Semaphorin 3A: Is a key player in the pathogenesis of asthma.

Immune semaphorins are key players in regulating immune mediated inflammation. Semaphorin3A (sema3A) a secreted and membrane bound member of this family, is well reported for its properties in maintaining self-tolerance. Semaphorin3A was recognized to be a marker for T-regulatory cells (Tregs), and as such is a useful tool for assessing the status of these cells in preventing immune mediated diseases. This study was designed aiming to evaluate how sema3A is possibly involved in bronchial asthma. Here, we found sema3A serum levels and the expression of sema3A on Tregs significantly lower in patients with moderate to severe asthma when compared to healthy individuals. Co-culture of condition medium with 2mcg/ml of recombinant human sema3A with CD4+ T cells, increased the expression of FoxP3 in Tregs, suggesting sema3A a potent immune-regulator of inflammation including that of asthma. Further in-vivo studies will better establish the beneficial effect of sema3A in regulating inflammation in asthma.

Interferon-gamma-release assay prevents unnecessary tuberculosis therapy.

BACKGROUND: The mass influx of immigrants from tuberculosis-endemic countries into Israel was followed by a considerable increase in the incidence of tuberculosis (TB). All contacts of active TB patients are obliged to be screened by tuberculin skin tests (TST) and, if found positive, prophylactic treatment is considered. OBJECTIVES: To assess the utility of interferon-gamma (IFNγ)-release assay with a prolonged follow-up in preventing unnecessary anti-TB therapy in individuals with suspected false positive results. METHODS: Between 2008 and 2012 the QuantiFERON TB gold-in-tube test (QFT-G) was performed in 278 sequential individuals who were mostly TST-positive and/or were in contact with an active TB patient. In all, whole blood was examined by the IFNγ-release assay. We correlated the TST diameter with the QFT-G assay and followed those patients with a negative assay. RESULTS: The QFT-G test was positive in only 72 (42%) of all 171 TST-positive individuals. There was no correlation between the diameter of TST and QFT-G positivity. Follow-up over 5 years was available in 128 (62%) of all QFT-G-negative individuals. All remained well and none developed active TB. CONCLUSIONS: A negative QFT-G test may obviate the need for anti-TB therapy in more than half of those with a positive TST.

The Involvement of Immune Semaphorins in the Pathogenesis of Inflammatory Bowel Diseases (IBDs).

BACKGROUND AND AIMS: Immune semaphorins are a large family of proteins involved in the pathogenesis of inflammatory diseases through the regulation of immune homeostasis and tissue inflammation. We aim to assess the possible involvement of semaphorin3A (sema3A) and 4A (sema4A) in peripheral immune responses and bowel tissue inflammation of patients suffering from Crohn's disease (CD) and ulcerative colitis (UC). PATIENTS AND METHODS: Twenty-seven CD patients and 10 UC patients were studied and compared to 10 patients followed for acute diverticulitis (disease control) and 12 healthy individuals. All were evaluated for sema3A expression on T regulatory cells (Tregs), serum levels of sema3A and sema4A, and tissue expression of sema3A and sema4A in bowel biopsies. RESULTS: The percentage (%) of T regulatory cells (Tregs) expressing sema3A in patients with active CD (64.5% ± 14.49%) and active UC (49.8% ± 16.45%) was significantly lower when compared to that of healthy controls (88.7% ± 3.6%, p< 0.001 and p< 0.0001, respectively). This expression was seen to be in negative correlation with CD activity. Serum levels of Sema4A were significantly lower in patients with CD and UC when compared to that of controls (5.69 ± 1 .48 ng\ml for CD, 5.26 ± 1.23 ng/ml for UC patients vs 9.74 ± 2.73 ng/ml for normal controls, P<0.001). Sema4A was highly expressed in lymphocytes of the lamina propria of CD and UC patients but absent in patients with diverticulitis or in normal individuals. CONCLUSIONS: Altered % of Tregs expressing sema3A in patients with inflammatory bowel diseases (IBD) is partially responsible for their failure in preventing CD4+ effector T cell induced inflammation in IBD in peripheral blood. The increased expression of sema4A in bowel biopsies from CD and UC patients is suggestive of its central role in regulating local tissue inflammation in the bowel.

Semaphorin 3A: an immunoregulator in systemic sclerosis.

ABSTARCT: Semaphorin 3A (sema3A) plays a regulatory role in immune responses, mainly affecting the activation of regulatory T cells. It has been found to correlate with disease activity in rheumatoid arthritis and systemic lupus erythematosus (SLE). To investigate the expression of sema3A in patients with systemic sclerosis (SSc) compared to healthy controls and SLE disease controls and to correlate it with clinical characteristics, 27 SSc patients, 42 SLE patients and 28 healthy controls were enrolled. Serum level of sema3A was measured by ELISA, and expression of sema3A on regulatory T cells was evaluated by FACS analysis. SSc patients were evaluated for demographics, clinical manifestations, routine laboratory results, nailfold videocapillaroscopy, pulmonary function tests, echocardiograms, modified Rodnan skin score, and disease activity and severity scores. Serum levels of semaphorin 3A were lower in SSc compared to healthy controls 14.38 ± 5.7 versus 27.14 ± 8.4 ng/ml, p < 0.0001 and similar to SLE 15.7 ± 4.3 ng/ml. The expression of semaphorin 3A on regulatory T cells was also lower in SSc compared to healthy controls 61.7 ± 15.7 versus 88.7 ± 3. 7 % (p < 0.0001). Semaphorin 3A serum level inversely correlated with the duration of disease: r = -0.4, p = 0.036 and with low C4 level r = 0.66, p = 0.026. SCL-70 antibody positivity was associated with a lower semaphorin 3A level (difference in mean of 3.44, p = 0.06). Sema3A expression is low in SSc serum and more specifically on regulatory T cells. This may help explain the reduced activation of regulatory T cells in SSc.

The role of B regulatory cells and Semaphorin3A in atopic diseases.

When the pathogenesis of allergic inflammatory diseases such as asthma, allergic rhinitis and atopic dermatitis is discussed, one should take into consideration the involvement of regulatory cells/molecules whose role is to prevent the induction and/or deterioration of such diseases. The involvement of T regulatory cells and FoxPp3 is well established in asthma, but only little is known about the involvement of B regulatory cells (Bregs) and the soluble regulatory molecule semaphorin3A (sema3A) in atopic diseases. During the last decade, research has sought to better define the various subtypes of Breg cells and how similar they are to their parallel subtypes of Tregs. In this review, we focus on the newly reported role of Bregs in both experimental and human models of asthma. Bregs are also involved in the pathophysiology of food allergy. We also show how sema3A plays a role in the pathogenesis of allergic rhinitis and atopic dermatitis. Determining the above processes could facilitate the use of regulatory molecules as therapeutic tools in treating these diseases.

Brief report: lysyl oxidase is a potential biomarker of fibrosis in systemic sclerosis.

OBJECTIVE: Fibrosis is a major cause of morbidity and mortality in systemic sclerosis (SSc). Levels of lysyl oxidase (LOX), an extracellular enzyme that stabilizes collagen fibrils, have been found to be elevated in the skin of SSc patients, but have not been evaluated in the serum or correlated with the clinical parameters. We undertook this study to evaluate serum LOX levels in SSc patients and to correlate these levels with clinical parameters of SSc. METHODS: SSc patients were evaluated for demographic features, clinical manifestations, routine laboratory tests, serum autoantibodies, serum LOX concentrations, and nailfold capillaroscopy patterns. They underwent pulmonary function testing, echocardiography, and high-resolution computed tomography scans of the lung, assessment of skin fibrosis by the modified Rodnan skin thickness score (MRSS), and assessment of disease severity and activity by the Medsger severity scale and the Valentini activity index. RESULTS: Twenty-six SSc patients were evaluated and compared with 25 healthy controls and with 9 disease control patients with primary myelofibrosis. Almost 62% of the SSc patients (16 of 26) had limited cutaneous SSc (lcSSc), while 38% had diffuse cutaneous SSc (dcSSc) (10 of 26); 31% of the patients (8 of 26) had lung involvement. The LOX concentration in SSc patients was higher than that in healthy controls and similar to that in disease controls (P < 0.0001), and it was significantly higher in patients with dcSSc than in those with lcSSc (P = 0.006). The LOX concentration correlated with the MRSS in patients without lung fibrosis. CONCLUSION: This study is the first to demonstrate high serum LOX levels in SSc patients that correlate specifically with skin fibrosis. These correlations suggest that LOX levels may serve as a novel biomarker of fibrosis. Future studies are warranted to determine whether LOX is a potential therapeutic target in SSc.

A regulatory role for CD72 expression on B cells in systemic lupus erythematosus.

BACKGROUND: B regulatory cells and their regulatory products/markers, such us semaphorin 3A (sema3A) and its receptor NP-1, FcγIIB, IL-10, and others, act at the very base of self-tolerance, maintenance, and prevention of autoimmune disease development. OBJECTIVES: The aim of the present study was to assess the involvement of CD72, a regulatory receptor on B cells, in systemic lupus erythematosus (SLE). In addition, the potential of soluble sema3A in enhancing the expression of CD72 on B cells of SLE patients was investigated. RESULTS: CD72 expression on activated B cells of SLE patients was significantly lower than that of normal controls. This lower expression of CD72 in SLE patients correlated inversely with SLE disease activity and was associated with lupus nephritis, the presence of anti-dsDNA antibodies, and low levels of complement. Co-culture of purified B cells from healthy controls with condition-media containing recombinant sema3A resulted in significant enhancement of CD72. Similar enhancement of CD72 on activated B cells from SLE patients, though significant, was still lower than in normal individuals. CONCLUSIONS: The lower expression of CD72 on activated B cells from SLE patients correlates with SLE disease activity, lupus nephritis, the presence of anti-dsDNA antibodies, and low levels of complement. The improvement of CD72 expression following the addition of soluble semaphorin 3A suggests that CD72 may be useful as a biomarker to be followed during the treatment of SLE.

B-regulatory cells in autoimmunity and immune mediated inflammation.

B cells are a source of inhibitory cytokines such as IL-10 and TGF-ß. The ability of being B-regulatory cells (B-regs) was shown to be driven by many stimulatory factors such as toll-like receptors, CD40-ligand and others. However, the characterization of B-regs is still underway. B-regs express high levels of CD25, CD86, IL-10 and TGF-ß. In addition, we propose that semaphorin3A is a regulatory molecule and therefore can serve as one of the additional markers for B-regs. This subset of B cells was able to suppress Th1 proliferation, thus contributing to the maintenance of self-tolerance. Finally, the potentiation of B-reg function should become the aim of many immunomodulatory drugs, contributing to a better control of autoimmune diseases.

Age-related autoimmunity.

Older persons have higher autoimmunity but a lower prevalence of autoimmune diseases. A possible explanation for this is the expansion of many protective regulatory mechanisms highly characteristic in the elderly. Of note is the higher production of peripheral T-regulatory cells.The frequent development of autoimmunity in the elderly was suggested to take place in part due to the selection of T cells with increased affinity to self-antigens or to latent viruses. These cells were shown to have a greater ability to be pro-inflammatory, thereby amplifying autoimmunity. During aging, thymic T-regulatory cell output decreases in association with the loss of thymic capacity to generate new T cells. However, to balance the above mentioned autoimmunity and prevent the development of autoimmune diseases, there is an age-related increase in peripheral CD4+ CD25highFoxP3+ T-regulatory cells. It remains unclear whether this is an age-related immune dysfunction or a defense response. Whatever the reason, the expansion of T-regulatory cells requires payment in terms of an increased incidence of cancer and higher susceptibility to infections.

Semaphorin 3A is a marker for disease activity and a potential immunoregulator in systemic lupus erythematosus.

INTRODUCTION: Semaphorin 3A (sema3A) and neuropilin-1 (NP-1) play a regulatory role in immune responses and have a demonstrated effect on the course of collagen induced arthritis. This study was undertaken to evaluate the role of sema3A and NP-1 in the pathogenesis of systemic lupus erythematosus (SLE) and the specific effect of sema3A on the auto-reactive properties of B cells in SLE patients. METHODS: Thirty two SLE and 24 rheumatoid arthritis (RA) patients were assessed and compared with 40 normal individuals. Sema3A serum levels were measured and correlated with SLE disease activity. The in vitro effect of sema3A in reducing Toll-like receptor 9 (TLR-9) expression in B cells of SLE patients was evaluated. RESULTS: Sema3A serum levels in SLE patients were found to be significantly lower than in RA patients (55.04 ± 16.30 ng/ml versus 65.54 ± 14.82 ng/ml, P = 0.018) and lower yet than in normal individuals (55.04 ± 16.30 ng/ml versus 74.41 ± 17.60 ng/ml, P < 0.0001). Altered serum sema3A levels were found to be in inverse correlation with SLE disease activity, mainly with renal damage. The expression of both sema3A and NP-1 on B cells from SLE patients was significantly different in comparison with normal healthy individuals. Finally, when sema3A was co-cultured with cytosine-phosphodiester-guanine oligodeoxynucleotides (CpG-ODN)-stimulated B cells of SLE patients, their TLR-9 expression was significantly reduced, by almost 50% (P = 0.001). CONCLUSIONS: This is the first study in which a reduced serum level of sema3A was found in association with SLE disease activity. It also raises the possibility that sema3A may have a regulatory function in SLE.

Human CD19(+)CD25(high) B regulatory cells suppress proliferation of CD4(+) T cells and enhance Foxp3 and CTLA-4 expression in T-regulatory cells.

Studies in both animal models and humans have shown a subset of B cells behaving as immuno-regulatory cells, being a source of inhibitory cytokines such as IL-10 and TGF-ß. Our aims were to establish the presence of human B regulatory (Breg) cells and to assess their ability to suppress proliferation of CD4(+) T cells and to mediate T regulatory (Treg) cells' properties. For this purpose, human Breg, CD4(+) T and Treg cells were purified using magnetic microbeads. CFSE-labeled CD4(+) T cells were stimulated and cultured alone or with Breg cells. Their proliferative response was determined 72 hours later based on the CFSE staining. In parallel, Treg cells were cultured alone or with Breg cells in different conditions for 24 hours, and then stained and analyzed for Foxp3 and CTLA-4 expression. We found that, the co-culture of Breg cells (defined as CD25(high) CD27(high) CD86(high) CD1d(high) IL-10(high) TGF-ß(high)) with autologous stimulated CD4(+) T cells decreased significantly (in a dose-dependent way) the proliferative capacity of CD4(+) T cells. Furthermore, Foxp3 and CTLA-4 expression in Treg cells were enhanced by non-stimulated and further by ODN-CD40L stimulated Breg cells. The regulatory function of Breg cells on Treg cells was mainly dependent on a direct contact between Breg and Treg cells, but was also TGF-ß but not IL-10 dependent. In conclusion, human Breg cells decrease the proliferation of CD4(+) T cells and also enhance the expression of Foxp3 and CTLA-4 in Treg cells by cell-to-cell contact.

IVIg attenuates TLR-9 activation in B cells from SLE patients.

INTRODUCTION: Toll-like receptor-9 (TLR-9) plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). The aim of this study was to evaluate the influence of intravenous immunoglobulin (IVIg) on CpG oligodeoxynucleotides (ODN-CpG) activated B cells from SLE patients. METHODS: Peripheral blood B cells were isolated from 16 SLE patients and 21 healthy age-matched controls. B cells were cultured with ODN-CpG 1µM alone or IVIg (10mg/ml) together with ODN-CpG. After 24-h incubation, B cells and supernatants were collected and analyzed for interleukin (IL)-10, IL-6 secretion, and TLR-9 expression. RESULTS: IVIg decreased the secretion of IL-10 from ODN-CpG-activated B cells isolated from both SLE patients and healthy controls (194 ± 46.2 to 103.2 ± 27.13 pg/ml, p < 0.016, 153.2 ± 19 vs 84.6 ± 7.5, p < 0.0001, respectively). Similarly, IVIg decreased the secretion of IL-6 from ODN-CpG-activated B cell isolated from both SLE patients and healthy controls (431.2 ± 83 to 307.6 ± 94.3 pg/ml, p < 0.0008, 319.5 ± 31 vs 193.3 ± 22.8, p < 0.0001, respectively). The decrement of IL-10 and IL-6 secretion was associated with a significant decrease in TLR-9 expression in memory B cells from SLE patients and healthy controls (11.47 ± 1.2 vs 13.29 ± 1.2, p = 0.005, 11 ± 0.8 vs 12.8 ± 0.98, p = 0.0016, respectively). CONCLUSIONS: IVIg attenuates the activation of TLR-9 in B cells from SLE patients, suggesting a novel additional mechanism of IVIg mode of action in these patients.