Az őssejtek részvétele a máj regenerációban és a carcinogenezisben = The role of stem cells in liver regeneration and carcinogenesis

Ovális sejtes reakció indulásakor a patkány májában sajátos fenotípusú CK19+/7- ductulusok hámsejtjei kezdenek proliferálni. Ez alapján arra lehet következtetni, hogy a máj őssejtek ebben a kompartmentben találhatóak. A CK19+/7- ductulusok hosszú, olykor elágazódó képleteket alkotnak, melyek nem terjednek be a hepatocyták közé. Ez a sajátos epeút fenotipus csak postnatalisan alakul ki. Az ovális sejtek többféle megoszlásban is képesek hepatocytákká differenciálódni, de celluláris szinten a differenciálódási program azonosnak tűnik. A folyamat HNF4 expresszióval és a bazális membrán degradálódásával kezdődik, amit gyorsan követ az epeút markerek (OV6,Cx43, integrin 1) eltűnése, a hepatocyta tulajdonságok (CYP, CD26, Cx32, integrin 1) megjelenése. A differenciálódás folyamata felgyorsítható hepatocyta mitogénekkel. Az ezt követő regeneráció szérum szinten is javuló májfunkcióval jár kísérleti állatokban. Csontvelő sejtekből nem sikerült transzdifferenciálódás útján hepatocytákat előállítanunk. Eredményeink szerint az ovális sejteken leírt haemopoetikus marker (Thy-1) is valójában az ovális sejtekkel szoros kontaktusban levő stellát sejtekben expresszálódik. A májukban fokozott mértékben TGF-t termelő transzgén egerekben a tioacetamid indukált májfibrosis felgyorsulása a regresszió lelassulása volt megfigyelhető. | There are biliary ductules in the rat liver with a unique CK19+/7- phenotype. This special immunophenotype develops only in the postnatal life These are the ductules which are proliferating first at the beginning of oval cell proliferation, indicating that they may harbour the hepatic stem cell compartment. These ductules, contrary to the traditional view of canals of Hering form occasionally long, winding and branching tubules but they do not spread into the liver lobule. The oval cells are able to differentiate into hepatocytes in different distributions. But the differentiation program on cellular level seems identical. The process is initiated by the upregulation of HNF-4 and the degradation of the basement membrane. This is followed by the disappearance of biliary markers (e.g. OV6,Cx43, 6 integrin) and expression of hepatocytic markers (CYP enzymes, Cx32, 1 integrin, CD26). The differentiation can be accelerated by primary hepatocyte mitogens. The improved hepatic function can be detected after the differentiation even in the serum of the animals. We did not succeed to generate hepatocytes from bone marrow cells by transdifferentiation. We also studied the expression of a haemopoetic stem cell marker, Thy-1 in our oval cell proliferation model and found it to be present not on the oval cells, as it had been reported, but on the stellate cells. Accelerated liver fibrosis and decelerated regression was observed following thioacetamide treatment in transgenic mice overexpressing TGF-beta in their liver

Immune cell profile of sentinel lymph nodes in patients with malignant melanoma - FOXP3+ cell density in cases with positive sentinel node status is associated with unfavorable clinical outcome

BACKGROUND: Besides being a preferential site of early metastasis, the sentinel lymph node (SLN) is also a privileged site of T-cell priming, and may thus be an appropriate target for investigating cell types involved in antitumor immune reactions. METHODS: In this retrospective study we determined the prevalence of OX40+ activated T lymphocytes, FOXP3+ (forkhead box P3) regulatory T cells, DC-LAMP+ (dendritic cell-lysosomal associated membrane protein) mature dendritic cells (DCs) and CD123+ plasmacytoid DCs by immunohistochemistry in 100 SLNs from 60 melanoma patients. Density values of each cell type in SLNs were compared to those in non-sentinel nodes obtained from block dissections (n = 37), and analyzed with regard to associations with clinicopathological parameters and disease outcome. RESULTS: Sentinel nodes showed elevated amount of all cell types studied in comparison to non-sentinel nodes. Metastatic SLNs had higher density of OX40+ lymphocytes compared to tumor-negative nodes, while no significant difference was observed in the case of the other cell types studied. In patients with positive sentinel node status, high amount of FOXP3+ cells in SLNs was associated with shorter progression-free (P = 0.0011) and overall survival (P = 0.0014), while no significant correlation was found in the case of sentinel-negative patients. The density of OX40+, CD123+ or DC-LAMP+ cells did not show significant association with the outcome of the disease. CONCLUSIONS: Taken together, our results are compatible with the hypothesis of functional competence of sentinel lymph nodes based on the prevalence of the studied immune cells. The density of FOXP3+ lymphocytes showed association with progression and survival in patients with positive SLN status, while the other immune markers studied did not prove of prognostic importance. These results, together with our previous findings on the prognostic value of activated T cells and mature DCs infiltrating primary melanomas, suggest that immune activation-associated markers in the primary tumor may have a higher impact than those in SLNs on the prognosis of the patients. On the other hand, FOXP3+ cell density in SLNs, but not in the primary tumor, was found predictive of disease outcome in melanoma patients

Role of the anatomic site in the association of HLA class I antigen expression level in metastases with clinical response to ipilimumab therapy in patients with melanoma

Background The clinical response to immune checkpoint inhibitors (ICIs) in only part of the treated patients, in conjunction with the potentially serious side effects associated with this type of therapy, has emphasized the need to identify biomarkers to select patients who may benefit from ICI treatment. The aim of our study was to test human leukocyte antigen (HLA) class I and II expression in melanoma metastases as potential biomarkers of response to ipilimumab and survival in patients with metastatic melanoma, since these molecules play a crucial role in the interactions of malignant cells with host’s immune system.Materials and methods HLA class I and II antigen expression level in pretreatment surgical tissue samples (50 lymph node and 35 cutaneous or subcutaneous metastases) from 30 patients was analyzed by immunohistochemical staining with monoclonal antibodies. Expression levels were correlated to intratumoral density of lymphocytes expressing cluster of differentiation (CD)8, CD45RO, CD4, forkhead box P3 (FOXP3) and/or programmed cell death protein 1 (PD-1), to clinical response to treatment, and to patients’ survival.Results HLA class I antigen expression level in lymph node metastases, but not in cutaneous or subcutaneous metastases was significantly correlated to density of CD8+ and CD45RO+ T cells and of lymphocytes expressing PD-1, as well as to clinical response and to patients’ survival.Conclusions Our results corroborate the role of HLA class I expression level (alone or in combination with T-cell density values) as a predictive biomarker of response to ipilimumab in patients with melanoma. In addition, our results show that this association is influenced by the anatomic site of the metastasis used to measure the HLA class I antigen expression level

Ectopic lymphoid structures in primary cutaneous melanoma.

Ectopic lymphoid structures have been described in several tumor types including metastatic lesions, but not primary tumors, of patients with melanoma. Here we present evidence of B-cell follicles in primary cutaneous melanomas, being present in 39 of 147 cases (27 %). B-cell clusters were associated with T lymphocytes, most of which belonging to CD45RO+ memory T cells. A network of CD21+ follicular dendritic cells was demonstrated in 8 of 22 cases studied (36 %). MECA-79+ HEV-like venules were observed in the neighborhood of the follicles in the majority of cases, however, their presence was not confined to tumors hosting ectopic lymphoid structures. The appearance of B-cell aggregates did not show association with the outcome of the disease, although a trend for their higher prevalence was observed in thicker tumors. Our results show that neogenesis of lymphoid structures does occur in primary melanomas, albeit with lower frequency compared to that reported in metastases

Role of the anatomic site in the association of HLA class I antigen expression level in metastases with clinical response to ipilimumab therapy in patients with melanoma

The clinical response to immune checkpoint inhibitors (ICIs) in only part of the treated patients, in conjunction with the potentially serious side effects associated with this type of therapy, has emphasized the need to identify biomarkers to select patients who may benefit from ICI treatment. The aim of our study was to test human leukocyte antigen (HLA) class I and II expression in melanoma metastases as potential biomarkers of response to ipilimumab and survival in patients with metastatic melanoma, since these molecules play a crucial role in the interactions of malignant cells with host's immune system.HLA class I and II antigen expression level in pretreatment surgical tissue samples (50 lymph node and 35 cutaneous or subcutaneous metastases) from 30 patients was analyzed by immunohistochemical staining with monoclonal antibodies. Expression levels were correlated to intratumoral density of lymphocytes expressing cluster of differentiation (CD)8, CD45RO, CD4, forkhead box P3 (FOXP3) and/or programmed cell death protein 1 (PD-1), to clinical response to treatment, and to patients' survival.HLA class I antigen expression level in lymph node metastases, but not in cutaneous or subcutaneous metastases was significantly correlated to density of CD8+ and CD45RO+ T cells and of lymphocytes expressing PD-1, as well as to clinical response and to patients' survival.Our results corroborate the role of HLA class I expression level (alone or in combination with T-cell density values) as a predictive biomarker of response to ipilimumab in patients with melanoma. In addition, our results show that this association is influenced by the anatomic site of the metastasis used to measure the HLA class I antigen expression level