Iron-mediated oxidative stress induces PD-L1 expression via activation of c-Myc in lung adenocarcinoma.

Introduction: The PD-1/PD-L1 axis is hijacked by lung adenocarcinoma (LUAD) cells to escape immune surveillance. PD-L1 expression in LUAD is affected, among others, by the metabolic trafficking between tumor cells and the tumor microenvironment (TME). Methods: Correlation between PD-L1 expression and iron content within the TME was established on FFPE LUAD tissue samples. The effects of an iron rich microenvironment on PD-L1 mRNA and protein levels were assessed in vitro in H460 and A549 LUAD by using qPCR, western blot and flow citometry. c-Myc knockdown was performed to validate the role of this transcription factor on PD-L1 expression. The effects of iron-induced PD-L1 on T cell immune function was assessed by quantifying IFN-γ release in a co-colture system. TCGA dataset was used to analyse the correlation between PD-L1 and CD71 mRNA expression in LUAD patients. Results: In this study, we highlight a significant correlation between iron density within the TME and PD-L1 expression in 16 LUAD tissue specimens. In agreement, we show that a more pronounced innate iron-addicted phenotype, indicated by a higher transferrin receptor CD71 levels, significantly correlates with higher PD-L1 mRNA expression levels in LUAD dataset obtained from TCGA database. In vitro, we demonstrate that the addition of Fe3+ within the culture media promotes the significant overexpression of PD-L1 in A549 and H460 LUAD cells, through the modulation of its gene transcription mediated by c-Myc. The effects of iron lean on its redox activity since PD-L1 up-regulation is counteracted by treatment with the antioxidant compound trolox. When LUAD cells are co-cultured with CD3/CD28-stimulated T cells in an iron-rich culture condition, PD-L1 up-regulation causes the inhibition of T-lymphocytes activity, as demonstrated by the significant reduction of IFN-γ release. Discussion: Overall, in this study we demonstrate that iron abundance within the TME may enhance PD-L1 expression in LUAD and, thus, open the way for the identification of possible combinatorial strategies that take into account the iron levels within the TME to improve the outcomes of LUAD patients treated with anti-PD-1/PD-L1-based therapies.

A challenging case of anemia, respiratory failure and seizures.

BACKGROUND: Hemorrhagic Hereditary Telangiectasia (HHT), or  Rendu-Osler-Weber syndrome,  is a rare genetic disorder characterized by mucocutaneous telangiectasias and visceral arteriovenous malformations. AIM AND METHODS: We describe the case of a 64-year old woman  in which radiology was useful to interpret an apparently unexplained constellation of symptoms. RESULTS: Brain MRI showing ischemic stroke, pulmonary angiography demonstrating arteriovenous malformations, and capsule endoscopy detecting telangiectasias in the jejunum, along with a clinical history of recurrent epistaxis, allowed us to diagnose HHT. CONCLUSIONS: HHT is rare and difficult to diagnose. Radiology can aid the clinical suspicion. www.actabiomedica.it.

Early subclinical rejection treated with low dose i.v. steroids is not associated to graft survival impairment: 13-years' experience at a single center.

Subclinical rejection (SCR) has been variably associated with reduced graft survival, development and progression of interstitial fibrosis/tubular atrophy and chronic allograft nephropathy, but data are controversial concerning SCR treatment in terms of graft survival improvement. In this single-center retrospective study, we enrolled 174 adult kidney transplant recipients with a protocol biopsy performed at 30 days after transplantation to evaluate the incidence rate and risk factors for early SCR and its impact on 10-year graft survival. Five patients showed primary non function and were excluded. Among 159/169 (94.08 %) patients with stable graft function who underwent protocol biopsy, 17 (10.7 %) showed signs of SCR and were treated with low-dose intravenous (i.v.) steroids. Ten patients showed functional impairment, 8 (4.73 %) resulting as acute rejection. At multivariate analysis, donor age [odds ratio (OR) 1.04, 95 % confidence interval (CI) 1.01-1.09], and delayed graft function (DGF) (OR 1.08, 95 % CI 1.03-1.12) were significantly associated with SCR. The 10-year graft survival rate in the SCR group was similar to that in the normal-findings group (76.5 vs. 74.9 % respectively; p = 0.61). At multivariate Cox regression, acute [hazard ratio (HR) 5.22, 95 % CI 1.70-16.01], but not sub-clinical, rejection was independently associated with long-term graft failure. In conclusion, early protocol biopsy is a useful and safe tool to detect early SCR which seems not to affect the long-term survival. We suggest that this could be, probably, linked to early SCR treatment with low dose i.v. steroids.

Adiponectin is expressed and secreted by renal tubular epithelial cells.

BACKGROUND: Adiponectin (ADPN) is predominantly produced by adipose tissue, and high ADPN levels have been detected in patients affected by proteinuric glomerulonephritis. In this study we investigate whether human tubular epithelial cells express and secrete ADPN. METHODS: In human proximal tubular epithelial cells, HK-2, ADPN mRNA was evaluated by real-time PCR assay, while protein expression levels were measured by Western blot analysis and immunofluorescence assay. Moreover, renal ADPN distribution was assessed by immunohistochemical analysis of kidney biopsy samples from healthy patients. Finally, by ELISA, we measured ADPN concentrations in culture media of HK-2 cells treated with 10 µg/mL lipopolysaccharide (LPS). RESULTS: Our analyses revealed that HK-2 cells express ADPN both in terms of mRNA and protein. These results were confirmed by the observed cytoplasmatic HK-2 intense immunoreactivity for ADPN antibody and by immunohistochemical analysis showing a diffuse ADPN distribution in normal kidney tissue. Furthermore, we observed that tubular cells secrete ADPN in the basal condition and, more interestingly, that this secretion significantly increases (p<0.05) upon LPS treatment in a time-dependent manner. Finally, immunohistochemical analysis of kidney biopsy samples obtained from patients affected by membranous and rapidly progressive glomerulonephritis showed a similar pattern of ADPN staining to that observed in healthy controls. CONCLUSIONS: Our study demonstrates for the first time that renal tubular cells express and secrete ADPN, and their concentration increases upon inflammatory stimulus. These results suggest that in renal inflammatory diseases, tubular cells may contribute to the increase in circulating ADPN levels, triggering a feedback response in order to self-mitigate the inflammatory process.