Brian P. Pollack

Gadolinium-Containing Magnetic Resonance Imaging Contrast and Nephrogenic Systemic Fibrosis: A Case-Control Study

BACKGROUND Nephrogenic systemic fibrosis (NSF) is a newly described disorder occurring in persons with renal failure. Gadolinium-based contrast used in magnetic resonance imaging (MRI) has been suggested as a cause. A cluster of patients with NSF was investigated to identify risk factors. Limited preliminary findings from this investigation were presented in the Morbidity and Mortality Weekly Report. STUDY DESIGN Matched case-control. SETTING & PARTICIPANTS Dialysis patients with and without a diagnosis of NSF treated at an academic medical center. PREDICTOR Exposure to gadolinium-based contrast. OUTCOMES & MEASUREMENTS Laboratory and clinical characteristics of NSF. RESULTS 19 of 28 cases identified at the hospital from December 2002 to August 2006 met inclusion criteria and were matched to 57 controls. In univariate analysis, receipt of gadolinium-containing MRI contrast in the preceding year (odds ratio [OR], 7.99; 95% confidence interval, 2.22 to 28.8) was associated with NSF; the measure of association increased as cumulative dose increased. Gadodiamide exposure (OR, 9.83; 95% confidence interval, 2.09 to 46.2) was associated more strongly with NSF than gadoversetamide (OR, 1.82; 95% confidence interval, 0.33 to 10.2). Although not statistically significant, cases were more likely than controls to have undergone primarily peritoneal dialysis in the preceding 6 months. There was no significant difference in receipt of high-dose recombinant erythropoietin between cases and controls. In multivariable analysis, gadolinium contrast exposure (OR, 8.97; 95% confidence interval, 1.28 to 63.0) remained significantly associated with NSF. LIMITATIONS Retrospective design, small sample size, inability to completely evaluate erythropoietin. CONCLUSIONS Receipt of gadolinium-containing MRI contrast is associated with NSF in a dose-dependent manner. The risk associated with gadolinium may differ by contrast agent and dialysis modality. Use of gadolinium-based contrast agents should be avoided when possible in patients with renal failure.

Vemurafenib enhances MHC induction in BRAFV600E homozygous melanoma cells

To optimally integrate targeted kinase inhibitors and immunotherapies in the treatment of melanoma, it will be critical to understand how BRAFV600E mutational status and BRAFV600E inhibition influence the expression of genes that govern antitumor immune responses. Because major histocompatibility complex (MHC) molecules are critical for interactions between tumor cells and lymphocytes, we investigated the impact of BRAFV600E-selective inhibitors on the expression of MHC molecules. We found that the treatment of A375 melanoma cells with vemurafenib enhances the induction of MHC Class I and Class II molecules by interferon γ and IFNα2b. Consistent with these findings, we observed that the forced overexpression of BRAFV600E has the opposite effect and can repress the baseline expression of MHC Class I molecules in A375 cells. Further studies utilizing eight other melanoma cell lines revealed that the vemurafenib-mediated enhancement of MHC induction by IFNγ only occurs in the context of homozygous, but not heterozygous, BRAFV600E mutation. These findings suggest that BRAFV600E activity directly influences the expression of MHC molecules and the response to Type I and Type II IFNs. Furthermore, our data suggest that the effect of vemurafenib on the expression of immune system-relevant genes may depend on the zygosity of the BRAFV600E mutation, which is not routinely assessed in melanoma patients.

Epidermal growth factor receptor inhibition augments the expression of MHC class I and II genes.

Purpose: Diverse immune-related effects occur with the use of epidermal growth factor receptor inhibitors (EGFRI). In addition to the cutaneous inflammation induced by EGFRIs, these agents have been associated with the exacerbation of autoimmune skin disease and contact hypersensitivity, antiviral effects, and fatal alveolar damage in the setting of lung transplantation. Because EGFR ligands can modulate MHC class I (MHCI) and II (MHCII) molecule expression, we hypothesized that some of the immune-related effects of EGFRIs are due to direct effects on the expression of MHCI and/or MHCII molecules. Experimental Design: Primary human keratinocytes and a malignant keratinocyte cell line (A431) were treated with EGFRIs alone or prior to IFN-γ, a potent inducer of MHCI and MHCII molecule expression. CIITA, MHCI, and MHCII RNA expression was measured using quantitative real-time reverse transcriptase PCR, and cell surface MHCI and MHCII protein expression was measured using flow cytometry. Skin biopsies from patients were analyzed for MHCI and MHCII protein expression before and during therapy with an EGFRI using immunohistochemistry. Results: Both EGFR tyrosine kinase inhibitors and ligand-blocking antibodies (cetuximab) augmented the induction of MHCI and MHCII molecules by IFN-γ in primary and malignant human keratinocytes. Unexpectedly, the increase in MHCI protein expression did not require the presence of IFN-γ. Consistent with these in vitro findings, skin biopsies from cancer patients exhibited increased epidermal MHCI protein expression during therapy with an EGFRI as well as increases in MHCI and MHCII molecule RNA. Conclusions: These studies suggest that EGFRIs may influence immune/inflammatory responses by directly modulating MHC expression. Clin Cancer Res; 17(13); 4400–13. ©2011 AACR.

Role of radiation therapy as immune activator in the era of modern immunotherapy for metastatic malignant melanoma.

Metastatic melanoma is difficult to treat, and often portends a grim prognosis. For patients with cerebral metastases, the prognosis is even more dire. Systemic immunotherapy and targeted agents are emerging as the mainstay of treatment for metastatic melanoma. Although immunotherapy has been shown to prolong relapse-free survival and long-term control of micrometastatic disease, the response rate is suboptimal, prompting the need to optimize and improve therapy. Accumulating evidence suggests that in addition to effective locoregional control, radiation therapy (RT) may induce immune activation and expansion of T lymphocytes recognizing melanocyte-specific antigens including activated cytotoxic T lymphocytes that can potentially kill melanoma cells. In some cases, RT contributes to the clearance of metastatic disease in distant, nonirradiated regions, a bystander phenomenon called the abscopal effect. Here, we evaluate the potential promise of ablative radiation treatment in the era of modern immunotherapy by presenting a patient with metastatic melanoma who remained disease free for over 3 years after an initial diagnosis of advanced metastatic melanoma with brain, subcutaneous tissue, mesenteric, pelvic, and retroperitoneal involvement. The patient failed initial stereotactic radiosurgery, but responded to whole-brain RT in combination with interleukin-2 immunotherapy. Thus, combination RT with immunotherapy may be synergistic by promoting the release and processing of melanoma antigens that can be presented by dendritic cells. This in turn may augment the response to therapies that center on expansion and/or activation of antitumor T cells.

Flagellin, a TLR5 Agonist, Reduces Graft-versus-Host Disease in Allogeneic Hematopoietic Stem Cell Transplantation Recipients While Enhancing Antiviral Immunity

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality in patients treated with allogeneic hematopoietic stem cell transplantation (HSCT). Posttransplant immunosuppressive drugs incompletely control GVHD and increase susceptibility to opportunistic infections. In this study, we used flagellin, a TLR5 agonist protein (∼50 kDa) extracted from bacterial flagella, as a novel experimental treatment strategy to reduce both acute and chronic GVHD in allogeneic HSCT recipients. On the basis of the radioprotective effects of flagellin, we hypothesized that flagellin could ameliorate GVHD in lethally irradiated murine models of allogeneic HSCT. Two doses of highly purified flagellin (administered 3 h before irradiation and 24 h after HSCT) reduced GVHD and led to better survival in both H-2b → CB6F1 and H-2K → B6 allogeneic HSCT models while preserving >99% donor T cell chimerism. Flagellin treatment preserved long-term posttransplant immune reconstitution characterized by more donor thymic-derived CD4+CD25+Foxp3+ regulatory T cells and significantly enhanced antiviral immunity after murine CMV infection. The proliferation index and activation status of donor spleen-derived T cells and serum concentration of proinflammatory cytokines in flagellin-treated recipients were reduced significantly within 4 d posttransplant compared with those of the PBS-treated control recipients. Allogeneic transplantation of radiation chimeras previously engrafted with TLR5 knockout hematopoietic cells showed that interactions between flagellin and TLR5 expressed on both donor hematopoietic and host nonhematopoietic cells were required to reduce GVHD. Thus, the peritransplant administration of flagellin is a novel therapeutic approach to control GVHD while preserving posttransplant donor immunity.

Ultraviolet Radiation‐induced Transcription is Associated with Gene‐specific Histone Acetylation

UVR is an important environmental carcinogen and a powerful modulator of the cutaneous immune system. Exposure to UVR activates many signaling pathways leading to changes in the expression of several hundred genes. While the covalent modification of histones has been shown to play a central role in regulating gene expression, the impact of UVR on histone modifications and the contribution of histone acetyltransferases (HATs) and histone deacetylases (HDACs) to the UVR‐induced transcriptional response have not been completely characterized. In this report, we have examined the impact of UVR on histone H3 K9/14 acetylation. The potential role of UVR‐induced histone acetylation in the UVR transcriptional response was also explored using the HAT inhibitor curcumin and HDAC inhibitor trichostatin A (TSA). We found that UVR caused an increase in histone H3 acetylation within the promoter regions of ATF3, COX2, IL‐8, MKP1 and MnSOD. In most of the regions examined, histone H3 acetylation peaked 24 h after UVR and then returned to baseline levels by 72 h. The induction of ATF3, COX2 and MKP1 was blocked in the presence of curcumin at doses that decrease in vivo histone H3 acetylation but not at lower doses that do not affect acetylation levels. We also provide evidence that for ATF3, a transcriptional superinduction occurs after repeat exposures to UVR that can be recapitulated when the second UVR exposure is replaced with TSA treatment. Thus, UVR can alter histone acetylation within human keratinocytes and these changes may contribute to the UVR‐transcriptional response.

Less Is More: Ebola Virus Surface Glycoprotein Expression Levels Regulate Virus Production and Infectivity

ABSTRACT The Ebola virus (EBOV) surface glycoprotein (GP1,2) mediates host cell attachment and fusion and is the primary target for host neutralizing antibodies. Expression of GP1,2 at high levels disrupts normal cell physiology, and EBOV uses an RNA-editing mechanism to regulate expression of the GP gene. In this study, we demonstrate that high levels of GP1,2 expression impair production and release of EBOV virus-like particles (VLPs) as well as infectivity of GP1,2-pseudotyped viruses. We further show that this effect is mediated through two mechanisms. First, high levels of GP1,2 expression reduce synthesis of other proteins needed for virus assembly. Second, viruses containing high levels of GP1,2 are intrinsically less infectious, possibly due to impaired receptor binding or endosomal processing. Importantly, proteolysis can rescue the infectivity of high-GP1,2-containing viruses. Taken together, our findings indicate that GP1,2 expression levels have a profound effect on factors that contribute to virus fitness and that RNA editing may be an important mechanism employed by EBOV to regulate GP1,2 expression in order to optimize virus production and infectivity. IMPORTANCE The Ebola virus (EBOV), as well as other members of the Filoviridae family, causes severe hemorrhagic fever that is highly lethal, with up to 90% mortality. The EBOV surface glycoprotein (GP1,2) plays important roles in virus infection and pathogenesis, and its expression is tightly regulated by an RNA-editing mechanism during virus replication. Our study demonstrates that the level of GP1,2 expression profoundly affects virus particle production and release and uncovers a new mechanism by which Ebola virus infectivity is regulated by the level of GP1,2 expression. These findings extend our understanding of EBOV infection and replication in adaptation of host environments, which will aid the development of countermeasures against EBOV infection.

EGFR inhibitors, MHC expression and immune responses : Can EGFR inhibitors be used as immune response modifiers?

A recent study from our laboratory demonstrated that epidermal growth factor receptor (EGFR) inhibitors (EGFRIs) augment the expression of class I and class II MHC molecules. This finding provides an additional mechanism through which EGFRIs may exert anti-tumor effects and supports the notion that EGFRIs may influence adaptive immune responses by altering immune gene expression.

Skin cancer screening: recommendations for data-driven screening guidelines and a review of the US Preventive Services Task Force controversy

Melanoma is usually apparent on the skin and readily detected by trained medical providers using a routine total body skin examination, yet this malignancy is responsible for the majority of skin cancer-related deaths. Currently, there is no national consensus on skin cancer screening in the USA, but dermatologists and primary care providers are routinely confronted with making the decision about when to recommend total body skin examinations and at what interval. The objectives of this paper are: to propose rational, risk-based, data-driven guidelines commensurate with the US Preventive Services Task Force screening guidelines for other disorders; to compare our proposed guidelines to recommendations made by other national and international organizations; and to review the US Preventive Services Task Forces 2016 Draft Recommendation Statement on skin cancer screening.

A protective role of murine langerin+ cells in immune responses to cutaneous vaccination with microneedle patches

Cutaneous vaccination with microneedle patches offers several advantages over more frequently used approaches for vaccine delivery, including improved protective immunity. However, the involvement of specific APC subsets and their contribution to the induction of immunity following cutaneous vaccine delivery is not well understood. A better understanding of the functions of individual APC subsets in the skin will allow us to target specific skin cell populations in order to further enhance vaccine efficacy. Here we use a Langerin-EGFP-DTR knock-in mouse model to determine the contribution of langerin+ subsets of skin APCs in the induction of adaptive immune responses following cutaneous microneedle delivery of influenza vaccine. Depletion of langerin+ cells prior to vaccination resulted in substantial impairment of both Th1 and Th2 responses, and decreased post-challenge survival rates, in mice vaccinated cutaneously but not in those vaccinated via the intramuscular route or in non-depleted control mice. Our results indicate that langerin+ cells contribute significantly to the induction of protective immune responses following cutaneous vaccination with a subunit influenza vaccine.