The effect of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells.

Here we have investigated and compared the effects of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells. Only CD4,45RO+ cells, but not CD4,45RA+ cells were able to promote B cell differentiation resulting in immunoglobulin production in vitro (IgM as well as IgG) which could be inhibited by anti-CD4 MoAbs (MAX.16H5 and T151). In pokeweed mitogen (PWM)-induced B cell proliferation a similar pattern of responsiveness was obtained. When we studied the anti-CD4 effects on cytokine production in T cells stimulated in mixed lymphocyte reaction (MLR) or by mitogens, we found that neither IL-2 nor IL-4 production was dramatically influenced by anti-CD4 in CD4,45RO+ cells. This led us to the conclusion that the inhibitory effect of anti-CD4 on B cell proliferation and immunoglobulin secretion was not due to inhibition of cytokine production. To clarify this point, we investigated the ability of anti-CD4 to inhibit conjugate formation between B and T cells. It was found that CD4,45RO+ T cells formed more conjugates than CD4,45RA+ cells, and that only the conjugate formation by CD4,45RO+ T cells was inhibited by anti-CD4. These results suggest that (i) anti-CD4 inhibits T helper functions primarily by affecting CD4,45RO+ cells, and (ii) this effect is probably mediated by contact inhibition in the early phase of T-B collaboration.     

IL-1, IL-18, and IL-33 families of cytokines

Summary: The interleukin-1 (IL-1), IL-18, and IL-33 families of cytokines are related by mechanism of origin, receptor structure, and signal transduction pathways utilized. All three cytokines are synthesized as precursor molecules and cleaved by the enzyme caspase-1 before or during release from the cell. The NALP-3 inflammasome is of crucial importance in generating active caspase-1. The IL-1 family contains two agonists, IL-1α and IL-1β, a specific inhibitor, IL-1 receptor antagonist (IL-1Ra), and two receptors, the biologically active type IL-1R and inactive type II IL-1R. Both IL-1RI and IL-33R utilize the same interacting accessory protein (IL-1RAcP). The balance between IL-1 and IL-1Ra is important in preventing disease in various organs, and excess production of IL-1 has been implicated in many human diseases. The IL-18 family also contains a specific inhibitor, the IL-18-binding protein (IL-18BP), which binds IL-18 in the fluid phase. The IL-18 receptor is similar to the IL-1 receptor complex, including a single ligand-binding chain and a different interacting accessory protein. IL-18 provides an important link between the innate and adaptive immune responses. Newly described IL-33 binds to the orphan IL-1 family receptor T1/ST2 and stimulates T-helper 2 responses as well as mast cells.     

TGF-β2 and PGE2 in Rabbit Blastocoelic Fluid Can Modulate GM-CSF Production by Human Lymphocytes

PROBLEM: During normal pregnancy, major changes occur in the production of Th2/Th1 cytokines at the feto-maternal interface. Th2 cytokines such as interleukin-4 (IL-4) or interleukin-10 (IL-10) are predominantly produced locally in the uterine and placental tissues, whereas the production of Th1 cytokines such as tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) are decreased. Because these modulations might be induced by the embryo, the current study was carried out to test the effect of rabbit blastocoelic fluid on the production of Th2/Th1 cytokines by lymphocytes, and to investiate the possible implication of transforming growth factor β₂ (TGF-β₂) prostaglandin E₂ (PGE₂) as modulators of the production of these cytokines. METHOD OF STUDY: Human peripheral blood lymphocytes (PBL) were cultured along with ConcanavalinA (Con A), and rabbit blastocoelic fluid was collected on day 12 of gestation (BF d-12). Concentrations of cytokines in culture media were determined by enzyme-linked immunoadsorbent assay (ELISA). RESULTS: Addition of BF d-12 in the culture medium induced a strong inhibition of IL-2, TNF-α, IL-10, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production. However, an initial pretreatment of the lymphocytes with BF d-12, followed by a Con A stimulation, led to a marked increase in GM-CSF production, whereas IL-2, TNF-α, and IL-10 secretions were inhibited. It was also demonstrated, for the first time, that a pretreatment of the lymphocytes with TGF-β₂ and PGE₂ increased GM-CSF production to the same level reached after the addition of BF d-12. Furthermore, removal of TGF-β₂ and PGE₂ from BF d-12 by affinity chromatography reduced the effect of BF d-12 on GM-CSF production. CONCLUSIONS: Taken together, these findings suggest that the embryo, in modulating harmful and beneficial cytokine production locally, plays an active role in its protection against maternal immune cellular assault. These results also emphasize the importance of growth factors for successfully maintaining pregnancy.     

Modulation of alpha 1-acid glycoprotein (AGP) gene induction following honey bee venom administration to adjuvant arthritic (AA) rats; possible role of AGP on AA development.

Honey bee venom (HBV) administration to adjuvant arthritic (AA) rats resulted in a significant suppression of arthritis and in suppression of the hepatic acute phase alpha 1-acid glycoprotein (AGP) gene induction at the early stages of disease development. AGP administration in AA rats resulted in acceleration of arthritis development and in increase of severity and duration of the disease. IL-1, IL-6, tumour necrosis factor (TNF) and glucocorticoids alone are not responsible for the HBV-mediated AGP gene down-regulation. These results indicate that AGP gene expression in AA and HBV-treated AA rats involves the interaction of several factors, and that AGP plays a role for AA development in rats.     

Retroviral gene therapy of collagen-induced arthritis by local delivery of IL-4

Rheumatoid arthritis (RA) is an autoimmune arthritis, for which treatment options remain limited. This study investigated the potential role of adoptive cellular gene therapy as a novel means for treating the RA animal model collagen-induced arthritis (CIA). Adoptive transfer of antigen-specific T-cell hybridomas retrovirally transduced to express IL-4 1 day before booster immunization significantly reduced the number of inflamed joints. Cell transfer after clinical onset of disease had no therapeutic effect. Bioluminescence imaging showed that the hybridomas migrated to the inflamed joints, thus delivering the regulatory protein locally at the site of inflammation. The homing was, at least in part, due to chemotaxis in response to proinflammatory chemokines that are expressed in inflamed joints. There were no significant changes in the cytokine milieu of the draining lymph nodes, nor in the systemic levels of anti-collagen antibodies in treated mice. We conclude that the beneficial clinical effects observed in our model were most likely based on the local action(s) of IL-4 in the inflamed joints and that the local delivery (and effects) of regulatory cytokines, like IL-4, constitutes a novel and effective method of preventing organ-specific autoimmune disease and of minimizing systemic adverse effects.     

Th2 dominance in nasal mucosa in patients with Wegener's granulomatosis

Wegener's granulomatosis initially affects upper respiratory tract organs including the nasal mucosa in more than 90% of patients. The inflammation is typically granulomatous with associated vasculitis. T lymphocytes are usually a prominent component of the leucocyte infiltrate. Previous studies using peripheral blood T cells have implicated IFN-gamma rich Th1-type responses. This study addressed the cytokine milieu in nasal mucosa from 10 patients with active Wegener's granulomatosis using immunohistochemistry. Increased levels of CD3+ T cells and eosinophils were present compared with normal and disease controls. There was increased expression of IL-4, down-regulation of IL-2 and no detectable IFN-gamma. There was increased expression of the chemokine receptor CCR3 by infiltrating cells, consistent with an IL-4 dominant, Th2-biased response. In contrast, renal biopsy tissue from 10 patients with active Wegener's granulomatosis showed expression of IL-2 and IL-4. The Th2-type environment within nasal mucosa, often the initial site of disease activity in Wegener's, is consistent with a local allergic response in these patients.     

Cyclosporin A (CsA) modulates the glomerular production of inflammatory mediators and proteoglycans in experimental nephrosis.

Nephrosis is characterized by glomerular epithelial cell injury and a decrease in the glomerular basement membrane (GBM) proteoglycan content. Although CsA is a useful treatment for a group of patients with this disease, its mechanism of action is unclear. We have previously shown that in experimental nephrosis there is an increase in the glomerular production of tumour necrosis factor-alpha (TNF-alpha) and platelet-activating factor (PAF). Here we have studied the effect of CsA on kidney generation of TNF-alpha and PAF in puromycin aminonucleoside (PAN) nephrosis as well as on the synthesis of proteoglycans by cultured glomerular epithelial cells. Rats receiving CsA had, on day 8 of PAN injection, a significant reduction in proteinuria, blood cholesterol levels and in interstitial mononuclear cells. A diminution in glomerular production and urinary excretion of TNF-alpha and PAF was also noted. In in vitro studies, at 24 h of incubation PAF and TNF-alpha induced in glomerular epithelial cells a significant decrease in proteoglycan synthesis. Neither PAF nor TNF-alpha had any significant effect on glomerular epithelial cell proliferation. CsA alone induced a dose-response increase in proteoglycan synthesis and a slight decrease in cell proliferation. CsA also reversed the inhibitory effect of PAF and TNF-alpha on proteoglycan synthesis. However, CsA did not alter the pattern of proteoglycan production, remaining around 50% chondroitinase ABC-, 15% heparitinase-sensitive. Our results indicate that PAF and TNF-alpha could be implicated in the pathogenesis of nephrosis through the inhibition of proteoglycan synthesis by glomerular epithelial cells. The beneficial effect of CsA in nephrosis may be due to the recovery of the GBM charge selectivity caused by the normalization of glomerular PAF and TNF-alpha synthesis and the increase in proteoglycan synthesis by glomerular epithelial cells.     

Immunohistochemical labelling of cytokines in lung lesions of pigs naturally infected with Mycoplasma hyopneumoniae

Mycoplasma hyopneumoniae (Mh) is the primary agent of porcine enzootic pneumonia (PEN), a chronic respiratory disease endemic to pig farms, and characterized histologically by infiltration of mononuclear cells in airways and prominent hyperplasia of the bronchus-associated lymphoid tissue (BALT). To gain further insight into the pathogenesis of PEN, cytokine expression in the lung, with particular attention to the BALT, was examined immunohistochemically in pigs naturally infected with Mh. An increase (P < 0.05) in proinflammatory and immunoregulatory cytokines (especially interleukin [IL]-2, IL-4 and tumour necrosis factor [TNF]-alpha, and to a lesser extent IL-1 [alpha and beta] and IL-6) was detected in the BALT, which showed intense lymphoid hyperplasia. IL-1beta and TNF-alpha were also detected in the bronchoalveolar exudate of infected pigs, and IL-6 and IL-8 were demonstrated in mononuclear cells of the alveolar septa. The results showed that in Mh infection, macrophage and lymphocyte activation results in the expression of a number of cytokines capable of inducing lung lesions and lymphoreticular hyperplasia of the BALT.