Maike Büttner

CLL-cells induce IDOhi CD14+HLA-DRlo myeloid-derived suppressor cells that inhibit T-cell responses and promote TRegs

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population that shares certain characteristics including an aberrant myeloid phenotype and the ability to suppress T cells. MDSCs have been predominantly studied in malignant diseases and findings suggest involvement in tumor-associated immune suppression. Chronic lymphocytic leukemia (CLL) is the leukemia with the highest incidence among adults. Immune defects occur already at early disease stages and impact the clinical course. We assessed presence, frequency, association to other immune parameters, and functional properties of circulating CD14(+) cells lacking HLA-DR expression (HLA-DR(lo)) in patients with untreated CLL. These monocytic cells represent one of the best-defined human MDSC subsets. Frequency of CD14(+)HLA-DR(lo) cells was significantly increased in CLL patients. Furthermore, MDSCs suppressed in vitro T-cell activation and induced suppressive regulatory T cells (TRegs). The MDSC-mediated modulation of T cells could be attributed to their increased indoleamine 2,3-dioxygenase (IDO) activity. CLL cells induced IDO(hi) MDSCs from healthy donor monocytes suggesting bidirectional crosstalk between CLL-cells, MDSCs, and TRegs. Overall, we identified a MDSC population that expands in CLL. The exact mechanisms responsible for such accumulation remain to be elucidated and it will be of interest to test whether antagonizing suppressive functions of CLL MDSCs could represent a mean for enhancing immune responses.

Expression of the Epstein-Barr virus (EBV)-encoded latent membrane protein 2A (LMP2A) in EBV-associated nasopharyngeal carcinoma.

The Epstein–Barr virus (EBV) is associated with virtually all cases of undifferentiated nasopharyngeal carcinoma (NPC) and has been classified as a group I carcinogen. In addition to its potential role in the pathogenesis of NPC, EBV also provides a possible target for immunotherapy of NPC, since a limited number of viral genes are expressed in the neoplastic cells. The EBV‐encoded latent membrane protein 2A (LMP2A) is considered a promising target since it provides epitopes recognized by EBV‐specific T‐cells. Using immunohistochemistry, the present study shows that LMP2A is expressed at the protein level in the neoplastic cells of 16 of 35 (45.7%) NPC biopsies. This finding provides further evidence suggesting that NPC tumour cells may be susceptible to lysis by cytotoxic T‐cells directed against LMP2A and should encourage efforts to develop immunotherapeutic approaches for the treatment of NPC. Copyright

Tumour infiltrating lymphocytes in squamous cell carcinoma of the oro- and hypopharynx: prognostic impact may depend on type of treatment and stage of disease.

he purpose of this study was to evaluate the prognostic influence of various subtypes of tumour infiltrating lymphocytes (TIL) in head and neck cancer, in particular the potential influence of regulatory T cells (Treg) in relation to different treatment modalities was addressed. A total of 115 patients with squamous cell carcinoma of the oro- and hypopharynx were selected. A low-risk group of 62 patients with early disease was treated by primary surgery followed by external radiotherapy. A high-risk group of 53 inoperable patients with advanced disease was treated by primary radiochemotherapy. Two-hundred and forty biopsy samples were evaluated by use of the tissue-micro-array technique employing the following markers: CD3, CD4, CD8, CD20, CD68, FOXP3, Granzyme B. In the low-risk group high CD20+ infiltration was associated with a significantly better NED-survival rate (p=0.02). Contrary, among high-risk patients low CD20+ counts indicated significantly better survival (p=0.03). Additionally, in the low-risk group higher numbers of intraepithelial CD8+ TIL (>66.6 per thousand) led to improved NED-survival of 95% vs. 52% (p=0.005). The impact of TIL on prognosis in patients with head and neck cancer may be affected by type of treatment and stage of disease. This finding will influence future studies on the role of TIL in human cancers.

Warburg phenotype in renal cell carcinoma: high expression of glucose-transporter 1 (GLUT-1) correlates with low CD8(+) T-cell infiltration in the tumor.

Many tumor cells are characterized by a dysregulated glucose metabolism associated with increased glycolysis in the presence of oxygen (“Warburg Effect”). Here, we analyzed for the first time a possible link between glucose metabolism and immune cell infiltration in renal cell carcinoma (RCC). RCC specimens revealed a highly significant increase in the expression of lactate dehydrogenase A (LDHA) and glucose‐transporter 1 (GLUT‐1) compared to the corresponding normal kidney tissue on mRNA level. Accordingly, tumor cell lines of different origin such as RCC, melanoma and hepatocellular carcinoma strongly expressed LDHA and GLUT‐1 compared to their nonmalignant counterparts. In line with this finding, tumor cells secreted high amounts of lactate. High expression of GLUT‐1 and LDH5, a tetramer of 4 LDHA subunits, was confirmed by tissue microarray analysis of 249 RCC specimens. Overall, 55/79 (69.6%) and 46/71 (64.7%) cases of clear cell carcinoma showed a constitutive, but heterogeneous expression of GLUT‐1 and LDH5, respectively. The number of CD3+, CD8+ and FOXP3+ T cells was significantly elevated in RCC lesions compared to normal kidney epithelium, but effector molecules such as granzyme B and perforin were decreased in tumor infiltrating T cells. Of interest, further analysis revealed an inverse correlation between GLUT‐1 expression and the number of CD8+ T cells in RCC lesions. Together, our data suggest that an accelerated glucose metabolism in RCC tissue is associated with a low infiltration of CD8+ effector T cells. Targeting the glucose metabolism may represent an interesting tool to improve the efficacy of specific immunotherapeutic approaches in RCC.

Encapsulating peritoneal sclerosis – an overview

Encapsulating peritoneal sclerosis (EPS) is a rare but life-threatening complication of peritoneal sclerosis (PD). In 2000, the International Society for Peritoneal Dialysis outlined diagnostic guidelines and a clinical definition of EPS. Over the intervening years, new evidence was published and several centers became more experienced managing patients with EPS. Although, further networking was initiated (European EPS Working Group), evidence regarding therapy and diagnosis of EPS is still lacking. Multicenter trials are needed to establish evidence regarding the management of EPS. Risk factors for EPS are identified and patients at risk should be monitored closely. In case of emerging signs of EPS, patients should be referred to an EPS-center before initiation of therapy. Morphology and immunohistochemistry will play a central role in the near future. Nowadays, most pathologists are not sophisticated in the pathology of peritoneal biopsies. Clear histological criteria are warranted. For the outcome of the patient, it is crucial that an EPS experienced surgeon conducts surgery.

BK viremia and polyomavirus nephropathy in 352 kidney transplants; risk factors and potential role of mTOR inhibition.

BackgroundPolyomavirus BK nephropathy (PyVAN) remains an important cause of early graft dysfunction and graft loss in kidney transplantation.MethodsIn this retrospective, single centre cohort study we studied the incidence and outcome of BK viral infection in 352 patients transplanted in 2008–2011.ResultsDuring follow-up viral replication was detected in 48 patients (13.6%); 22 patients (6.2%) had biopsy proven PyVAN.In multivariate logistic regression analyses risk factors for BK-viremia were lack of enrolment into randomized controlled trials (RCTs), biopsy proven acute rejections, cytomegaly virus (CMV) serostatus of both donor and recipient and previous transplantation.In patients without PyVAN reduction or switch of immunosuppression was associated with rapid viral clearance and stable graft function. In contrast, in most patients with PyVAN graft function deteriorated and 5 patients prematurely lost their allograft. Switch of immunosuppression to a low dose cyclosporine plus mTOR inhibitor based regimen in patients with PyVAN was safe, well tolerated and tended to be associated with a better short-term outcome in terms of graft function compared to reduction of existing immunosuppression alone.ConclusionsWith the lack of licensed anti-polyoma viral drugs reduction or conversion of immunosuppression remains the mainstay of therapy in patients with PyVAN. The combination of low dose cyclosporine plus mTOR inhibition appears to be safe and warrants further investigation.

Radiochemotherapy induces a favourable tumour infiltrating inflammatory cell profile in head and neck cancer

Head and neck squamous cell cancers (HNSSC) generate an immune-suppressive micro-environment by a specific pattern of tumour infiltrating inflammatory cells. The aim of our study was to evaluate the impact of radiochemotherapy on the numbers and composition of inflammatory cells and its influence on outcome. Fifty-eight patients suffering from oral cavity cancer were studied, whose therapy consisted of concurrent radiochemotherapy followed by surgery. Numbers and ratios of tumour infiltrating inflammatory cells were compared prior to and after radiochemotherapy. Intraepithelial and stromal location of tumour infiltrating inflammatory cells was analysed separately. Infiltration of CD3(+), CD4(+), CD25(+), FoxP3(+), CD8(+), Granzyme B(+), CD20(+) and CD68(+) cells predominated in the peritumoural stromal compartment, whereas CD1a(+) dendritic cells were found more frequently in the intraepithelial compartment. Neoadjuvant treatment was associated with a general decrease of tumour infiltrating inflammatory cells in both compartments. The CD8(+) and Granzyme B(+) cytotoxic cells decreased only slightly after RCT. In contrast, the decrease of FoxP3(+) regulatory T cells was more pronounced and the cytotoxic T-cell/FoxP3(+) ratio increased 2- to 3-fold in both compartments, respectively. Patients with high cytotoxic cell numbers, high dendritic cell numbers and a high ratio of cytotoxic cells to regulatory T cells had a better disease free survival. Concurrent radiochemotherapy of oral squamous cell carcinoma was shown to drive the composition of inflammatory cells in a direction which is supposed to be prognostically favourable.

Cytotoxic effect of efavirenz is selective against cancer cells and associated with the cannabinoid system.

Background:Recently, a regression of precancerous lesions in HIV-1-infected patients after initiation of HAART was reported. Nonnucleoside reverse transcriptase inhibitors (NNRTIs) as efavirenz (EFV) might be mediators of this effect, as they are known to have a cytotoxic effect on tumour cells. A potential mechanism involved in this effect may be the activation of the cannabinoid receptor to mediate tumour toxicity. Methods:Several tumour-derived and fibroblast cell lines were studied. Cytotoxicity of EFV was evaluated by Annexin-Pi staining. The expression of the cannabinoid receptors CB1, CB2 and GPR55 was analysed by western blot, quantitative reverse transcriptase (qRT-PCR) and fluorescence activated cell sorting. The influence of the cannabinoid agonists and antagonists on the effects of EFV was investigated. Furthermore, the effect of EFV on the phosphorylation state of the growth factors Erk, Akt and the tumour suppressor protein p53 was tested. Results:EFV revealed a selective cytotoxic effect on several tumour cell lines, whereas primary fibroblasts were not affected. The cytotoxic effect was associated with the expression of CB1. The combination of EFV with cannabinoid agonists showed an increase in toxicity. The phosphorylation state of Erk and Akt was not affected by EFV, whereas p53 showed an increased phosphorylation. Conclusion:EFV has a selective cytotoxic effect on several tumour cells. Furthermore, EFV led to an activating phosphorylation of the tumour suppressor protein p53 going in line with earlier reports that EFV may be antitumourigenic and a potential cytostatic drug. The observed synergistic effect with cannabinoid agonists implicates an involvement of the cannabinoid system.

Characterisation of renal immune cell infiltrates in children with nephrotic syndrome

There is increasing evidence that not only T cells but also B cells may play an important role in the pathogenesis of idiopathic nephrotic syndrome (NS). We have evaluated the infiltrating immune cells found in renal biopsies from 38 children with NS using immunohistochemistry techniques involving antibodies against T cells (CD3, CD4, CD8, FoxP3), B cells (CD20), macrophages (CD68) and follicular dendritic cells (CD21). Kidney biopsies with thin basement membrane disease were used as controls. We found higher numbers of interstitial CD3-positive T cells and macrophages in patients with focal segmental glomerulosclerosis (FSGS) than in those with minimal change glomerulopathy (MCGN) and in the controls, and significantly lower FoxP3-positive cells in patients with FSGS, MCGN and steroid-dependent NS than in the controls. Significantly higher numbers of glomerular B cells were found in FSGN patients than in MCGN patients and controls. Of note, in three patients who were later successfully treated with anti-CD20 antibody rituximab, the number of renal B cells was negligible in the preceding biopsy. In conclusion, the higher numbers of interstitial CD3-positive T cells in renal biopsies of pediatric patients with FSGS argue for a higher inflammatory activity. The significantly higher number of glomerular B cells in FSGS patients may indicate a particular pathogenetic role or epiphenomenon in this disease. However, patients with no interstitial or glomerular B cells could also benefit from rituximab treatment.

Complement Factor H-Related 5-Hybrid Proteins Anchor Properdin and Activate Complement at Self-Surfaces

C3 glomerulopathy (C3G) is a severe kidney disease for which no specific therapy exists. The causes of C3G are heterogeneous, and defective complement regulation is often linked to C3G pathogenesis. Copy number variations in the complement factor H-related (CFHR) gene cluster on chromosome 1q32 and CFHR5 mutant proteins associate with this disease. Here, we identified CFHR5 as a pattern recognition protein that binds to damaged human endothelial cell surfaces and to properdin, the human complement activator. We found the two N-terminal short consensus repeat domains of CFHR5 contact properdin and mediate dimer formation. These properdin-binding segments are duplicated in two mutant CFHR5 proteins, CFHR2-CFHR5Hyb from German patients with C3G and CFHR5Dup from Cypriot patients with C3G. Each of these mutated proteins assembled into large multimeric complexes and, compared to CFHR5, bound damaged human cell surfaces and properdin with greater intensity and exacerbated local complement activation. This enhanced surface binding and properdin recruitment was further evidenced in the mesangia of a transplanted and explanted kidney from a German patient with a CFHR2-CFHR5Hyb protein. Enhanced properdin staining correlated with local complement activation with C3b and C5b-9 deposition on the mesangial cell surface in vitro This gain of function in complement activation for two disease-associated CFHR5 mutants describes a new disease mechanism of C3G, which is relevant for defining appropriate treatment options for this disorder.