APRIL is Involved in the Proliferation and Metastasis of Acute Lymphoblastic Leukemia Cells.

Our previous work showed that a proliferation-inducing ligand (APRIL) was involved in the development of acute lymphoblastic leukemia (ALL) in children. However, the precise role of APRIL in ALL remains unknown. To investigate this issue, we silenced and overexpressed APRIL in Nalm-6 ALL cells using short hairpin RNA targeting the APRIL gene and recombinant human APRIL, respectively, and evaluated the effects on cell proliferation, apoptosis, and migration. APRIL mRNA and APRIL and matrix metalloproteinase-2 protein levels were evaluated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and western blott, respectively. We found that APRIL expression was reduced by shRNA-mediated knockdown in Nalm-6 cells; this was associated with a decrease in cell proliferation (P<0.05). APRIL knockdown increased apoptosis (P<0.01) but suppressed cell migration along with matrix metalloproteinase-2 protein level. Overexpressing recombinant human APRIL had the opposite effects in each case (P<0.05). These results demonstrate a link between APRIL expression and ALL development and suggest that APRIL is a potential therapeutic target for ALL treatment.

Toll-Like Receptor 9 Stimulation Induces Aberrant Expression of a Proliferation-Inducing Ligand by Tonsillar Germinal Center B Cells in IgA Nephropathy.

The TNF family member a proliferation-inducing ligand (APRIL; also known as TNFSF13), produced by myeloid cells, participates in the generation and survival of antibody-producing plasma cells. We studied the potential role of APRIL in the pathogenesis of IgA nephropathy (IgAN). We found that a significant proportion of germinal centers (GCs) in tonsils of patients with IgAN contained cells aberrantly producing APRIL, contributing to an overall upregulation of tonsillar APRIL expression compared with that in tonsils of control patients with tonsillitis. In IgAN GC, antigen-experienced IgD-CD38+/-CD19+ B cells expressing a switched IgG/IgA B cell receptor produced APRIL. Notably, these GC B cells expressed mRNA encoding the common cleavable APRIL-α but also, the less frequent APRIL-δ/ζ mRNA, which encodes a protein that lacks a furin cleavage site and is, thus, the uncleavable membrane-bound form. Significant correlation between TLR9 and APRIL expression levels existed in tonsils from patients with IgAN. In vitro, repeated TLR9 stimulation induced APRIL expression in tonsillar B cells from control patients with tonsillitis. Clinically, aberrant APRIL expression in tonsillar GC correlated with greater proteinuria, and patients with IgAN and aberrant APRIL overexpression in tonsillar GC responded well to tonsillectomy, with parallel decreases in serum levels of galactose-deficient IgA1. Taken together, our data indicate that antibody disorders in IgAN associate with TLR9-induced aberrant expression of APRIL in tonsillar GC B cells.

Significance of BAFF/APRIL Expression and Their Receptors in Pediatric Patients With Acute Lymphoblastic Leukemia.

In this study, we investigated the mRNA expression and protein levels of B-cell activating factor (BAFF)/a proliferation-inducing ligand (APRIL) and their receptors in acute lymphoblastic leukemia (ALL) cell lines and pediatric patients with ALL using real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting. The location and level of the BAFF/APRIL proteins in ALL cell lines were also detected by immunofluorescence cytochemistry and flow cytometry. Correlations between plasma protein levels of BAFF/APRIL and primary clinical parameters were analyzed. We found that BAFF/APRIL was highly expressed in pediatric ALL patients and ALL cell lines. The BAFF/APRIL proteins were located on the cell membrane, and the proportion of positive cells and mean fluorescence intensity were significantly higher than in the healthy control group (P<0.05). The mRNA expression and protein levels of BAFF/APRIL and their receptors in untreated ALL children were significantly higher than in healthy controls (P<0.05) as well as were significantly reduced in the remission group (P<0.05). The plasma protein levels of BAFF/APRIL were positively correlated with the white blood cell count, lactate dehydrogenase, and serum ferritin. Abnormal levels of BAFF/APRIL in pediatric ALL suggest that BAFF/APRIL are associated with the development and progression of ALL in children and may provide information for the development of BAFF-based and APRIL-based targeted therapies.

The up-regulation expression of APRIL is a marker of glottic malignant disease.

A proliferation-inducing ligand (APRIL) is a member of the tumor necrosis factor (TNF) family. Recent studies have implied that APRIL is closely related to solid tumors and hematological tumors, indicating that APRIL could be a potential marker to diagnose glottic malignant disease. The purpose of this study was to investigate the difference of the APRIL mRNA and protein expression in glottic malignant disease, corresponding adjacent non-neoplastic tissues and glottic benign lesion, and detect the influence of different clinical parameter in glottic carcinoma. The APRIL mRNA expression in the glottic carcinoma, corresponding adjacent non-neoplastic tissues and glottic polypus tissue samples from patients was detected by qRT-PCR. Moreover, we studied the APRIL protein expression in pathological sections of other patients with glottic carcinoma or glottic polypus using immunohistochemistry. All the patients with different clinical parameter underwent surgery. Using qRT-PCR, we revealed an up-regulation of APRIL mRNA expression in glottic carcinoma as compared to glottic polypus and corresponding adjacent non-neoplastic tissues, but no significant difference with T stages, histopathological differentiation grade or lymph node metastasis in glottic carcinoma. The result of the immunohistochemistry was the same, with no influence of different clinical parameter in glottic carcinoma. These results strongly suggest that APRIL could be a potential diagnosed marker to distinguish glottic malignant disease from glottic benign lesion, and it may play an important role in the development of glottic malignant disease.

Immunization induces activation of bone marrow eosinophils required for plasma cell survival.

Eosinophils not only have multiple functions as effector cells of the innate immune system but also as modulators of immune responses. As producers of cytokines required for plasma cell survival, they are essential for the long-term maintenance of plasma cells in the BM. Here we show that the activation of eosinophils both in vitro and in vivo enhances the expression of the plasma cell survival factors APRIL, IL-6, IL-4, IL-10 and TNF-α. The in vivo activation of eosinophils was independent of the type of adjuvant used for primary immunization. Although eosinophils were activated by adjuvant itself, a stable activation and a constant increase in BM eosinophils were observed only in the presence of antigen. Thus, the numbers and the quality of eosinophils were dependent on priming the adaptive immune system. With secondary immunization and re-activation of antigen-dependent memory cells, the ability of eosinophils to promote plasma cell survival was further increased. These findings suggest that in T-cell-dependent immune responses eosinophils are conditioned to support the long-term survival of plasma cells in the BM, and furthermore imply that through accelerated numbers of eosinophils, stable plasma cell survival niches are established and the long-term survival of plasma cells is ensured.

A BAFF/APRIL-dependent TLR3-stimulated pathway enhances the capacity of rheumatoid synovial fibroblasts to induce AID expression and Ig class-switching in B cells.

OBJECTIVES: To dissect the role of toll-like receptor (TLR) signalling and B cell survival/proliferating factors in the crosstalk between rheumatoid arthritis synovial fibroblasts (RASF) and B cells. METHODS: RASF, rheumatoid arthritis dermal fibroblasts (RADF) and osteoarthritis synovial fibroblasts (OASF) were analysed for the expression of B cell survival/proliferating factors BAFF and APRIL in resting conditions and upon stimulation with TLR2/TLR3/TLR4 ligands. Unswitched IgD+ B cells were co-cultured with RASF/OASF/RADF in the presence/absence of TLR ligands and with/without BAFF/APRIL blocking antibodies. Activation-induced cytidine deaminase (AID) mRNA expression, Iγ-Cµ and Iα-Cµ circular transcripts (CTs; markers of ongoing class-switching to IgG and IgA) and IgM/A/G production were measured to assess functional activation of B cells. RESULTS: TLR3 and to a lesser extent TLR4, but not TLR2 stimulation, induced up to ∼1000-fold BAFF mRNA and increased soluble BAFF release. APRIL was less significantly regulated by TLR3. Resting and TLR3-stimulated RASF released higher levels of BAFF/APRIL compared with RADF. TLR3 stimulation of RASF but not RADF in co-culture with B cells strongly enhanced AID expression, Iγ-Cµ and Iα-Cµ CTs and class-switching to IgG/IgA. Blockade of BAFF/APRIL signalling completely inhibited TLR3-induced, RASF-dependent expression of AID, CTs and the secretion of IgG/IgA. CONCLUSIONS: RASF produce high levels of BAFF and APRIL constitutively and in response to TLR3 stimulation. These factors are critical in directly modulating AID expression, class-switch recombination and IgG/IgA production in IgD+ B cells. Overall, this work highlights a novel and fundamental role for the TLR3/B cell survival factor axis in sustaining B cell activation in the rheumatoid arthritis synovium.

Adipocytes as immune cells: differential expression of TWEAK, BAFF, and APRIL and their receptors (Fn14, BAFF-R, TACI, and BCMA) at different stages of normal and pathological adipose tissue development.

Adipose tissue represents a rich source of multipotent stem cells. Mesenchymal cells, isolated from this source, can differentiate to other cell types in vitro and therefore can be used for a number of regenerative therapies. Our view of adipose tissue has recently changed, establishing adipocytes as new members of the immune system, as they produce a number of proinflammatory cytokines (such as IL-6 and TNFalpha and chemokines, in addition to adipokines (leptin, adiponectin, resistin) and molecules associated with the innate immune system. In this paper, we report the differential expression of TNF-superfamily members B cell activating factor of the TNF Family (BAFF), a proliferation inducing ligand (APRIL), and TNF-like weak inducer of apoptosis (TWEAK) in immature-appearing and mature adipocytes and in benign and malignant adipose tissue-derived tumors. These ligands act through their cognitive receptors, BAFF receptor, transmembrane activator and calcium signal-modulating cyclophilic ligand (TACI), B cell maturation Ag (BCMA), and fibroblast growth factor-inducible 14 (Fn14), which are also expressed in these cells. We further report the existence of functional BCMA, TACI, and Fn14 receptors and their ligands BAFF, APRIL, and TWEAK on adipose tissue-derived mesenchymal cells, their interaction modifying the rate of adipogenesis. Our data integrate BAFF, APRIL, and TWEAK and their receptors BCMA, TACI, and Fn14 as novel potential mediators of adipogenesis, in addition to their specific role in immunity, and define immature and mature adipocytes as source of immune mediators.

Neutrophil Expression of T and B Immunomodulatory Molecules in HIV Infection.

Objective: Evaluate the expression of B and T cell immunomodulatory molecules in polymorphonuclear neutrophils (PMN) in HIV-infected patients. Methods: HIV load, bacterial translocation and neutrophils' expression of T [programmed death ligand, interleukin-10+, arginase 1+] and B [BAFF, APRIL] molecules were analyzed in different cohorts and time points: a control group of 25 healthy individuals and two groups of HIV-infected patients. Group 1 of patients included 35 untreated patients, studied at baseline and after antiretroviral therapy (ART). Group 2 was composed of 25 patients with undetectable viral load after a median of 101 months of ART prior to inclusion in the study. Results: Compared with the control group, group 1 patients showed increased bacterial translocation and their PMN had a significantly higher expression of T and B-cell immunomodulatory molecules, both at baseline and after 12 months of ART. Group 2 patients showed reduced bacterial translocation levels when compared with group 1 patients after 12 months of treatment. PMN expression of B-cell modulators was similar between group 2 patients and healthy controls, although the expression of T-cell modulators remained increased. Conclusion: In HIV-infected patients, the expression of B-cell stimulatory and T-cell suppressive molecules by neutrophils was increased at baseline and after a limited time of therapy. After a prolonged period of ART, only PMNs expression of T-cell immunosuppressive molecules remained elevated.

Polarized Secretion of APRIL by the Tonsil Epithelium Upon Toll-Like Receptor Stimulation.

In mucosa such as tonsil, antibody-producing plasmocytes (PCs) lie in sub-epithelium space, which is thought to provide a suitable environment for their survival. A proliferation inducing ligand (APRIL) is one key survival factor for PCs present in this area. According to in situ staining, apical epithelial cells produced APRIL, and the secreted product had to migrate all through the stratified surface epithelium to reach basal cells. A similar process also occurred in the less-organized crypt epithelium. Tonsil epithelial cells captured secreted APRIL, thanks to their surface expression of the APRIL coreceptor, either syndecan-1 or -4 depending on their differentiation stage. In the most basal epithelial cells, secreted APRIL accumulated inside secretory lamp-1+ vesicles in a polarized manner, facing the sub-epithelium. The tonsil epithelium upregulated APRIL production by apical cells and secretion by basal cells upon Toll-like receptor stimulation. Furthermore, LPS-stimulated epithelial cells sustained in vitro PC survival in a secreted APRIL-dependent manner. Taken together, our study shows that the tonsil epithelium responds to pathogen sensing by a polarized secretion of APRIL in the sub-epithelial space, wherein PCs reside.

[Effect of APRIL on growth and apoptosis in transplanted tumor with human colorectal cancer cell line SW480 in nude mice].

OBJECTIVE: To study the effect of pGCsi-H1-APRIL on the growth of human colorectal cancer cells in transplated tumor in nude mice and to improve the effect of APRIL on proliferation and apoptosis of colorectal cancer (CRC). METHODS: Human CRC model was established in nude mice, and the nude mice were treated with APRIL siRNA twice per week for 2 weeks. APRIL mRNA expression was surveyed by PCR and APRIL protein expression was detected by immunohistochemistry. The expression of PCNA protein was detected by ELISA. The expression of bcl-2 and bcl-xl was assessed by immunohistochemical staining, and TUNEL staining was used to detect apoptosis. RESULTS: The expression of APRIL mRNA in the APRIL siRNA group was (0.13 ± 0.05) × 10(-3), significantly lower than that in the vector group (0.95 ± 0.04) × 10(-3) and the PBS group (0.96 ± 0.05) × 10(-3). The expression of APRIL protein in the APRIL siRNA group was (87.5 ± 5.0)% lower than that in the vector and PBS groups (P < 0.05). APRIL siRNA significantly suppressed the growth of SW480 tumor: the IR (inhibitory rate) of APRIL siRNA group was (60.7 ± 1.5)% (P < 0.05). The expression of PCNA in APRIL siRNA group was (176.8 ± 18.1) ng/ml, was (56.5 ± 2.0)% lower than that of PBS group (328.4 ± 22.8) ng/ml. Furthermore, the expressions of anti-apoptosis proteins bcl-2 and bcl-xl of APRIL siRNA group were (82.6 ± 4.5)% and (79.2 ± 3.5)% lower than those of the PBS group. The apoptotic rate of the APRIL siRNA group was 40.1% ± 2.5%, significantly higher than that in the vector group (2.5 ± 0.1)% and PBS group (2.5 ± 0.2)% (P < 0.05). CONCLUSION: APRIL siRNA may significantly suppress the growth and promote apoptosis in transplanted tumor of human colorectal cancer in nude mice. APRIL may become a candidate gene of gene therapy of human colorectal cancer.

The tumour necrosis factor superfamily ligand APRIL (TNFSF13) is released upon platelet activation and expressed in atherosclerosis.

Activated platelets release a wide range of inflammatory mediators, including members of the tumour necrosis factor (TNF) superfamily (e.g. CD40 ligand [CD40L] and LIGHT). Such platelet-mediated inflammation could be involved in atherogenesis and plaque destabilisation. In the present study we investigated whether APRIL, another member of the TNF superfamily that has been detected in megakaryocytes, could be released from platelets upon activation. The release of APRIL was studied in thrombin receptor (SFLLRN) activated platelets, and the expression of APRIL was examined in plasma and within the atherosclerotic lesion in patients with carotid and coronary atherosclerosis. Upon SFLLRN activation, there was a gradual release of APRIL, reaching maximum after 90 minutes. While this pattern is similar to that of CD40L and LIGHT, the release of APRIL was quite differently regulated. Thus, prostaglandin E1, but not inhibitors of metal-dependent proteases and actin polymerisation or the lack of GP IIb/IIIa, blocks APRIL release in activated platelets. With relevance to atherogenesis, we found that patients with coronary artery disease (n=80) had raised plasma levels of APRIL as compared with controls (n=20), and APRIL immunoreactivity was detected in aggregated platelets within the ruptured plaque in patients with myocardial infarction and within macrophages in symptomatic carotid plaques. In conclusion, activated platelets release significant amounts of APRIL in a long-lasting manner, differently regulated than the gradual release of other platelet-derived TNF superfamily ligands. The enhanced expression of APRIL in atherosclerotic disorders, both systemically and within the lesion, may suggest a potential involvement of APRIL in atherogenesis.

Molecular cloning, in vitro expression and bioactivity of dog A proliferation-inducing ligand (APRIL).

A proliferation-inducing ligand (APRIL) is a novel member of the tumor necrosis factor (TNF) family, which is involved in immune regulation. In this study, the cDNA of dog APRIL (dAPRIL) was amplified from dog spleen by RT-PCR. The open reading frame (ORF) of dAPRIL encodes a protein of 250-amino acid, containing a predicted transmembrane domain and a putative furin protease cleavage site like other mammalian APRILs. The amino acid identities between biologically soluble dAPRIL and its pig, human, rabbit and mouse counterparts are 91%, 86%, 88% and 86%, respectively, dramatically higher than most other known cytokines. The result of real-time PCR revealed that dAPRIL is expressed in various tissues and is elevated in thymus and spleen. Recombinant soluble dAPRIL (dsAPRIL) fused with NusA.tag was efficiently produced in Origami B (DE3) pLysS expression host strain. In vitro, purified dsAPRIL was able to co-stimulate the proliferation of dog splenic B cells in response to anti-IgM. These findings indicate that dAPRIL plays an important role in survival/proliferation of dog B cells and provide the basis for investigation on the roles of APRIL in this important domestic species.

Evidence of a role for B cell-activating factor of the TNF family in the pathogenesis of chronic rhinosinusitis with nasal polyps.

BACKGROUND: The polypoid form of chronic rhinosinusitis (chronic rhinosinusitis with nasal polyps [CRSwNP]) is a highly prevalent disease that often requires surgical intervention for treatment. Nasal polyps contain large quantities of B lymphocytes and immunoglobulin as well as eosinophils. OBJECTIVES: The objective of this study was to investigate the expression of B cell-activating factor of the TNF family (BAFF), an important regulator of class-switch recombination and immunoglobulin production, in patients with chronic rhinosinusitis (CRS). METHODS: We collected nasal tissue and nasal lavage fluid from patients with CRS and control subjects. We assayed mRNA for BAFF and B-lymphocyte markers, CD20 and transmembrane activator and calcium-modulator and cyclophilin ligand interactor, by using real-time PCR, and assayed BAFF protein by using ELISA and immunohistochemistry. RESULTS: BAFF mRNA was significantly increased in nasal polyps from patients with CRSwNP (P < .001) compared with inferior turbinate tissue from patients with CRS or healthy subjects. BAFF protein was also elevated in polypoid tissue and nasal lavage from patients with CRSwNP. Immunohistochemistry showed considerable BAFF staining in mucosal epithelial cells in nasal polyps along with unidentified cells in the lamina propria. Expression of mRNA for BAFF in sinonasal tissue was significantly correlated with CD20 and transmembrane activator and CAML interactor in sinus tissue. IgA, an immunoglobulin isotype known to activate eosinophils, was also significantly elevated in the polypoid tissue. CONCLUSION: Overproduction of BAFF in nasal polyps may contribute to the pathogenesis of CRSwNP via the local induction of IgA and activation of eosinophils.

Expression of TNF-superfamily members BAFF and APRIL in breast cancer: immunohistochemical study in 52 invasive ductal breast carcinomas.

BACKGROUND: Recent studies suggest an association between chronic inflammation, modulating the tissue microenvironment, and tumor biology. Tumor environment consists of tumor, stromal and endothelial cells and infiltrating macrophages, T lymphocytes, and dendritic cells, producing an array of cytokines, chemokines and growth factors, accounting for a complex cell interaction and regulation of differentiation, activation, function and survival of tumor and surrounding cells, responsible for tumor progression and spreading or induction of antitumor immune responses and rejection. Tumor Necrosis Factor (TNF) family members (19 ligands and 29 receptors) represent a pleiotropic family of agents, related to a plethora of cellular events from proliferation and differentiation to apoptosis and tumor reduction. Among these members, BAFF and APRIL (CD257 and CD256 respectively) gained an increased interest, in view of their role in cell protection, differentiation and growth, in a number of lymphocyte, epithelial and mesenchymal structures. METHODS: We have assayed by immunohistochemistry 52 human breast cancer biopsies for the expression of BAFF and APRIL and correlated our findings with clinicopathological data and the evolution of the disease. RESULTS: BAFF was ubiquitely expressed in breast carcinoma cells, DCIS, normal-appearing glands and ducts and peritumoral adipocytes. In contrast, APRIL immunoreactive expression was higher in non-malignant as compared to malignant breast structures. APRIL but not BAFF immunoreactivity was higher in N+ tumors, and was inversely related with the grade of the tumors. Neither parameter was related to DFS or the OS of patients. CONCLUSION: Our data show, for the first time, an autocrine secretion of BAFF and APRIL from breast cancer cells, offering new perspectives for their role in neoplastic and normal breast cell biology and offering new perspectives for possible selective intervention in breast cancer.

cDNA cloning, genomic structure, expression analysis and biological activity of porcine A Proliferation-Inducing Ligand (APRIL).

A Proliferation-Inducing Ligand (APRIL) is a novel member of the tumor necrosis factor (TNF) superfamily. In this study, a novel cDNA has been isolated from pig spleen by homology cloning and 3'- and 5'-rapid amplification of cDNA ends (RACE) strategies and designates porcine APRIL (pAPRIL). The open reading frame (ORF) of this cDNA covers 756 bases, encoding 251 amino acids. The soluble part of pAPRIL shows 89% identity with its human counterpart at the level of the primary protein structure. The pAPRIL gene is approximately 2.1kb in size and comprises six exons and five introns. Southern blotting analysis indicated that the pAPRIL gene is a single copy gene. Real-time PCR analysis revealed that pAPRIL is constitutively expressed in various tissues. Recombinant His(6)-tagged psAPRIL protein was efficiently expressed in Escherichia coli BL21 (DE3) and its expression was confirmed by SDS-PAGE and Western blotting analysis. In vitro, purified recombinant psAPRIL protein co-stimulated the proliferation of porcine splenic B-cells in response to formalin-fixed Staphylococcus aureus Cowan 1 (SAC).

The source of APRIL up-regulation in human solid tumor lesions.

Abundant mRNA expression for a proliferation-inducing ligand (APRIL) from tumor necrosis factor (TNF) family is observed in many solid tumors. Here, we analyzed in situ the cellular source of APRIL in human solid tumors with anti-APRIL antibodies. In most cases, neutrophils present in the tumor stroma constituted the main source of APRIL. In cutaneous lesions such as melanoma or basal cell carcinoma, tumor-adjacent keratinocytes also produced APRIL. APRIL production by tumor cells themselves was a rare event, only observed in urothelial bladder cancer and squamous cell carcinoma. Detailed analysis revealed that APRIL dissociated from producing cells, and secreted APRIL was retained in the tumor lesions. A direct binding onto tumor cells via heparan sulfate proteoglycans (HSPG) was observed in in vitro experiments and confirmed in situ. Taken together, our analysis indicates a potential role for HSPG/APRIL interactions in the development of solid tumors.

CXCL-8/IL8 Produced by Diffuse Large B-cell Lymphomas Recruits Neutrophils Expressing a Proliferation-Inducing Ligand APRIL.

Tumor-infiltrating neutrophils have been implicated in malignant development and progression, but mechanisms are ill defined. Neutrophils produce a proliferation-inducing ligand APRIL/TNFSF13, a factor that promotes development of tumors from diverse origins, including diffuse large B-cell lymphoma (DLBCL). High APRIL expression in DLBCL correlates with reduced patient survival, but the pathway(s) dictating APRIL expression are not known. Here, we show that all blood neutrophils constitutively secrete APRIL, and inflammation-associated stimuli, such as TNF, further upregulate APRIL. In a significant fraction of DLBCL patients, tumor cells constitutively produced the ELC-CXC chemokine CXCL-8 (IL8), enabling them to recruit APRIL-producing blood neutrophils. CXCL-8 production in DLBCL was unrelated to the cell of origin, as APRIL-producing neutrophils infiltrated CXCL-8+ DLBCL from both germinal center (GC) and non-GC subtypes. Rather, CXCL-8 production implied events affecting DNA methylation and acetylation. Overall, our results showed that chemokine-mediated recruitment of neutrophils secreting the tumor-promoting factor APRIL mediates DLBCL progression. Cancer Res; 77(5); 1097-107. ©2016 AACR.

BAFF and APRIL from Activin A-Treated Dendritic Cells Upregulate the Antitumor Efficacy of Dendritic Cells In Vivo.

The members of the TGFß superfamily play a key role in regulating developmental and homeostasis programs by controlling differentiation, proliferation, polarization, and survival of different cell types. Although the role of TGFß1 in inflammation and immunity is well evident, the contribution of other TGFß family cytokines in the modulation of the antitumor immune response remains less documented. Here we show that activin A triggers SMAD2 and ERK1/2 pathways in dendritic cells (DC) expressing type I and II activin receptors, and upregulates production of the TNFα family cytokines BAFF (TALL-1, TNFSF13B) and APRIL (TALL-2, TNFSF13A), which is blocked by SMAD2 and ERK1/2 inhibitors, respectively. BAFF and APRIL derived from activin A-treated DCs upregulate proliferation and survival of T cells expressing the corresponding receptors, BAFF-R and TACI. In vivo, activin A-stimulated DCs demonstrate a significantly increased ability to induce tumor-specific CTLs and inhibit the growth of melanoma and lung carcinoma, which relies on DC-derived BAFF and APRIL, as knockdown of the BAFF and APRIL gene expression in activin A-treated DCs blocks augmentation of their antitumor potential. Although systemic administration of activin A, BAFF, or APRIL for the therapeutic purposes is not likely due to the pluripotent effects on malignant and nonmalignant cells, our data open a novel opportunity for improving the efficacy of DC vaccines. In fact, a significant augmentation of the antitumor activity of DC pretreated with activin A and the proven role of DC-derived BAFF and APRIL in the induction of antitumor immunity in vivo support this direction. Cancer Res; 76(17); 4959-69. ©2016 AACR.

Disruption of Splenic Lymphoid Tissue and Plasmacytosis in Canine Visceral Leishmaniasis: Changes in Homing and Survival of Plasma Cells.

Visceral leishmaniasis (VL) is a disease caused by Leishmania infantum, which is transmitted by phlebotomine sandflies. Dogs are the main urban reservoir of this parasite and the disease presents similar characteristics in both humans and dogs. In this paper, we investigated the potential pathways involved in plasma cell replacement of normal cell populations in the spleen, with respect to disease severity in dogs from an endemic area for visceral leishmaniasis. To this end, canine spleen samples were grouped into three categories: TYPE1SC- (non-infected dogs or without active infection with organized white pulp), TYPE1SC+ (infected dogs with organized white pulp) or TYPE3SC+ (infected animals with disorganized white pulp). We analyzed the distribution of different plasma cell isotypes (IgA, IgG and IgM) in the spleen. The expression of cytokines and chemokines involved in plasma cell homing and survival were assessed by real time RT-PCR. Polyclonal B cell activation and hypergammaglobulinemia were also evaluated. The proportion of animals with moderate or intense plasmacytosis was higher in the TYPE3SC+ group than in the other groups (Fisher test, P<0.05). This was mainly due to a higher density of IgG+ plasma cells in the red pulp of this group. The albumin/globulin ratio was lower in the TYPE3SC+ animals than in the TYPE1SC- or TYPE1SC+ animals, which evidences VL-associated dysproteinemia. Interestingly, TYPE3SC+ animals showed increased expression of the BAFF and APRIL cytokines, as well as chemokine CXCL12. Aberrant expression of BAFF, APRIL and CXCL12, together with amplified extrafollicular B cell activation, lead to plasma cell homing and the extended survival of these cells in the splenic red pulp compartment. These changes in the distribution of immunocompetent cells in the spleen may contribute to the progression of VL, and impair the spleen's ability to protect against blood borne pathogens.