T and B cell collaboration: induction of motility in small, resting B cells by interleukin 4

Association study between clinicopathological variables and periodontal breakdown in gingival pyogenic granuloma

OBJECTIVE

The aim was to investigate a possible association between the immunoexpression of interleukin (IL)-4 and clinicopathological parameters with the periodontal breakdown observed in gingival pyogenic granuloma (PG).

MATERIALS AND METHODS

Paraffin-embedded samples of gingival PG (n = 46) were prepared for histological and immunohistochemical assessment. Demographic and clinical parameters were assessed by criteria based on age stratum, gender, smoking habit, evolution course, location, lesion size, macroscopic appearance, predisposing factors, recurrence, and periodontal breakdown. Histological assessment included the appearance of epithelial lining, microvessel density, inflammatory infiltrate density, interstitial fibrosis, and histological arrangement. A staining intensity distribution (SID) score was used to assess IL-4 immunoreactivity. The association between candidate predictor variables and periodontal breakdown was analyzed individually and adjusted for confounding using a bivariate binary logistic regression model.

RESULTS

Mean IL-4 SID values were significantly increased for long-standing and large lesions, presence of periodontal breakdown, high microvessel density, and moderate-to-severe inflammatory infiltrate density. While bivariate and univariate analyses revealed a positive association of the evolution course ≥12 months, lesion size >1 cm, high microvessel density, moderate-to-severe inflammatory infiltrate density, and IL-4 SID score ≥8.04 with periodontal breakdown, after bivariate logistic regression analysis, only the evolution course ≥12 months, moderate-to-severe inflammatory infiltrate density, and IL-4 SID score ≥8.04 remained as robust predictors of periodontal damage. Confounding and interaction effects between candidate predictor variables were also noted.

CONCLUSION

These findings suggest that while evolution course, inflammatory infiltrate density, and the overexpression of IL-4 may act as predictors of periodontal breakdown in gingival PG, there are mutual confounding and synergistic biological interactive effects with respect to the lesion size and microvessel density in the susceptible host that may be also associated with the bone resorption and tissue destruction.

CLINICAL RELEVANCE

Although the first-line therapy of gingival PG continues to be the surgical excision, this approach poses unwanted complications such as severe mucogingival defects and recurrence. Hence, early diagnosis and detection of these three significant predictor variables as well as timely surgical excision might help prevent the periodontal tissue destruction observed in some of these lesions.

Interleukin (IL)-4 induces production of cytokine-induced neutrophil chemoattractants (CINCs) and intercellular adhesion molecule (ICAM)-1 in lungs of asthmatic rats

The present study aimed to examine the effect of interleukin (IL)-4 on neutrophil chemotaxis in airway inflammation in asthmatic rats and the possible mechanism. Male Wistar rats were intranasally instilled with recombinant rat (rr) IL-4 (rrIL-4) at different doses [2, 4 or 8 μg/animal, dissolved in 200 μL normal saline (NS)] or rrIL-4 at 4 μg/animal (dissolved in 200 μL NS). NS (200 μL) and LPS (6 mg/kg/animal, dissolved in 200 μL NS) were intranasally given respectively in the negative and positive control groups. Moreover, the asthmatic lung inflammation was induced in rats which were then intranasally treated with rrIL-4 (4 μg/animal) or LPS (6 mg/kg/animal). The normal rats treated with different doses of rrIL-4 and those asthmatic rats were sacrificed 6 h later. And animals instilled with rrIL-4 at 4 μg were sacrificed 6, 12 or 24 h later. The bronchoalveolar lavage fluid (BALF) and lungs were harvested for detection of leukocyte counts by Wright-Giemsa staining and lung histopathology by haematoxylin-eosin (HE) staining. The levels of cytokine-induced neutrophil chemoattractant (CINC)-1 and intercellular adhesion molecule (ICAM)-1 in BALF were determined by ELISA. Real-time PCR was used to measure the mRNA expression of CINCs (CINC-1, CINC-2α, CINC-2β, CINC-3) and ICAM-1 in lung tissues. The results showed that the intranasal instillation of IL-4 did not induce a recruitment of neutrophils in BALF in rats. However, IL-4 could increase the CINC-1 level in BALF in a dose-dependent manner at 6 h. But the mRNA expression levels of CINC-1, CINC-2α, CINC-2β, CINC-3 were not significantly increased in lungs of IL-4-treated rats relative to NS negative control group. Moreover, IL-4 was found to augment the mRNA expression of ICAM-1 in lungs and the ICAM-1 level in BALF at 6 h. However, the increase in CINC-1 and ICAM-1 levels in BALF of IL-4-treated asthmatic rats was not significantly different from that in untreated asthmatic rats. These findings indicate that IL-4 does not directly recruit neutrophils in the rat lungs, but it may contribute to airway neutrophilia through up-regulation of CINC-1 and ICAM-1.

Kaposi's sarcoma-associated herpesvirus inhibits interleukin-4-mediated STAT6 phosphorylation to regulate apoptosis and maintain latency

Cytokine-mediated JAK/STAT signaling controls numerous important biologic responses like immune function, cellular growth, and differentiation. Inappropriate activation of this signaling pathway is associated with a range of malignancies. Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious viral agent associated with Kaposi's sarcoma and may also contribute to B-cell disorders, which include primary effusion lymphoma (PEL) and multicentric Castleman's disease. However, regulation of cytokine-mediated lymphocytic immune response by KSHV is not fully understood. In this report, we demonstrate that KSHV suppresses the interleukin-4 (IL-4)-stimulated immune response of B-lymphocyte activation and cell proliferation. Moreover, we show that the latency-associated nuclear antigen (LANA) encoded by KSHV is essential for viral blocking of IL-4-induced signaling. LANA reduces phosphorylation of the signal transducers and activators of transcription 6 (STAT6) on Y-641 and concomitantly its DNA binding ability. Importantly, knockdown of endogenous STAT6 dramatically increases the sensitivity of PEL cells to low-serum stress or chemical-mediated cellular apoptosis and reactivation of KSHV from latent replication. Thus, these findings suggest that the IL-4/STAT6 signaling network is precisely controlled by KSHV for survival, maintenance of latency, and suppression of the host cytokine immune response of the virus-infected cells.

Interleukin (IL)-4 induces leukocyte infiltration in vivo by an indirect mechanism

Interleukin (IL)-4 is a cytokine known mainly for its anti-inflammatory activity. Using the in vivo murine air pouch model, we found that IL-4 significantly increased the number of leukocytes after 9 hours of treatment, consisting mainly of neutrophil (60%) and monocytic (40%) cell populations. Using an antibody array, we found that the expression of several analytes (predominantly CCL2) was increased by IL-4 before the arrival of leukocytes. The IL-4-induced expression of CCL-2 was confirmed by ELISA. Air pouch resident lining cells were harvested and were found to express IL-4Rα. CCL2 mRNA expression was monitored in lining cells, cells isolated from the air pouch skin, in RAW264.7 macrophage and in epithelial Mode-K cells and its expression was increased in response to IL-4 in all conditions. We conclude that IL-4 can attract leukocytes in vivo by an indirect mechanism involving the production of several analytes by, at least, resident cells.

Regulation of adhesion and motility in B lymphocytes

During the differentiation process of B lymphocytes, they go through changes in adhesion and motility. In order to investigate the molecular mechanism of such changes, in vitro culture systems are necessary. When B cells are activated by various stimuli, they form different types of homotypic aggregates. In addition, they might also spread and express microvilli and/or become polarized, the latter being a sign of motility. In this review, we summarize our own research in this area. We give evidence for involvement of different adhesion and signalling molecules, and by the end, we speculate on the in vivo significance of our findings.

Efficient antigen presentation of soluble, but not particulate, antigen in the absence of Wiskott-Aldrich syndrome protein

B cells and dendritic cells, lacking functional Wiskott-Aldrich syndrome protein (WASP), have aberrant formation of membrane protrusions. We hypothesized that protrusions may play a role in antigen presentation, and consequently, that impaired antigen presentation may be an underlying factor of the immune deficiency in patients with Wiskott-Aldrich syndrome. In this paper, we investigated the antigen presentation capacity of B cells and dendritic cells from WASP knockout mice, using soluble and particulate antigen, to CD4+ T cells from T-cell receptor transgenic DO11.10 mice. As antigen we used soluble ovalbumin (OVA), a peptide thereof (amino acids 323-339) or bacteria expressing OVA. We found that WASP-deficient B cells and dendritic cells efficiently processed and presented soluble OVA protein as well as its peptide in vitro, inducing proliferation and cytokine production from CD4+ T cells. Antigen presentation of soluble protein was efficient also in vivo, because immunization of WASP-deficient mice with OVA elicited proliferation of transferred, fluorescent-labelled, CD4+ T cells. Although we could detect uptake of bacteria in dendritic cells, processing and presentation of bacterial-expressed OVA was impaired in WASP-deficient dendritic cells. In conclusion, our data suggest that WASP is not needed for processing and presentation of soluble antigen, but that efficient presentation of particulate antigen require WASP.

Cdc42, Rac1, and the Wiskott-Aldrich syndrome protein are involved in the cytoskeletal regulation of B lymphocytes

Patients with the immunodeficiency disorder Wiskott-Aldrich syndrome (WAS) have lymphocytes with aberrant microvilli, and their T cells, macrophages, and dendritic cells are impaired in cytoskeletal-dependent processes. WAS is caused by a defective or a missing WAS protein (WASP). Signal mediators interleukin-4 (IL-4) and CD40 are important for actin-dependent morphology changes in B cells. A possible function of WASP and its interacting partners, Cdc42 and Rac1, was investigated for these changes. It was found that active Cdc42 and Rac1 induced filopodia and lamellipodia, respectively, in activated B cells. Evidence is given that IL-4 has a specific role in the regulated cycling of Cdc42 because IL-4 partially and transiently depleted active Cdc42 from detergent extract of activated B cells. WASP-deficient B lymphocytes were impaired in IL-4-- and CD40-dependent induction of polarized and spread cells. Microvilli were expressed on WASP-deficient B cells, but they appeared shorter and less dense in cell contacts than in wild-type cells. In conclusion, evidence is provided for the involvement of Cdc42, Rac1, and WASP in the cytoskeletal regulation of B lymphocytes. Aberrations in WASP-deficient B lymphocytes, described here, provide further evidence that WAS is a cytoskeletal disease of hematopoietic cells. (Blood. 2001;98:1086-1094)

T(h)1 versus T(h)2 cytokine profile determines the modulation of in vitro T cell-independent type 2 responses by IL-4

We have previously demonstrated that stimulation of B cells by multivalent membrane Ig cross-linking, using dextran-conjugated anti-IgD mAb (alpha delta-dex), in the presence of cytokines, is an in vitro model for T cell-independent type 2 (TI-2) Ig secretory responses. Earlier studies have shown that IL-4 enhances IgM secretion upon stimulation with alpha delta-dex plus IL-5 and induces IgG1 isotype-switching, without altering the proliferative response to alpha delta-dex. Here we show that IL-4 can have both stimulatory and inhibitory effects on alpha delta-dex-induced Ig secretion. Both the kinetics and time of exposure to IL-4, and the nature of the cytokine additions, T(h)1 versus T(h)2, determine whether stimulation or inhibition is observed. Preincubation of sort-purified B cells with IL-4 caused a 6- to 8-fold increase in Ig secretory responses to subsequent stimulation with alpha delta-dex plus IL-1, IL-2 or a combination of both. However, the continued presence of IL-4 during B cell stimulation suppressed responses to all cytokine combinations tested, except for those which included IL-5. Of 11 cytokines tested, only IL-4 showed this dual effect of enhancement and suppression. The stimulatory effect of IL-4 required a minimum of 4 h of preincubation and could be inhibited by the addition of IFN-gamma. Thus stimulation of non-MHC class II-dependent T or non-T cells by multivalent antigens to secrete IL-4 may regulate the response to these antigens, such that early and brief exposure of B cells to IL-4 will enhance a subsequent TI-2 response in the presence of T(h)1-dependent cytokines, while continuous exposure will result in inhibition of the response.

STAT6 is required for the regulation of IL-4-induced cytoskeletal events in B cells

During lymphocyte activation, changes in cell morphology are commonly observed. This reflects cell functions important for the regulation of immune responses such as cell adhesion or cell migration. Notably, IL-4 has been shown to induce adhesion and locomotion in B cells, and we have recently described that IL-4 causes dramatic changes in B cell morphology. Thus, such B cells spread with dendritic cell protrusions and produce microvilli-like structures. The molecular mechanisms by which IL-4 induces these complex changes are currently unknown. Two signal transduction pathways are well described for IL-4, i.e. one involving insulin receptor substrate (IRS)-2 and a Janus kinase (JAK)/ signal transducer and activator of transcription (STAT) pathway mediated by STAT6. In this study we therefore used B cells from STAT6-deficient mice to address the question of a possible STAT6 dependence in IL-4-induced morphology changes. By light and electron microscopy, cell spreading and polarization were found to be severely impaired and microvilli formation was reduced. In contrast, only mild impairment was observed in cell adhesion in B cells from STAT6-deficient mice. Our results show that adhesion can be induced in the absence of STAT6. However, expression of STAT6 is necessary for optimal responses in both cell adhesion and microvilli induction. STAT6 is also essential to allow an IL-4-dependent spreading or polarization response. A possible interpretation of our results is that STAT6-dependent expression of a specific gene or genes is required for IL-4 to affect changes in B cell morphology.

rC5a Directs the In Vitro Migration of Human Memory and Naive Tonsillar B Lymphocytes: Implications for B Cell Trafficking in Secondary Lymphoid Tissues

Human C5a is a potent chemoattractant for granulocytes, monocytes, and dendritic cells. In mice C5a has been shown to be chemotactic for germinal center (GC) B cells. To date, no information is available on the effects of C5a on human B cell locomotion. Here we demonstrate that rC5a increases polarization and migration of human tonsillar B cells. The locomotory response was due to both chemokinetic and chemotactic activities of rC5a. Moreover, memory and, at a lesser extent, naive B cell fractions from purified tonsillar populations displayed rC5a-enhanced migratory properties, whereas GC cells did not. Flow cytometry revealed C5aR (CD88) on approximately 40% memory and 10% naive cells, respectively, whereas GC cells were negative. Immunohistochemistry showed that a few CD88+ cells were of the B cell lineage and localized in tonsillar subepithelial areas, where the majority of memory B cells settle. Pretreatment of memory B cells with the CD88 mAb abolished their migratory responsiveness to rC5a. Finally, the C5 gene was found to be expressed in naive, GC, and memory B lymphocytes at both the mRNA and the protein level. This study delineates a novel role for C5a as a regulator of the trafficking of human memory and naive B lymphocytes and supports the hypothesis that the B cells themselves may serve as source of C5 in secondary lymphoid tissues.

Regulation of Cell Morphology in B Lymphocytes by IL-4: Evidence for Induced Cytoskeletal Changes

Lymphocyte activation is often accompanied by changes in cell morphology, for example, in cell adhesion or motility. IL-4 is a cytokine exerting many effects on B lymphocytes. In this study, we show that stimulation with LPS in combination with IL-4, but not LPS or IL-4 alone, results in a pronounced dendritic morphology of B cells. Using a culture system in which Abs directed to B cell surface markers are immobilized on the tissue culture plastic, we find that cell spreading can be mediated by a variety of Abs, including anti-CD44, -CD23, -LFA-1, -VLA-4, -ICAM-1, and -Ig. B cells stimulated with anti-Ig Abs plus IL-4, or anti-CD40 Abs in the presence or absence of IL-4, are also induced to spread, while IL-2, IL-5, or IL-10 in combination with LPS or alone fail to induce this. Spreading correlates with induction of tight cell aggregation. It is sensitive to cytochalasin B, indicating a requirement for intact actin cytoskeleton. CD44 is selectively detected in the detergent-insoluble fraction of cell lysates prepared from LPS plus IL-4-stimulated B cell cultures after Ab cross-linking of CD44, suggesting a membrane protein-cytoskeleton interaction. Interestingly, electron microscopy studies reveal induction of microvilli-like structures on LPS plus IL-4-stimulated blasts, suggesting that IL-4 can influence cell morphology on an ultra-structural level. In summary, our data show that stimulation with LPS plus IL-4 or ligation of CD40 is capable of inducing dramatic morphologic changes in murine B cells, which correlates with in vitro induction of strong cell adhesion.

Locomotion and chemotaxis of lymphocytes

The behaviour of locomotor T and B lymphocytes and the chemoattractants to which they respond in vitro are reviewed. Following activation, T cells respond by locomotion and chemotaxis to cytokine attractants including IL-15 and IL-2 and several chemokines. In activated B cells chemotaxis may be signalled through the antigen receptor. Conversely resting lymphocytes respond poorly to the above signals though their locomotion is activated by contact with high endothelial venular cells. These differences in locomotion between resting and activated lymphocytes, together with differences in adhesion, may explain why activated lymphocytes migrate preferentially into inflammatory sites while resting cells recirculate.

Locomotor properties of human germinal centre B cells: activation by anti-CD40 and IL-4 allows chemoattraction by anti-immunoglobulin

The locomotor properties of B cells isolated from the germinal centres (GC) of human tonsils were studied using polarization, collagen gel invasion and micropore filter assays. The proportion of motile GC cells in the freshly isolated population was small. During culture in interleukin-4 (IL-4)+anti-CD40, but not in control medium, the proportion of polarized cells increased and these cells migrated actively into collagen gels. After 24 hr culture, most of the surviving population was in locomotor morphology. The locomotor population consisted mainly of centrocytes in the G1 phase of growth. More locomotor cells than spherical cells took up [3H]uridine, but locomotor cells did not take up [3H]thymidine. After culture for 6 hr in IL-4+anti-CD40, GC B cells were tested in short-term polarization assays and filter assays for their response to chemoattractants. In both assays, a proportion of the cells responded to anti-IgA and to anti-IgA F(ab')2 fragments at 1 ng/ml., or to anti-IgG, anti-IgM and F(ab')2 fragments of these antibodies at 100 ng-1 microgram/ml. A checkerboard filter assay showed a good chemokinetic response and a weaker chemotactic response of GC cells to anti-IgA. Expression of Fc gamma RII (CD32) was increased after culture in IL-4+anti-CD40, and these cultured cells responded in filter and polarization assays to anti-CD32. Thus culture in IL-4 and anti-CD40 not only rescues GC B cells, but also increases their locomotor capacity and allows them to respond in chemotaxis assays to anti-immunoglobulin.

CD44-stimulated dendrite formation ('spreading') in activated B cells

A rat monoclonal antibody (mAb) (NIM-R8), insolubilized by binding to plastic plates, induced a rapid and extensive formation of dendrite processes ('spreading') in B lymphocytes activated by anti-IgM and interleukin-4 (IL-4) or anti-CD38 and IL-4. In contrast, resting B cells were unable to spread similarly on the NIM-R8-coated plates. The NIM-R8 antibody recognized a 90,000 MW surface glycoprotein (gp90) present on both B and T lymphocytes. The expression of this molecule was greatly increased after polyclonal (lipopolysaccharide, anti-IgM plus IL-4 or concanavalin A) activation. The NIM-R8 mAb with or without IL-2 or IL-4 was unable to induce proliferation of splenic lymphocytes. Following the demonstration that the NIM-R8 mAb recognizes the murine equivalent of human CD44, the induction of spreading of activated B lymphocytes was studied using a panel of mAb recognizing different epitopes of murine CD44. All of these different mAb induced similar spreading of activated B cells. The ligand-inducible spreading of activated B lymphocytes may be an important mechanism for providing an increased cell-surface area for cell-cell or cell-matrix interactions, and thus may be an important factor controlling the response of activated lymphocytes.

Interleukin-4 induces in vitro migration in naive B cells through direct mechanisms

Interleukin-4 (IL-4) mediated locomotor responses by murine B cells in vitro were examined in this paper. The IL-4 induced migration was found to act directly on purified, splenic B cells, without involvement of secondary mediators. It appeared that only a subpopulation of B cells was able to respond in migration assays. Flowcytometric analysis showed that the migrating cells had the characteristics of naive B cells: I-Alo, J11dhi, IgDhi. They also displayed high expression of the adhesion molecule L-selectin and made predominantly IgM antibodies. This is contrary to what has previously been observed regarding motile responses to chemotactic factors by T cells, which mostly affect memory or activated T cells. However, this is in accordance with other studies indicating that IL-4 is a cytokine that exerts its effect mainly on resting B cells.

Individual cells simultaneously produce both IL-4 and IL-6 in vivo

IL-4 and IL-6 are pleiotropic cytokines that can act independently or synergistically to regulate lymphocyte growth and differentiation. Both of these factors are produced by cultures of Th2 cells but it is uncertain whether they are secreted simultaneously by a single cell. We used a sensitive and specific ELIspot assay to identify individual cells spontaneously producing IL-4 or IL-6 under physiological conditions in vivo. The fraction of cells producing these two lymphokines was regulated concurrently in cloned Th2 cells but varied independently in the lymphoid organs of normal BALB/c mice. A sandwich ELIspot assay was developed to determine whether individual cells simultaneously produced both cytokines. Thirteen per cent of cells in the spleen and 25% of those in the bone marrow of 10-week-old BALB/c mice secreting either IL-4 or IL-6 concurrently produced both of these lymphokines. These observations establish a physiological mechanism by which the concurrent production of synergistic cytokines is regulated in a given micro-environment.