Literatura académica sobre el tema "IMMUNOESCAPE"

The expression of programmed death 1 (PD-1) and programmed death-ligand 1 (PD-L1) indicate the efficacy of anti-PD-1/PD-L1 therapy in colorectal cancer (CRC), but are less useful for monitoring the efficacy of therapy of CRC liver metastasis (CRLM). This study investigated the effects of immune molecules on the prognosis of CRLM. We enrolled 71 patients with CRLM who underwent curative resection for CRC. We used immunohistochemistry to analyze the expression of PD-1, PD-L1, indoleamine-pyrrole 2,3-dioxygenase (IDO), and CD163 (a marker of tumor-associated macrophages [TAMs]) in metastatic tumors. The immune molecules PD-1, PD-L1, IDO, and TAMs were expressed in 32.3%, 47.8%, 45.0%, and 47.9% of metastatic CRC samples, respectively. The 5-year overall survival rates associated with immune molecule-positive groups were significantly better than in the negative groups (PD-1: 87.7% vs 53.2%, p = 0.023; PD-L1: 82.4% vs 42.3%, p = 0.007; IDO: 80.7% vs 43.5%, p = 0.007; TAMs: 82.6% vs 48.0%, p = 0.005). Multivariate analysis revealed PD-1 expression (p = 0.032, hazard ratio: 0.19), IDO expression (p = 0.049, hazard ratio: 0.37), and tumor differentiation (p<0.001, hazard ratio: 0.02) as independent prognostic indicators. PD-1 and TAMs in metastases were associated with less aggressive features such as smaller tumors. Furthermore, TAMs positively and significantly correlated with PD-1 expression (p = 0.011), PD-L1 expression (p = 0.024), and tended to correlate with IDO expression (p = 0.078). PD-1, PD-L1, IDO, and TAMs in CRLM were associated with less aggressive features and better prognosis of patients with CRC, indicating adaptive antitumor immunity vs immune tolerance. These molecules may therefore serve as prognostic markers for CRLM.

It is now well known that tumor immunosurveillance contributes to the control of cancer growth. Many mechanisms can be used by cancer cells to avoid the antitumor immune response. One such mechanism relies on the capacity of cancer cells or more generally of the tumor microenvironment to generate adenosine, a major molecule involved in antitumor T cell response suppression. Adenosine is generated by the dephosphorylation of extracellular ATP released by dying tumor cells. The conversion of ATP into adenosine is mediated by ectonucleotidase molecules, namely, CD73 and CD39. These molecules are frequently expressed in the tumor bed by a wide range of cells including tumor cells, regulatory T cells, Th17 cells, myeloid cells, and stromal cells. Recent evidence suggests that targeting adenosine by inhibiting ectonucleotidases may restore the resident antitumor immune response or enhance the efficacy of antitumor therapies. This paper will underline the impact of adenosine and ectonucleotidases on the antitumor response.

Mestrado em Bioquímica - Bioquímica Clínica
Breast cancer is the most prevalent cancer among women and also one of the oncologic pathologies that causes more deaths. In the last decades several studies have reported that solid tumors generate an immunosuppressive microenvironment. This microenvironment (acidosis, hypoxia, glucose deprivation and cytokines) is favourable to endoplasmic reticulum (ER) stress induction. ER stress is primarily a response towards the re-establishment of homeostasis; however if not resolved it usually results in cell death by apoptosis. Nevertheless, ER stress and unfolded protein response (UPR) play a paradoxical role in cancer physiopathology: the three branches of UPR, PERK, IRE1 and ATF6 actively contribute to signalling of survival and metastasis mechanisms. Recently it was reported a possible transmission of ER stress from tumor cells to immune cells, modulating the phenotype and function of recipient cells. Thus, the aim of the present work is to assess the ability and the respective mechanisms by which T-47D tumor cells transmit ER stress to THP-1 monocytes, and the consequences of this transmission. ER stress transmission was only observed when pharmacological ER stress inducers were used, such as tunicamycin, contrarily to physiological stimulation, as glucose deprivation. Additionally, it was found that tunicamycin seems to be transported within exosomes which, in turn, directly induces ER stress on monocytes. It was also observed that exosomes derived from glucose deprived T-47D cells do not transmit ER stress; however these exosomes conduct monocytes towards a particular proinflammatory profile, accompanied by the decrease of its maturation status. Overall, our results question the ER stress mechanism originally described, showing that pharmacological ER stress inducers can be transported within exosomes and directly inducing ER stress on recipient cells.
O cancro da mama é o cancro de maior incidência entre as mulheres, sendo também uma das situações oncológicas que mais mortes causa. Na última década inúmeros estudos têm demonstrado que os tumores sólidos geram um microambiente favorável à evasão/subversão do sistema imune. Esse microambiente (acidose, hipoxia, deprivação de glucose, citoquinas) é muita das vezes propicio à indução de stress do reticulo endoplasmático (RE). O stress do RE é primariamente uma resposta no sentido de restabelecer a homeostasia no entanto se não resolvido resulta normalmente na morte celular por apoptose. O stress do RE e a respetiva resposta às proteínas mal conformadas (UPR), desempenham um papel paradoxal na fisiopatologia do cancro: os três ramos da UPR, PERK, IRE1 e ATF6, contribuem ativamente para a sinalização de alguns mecanismos de sobrevivência e metastização. Recentemente, foi descrita uma possível transmissão do stress do RE das células tumorais para as células do sistema imunitário, modulando a ação destas. Desta forma, pretendeu avaliar-se com o presente trabalho a capacidade e os mecanismos pelos quais células tumorais T-47D transmitem o stress do RE para células monocíticas THP-1, e quais as consequências desta transmissão. A transmissão foi apenas observada aquando da utilização de indutores farmacológicos como a tunicamicina, não se registando para estímulos fisiológicos como a deprivação de glucose. Por outro lado, verificou-se que a tunicamicina parece ser transportada via exossomas e desta forma induzir diretamente stress do RE nos monócitos. Observou-se ainda que os exossomas provenientes das células T-47D em stress do RE por deprivação de glucose apesar de não transmitirem o referido stress conduzem os monócitos para um perfil pró-inflamatório específico diminuindo ainda a sua capacidade de maturação. Em geral, os nossos resultados questionam seriamente o mecanismo de transmissão de stress ER tal como originalmente descrito, mostrando que no uso de indutores farmacológicos o que parece ocorrer é o transporte do fármaco em vesículas e a indução direta nas células recetoras.

Nel modello di mieloma murino rappresentato dall’ibridoma Sp6 nel topo Balb/c, l’espressione de novo della molecola costimolatoria B7-1, ottenuta mediante transfezione del relativo cDNA (transfettanti Sp6/B7), inibisce la crescita tumorale in vivo e attiva una risposta immunitaria mediata da linfociti T citotossici (CTL), protettiva contro il tumore Sp6 parentale (wild type Sp6 =WT Sp6). Nel background genetico del topo Balb/c, la molecola MHC-I H-2 Ld è l’elemento di restrizione che presenta gli epitopi immunodominanti di due fra i più comuni antigeni associati a tumore nel topo: gp70 e P1A. Le cellule WT Sp6 e Sp6/B7 mostrano una ridotta espressione di H-2 Ld, mantenendo livelli di espressione normali per quanto riguarda H-2 Kd e Dd. Le cellule Sp6 sono lisate in vitro da CTL Ld-ristretti, specifici per gp70 (ma non per P1A): questo indica che le cellule Sp6 sono in grado di presentare epitopi di gp70 nonostante la ridotta espressione di Ld. L’aumento dell’espressione di Ld in Sp6 WT e Sp6/B7 mediante transfezione con il relativo cDNA (transfettanti Sp6/Ld e Sp6/B7/Ld) guida la risposta immunitaria verso antigeni ristretti per H-2 Ld, mentre una ridotta espressione di Ld, Sp6 WT e Sp6/B7, induce uno spostamento della risposta immunitaria verso antigeni subdominanti presentati da H-2 Kd. Nonostante questo, la risposta immunitaria che si ottiene in seguito a immunizzazione con il vaccino cellulare autologo B7-1 positivo, rappresentato sia da Sp6/B7 che da Sp6/B7/Ld, non è mai gp70-specifica. L’analisi dell’espressione di gp70 negli organi linfoidi periferici ha dimostrato la presenza di trascritti specifici per gp70 sia nella milza che nei linfonodi di animali immunizzati con Sp6/B7 e Sp6/B7/Ld, assenti negli animali naïve. L’analisi al microscopio elettronico di Sp6 WT e dei suoi transfettanti ha evidenziato la presenza di particelle simil-virali sia nel citoplasma che in vescicole di esocitosi. Possiamo ipotizzare che, durante la fase di immunizzazione, una lisi dipendente da CTL delle cellule Sp6/B7 e Sp6/B7/Ld migrate nei linfonodi drenanti determini il rilascio di un elevato numero di virioni, in grado di infettare rapidamente l’intera popolazione di cellule B residenti. La conseguente presentazione degli epitopi antigenici virali immunodominanti da parte di un gran numero di cellule B infette indurrà morte cellulare dovuta ad attivazione delle cellule T con TCR ad alta affinità, portando alla delezione clonale dei linfociti T CD8+ gp70 specifici. In conclusione, il tumore Sp6 sembra in grado di attuare due meccanismi di evasione immunitaria: 1) induzione di tolleranza periferica nei confronti dell’ antigene immunodominante gp70; 2) riduzione dell’espressione di H-2 Ld, per sfuggire alla risposta immunitaria tumore-specifica contro epitopi Ld-ristretti di altri antigeni precedentemente subdominanti, che la tolleranza periferica contro gp70 ha infine reso immunodominanti. I nostri dati dimostrano che, quando i tumori adottano questi meccanismi di evasione immunitaria, i vaccini autologhi basati su cellule tumorali intere rimangono ancora un potente mezzo per l’instaurarsi di un’immunità anti-tumorale, poiché permettono di recuperare e amplificare le risposte immunitarie protettive dirette contro antigeni tumorali subdominanti. Successivamente, abbiamo analizzato il potenziale terapeutico di cellule stromali mesenchimali (MSC) come vettori cellulari per il trasporto all’interno del tumore di molecole attive. Le MSC derivate da midollo osseo (BM-MSC) possono sopravvivere e proliferare in presenza di cellule neoplastiche. La somministrazione di MSC ne permette l’incorporazione attiva nel tumore come fibroblasti stromali, andando così a competere con i precursori delle cellule mesenchimali locali. Per questa ragione, le MSC vengono considerate un carrier adatto per strategie di terapia genica, poiché possono essere ingegnerizzate con geni che codificano molecole biologicamente attive, che possono inibire la proliferazione delle cellule tumorali e aumentare la risposta immunitaria anti-tumore. Noi abbiamo utilizzato BM-MSC ingegnerizzate con il gene dell’interferone-alfa (IFN-a) murino (BM-MSC/IFN-a) per valutare l’efficacia di questo approccio verso plasmacellule neoplastiche, nel modello murino di mieloma rappresentato da Sp6. Abbiamo visto che l’IFN-a può essere efficientemente prodotto e portato all’interno del microambiente tumorale. Somministrazioni sottocutanee multiple di BM-MSC/IFN-a impediscono la crescita tumorale in vivo in maniera significativa e prolungano la sopravvivenza dei topi. L’effetto anti-tumorale è stato associato ad un’aumentata apoptosi delle cellule tumorali, a una riduzione della densità vascolare e all’induzione di necrosi ischemica. Al contrario, la somministrazione endovenosa di BM-MSC/IFN-a non ha modificato significativamente la sopravvivenza dei topi, soprattutto come conseguenza dell’eccessivo intrappolamento delle cellule iniettate nei vasi polmonari. In conclusione, le BM-MSC/IFN-a sono efficaci nell’inibire la crescita di plasmacellule neoplastiche, anche se la somministrazione sistemica di MSC ingegnerizzate necessita ancora di miglioramenti per rendere questo approccio potenzialmente utilizzabile nel trattamento del mieloma multiplo.
In the mouse Balb/c-derived myeloma model represented by the Sp6 hybridoma, de novo expression of the B7-1 costimulatory molecule obtained by transfection of the relative cDNA (Sp6/B7 transfectants) inhibits tumor growth in vivo and activates a memory immune response mediated by cytotoxic T lymphocytes (CTLs), protective against wild type (WT) Sp6. In the Balb/c genetic background, the MHC-I H-2 Ld molecule is the restriction element presenting the immunodominant epitopes of the two most common mouse tumor associated antigens: P1A and gp70. WT Sp6 and Sp6/B7 show a downregulated cell surface expression of H-2 Ld, still maintaining normal expression levels of H-2 Kd and Dd. Sp6 cells are lysed in vitro by gp70-Ld-restricted CTLs (not by P1A-Ld-restricted), indicating that they are able to present gp70 epitopes in spite of the low Ld expression. Increase of H-2 Ld expression in WT Sp6 and Sp6/B7 by transfection of the relative cDNA (Sp6/Ld and Sp6/B7/Ld transfectants) drives the immune response towards H-2 Ld-restricted antigens, whilst the H-2 Ld-downregulated state of WT Sp6 and Sp6/B7 determines a shift of the immune response towards subdominant antigens presented by H-2 Kd. Nevertheless, the immune response elicited by in vivo immunization with the autologous B7-1 positive cellular vaccine, either Sp6/B7 or Sp6/B7/Ld, is never gp70-specific. Analysis of gp70 expression in peripheral lymphoid organs showed the presence of gp70 specific transcripts in both spleen and lymph nodes of animals immunized with Sp6/B7 and Sp6/B7/Ld, absent in naïve animals. Electron mycroscope analysis of WT Sp6 and transfectants showed the presence of virus-like particles in both cytoplasma and exocytosis vesicles. We may hypothesize that, during immunization phase, a CTL-dependent lysis of Sp6/B7 and/or Sp6/B7/Ld cells migrated to the draining lymph nodes results in the release of a high number of virions, rapidly infecting the whole resident B cell population. The subsequent presentation of the immunodominant viral antigen epitopes by a large number of infected B cells can generate an activation-induced cell death of high affinity TCR-T cells, leading to clonal deletion of gp70-specific CD8+ T cells. In conclusion, Sp6 tumor appears to carry out two immunoescape mechanisms: 1) induction of peripheral tolerance against the gp70 immunodominant antigen; 2) H-2 Ld downregulation, to escape the tumor-specific immune response against the Ld-restricted epitopes of previously subdominant antigens, that the established gp70-peripheral tolerance has eventually made dominant. Our data show that, when tumors adopt these immunoescape mechanisms, autologous whole tumor cell vaccines still remain a potent tool for generating anti-tumor immunity, because they allow to rescue and amplify the protective immune responses against subdominant tumor antigens. Then, we have analyzed the therapeutic potential of mesenchymal stromal cells (MSCs) as cellular vehicle for intra-tumoral delivery of active molecules. Bone marrow derived MSCs (BM-MSCs) may survive and proliferate in the presence of cycling neoplastic cells. Exogenously administered MSCs are actively incorporated in the tumor as stromal fibroblasts, thus competing with the local mesenchymal cell precursors. For this reason, MSCs have been suggested as a suitable carrier for gene therapy strategies, as they can be engineered with genes encoding for biologically active molecules, which can inhibit tumor cell proliferation and enhance the anti-tumor immune response. We used BM-MSCs engineered with the murine interferon-alpha (IFN-a) gene (BM-MSCs/IFN-a) to assess in the mouse myeloma model represented by Sp6 the efficacy of this approach towards neoplastic plasma cells. We found that IFN-a can be efficiently produced and delivered inside the tumor microenvironment. Subcutaneous multiple administration of BM-MSCs/IFN-a significantly hampered the tumor growth in vivo and prolonged the overall survival of mice. The anti-tumor effect was associated with enhanced apoptosis of tumor cells, reduction in microvessel density, and ischemic necrosis. By contrast, intravenous administration of BM-MSCs/IFN-a did not significantly modify the survival of mice, mainly as a consequence of an excessive entrapment of injected cells in the pulmonary vessels. In conclusion, BM-MSCs/IFN-a are effective in inhibiting neoplastic plasma cell growth; however, systemic administration of engineered MSCs still needs to be improved to make this approach potentially suitable for the treatment of multiple myeloma.