Giovanni Franco

Mast Cells and Th17 Cells Contribute to the Lymphoma-Associated Pro-Inflammatory Microenvironment of Angioimmunoblastic T-Cell Lymphoma

Reports focusing on the immunological microenvironment of peripheral T-cell lymphomas (PTCL) are rare. Here we studied the reciprocal contribution of regulatory (Treg) and interleukin-17-producing (Th17) T-cells to the composition of the lymphoma-associated microenvironment of angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified on tissue microarrays from 30 PTCLs not otherwise specified and 37 AITLs. We found that Th17 but not Treg cells were differently represented in the two lymphomas and correlated with the amount of mast cells (MCs) and granulocytes, which preferentially occurred in the cellular milieu of AITL cases. We observed that MCs directly synthesized interleukin-6 and thus contribute to the establishment of a pro-inflammatory, Th17 permissive environment in AITL. We further hypothesized that the AITL clone itself could be responsible for the preferential accumulation of MCs at sites of infiltration through the synthesis of CXCL-13 and its interaction with the CXCR3 and CXCR5 receptors expressed on MCs. Consistent with this hypothesis, we observed MCs efficiently migrating in response to CXCL-13. On these bases, we conclude that MCs have a role in molding the immunological microenvironment of AITL toward the maintenance of pro-inflammatory conditions prone to Th17 generation and autoimmunity.

The bone marrow stroma in hematological neoplasms-a guilty bystander

In the setting of hematological neoplasms, changes in the bone marrow (BM) stroma might arise from pressure exerted by the neoplastic clone in shaping a supportive microenvironment, or from chronic perturbation of the BM homeostasis. Under such conditions, alterations in the composition of the BM stroma can be profound, and could emerge as relevant prognostic factors. In this Review, we delineate the multifaceted contribution of the BM stroma to the pathobiology of several hematological neoplasms, and discuss the impact of stromal modifications on the natural course of these diseases. Specifically, we highlight the involvement of BM stromal components in lymphoid and myeloid malignancies, and present the most relevant processes responsible for remodeling the BM stroma. The role of bystander BM stromal elements in the setting of hematological neoplasms is discussed, strengthening the rationale for treatment strategies that target the BM stroma.

CD146+ bone marrow osteoprogenitors increase in the advanced stages of primary myelofibrosis

CD146+ bone marrow stromal cells have been recently recognized as clonogenic osteoprogenitors able to organize a complete hematopoietic microenvironment. This study shows their involvement in bone marrow stromal changes occurring in primary myelofibrosis. CD146+ bone marrow stromal cells have been recently recognized as clonogenic osteoprogenitors able to organize a complete hematopoietic microenvironment. In this study we used immunohistochemical analysis to investigate the contribution of CD146+ bone marrow osteoprogenitors to the stromal remodeling occurring in the different stages of primary myelofibrosis. We found that CD146+ cells sited at the abluminal side of the bone marrow vessels and branching among hematopoietic cells significantly increased in the advanced stages of primary myelofibrosis (p<0.001), paralleling the extent of fibrosis (ρ=0.916, p<0.0001) and the microvascular density (r=0.883, p<0.0001). Coherently with a mural cell function, such cells also displayed smooth-muscle actin expression. Our data providing evidence of CD146+ cell involvement in bone marrow stromal changes occurring in primary myelofibrosis are consistent with the capability of these cells to participate in fiber deposition, angiogenesis, and bone formation. They could also represent rationale for new therapies targeting the bone marrow stroma in primary myelofibrosis.

Stromal SPARC contributes to the detrimental fibrotic changes associated with myeloproliferation whereas its deficiency favors myeloid cell expansion

In myeloid malignancies, the neoplastic clone outgrows normal hematopoietic cells toward BM failure. This event is also sustained by detrimental stromal changes, such as BM fibrosis and osteosclerosis, whose occurrence is harbinger of a dismal prognosis. We show that the matricellular protein SPARC contributes to the BM stromal response to myeloproliferation. The degree of SPARC expression in BM stromal elements, including CD146(+) mesenchymal stromal cells, correlates with the degree of stromal changes, and the severity of BM failure characterizing the prototypical myeloproliferative neoplasm primary myelofibrosis. Using Sparc(-/-) mice and BM chimeras, we demonstrate that SPARC contributes to the development of significant stromal fibrosis in a model of thrombopoietin-induced myelofibrosis. We found that SPARC deficiency in the radioresistant BM stroma compartment impairs myelofibrosis but, at the same time, associates with an enhanced reactive myeloproliferative response to thrombopoietin. The link betwen SPARC stromal deficiency and enhanced myeloid cell expansion under a myeloproliferative spur is also supported by the myeloproliferative phenotype resulting from the transplantation of defective Apc(min) mutant hematopoietic cells into Sparc(-/-) but not WT recipient BM stroma. Our results highlight a complex influence of SPARC over the stromal and hematopoietic BM response in myeloproliferative conditions.

Bendamustine with or without rituximab in the treatment of relapsed chronic lymphocytic leukaemia: an Italian retrospective study

To retrospectively assess the efficacy of bendamustine alone and with rituximab (R–B), 109 patients with relapsed chronic lymphocytic leukaemia (CLL) were enrolled in 24 Italian centres. The median age was 66 years (range 39–85). Forty‐three percent of patients had relapsed and 57% were resistant (median previous therapies = 3; range 1–8). Twenty‐two patients received bendamustine alone and 87 patients received R–B (median B dosage: 100 mg/m2 per day, range 90–130 mg/m2 per day). The overall response rate was 69·6% (complete response 28·6%; partial response 41%), and was significantly higher in patients treated with R–B (P = 0·014) and in those responsive to the previous treatment (P = 0·04). After a median follow‐up of 7·9 months (range 1–148), the median progression‐free survival was 16 months and the median duration of response was 13 months. Median overall survival (OS) was 16·8 months for the whole cohort; patients not responding to the treatment had a significantly worse outcome than those who attained a response (P = 0·0001). In multivariate analysis, only resistant disease status at start of bendamustine treatment (HR 3·2, 95% CI 1·4–7·3, P = 0·006) had an independent prognostic value for OS. Toxicity was manageable and mostly haematological. In conclusion, in our experience R–B was an effective and well‐tolerated treatment for relapsed/refractory CLL patients, producing a remarkable high CR rate and mild toxicity.

Bone marrow stroma CD40 expression correlates with inflammatory mast cell infiltration and disease progression in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a mature B-cell neoplasm characterized by rather indolent clinical course. However, nearly one third of patients experience a rapidly progressive disease with a dismal outcome. Despite the characterization of clone genetics and the recognition of deregulated immunologic stimulation in the pathogenesis of SMZL, little is known about microenvironment dynamics and their potential biological influence on disease outcome. Here we investigate the effect of stroma-intrinsic features on SMZL disease progression by focusing on the microenvironment of the bone marrow (BM), which represents an elective disease localization endorsing diagnostic and prognostic relevance. We show that the quality of the BM stromal meshwork of SMZL infiltrates correlates with time to progression. In particular, we describe the unfavorable prognostic influence of dense CD40 expression by BM stromal cells, which involves the contribution of CD40 ligand (CD40L)-expressing bystander mast cells infiltrating SMZL BM aggregates. The CD40/CD40L-assisted crosstalk between mesenchymal stromal cells and mast cells populating the SMZL microenvironment finds correlation in p53(-/-) mice developing SMZL and contributes to the engendering of detrimental proinflammatory conditions. Our study highlights a dynamic interaction, playing between nonneoplastic elements within the SMZL niche, toward disease progression.

Humoral immunotherapy of multiple myeloma: perspectives and perplexities

Importance of the field: Multiple myeloma (MM) is a hematological malignancy still remaining incurable despite the various therapies available, mainly because of the high fraction of refractory/relapsing cases. Therefore, the development of novel therapeutic approaches is urgently needed to overcome conventional treatment resistance. Areas covered in this review: In the era of targeted therapies, treatments combining a high specificity for neoplastic cells and the capability to interfere with environmental signals should be regarded as the weapons of choice. Monoclonal antibody (mAb)-based humoral immunotherapy could satisfy both these requirements when applied to MM. Indeed, many of the molecules expressed on MM cells, such as CD38, CD40, CD49d, CD138 and CD162 are involved in the adhesive dynamics regulating the crosstalk between MM and the BM-microenvironment. What the reader will gain: In this study we review those MM-associated molecules that have shown promising antitumor effects as targets of specific mAbs in preclinical settings, thus deserving to be considered for clinical investigation. Take home message: mAbs directed against MM-associated adhesion markers should be taken into account in clinical practice, since they could possibly represent the best available combination of tumor cytotoxicity, environmental signal deprivation and immune system redirection.

Challenges and new prospects in hepatosplenic γδ T-cell lymphoma

Abstract Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoid neoplasms characterized by aggressive clinical behavior and dismal prognosis. Hepatosplenic γδ T-cell lymphoma (γδ-HSTL) is a particular form of PTCL that arises from a small subset of γ/δ T-cell receptor-expressing lymphocytes. γδ-HSTL has a rapidly progressive course and poor outcome due also to its refractoriness to conventional chemotherapy regimens. The very low incidence of γδ-HSTL, along with its propensity to mimic different pathological entities, makes this lymphoma a true diagnostic challenge. In this review, we highlight the biological and clinical features of γδ-HSTL that contribute to making this lymphoma a mostly incurable disease. Moreover, we provide a new insight into the crosstalk between HSTL clones and the bone marrow, liver and spleen vascular microenvironment, in which neoplastic cells reside and proliferate. We further discuss γδ-HSTL associated molecules that might be proposed as potential targets for novel therapeutic approaches.

T Cell Large Granular Lymphocytic Leukemia in Association with Sjögren’s Syndrome

T cell large granular lymphocytic (LGL) leukemia is a rare condition accounting for 2–3% of all mature lymphoid leukemias. Here, we present the case of a 73-year-old woman presenting with neutropenia and anemia (hemoglobin 9.9 g/dl). Hematological assessment revealed the presence of a T cell LGL leukemia. At the time of T cell LGL leukemia diagnosis, the patient developed xerophthalmia and xerostomia, and a diagnosis of Sjögren’s syndrome was made following salivary gland biopsy. The finding of large granular lymphocytes in the context of autoimmune disorders is well-known, though it often occurs with rheumatoid arthritis or in association with a positive autoantibody titer in the absence of an overt clinical picture. The concomitant presentation of T cell LGL leukemia with Sjögren’s syndrome is a rare event which is worth reporting. Our patient was managed with immunosuppressive therapy and is still alive.