Subcapsular Sinus Macrophage Fragmentation and CD169+ Bleb Acquisition by Closely Associated IL-17-Committed Innate-Like Lymphocytes

Subcapsular sinus macrophages (SSMs) in lymph nodes are rapidly exposed to antigens arriving in afferent lymph and have a role in their capture and display to B cells. In tissue sections SSMs exhibit long cellular processes and express high amounts of CD169. Here, we show that many of the cells present in lymph node cell suspensions that stain for CD169 are not macrophages but lymphocytes that have acquired SSM-derived membrane blebs. The CD169 bleb+ lymphocytes are enriched for IL-17 committed IL-7RαhiCCR6+ T cells and NK cells. In addition, the CD169 staining detected on small numbers of CD11chi dendritic cells is frequently associated with membrane blebs. Counter intuitively the CD169 bleb+ lymphocytes are mostly CD4 and CD8 negative whereas many SSMs express CD4. In situ, many IL-7Rαhi cells are present at the subcapsular sinus and interfollicular regions and migrate in close association with CD169+ macrophages. These findings suggest SSMs undergo fragmentation during tissue preparation and release blebs that are acquired by closely associated cells. They also suggest an intimate crosstalk between SSMs and IL-17 committed innate-like lymphocytes that may help provide early protection of the lymph node against lymph-borne invaders

CD98hc facilitates B cell proliferation and adaptive humoral immunity.

The proliferation of antigen-specific lymphocytes and resulting clonal expansion are essential for adaptive immunity. We report here that B cell-specific deletion of the heavy chain of CD98 (CD98hc) resulted in lower antibody responses due to total suppression of B cell proliferation and subsequent plasma cell formation. Deletion of CD98hc did not impair early B cell activation but did inhibit later activation of the mitogen-activated protein kinase Erk1/2 and downregulation of the cell cycle inhibitor p27. Reconstitution of CD98hc-deficient B cells with CD98hc mutants showed that the integrin-binding domain of CD98hc was required for B cell proliferation but that the amino acid-transport function of CD98hc was dispensable for this. Thus, CD98hc supports integrin-dependent rapid proliferation of B cells. We propose that the advantage of adaptive immunity favored the appearance of CD98hc in vertebrates

A functional PTPN22 polymorphism associated with several autoimmune diseases is not associated with IgA deficiency in the Spanish population

BACKGROUND: The 1858C/T SNP of the PTPN22 gene has been associated with many autoimmune diseases, suggesting the existence of an inflammatory process common to all of them. We studied the association of that polymorphism with immunoglobulin A deficiency (IgAD) following a double approach: a case-control and a TDT study. METHODS: A total of 259 IgAD patients and 455 unrelated matched controls, and 128 families were used for each approach. Comparisons were performed using Chi-Square tests or Fisher's exact test when necessary. RESULTS: No association between the PTPN22 1858C/T SNP and IgA deficiency was found in any case (allelic frequencies 8% vs. 6% in patients and controls, respectively, OR= 1.14 (0.72–1.79), p= 0.56; TDT p = 0.08). CONCLUSION: The result obtained seems to reinforce the consideration of IgA deficiency as a primary immunodeficiency rather than an autoimmune disease

Disrupted lymph node and splenic stroma in mice with induced inflammatory melanomas is associated with impaired recruitment of T and dendritic cells

International audienceMigration of dendritic cells (DC) from the tumor environment to the T cell cortex in tumor-draining lymph nodes (TDLN) is essential for priming naïve T lymphocytes (TL) to tumor antigen (Ag). We used a mouse model of induced melanoma in which similar oncogenic events generate two phenotypically distinct melanomas to study the influence of tumor-associated inflammation on secondary lymphoid organ (SLO) organization. One tumor promotes inflammatory cytokines, leading to mobilization of immature myeloid cells (iMC) to the tumor and SLO; the other does not. We report that inflammatory tumors induced alterations of the stromal cell network of SLO, profoundly altering the distribution of TL and the capacity of skin-derived DC and TL to migrate or home to TDLN. These defects, which did not require tumor invasion, correlated with loss of fibroblastic reticular cells in T cell zones and in impaired production of CCL21. Infiltrating iMC accumulated in the TDLN medulla and the splenic red pulp. We propose that impaired function of the stromal cell network during chronic inflammation induced by some tumors renders spleens non-receptive to TL and TDLN non-receptive to TL and migratory DC, while the entry of iMC into these perturbed SLO is enhanced. This could constitute a mechanism by which inflammatory tumors escape immune control. If our results apply to inflammatory tumors in general, the demonstration that SLO are poorly receptive to CCR7-dependent migration of skin-derived DC and naïve TL may constitute an obstacle for proposed vaccination or adoptive TL therapies of their hosts

Reduced Plasma Levels of 25-Hydroxycholesterol and Increased Cerebrospinal Fluid Levels of Bile Acid Precursors in Multiple Sclerosis Patients

Multiple sclerosis (MS) is an autoimmune, inflammatory disease of the central nervous system (CNS). We have measured the levels of over 20 non-esterified sterols in plasma and cerebrospinal fluid (CSF) from patients suffering from MS, inflammatory CNS disease, neurodegenerative disease and control patients. Analysis was performed following enzyme-assisted derivatisation by liquid chromatography-mass spectrometry (LC-MS) exploiting multistage fragmentation (MS n ). We found increased concentrations of bile acid precursors in CSF from each of the disease states and that patients with inflammatory CNS disease classified as suspected autoimmune disease or of unknown aetiology also showed elevated concentrations of 25-hydroxycholestertol (25-HC, P < 0.05) in CSF. Cholesterol concentrations in CSF were not changed except for patients diagnosed with amyotrophic lateral sclerosis (P < 0.01) or pathogen-based infections of the CNS (P < 0.05) where they were elevated. In plasma, we found that 25-HC (P < 0.01), (25R)26-hydroxycholesterol ((25R)26-HC, P < 0.05) and 7α-hydroxy-3-oxocholest-4-enoic acid (7αH,3O-CA, P < 0.05) were reduced in relapsing-remitting MS (RRMS) patients compared to controls. The pattern of reduced plasma levels of 25-HC, (25R)26-HC and 7αH,3O-CA was unique to RRMS. In summary, in plasma, we find that the concentration of 25-HC in RRMS patients is significantly lower than in controls. This is consistent with the hypothesis that a lower propensity of macrophages to synthesise 25-HC will result in reduced negative feedback by 25-HC on IL-1 family cytokine production and exacerbated MS. In CSF, we find that the dominating metabolites reflect the acidic pathway of bile acid biosynthesis and the elevated levels of these in CNS disease is likely to reflect cholesterol release as a result of demyelination or neuronal death. 25-HC is elevated in patients with inflammatory CNS disease probably as a consequence of up-regulation of the type 1 interferon-stimulated gene cholesterol 25-hydroxylase in macrophage

Effects of chemokines on proliferation and apoptosis of human mesangial cells

BACKGROUND: Proliferation and apoptosis of mesangial cells (MC) are important mechanisms during nephrogenesis, for the maintenance of glomerular homeostasis as well as in renal disease and glomerular regeneration. Expression of chemokines and chemokine receptors by intrinsic renal cells, e.g. SLC/CCL21 on podocytes and CCR7 on MC is suggested to play a pivotal role during these processes. Therefore the effect of selected chemokines on MC proliferation and apoptosis was studied. METHODS: Proliferation assays, cell death assays including cell cycle analysis, hoechst stain and measurement of caspase-3 activity were performed. RESULTS: A dose-dependent, mesangioproliferative effect of the chemokine SLC/CCL21, which is constitutively expressed on human podocytes was seen via activation of the chemokine receptor CCR7, which is constitutively expressed on MC. In addition, in cultured MC SLC/CCL21 had a protective effect on cell survival in Fas-mediated apoptosis. The CXCR3 ligands IP-10/CXCL10 and Mig/CXCL9 revealed a proproliferative effect but did not influence apoptosis of MC. Both the CCR1 ligand RANTES/CCL5 and the amino-terminally modified RANTES analogue Met-RANTES which blocks CCR1 signalling had no effect on proliferation and apoptosis. CONCLUSIONS: The different effects of chemokines and their respective receptors on proliferation and apoptosis of MC suggest highly regulated, novel biological functions of chemokine/chemokine receptor pairs in processes involved in renal inflammation, regeneration and glomerular homeostasis

Expression of endothelia and lymphocyte adhesion molecules in bronchus-associated lymphoid tissue (BALT) in adult human lung

BACKGROUND: Bronchus-associated lymphoid tissue (BALT) is the secondary lymphoid tissue in bronchial mucosa and is involved in the development of bronchopulmonary immune responses. Although migration of lymphocytes from blood vessels into secondary lymphoid tissues is critical for the development of appropriate adaptive immunity, the endothelia and lymphocyte adhesion molecules that recruit specific subsets of lymphocytes into human BALT are not known. The aim of this study was to determine which adhesion molecules are expressed on lymphocytes and high endothelial venules (HEVs) in human BALT. METHODS: We immunostained frozen sections of BALT from lobectomy specimens from 17 patients with lung carcinoma with a panel of monoclonal antibodies to endothelia and lymphocyte adhesion molecules. RESULTS: Sections of BALT showed B cell follicles surrounded by T cells. Most BALT CD4+ T cells had a CD45RO+ memory phenotype. Almost all BALT B cells expressed alpha4 integrin and L-selectin. In contrast, 43% of BALT T cells expressed alpha4 integrin and 20% of BALT T cells expressed L-selectin. Almost all BALT lymphocytes expressed LFA-1. HEVs, which support the migration of lymphocytes from the bloodstream into secondary lymphoid tissues, were prominent in BALT. All HEVs expressed peripheral node addressin, most HEVs expressed vascular cell adhesion molecule-1, and no HEVs expressed mucosal addressin cell adhesion molecule-1. CONCLUSION: Human BALT expresses endothelia and lymphocyte adhesion molecules that may be important in recruiting naive and memory/effector lymphocytes to BALT during protective and pathologic bronchopulmonary immune responses

Combinatorial Guidance by CCR7 Ligands for T Lymphocytes Migration in Co-Existing Chemokine Fields

Chemokines mediate the trafficking and positioning of lymphocytes in lymphoid tissues that is crucial for immune surveillance and immune responses. In particular, a CCR7 ligand, CCL21, plays important roles in recruiting T cells to secondary lymphoid tissues (SLT). Furthermore, CCL21 together with another CCR7 ligand, CCL19, direct the navigation and compartmentation of T cells within SLT. However, the distinct roles of these two chemokines for regulating cell trafficking and positioning are not clear. In this study, we explore the effect of co-existing CCL19 and CCL21 concentration fields on guiding T cell migration. Using microfluidic devices that can configure single and superimposed chemokine fields we show that under physiological gradient conditions, human peripheral blood T cells chemotax to CCL21 but not CCL19. Furthermore, T cells migrate away from the CCL19 gradient in a uniform background of CCL21. This repulsive migratory response is predicted by mathematical modeling based on the competition of CCL19 and CCL21 for CCR7 signaling and the differential ability of the two chemokines for desensitizing CCR7. These results suggest a new combinatorial guiding mechanism by CCL19 and CCL21 for the migration and trafficking of CCR7 expressing leukocytes

Human breast cancer-derived soluble factors facilitate CCL19-induced chemotaxis of human dendritic cells

Breast cancer remains as a challenging disease with high mortality in women. Increasing evidence points the importance of understanding a crosstalk between breast cancers and immune cells, but little is known about the effect of breast cancer-derived factors on the migratory properties of dendritic cells (DCs) and their consequent capability in inducing T cell immune responses. Utilizing a unique 3D microfluidic device, we here showed that breast cancers (MCF-7, MDA-MB-231, MDA-MB-436 and SK-BR-3)-derived soluble factors increase the migration of DCs toward CCL19. The enhanced migration of DCs was mainly mediated via the highly activated JNK/c-Jun signaling pathway, increasing their directional persistence, while the velocity of DCs was not influenced, particularly when they were co-cultured with triple negative breast cancer cells (TNBCs or MDA-MB-231 and MDA-MB-436). The DCs up-regulated inflammatory cytokines IL-1?? and IL-6 and induced T cells more proliferative and resistant against activation-induced cell death (AICD), which secret high levels of inflammatory cytokines IL-1??, IL-6 and IFN-??. This study demonstrated new possible evasion strategy of TNBCs utilizing their soluble factors that exploit the directionality of DCs toward chemokine responses, leading to the building of inflammatory milieu which may support their own growth.ope