Neuropilin-1 expression identifies a subset of regulatory T cells in human lymph nodes that is modulated by preoperative chemoradiation therapy in cervical cancer Introduction CD4 + T cells that constitutively express the interleukin-2 (IL-2) receptor a-chain CD25 (regulatory T cells, Treg) and the master regulator Foxp3 transcription factor play a central and prominent role in maintaining self-tolerance and in regulating responses to infectious agents, transplantation antigens and tumour antigens. SummaryWe examined the phenotype and function of CD4 + T cells expressing the semaphorin III receptor neuropilin-1 (Nrp1) in human lymph nodes and peripheral blood. In lymph nodes, Nrp1 identified a small regulatory CD4 + CD25 high T-cell subpopulation (Nrp1 + Treg) that expressed higher levels of Forkhead box P3 (Foxp3) message and protein than Nrp1 ) Treg, and various molecular markers of activated Treg, i.e. CD45RO, human leucocyte antigen (HLA)-DR and glucocorticoid-induced tumour necrosis factor receptor (GITR). Similarly to conventional Treg, Nrp1 + Treg proliferated poorly in vitro, and exerted contact-dependent in vitro suppression of T-cell proliferation and cytokine secretion. However, Nrp1 + Treg were more efficient than Nrp1 ) Treg at inducing suppression. Nrp1 was also expressed on a small subpopulation of CD25 int and CD25 ) CD4 + T cells that expressed more Foxp3, CD45RO, HLA-DR and GITR than their Nrp1 ) counterparts. In contrast, in peripheral blood Nrp1 identified a minor CD4 + T-cell subset that did not display the phenotypic features of Treg lacking Foxp3 expression and marginally expressing CD25. Hence, the function of Nrp1 + CD4 + T cells seemingly depends on their anatomical location. In a previous report, we proposed that Treg may curb the anti-tumour T-cell response in cervical cancer. We show here that Treg and Nrp1 + Treg levels dropped in the tumour-draining lymph nodes of patients with cervical cancer following preoperative chemoradiotherapy in a direct relationship with the reduction of tumour mass, suggesting that suppressor cell elimination facilitated the generation of T cells mediating the destruction of the neoplastic cells left behind after cytotoxic therapy.

Summary Accumulating evidence indicates an immunosuppressive role of the thymus‐derived CD4+ T‐cell population constitutively expressing high level of CD25, T regulatory (Treg) cells, in autoimmune diseases. Here we show that the number of Treg cells in the blood is significantly lower in untreated myasthenia gravis patients than in age‐matched healthy subjects, whereas it is normal or elevated in patients on immunosuppressive therapy (prednisone frequently associated with azathioprine). Therapeutic thymectomy (Tx) for either the thymoma or non‐neoplastic thymic alterations that are often associated with myasthenia gravis provided unique material for studying intrathymic Treg cells and correlating them with their peripheral counterparts. We observed that Tx prevents the increase of Treg cells in the circulation that follows immunosuppressive therapy (particularly evident if the thymus is not neoplastic), indicating that the thymus contributes to Treg‐cell normalization. However, thymic Treg cells are not modulated by immunosuppressive therapy and even in thymectomized patients Treg‐cell numbers in the blood eventually recover. The present findings suggest that a deficiency in Treg cells favours the development of myasthenia gravis and that their normalization is an important clinical benefit of immunosuppressive therapy. Treg normalization appears to be largely thymus independent and possibly reflects the reported capacity of corticosteroids to promote Treg‐cell development.

The increased recruitment of suppressor type cells concomitant with the scarcity of cytotoxic type cells suggests that in mTDLN the presence of tumour cells could tip the balance against anti-tumour immune response facilitating the survival of metastatic tumour cells and possibly contributing to systemic tolerance.

SummaryInterleukin-2 (IL-2) is a mainstay for current immunotherapeutic protocols but its usefulness in patients is reduced by severe toxicities and because IL-2 facilitates regulatory T (Treg) cell development. IL-21 is a type I cytokine acting as a potent T-cell co-mitogen but less efficient than IL-2 in sustaining T-cell proliferation. Using various in vitro models for T-cell receptor (TCR)-dependent human T-cell proliferation, we found that IL-21 synergized with IL-2 to make CD4 + and CD8 + T cells attain a level of expansion that was impossible to obtain with IL-2 alone. for evaluating a combinatorial approach that would reduce the IL-2 needed to sustain T-cell proliferation efficiently, thereby reducing toxicity and controlling a tolerizing mechanism responsible for the contraction of the T-cell response.

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Cervical cancer (CC) is the fourth most common cause of cancer-related death in women. According to international guidelines, a standard treatment for locally advanced cervical cancer (LACC) consists of exclusive concurrent chemoradiation treatment (CRT). However, chemoradioresistance and subsequent relapse and metastasis of cancer occur in many patients, and survival for these women has generally remained poor. Therefore, strategies to overcome resistance are urgently needed. We have recently reported a radiosensitizing effect of the signal transducer and activator of transcription 1 (STAT1) in CC, associated with the control of [Poly(ADP-ribose) polymerase −1] PARP1 levels, a key factor in cell response to DNA damage induced by radiation. Here, we sought to decipher the underlying mechanism of STAT1-mediated control of PARP1, elucidating its role as a radiosensitizer in CC. Functional and molecular biology studies demonstrated that STAT1 may act at both transcriptional and posttranscriptional levels to modulate PARP1 expression in CC cells. In light of these results, we tested the effect of Olaparib in sensitizing CC cells to radiation and investigated signaling pathways involved in the activity observed. Results showed that PARP1 inhibition, at clinically achievable doses, may indeed selectively improve the sensitivity of resistant CC cells to DNA-damaging treatment. The translational relevance of our findings was supported by preliminary results in a limited patient cohort, confirming that higher PARP1 levels are significantly associated with a radioresistant phenotype. Finally, bioinformatics analysis of GEPIA and TCGA databases, demonstrated that PARP1 mRNA is higher in CC than in normal tissues and that increased PARP1 mRNA expression levels are associated with poor prognosis of LACC patients. Overall, our data open new opportunities for the development of personalized treatments in women diagnosed with CC.

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