Pyrin Inflammasome Activation Defines Colchicine-Responsive SURF Patients from FMF and Other Recurrent Fevers.

Syndrome of undifferentiated recurrent fever (SURF) is characterized by recurrent fevers, a lack of confirmed molecular diagnosis, and a complete or partial response to colchicine. Despite the clinical similarities to familial Mediterranean fever (FMF), the underlying inflammatory mechanisms of SURF are not yet understood. We here analyzed the in vitro activation of the pyrin inflammasome in a cohort of SURF patients compared to FMF and PFAPA patients. Peripheral blood mononuclear cells (PBMC) were collected from SURF (both colchicine-treated and untreated), FMF, PFAPA patients, and healthy donors. PBMC were stimulated ex vivo with Clostridium difficile toxin A (TcdA) and a PKC inhibitor (UCN-01), in the presence or absence of colchicine. The assembly of the pyrin inflammasome was evaluated by measuring the presence of apoptosis-associated Speck-like protein containing caspase recruitment domain (ASC) specks in monocytes using flow cytometry. IL-1ß secretion was quantified using an ELISA assay. No differences in TcdA-induced activation of pyrin inflammasome were observed among FMF, PFAPA, and healthy donors. Untreated SURF patients showed a reduced response to TcdA, which was normalized after colchicine treatment. In contrast to FMF, SURF patients, similar to PFAPA patients and healthy donors, did not exhibit pyrin inflammasome activation in response to UCN-01-mediated pyrin dephosphorylation. These data demonstrate that in vitro functional analysis of pyrin inflammasome activation can differentiate SURF from FMF and PFAPA patients, suggesting the involvement of the pyrin inflammasome in the pathophysiology of SURF.

Spontaneous NLRP3 inflammasome-driven IL-1-ß secretion is induced in severe COVID-19 patients and responds to anakinra treatment.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may result in a severe pneumonia associated with elevation of blood inflammatory parameters, reminiscent of cytokine storm syndrome. Steroidal anti-inflammatory therapies have shown efficacy in reducing mortality in critically ill patients; however, the mechanisms by which SARS-CoV-2 triggers such an extensive inflammation remain unexplained. OBJECTIVES: To dissect the mechanisms underlying SARS-CoV-2-associated inflammation in patients with severe coronavirus disease 2019 (COVID-19), we studied the role of IL-1ß, a pivotal cytokine driving inflammatory phenotypes, whose maturation and secretion are regulated by inflammasomes. METHODS: We analyzed nod-like receptor protein 3 pathway activation by means of confocal microscopy, plasma cytokine measurement, cytokine secretion following in vitro stimulation of blood circulating monocytes, and whole-blood RNA sequencing. The role of open reading frame 3a SARS-CoV-2 protein was assessed by confocal microscopy analysis following nucleofection of a monocytic cell line. RESULTS: We found that circulating monocytes from patients with COVID-19 display ASC (adaptor molecule apoptotic speck like protein-containing a CARD) specks that colocalize with nod-like receptor protein 3 inflammasome and spontaneously secrete IL-1ß in vitro. This spontaneous activation reverts following patient's treatment with the IL-1 receptor antagonist anakinra. Transfection of a monocytic cell line with cDNA coding for the ORF3a SARS-CoV-2 protein resulted in ASC speck formation. CONCLUSIONS: These results provide further evidence that IL-1ß targeting could represent an effective strategy in this disease and suggest a mechanistic explanation for the strong inflammatory manifestations associated with COVID-19.

Bone Marrow CX3CL1/Fractalkine is a New Player of the Pro-Angiogenic Microenvironment in Multiple Myeloma Patients.

C-X3-C motif chemokine ligand 1 (CX3CL1)/fractalkine is a chemokine released after cleavage by two metalloproteases, ADAM metallopeptidase domain 10 (ADAM10) and ADAM metallopeptidase domain 17 (ADAM17), involved in inflammation and angiogenesis in the cancer microenvironment. The role of the CX3CL1/ C-X3-C motif chemokine receptor 1(CX3CR1) axis in the multiple myeloma (MM) microenvironment is still unknown. Firstly, we analyzed bone marrow (BM) plasma levels of CX3CL1 in 111 patients with plasma cell disorders including 70 with active MM, 25 with smoldering myeloma (SMM), and 16 with monoclonal gammopathy of undetermined significance (MGUS). We found that BM CX3CL1 levels were significantly increased in MM patients compared to SMM and MGUS and correlated with BM microvessel density. Secondly, we explored the source of CX3CL1 in MM and BM microenvironment cells. Primary CD138⁺ cells did not express CXC3L1 but up-regulated its production by endothelial cells (ECs) through the involvement of tumor necrosis factor alpha (TNFα). Lastly, we demonstrated the presence of CX3CR1 on BM CD14⁺CD16⁺ monocytes of MM patients and on ECs, but not on MM cells. The role of CX3CL1 in MM-induced angiogenesis was finally demonstrated in both in vivo chick embryo chorioallantoic membrane and in vitro angiogenesis assays. Our data indicate that CX3CL1, present at a high level in the BM of MM patients, is a new player of the MM microenvironment involved in MM-induced angiogenesis.

IL-25 dampens the growth of human germinal center-derived B-cell non Hodgkin Lymphoma by curtailing neoangiogenesis.

Interleukin (IL)-25, a member of the IL-17 cytokine superfamily, is produced by immune and non-immune cells and exerts type 2 pro-inflammatory effects in vitro and in vivo. The IL-25 receptor(R) is composed of the IL-17RA/IL-17RB subunits. Previous work showed that germinal centre (GC)-derived B-cell non Hodgkin lymphomas (B-NHL) expressed IL-17AR, formed by IL-17RA and IL-17RC subunits, and IL-17A/IL-17AR axis promoted B-NHL growth by stimulating neoangiogenesis. Here, we have investigated expression and function of IL-25/IL-25R axis in lymph nodes from human GC-derived B-NHL, i.e. Follicular Lymphoma (FL,10 cases), Diffuse Large B Cell Lymphoma (6 cases) and Burkitt Lymphoma (3 cases). Tumor cells expressed IL-25R and IL-25 that was detected also in non-malignant cells by flow cytometry. Immunohistochemical studies confirmed expression of IL-25R and IL-25 in FL cells, and highlighted IL-25 expression in bystander elements of the FL microenvironment. IL-25 i) up-regulated phosphorylation of NFkBp65, STAT-1 and JNK in B-NHL cells; ii) inhibited in vitro proliferation of the latter cells; iii) exerted anti-tumor activity in two in vivo B-NHL models by dampening expression of pro-angiogenic molecules as VEGF-C, CXCL6 and ANGPT3. In conclusion, IL-25, that is intrinsically pro-angiogenic, inhibits B-NHL growth by reprogramming the angiogenic phenotype of B-NHL cells.

Interleukin-31 and thymic stromal lymphopoietin expression in plasma and lymph node from Hodgkin lymphoma patients.

Hodgkin Lymphoma (HL) is a tumor of B-cell origin characterized by Hodgkin and Reed-Stenberg (H/RS) cells embedded in an inflammatory tissue where numerous cytokines/chemokines contribute to shape the microenvironment, leading to the typical clinical symptoms. We investigated: i) the expression of Interleukin-IL-31 (IL-31) and Thymic Stromal Lymphopoietin (TSLP), two Th2-related cytokines with tumor-promoting and pruritogenic functions, and of the respective receptors in HL invaded lymph nodes by flow cytometry, and ii) the potential association of IL-31/TSLP plasma concentrations with clinical characteristics by ELISA. H/RS cells and the major immune cell types infiltrating HL lymph nodes expressed intracytoplasmic and surface IL-31/TSLP, and their receptors. A subgroup of patients showing at diagnosis elevated IL-31 and TSLP plasma levels had an International Prognostic Score>2, indicative of high risk of relapse, and a subsequent positive interim PET-scan, indicative of insufficient response to chemotherapy. No correlation was found between IL-31/TSLP plasma levels and overall or event-free survival. In conclusion, IL-31/TSLP and their receptors are expressed in HL cells and in immune cells infiltrating affected lymph nodes, where both cytokines may contribute to local immune suppression. The clinical impact of IL-31 and TSLP plasma levels has to be further defined in larger patient cohorts.

The IL-31/IL-31 receptor axis: general features and role in tumor microenvironment.

IL-31 is a recently identified cytokine with a well-defined role in the pathogenesis of pruritus. IL-31, whose production is induced by IL-4 and IL-33, binds a heterodimeric receptor (R) composed of the exclusive IL-31RA chain and the shared oncostatin M R. Signaling through the IL-31R involves the MAPK, PI3K/AKT and Jak/STAT pathways. Different variants and isoforms of IL-31RA with different signaling activities have been identified. IL-31 is produced predominantly by circulating Th2 lymphocytes and skin-homing CLA+CD45RO+ T cells. Studies in humans have demonstrated a pathogenic role for IL-31 in atopic dermatitis and allergic asthma. The first demonstration of the involvement of the IL-31/IL-31R axis in cancer came from studies in patients with mycosis fungoides/Sézary syndrome, the most frequent, cutaneous T cell lymphoma. Tumor cells were shown to produce IL-31, whose serum levels correlated with pruritus intensity. Follicular lymphoma (FL) B cells and their counterparts-germinal center B cells-produced IL-31 and expressed IL-31R, which signaled in the former, but not the latter, cells. IL-31 released in association with microvesicles promoted tumor growth through autocrine/paracrine loops. Malignant mast cells from patients with mastocytosis or Philadelphia-negative myeloproliferative disorder produced IL-31, which contributed to pruritus pathogenesis. Finally, patients with endometrial carcinoma displayed high serum levels of IL-31 and IL-33, which may represent promising disease biomarkers. Targeting strategies for the IL-31/IL-31R axis have been developed, including the CIMM331 humanized anti-human IL-31RA antibody recently tested in a phase I/Ib study.

Interleukin-17A promotes the growth of human germinal center derived non-Hodgkin B cell lymphoma.

Interleukin (IL)-17A belongs to IL-17 superfamily and binds the heterodimeric IL-17 receptor (R)(IL-17RA/IL-17RC). IL-17A promotes germinal center (GC) formation in mouse models of autoimmune or infectious diseases, but the role of IL-17A/IL-17AR complex in human neoplastic GC is unknown. In this study, we investigated expression and function of IL-17A/IL-17AR in the microenvironments of 44 B cell non-Hodgkin lymphomas (B-NHL) of GC origin (15 follicular lymphomas, 17 diffuse large B cells lymphomas and 12 Burkitt lymphomas) and 12 human tonsil GC. Furthermore, we investigated the role of IL-17A in two in vivo models of GC B cell lymphoma, generated by s.c. injection of SU-DHL-4 and OCI-Ly8 cell lines in Severe combined immunodeficiency (SCID)/Non Obese Diabetic (NOD) mice. We found that: (i) B-NHL cell fractions and tonsil GC B cells expressed IL-17RA/IL-17RC, (ii) IL-17A signaled in both cell types through NF-kBp65, but not p38, ERK-1/2, Akt or NF-kBp50/105, phosphorylation, (iii) IL-17A was expressed in T cells and mast cells from neoplastic and normal GC microenvironments, (iv) IL-17A rendered tonsil GC B cells competent to migrate to CXCL12 and CXCL13 by downregulating RGS16 expression; (v) IL-17A stimulated in vitro proliferation of primary B-NHL cells; (vi) IL-17A (1 µg/mouse-per dose) stimulated B-NHL growth in two in vivo models by enhancing tumor cell proliferation and neo-angiogenesis. This latter effect depended on IL-17A-mediated induction of pro-angiogenic gene expression in tumor cells and direct stimulation of endothelial cells. These data define a previously unrecognized role of human IL-17A in promoting growth of GC-derived B-NHL and modulating normal GC B cell trafficking.

Role of fractalkine/CX3CL1 and its receptor in the pathogenesis of inflammatory and malignant diseases with emphasis on B cell malignancies.

Fractalkine/CX3CL1, the only member of the CX3C chemokine family, exists as a membrane-anchored molecule as well as in soluble form, each mediating different biological activities. It is constitutively expressed in many hematopoietic and nonhematopoietic tissues such as endothelial and epithelial cells, lymphocytes, neurons, microglial osteoblasts. The biological activities of CX3CL1 are mediated by CX3CR1, that is expressed on different cell types such as NK cells, CD14(+) monocytes, cytotoxic effector T cells, B cells, neurons, microglia, smooth muscle cells, and tumor cells. The CX3CL1/CX3CR1 axis is involved in the pathogenesis of several inflammatory cancer including various B cell malignancies. In tumors the interaction between cancer cells and cellular microenvironment creates a context that may promote tumor growth, increase tumor survival, and facilitate metastasis. Therefore the role of the CX3CL1/CX3CR1 has attracted interest as to the development of potential therapeutic approaches. Here we review the different effects of the CX3CL1/CX3CR1 axis in several inflammatory and neurodegenerative diseases and in cancer, with emphasis on human B cell lymphomas.

CX3CL1/fractalkine is a novel regulator of normal and malignant human B cell function.

CX(3)CL1, or fractalkine, the unique member of the CX(3)C chemokine family, exists as a transmembrane glycoprotein, as well as in soluble form, each mediating different biological activities, and is constitutively expressed in many hematopoietic and nonhematopoietic tissues. CX(3)CR1, the CX(3)CL1 exclusive receptor, is a classical GPCR, expressed on NK cells, CD14(+) monocytes, and some subpopulation of T cells, B cells, and mast cells. A recent paper by our group has demonstrated for the first time that highly purified human B cells from tonsil and peripheral blood expressed CX(3)CR1 at mRNA and protein levels. In particular, tonsil naïve, GC, and memory B cells expressed CX(3)CR1, but only GC centrocytes were attracted by soluble CX(3)CL1, which with its receptor, are also involved in the pathogenesis of several inflammatory disorders, as well as of cancer. Previous studies have shown that CX(3)CR1 is up-regulated in different types of B cell lymphoma, as well as in B-CLL. Recently, we have demonstrated that the CX(3)CL1/CX(3)CR1 axis is involved in the interaction of B-CLL cells with their microenvironment. Taken together, our data delineate a novel role for the CX(3)CL1/CX(3)CR1 complex in the biology of normal B cells and B-CLL cells. These topics are the subject of this review article.

CX3CR1 is expressed by human B lymphocytes and mediates [corrected] CX3CL1 driven chemotaxis of tonsil centrocytes.

BACKGROUND: Fractalkine/CX(3)CL1, a surface chemokine, binds to CX(3)CR1 expressed by different lymphocyte subsets. Since CX(3)CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX(3)CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX(3)CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX(3)CR1 but only germinal centre B cells were attracted by soluble CX(3)CL1 in a transwell assay. CX(3)CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX(3)CR1(+) germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX(3)CL1. ELISA assay showed that soluble CX(3)CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX(3)CL1 did not attract spleen B cells from wild type mice. OVA immunized CX(3)CR1(-/-) or CX(3)CL1(-/-) mice showed significantly decreased specific IgG production compared to wild type mice. CONCLUSION/SIGNIFICANCE: We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX(3)CL1 that attracts centrocytes. The functional implications of these results warrant further investigation.

Phenotypic and functional characterization of switch memory B cells from patients with oligoarticular juvenile idiopathic arthritis.

INTRODUCTION: In chronic inflammatory disorders, B cells can contribute to tissue damage by autoantibody production and antigen presentation to T cells. Here, we have characterized synovial fluid and tissue B-cell subsets in patients with oligoarticular juvenile idiopathic arthritis (JIA), an issue not addressed before in detail. METHODS: B cells from synovial fluid (SF) and peripheral blood (PB) of 25 JIA patients, as well as from PB of 20 controls of comparable age, were characterized by multicolor flow cytometry. Immunoglobulin-secreting cells were detected by ELISPOT. Immunohistochemical analyses of synovial tissue from three JIA patients were performed. RESULTS: JIA SF B cells were enriched in CD27+ and CD27- switch memory B cells, but not in CD27+ IgM memory B cells, compared with patient and control PB. Plasma blasts were more abundant in SF and secreted higher amounts of IgG. Lymphoid aggregates not organized in follicle-like structures were detected in synovial tissue sections and were surrounded by CD138+ plasma cells. Finally, transitional B cells were significantly increased in JIA PB versus SF or control PB. CCR5, CCR8, CXCR2, and CXCR3 were upregulated, whereas CCR6, CCR7, and CXCR5 were downregulated on SF CD27+ and CD27- switch memory B cells compared with their circulating counterparts. SF CD27+ and CD27- switch memory B cells expressed at high levels the costimulatory molecule CD86 and the activation marker CD69. CONCLUSIONS: This study demonstrates for the first time an expansion of activated switch memory B cells and of IgG-secreting plasma blasts in the SF from oligoarticular JIA patients. Memory B cells belonged to either the CD27+or the CD27- subsets and expressed CD86, suggesting their involvement in antigen presentation to T cells. Patterns of chemokines-receptor expression on CD27+ and CD27- switch memory B cells delineated potential mechanisms for their recruitment to the inflamed joints.

Changes in cytokine profile pre- and post-immunosuppression in acquired aplastic anemia.

Cytokine expression assessed by flow cytometry in 53 acquired aplastic anemia patients before and after combined immunosuppression (EBMT WPSAA protocols) showed that CD3(+) marrow cells containing TNF-alpha, IFN-gamma and IL4 were similar in subjects with disease at onset (DO) and responsive to treatment who had more CD3(+)/TNF-alpha(+) and CD 3(+)/IFN-gamma(+) cells than normal controls. In vitro block of TNF-alpha and/or IFN-gamma significantly increased BFU-e over baseline in 28 patients. In responsive to treatment patients only TNF-alpha block significantly incremented colonies over normal controls. Absolute marrow CD3(+)/TNF-alpha(+) and CD3(+)/IFN-gamma(+) cells prospectively tested in a group of 21 subjects declined significantly more in Responders than in Non Responders to immunosuppression at Response Evaluation Time respect to Diagnosis. Both in Responders and in Non Responders these cells remained higher than in normal controls. This study suggests that immunosuppression does not fully clear excess TNF-alpha and IFN-gamma from marrow of patients with good outcome and raises the hypothesis that additional cytokine blockade might be useful in immunosuppression for acquired aplastic anemia.

Congenital amegakaryocytic thrombocytopenia: clinical and biological consequences of five novel mutations.

BACKGROUND AND OBJECTIVES: Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, autosomal recessive disorder induced by mutations of the gene coding for thrombopoietin (TPO) receptor (c-MPL). Patients initially present with isolated thrombocytopenia that subsequently progresses into pancytopenia. Although the mechanisms leading to aplasia are unknown, the age of onset has been reported to depend on the severity of the c-MPL functional defect. To improve our knowledge in this field, we studied clinical and biological features of five new patients. DESIGN AND METHODS: We diagnosed five CAMT patients, identified c-MPL mutations, including five novel alterations and investigated relationships between mutations and their clinical-biological consequences. RESULTS: In all cases, platelet c-MPL and bone marrow colonies were reduced, while serum TPO levels were elevated. We also documented that the percentage of bone marrow cells expressing tumor necrosis factor-a and interferon-g was increased during pancytopenia as compared to in controls, suggesting that, as in other bone marrow failure diseases, these inhibitory cytokines contributed to the pancytopenia. Contrary to previously published data, we found no evidence of correlations between different types of mutations and the clinical course. INTERPRETATION AND CONCLUSIONS: These results suggest that therapies, such as hematopoietic stem cell transplantation, which are potentially curative although associated with a risk of treatment-related mortality, should not be postponed even in those CAMT patients whose c-MPL mutations might predict residual activity of the TPO receptor.

Human Fanconi A cells are susceptible to TRAIL-induced apoptosis.

Tumour necrosis factor (TNF) contributes to the pathogenesis of bone marrow failure in Fanconi anaemia (FA) patients. The sensitivity of haematopoietic cells from FA, complementation group A (FANCA) subjects, who represent the majority of FA patients, to TNF-related apoptosis-inducing ligand (TRAIL) is unknown. The human lymphoblastoid FANCA HSC072 cell line and the genetically corrected counterpart HSC072FANCA-neo were tested for apoptoptic response to TRAIL using flow cytometry and Western blotting. FANCA cells were more sensitive to TRAIL-induced apoptosis than their corrected counterparts, indicating that TRAIL negatively regulates haematopoietic FANCA cell lines. This effect involved poly(ADP-ribose) polymerase-1 cleavage and caspase-8 activation.

Mechanisms of the adaptive immune response inside the central nervous system during inflammatory and autoimmune diseases.

In this review we will discuss the unique features that make the central nervous system (CNS) a specialized microenvironment where immune responses are tightly regulated in order to properly face pathogens without damaging the neural cells. We will show how every paradigm of this theoretical model has been addressed by the scientific literature over the past decades providing new insights on the immune response within the CNS. In particular, new light has been shed on the trafficking of the immune cells inside and outside the CNS. Dendritic cells (DCs) have been described in the context of structures in direct contact with the cerebrospinal fluid (CSF) and their migration, upon antigen encounter, outside the CNS into deep cervical lymph nodes (DCLNs) has been further clarified. T-cells, B-cells, and antibody-secreting cells (ASCs) have been found in the CSF and CNS parenchymal lesions of inflammatory disorders and their phenotype depicted. Moreover, in chronically inflamed CNS, ectopic lymphoid structures have been observed and a germinal center reaction similar to the one found in peripheral lymph nodes has been described. These structures may play a role in the maintenance and expansion of the local autoimmune response. Although the complex interactions between immune and neural cells still remain far to be elucidated, the data discussed here suggest that the physiopathology of the adaptive immune response inside the CNS mimics, although in a mitigated fashion, what occurs in other organs and tissues.

Human mesenchymal stem cells modulate B-cell functions.

Human mesenchymal stem cells (hMSCs) suppress T-cell and dendritic-cell function and represent a promising strategy for cell therapy of autoimmune diseases. Nevertheless, no information is currently available on the effects of hMSCs on B cells, which may have a large impact on the clinical use of these cells. hMSCs isolated from the bone marrow and B cells purified from the peripheral blood of healthy donors were cocultured with different B-cell tropic stimuli. B-cell proliferation was inhibited by hMSCs through an arrest in the G0/G1 phase of the cell cycle and not through the induction of apoptosis. A major mechanism of B-cell suppression was hMSC production of soluble factors, as indicated by transwell experiments. hMSCs inhibited B-cell differentiation because IgM, IgG, and IgA production was significantly impaired. CXCR4, CXCR5, and CCR7 B-cell expression, as well as chemotaxis to CXCL12, the CXCR4 ligand, and CXCL13, the CXCR5 ligand, were significantly down-regulated by hMSCs, suggesting that these cells affect chemotactic properties of B cells. B-cell costimulatory molecule expression and cytokine production were unaffected by hMSCs. These results further support the potential therapeutic use of hMSCs in immune-mediated disorders, including those in which B cells play a major role.

Chemokine receptor expression and function in childhood acute lymphoblastic leukemia of B-lineage.

Scanty information is available on chemokine receptor expression and function in childhood B-lineage acute lymphoblastic leukemia (ALL). Thirteen pro-B, 17 early pre-B, 12 pre-B, and 9 B-ALL/Burkitt lymphoma (BL) pediatric cases were tested for CXCR1 to CXCR5 and CCR1 to CCR7 expression. CXCR2, CXCR3, and CXCR4 were expressed in the majority of cases, while the other receptors were variably expressed or absent. CXCR4 mediated chemotaxis of all leukemic cell subtypes. Freshly isolated CCR7(+) early pre-B-ALL cells migrated to CCL19, whereas CCR7(+) pro-B- and pre-B-ALL cells were attracted by CCL19 only following culture with soluble recombinant CD40 ligand.