Malignant melanoma, a highly aggressive cancer, arises from melanocytes. SWI/SNF enzymes are multiprotein complexes that remodel chromatin structure and have extensive roles in cellular differentiation. Components of the complex have been found to be mutated or lost in several human cancers. This review focuses on studies that implicate SWI/SNF enzymes in melanocyte differentiation and in melanoma.

Monitoring T cell alloreactivity

Currently, immunosuppressive therapy in kidney transplant recipients is center-specific, protocol-driven, and adjusted according to functional or histological evaluation of the allograft and/or signs of drug toxicity or infection. As a result, a large fraction of patients receive too much or too little immunosuppression, exposing them to higher rates of infection, malignancy and drug toxicity, or increased risk of acute and chronic graft injury from rejection, respectively. The individualization of immunosuppression requires the development of assays able to reliably quantify and/or predict the magnitude of the recipient's immune response toward the allograft. As alloreactive T cells are central mediators of allograft rejection, monitoring T cell alloreactivity has become a priority for the transplant community. Among available assays, flow cytometry based phenotyping, T cell proliferation, T cell cytokine secretion, and ATP release (ImmuKnow), have been the most thoroughly tested. While numerous cross-sectional studies have found associations between the results of these assays and the presence of clinically relevant post-transplantation outcomes, data from prospective studies are still scanty, thereby preventing widespread implementation in the clinic. Future studies are required to test the hypothesis that tailoring immunosuppression on the basis of results offered by these biomarkers leads to better outcomes than current standard clinical practice.

The Kidney Donor Profile Index (KDPI) of marginal donors allocated by standardized pretransplant donor biopsy assessment: distribution and association with graft outcomes

Pretransplant donor biopsy (PTDB)-based marginal donor allocation systems to single or dual renal transplantation could increase the use of organs with Kidney Donor Profile Index (KDPI) in the highest range (e.g. >80 or >90), whose discard rate approximates 50% in the United States. To test this hypothesis, we retrospectively calculated the KDPI and analyzed the outcomes of 442 marginal kidney transplants (340 single transplants: 278 with a PTDB Remuzzi score<4 [median KDPI: 87; interquartile range (IQR): 78-94] and 62 with a score=4 [median KDPI: 87; IQR: 76-93]; 102 dual transplants [median KDPI: 93; IQR: 86-96]) and 248 single standard transplant controls (median KDPI: 36; IQR: 18-51). PTDB-based allocation of marginal grafts led to a limited discard rate of 15% for kidneys with KDPI of 80-90 and of 37% for kidneys with a KDPI of 91-100. Although 1-year estimated GFRs were significantly lower in recipients of marginal kidneys (-9.3, -17.9 and -18.8 mL/min, for dual transplants, single kidneys with PTDB score<4 and =4, respectively; p<0.001), graft survival (median follow-up 3.3 years) was similar between marginal and standard kidney transplants (hazard ratio: 1.20 [95% confidence interval: 0.80-1.79; p=0.38]). In conclusion, PTDB-based allocation allows the safe transplantation of kidneys with KDPI in the highest range that may otherwise be discarded.

Immunosuppressive effects of erythropoietin on human alloreactive T cells

Correction of anemia with erythropoietin (EPO) is associated with improved kidney transplant outcomes. Emerging evidence, predominantly from animal models, indicates that these observations may be erythropoiesis-independent and that EPO exhibits immunosuppressive properties. We examined the effects of EPO on human T-cell alloimmunity by first documenting that CD4(+) and CD8(+) T cells express EPO receptor (EPO-R) on their surfaces. In mixed lymphocyte reactions, EPO induced a dose-dependent decrease in allogeneic CD4(+) T-cell proliferation (EPO 1000 U/ml: 44.6%±22.9% of vehicle, P<0.05; 2000 U/ml: 11.1%±4% of vehicle, P<0.001) without inducing cell death. The effects required signals transmitted directly through the EPO-R expressed on T cells, resulting in diminished Th1 differentiation without effects on regulatory T-cell induction. Mechanistic studies revealed that EPO prevented IL-2-induced proliferation by uncoupling IL-2 receptor signaling, inhibiting phosphorylation of the intracellular intermediaries AKT and extracellular signal-regulated kinase that are known to mediate T-cell expansion. EPO treatment reduced expansion of human naïve CD4(+) T cells after adoptive transfer into NOD scid γc(null) mouse recipients, verifying the effects in vivo. Although activated T cells expressed CD131, an alternative EPO receptor, addition of a specific CD131 agonist peptide, ARA290, did not alter T-cell proliferation or cytokine production. Our findings link EPO-R signaling on T cells to inhibition of T-cell immunity, providing one mechanism that could explain the observed protective effects of EPO in kidney transplant recipients.

Diabetic nephropathy in a nonobese mouse model of type 2 diabetes mellitus

A large body of research has contributed to our understanding of the pathophysiology of diabetic nephropathy. Yet, many questions remain regarding the progression of a disease that accounts for nearly half the patients entering dialysis yearly. Several murine models of diabetic nephropathy secondary to Type 2 diabetes mellitus (T2DM) do exist, and some are more representative than others, but all have limitations. In this study, we aimed to identify a new mouse model of diabetic nephropathy secondary to T2DM in a previously described T2DM model, the MKR (MCK-KR-hIGF-IR) mouse. In this mouse model, T2DM develops as a result of functional inactivation of insulin-like growth factor-1 receptor (IGF-1R) in the skeletal muscle. These mice are lean, with marked insulin resistance, hyperinsulinemia, hyperglycemia, and dyslipidemia and thus are representative of nonobese human T2DM. We show that the MKR mice, when under stress (high-fat diet or unilateral nephrectomy), develop progressive diabetic nephropathy with marked albuminuria and meet the histopathological criteria as defined by the Animal Models of Diabetic Complications Consortium. Finally, these MKR mice are fertile and are on a common background strain, making it a novel model to study the progression of diabetic nephropathy.

Low Dietary Intake of Vitamin D and Vitamin D Deficiency in Hemodialysis Patients

BACKGROUND

The purpose of this study was to test the hypothesis that decreased dietary intake of Vitamin D contributes to Vitamin D deficiency in end-stage renal disease (ESRD) patients on hemodialysis (HD).

METHODS

We performed a cross-sectional study of 58 hemodialysis outpatients from two Mount Sinai Medical Center (MSMC)-affiliated outpatient HD units in New York City and 648 outpatients at MSMC with CKD stages I-IV. Serum 25(OH)D concentrations were measured from August 2010 to July of 2011 in recruited hemodialysis patients (n=58) and linked with results of dietary and lifestyle surveys. The Mount Sinai Data Warehouse (electronic medical record) was used to capture 25(OH) Vitamin D levels for outpatients with CKD stages I-IV who had Vitamin D testing during the same time period.

RESULTS

The prevalence of Vitamin D insufficiency/deficiency in the HD cohort was 96.6%. Mean (SD) and median (IQR) 25(OH)D concentrations were 15.65 (6.82) and 13.55 (10.15) ng/mL, respectively. Dietary surveys showed a median weekly Vitamin D intake of 1044 IU (IQR=808, vs. a recommended weekly allowance of 4200 IU) and specific avoidance of foods containing both Vitamin D and phosphorus. In contrast, mean and median 25(OH)D concentrations in patients with CKD stages I-IV were 25.66 (13.44) and 23.60 (15.48) ng/mL (p<0.001 vs. HD patients).

CONCLUSIONS

Vitamin D deficiency is more prevalent in HD patients than in pre-dialysis patients with CKD and is associated with decreased dietary intake of Vitamin D. Dialysis restrictions imposed to reduce dietary phosphorus intake likely contributes to the development of hypovitaminosis D in ESRD patients.

The association of IL28B polymorphism and graft survival in patients with hepatitis C undergoing liver transplantation

Hepatitis C virus (HCV) infection is the leading cause of liver transplantation (LT) in Western countries. Polymorphism in the IL28B gene region has a major impact on the natural history and response to antiviral treatment in HCV. We investigated whether IL28B polymorphism was associated with graft survival in patients with or without HCV undergoing LT. 1,060 adult patients (age >18 years) underwent LT between years 2000 and 2008. Patients with previous LT, living donor LT and patients dying or requiring retransplants within 30 days of LT were excluded. DNA samples of 620 (84%) recipients and 377 (51%) donors were available for genotyping of IL28B rs12979860C>T. Donor IL28B genotypes had no significant differences in graft survival irrespective of HCV status. There was no difference in graft outcome in the non-HCV cohort (n = 293) based on recipient IL28B genotype. In the HCV group (n = 327), recipients with CC or CT genotype had better graft survival compared to TT genotype (62% vs. 48%, p = 0.02). HCV recipients with CC or CT genotype had delayed time to clinically relevant HCV recurrence compared to TT (10.4 vs. 6.7 months, p = 0.002). The beneficial effect of the CC/CT genotype on HCV recurrence and graft survival was independent of antiviral treatment. In conclusion, our study demonstrated that in contrast to donor IL28B genotype recipient IL28B was associated with graft survival and clinically relevant HCV recurrence in HCV infected recipients. No effect of IL28B genotype was manifest in non-HCV LT recipients.

Congenital paediatric atlantoaxial dislocation: clinico-radiological profile and surgical outcome

INTRODUCTION

Congenital atlantoaxial dislocation (AAD) is the most common bony abnormality affecting the craniovertebral junction. The paediatric population has specific problems like preoperative diagnostic difficulties, precise neurological examination, radiological diagnosis, surgical problems including physical fitness to tolerate surgery (including problems of anaesthesia), technical difficulties in surgery and problems related to immobilization.

MATERIAL AND METHODS

A total of 229 consecutive paediatric (≤18 years) patients of AAD visited our centre from the period of January 1997 to August 2011. Twenty-nine cases were excluded from the study as these cases were diagnosed as CVJ tuberculosis, 31 cases were excluded as they were traumatic and the remaining 169 cases were retrospectively analysed. These patients were operated by a single experienced surgeon (the senior author) at the Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow. The preoperative and the postoperative clinical evaluation of the patient was done by the Kumar and Kalra myelopathic scoring system. The score was recorded in the preoperative period, at the time of discharge, at 3 months follow-up and at 6 months follow-up.

RESULTS

Ninety-four were males and 75 were females. The age range was 4 to 18 years with mean age 9.96±3.78 years. The follow-up ranged from 3 to 120 months with mean follow-up being 39.03±13.38 months. One hundred five cases were of fixed/irreducible AAD, and 64 were cases of mobile/reducible AAD. Majority of these cases presented with features of pyramidal tract involvement, and 108 cases had compromised pulmonary function test. One hundred thirty-seven cases had improved outcome, and 18 cases were in the same grade in the postoperative period with only 14 cases either deteriorated or died.

CONCLUSIONS

Congenital paediatric AAD are a different subset of abnormalities and have a satisfactory outcome. Preoperative evaluation must also include identification of various syndromes associated with paediatric AAD and respiratory reserve. Cormack-Lehane grade can be helpful in selecting borderline cases for postoperative need of tracheostomy. Majority of the cases have a good outcome, and therefore, surgery should be offered even in severe grade.

Deterministic characterization of phase noise in biomolecular oscillators

On top of the many external perturbations, cellular oscillators also face intrinsic perturbations due the randomness of chemical kinetics. Biomolecular oscillators, distinct in their parameter sets or distinct in their architecture, show different resilience with respect to such intrinsic perturbations. Assessing this resilience can be done by ensemble stochastic simulations. These are computationally costly and do not permit further insights into the mechanistic cause of the observed resilience. For reaction systems operating at a steady state, the linear noise approximation (LNA) can be used to determine the effect of molecular noise. Here we show that methods based on LNA fail for oscillatory systems and we propose an alternative ansatz. It yields an asymptotic expression for the phase diffusion coefficient of stochastic oscillators. Moreover, it allows us to single out the noise contribution of every reaction in an oscillatory system. We test the approach on the one-loop model of the Drosophila circadian clock. Our results are consistent with those obtained through stochastic simulations with a gain in computational efficiency of about three orders of magnitude.

Anticardiac myosin immunity and chronic allograft vasculopathy in heart transplant recipients

Chronic allograft vasculopathy (CAV) contributes to heart transplant failure, yet its pathogenesis is incompletely understood. Although cellular and humoral alloimmunity are accepted pathogenic mediators, animal models suggest that T cells and Abs reactive to graft-expressed autoantigens, including cardiac myosin (CM), could participate. To test the relationship between CAV and anti-CM autoimmunity in humans, we performed a cross-sectional study of 72 heart transplant recipients: 40 with CAV and 32 without. Sera from 65% of patients with CAV contained anti-CM Abs, whereas <10% contained Abs to other autoantigens (p < 0.05), and only 18% contained anti-HLA Abs (p < 0.05 versus anti-CM). In contrast, 13% of sera from patients without CAV contained anti-CM Abs (p < 0.05; odds ratio [OR], associating CAV with anti-CM Ab = 13, 95% confidence interval [CI] 3.79-44.6). Multivariable analysis confirmed the association to be independent of time posttransplant and the presence of anti-HLA Abs (OR = 28, 95% CI 5.77-133.56). PBMCs from patients with CAV responded more frequently to, and to a broader array of, CM-derived peptides than those without CAV (p = 0.01). Detection of either CM-peptide-reactive T cells or anti-CM Abs was highly and independently indicative of CAV (OR = 45, 95% CI 4.04-500.69). Our data suggest detection of anti-CM immunity could be used as a biomarker for outcome in heart transplantation recipients and support the need for further studies to assess whether anti-CM immunity is a pathogenic mediator of CAV.

Antibodies reactive to non-HLA antigens in transplant glomerulopathy

Although T and B cell alloimmunity contribute to transplant injury, autoimmunity directed at kidney-expressed, non-HLA antigens may also participate. Because the specificity, prevalence, and importance of antibodies to non-HLA antigens in late allograft injury are poorly characterized, we used a protein microarray to compare antibody repertoires in pre- and post-transplant sera from several cohorts of patients with and without transplant glomerulopathy. Transplantation routinely induced changes in antibody repertoires, but we did not identify any de novo non-HLA antibodies common to patients with transplant glomerulopathy. The screening studies identified three reactivities present before transplantation that persisted after transplant and strongly associated with transplant glomerulopathy. ELISA confirmed that reactivity against peroxisomal-trans-2-enoyl-coA-reductase strongly associated with the development of transplant glomerulopathy in independent validation sets. In addition to providing insight into effects of transplantation on non-HLA antibody repertoires, these results suggest that pretransplant serum antibodies to peroxisomal-trans-2-enoyl-coA-reductase may predict prognosis in kidney transplantation.

Late post-transplant erythrocytosis in a hepatitis C-positive allograft recipient on sirolimus

Hematological complications in renal transplant recipients include anemia, leukopenia, and post-transplant erythrocytosis (PTE). There are numerous causes for these which include immunosuppressive drugs, viral infections, etc. We report here a hepatitis C (HCV)-positive case who developed PTE while receiving rapamycin. As both HCV infection and rapamycin through different mechanisms can produce anemia, this case report highlights the rarity of erythrocytosis.

Complement component C3 allotypes and outcomes in liver transplantation

The complement system has been implicated in the pathogenesis of liver diseases. Human complement component C3 (C3) exists as 2 allotypes, fast (F) and slow (S). We conducted a study to address the influence of these alleles on ischemia-reperfusion (IR) injury and graft survival in liver transplant recipients. Four hundred thirty patients receiving liver transplants from 2000 to 2004 were included. C3 allotypes of 296 donor-recipient pairs were determined and correlated with clinical outcomes. Four groups were analyzed according to the C3 genotype: C3 SS donor and recipient, C3 FS or C3 FF donor and C3 SS recipient, C3 SS donor and C3 FS or C3 FF recipient, and C3 FS or C3 FF donor and recipient. Baseline characteristics of the 4 groups were similar. The mean follow-up time was 4.3 +/- 2.2 years. The 4 groups had similar rates of IR injury (P = 0.16). The hazard ratios for liver allograft survival in the C3 SS donor and recipient group in comparison with the other 3 groups (C3 FS or C3 FF donor and C3 SS recipient, C3 SS donor and C3 FS or C3 FF recipient, and C3 FS or C3 FF donor and recipient) were not significantly different: 1.13 (P = 0.60), 0.99 (P = 0.97), and 1.02 (P = 0.95), respectively. In conclusion, donor and recipient C3 genotypes are not associated with liver transplantation outcomes.

Trastuzumab (Herceptin)-associated lung injury

We report a case of trastuzumab pneumonitis in a patient with metastatic breast cancer. Bronchoalveolar lavage showed marked neutrophilia. A CT scan of the chest showed diffuse ground-glass opacities. The patient was treated with corticosteroids with a partial response. Trastuzumab-associated pneumonitis is not well described, and data in the literature is sparse. We describe the clinical and radiographical findings of trastuzumab-associated pneumonitis.