Original Paper

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Acta Biochim Biophys Sin 2008, 40: 116-124

doi:10.1111/j.1745-7270.2008.00384.x

Co-expression of IL-18 binding protein and IL-4 regulates Th1/Th2 cytokine response in murine collagen-induced arthritis

 

Jianhang Leng1*, Hangping Yao2, Junya Shen1, Keyi Wang1, Guangchao Zhuo1, and Ziwei Wang1

 

1 Center of Clinical Experimental Medicine, The First People's Hospital of Hangzhou, Hangzhou 310006, China

2 The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China

 

Received: August 4, 2007�������

Accepted: October 30, 2007

This work was supported by grants from the Science and Technology Foundation of Zhejiang Province (No. 2005C33008) and the Medical and Health Science Foundation of Zhejiang Province (No. 2004B069), China

*Corresponding author: Tel, 86-571-87065701, ext 10544; Fax, 86-571-87065701, ext 10549; E-mail, [email protected]

 

We constructed a recombinant adenoviral vector containing a murine interleukin (IL)-18 binding protein (mIL-18BP) and murine IL-4 (mIL-4) fusion gene (AdmIL-18BP/mIL-4) and used a gene therapy approach to investigate the role of IL-18BP and IL-4 in modulating the T-helper1 and T-helper2 (Th1/Th2) balance in mice with collagen-induced arthritis (CIA). Mice with CIA were intra-articularly injected with 107 pfu/6 ml of either AdmIL-18BP/mIL-4, or a control adenovirus, or with the control vehicle (phosphate-buffered saline). After intra-articular gene therapy with AdmIL-18BP/mIL-4, the serum levels of tumor necrosis factor-a (TNF-a), g-interferon (IFN-g), IL-4, IL-10, and IL-18 in mice with CIA were assessed by ELISA. IFN-g-expressing and IL-4-expressing CD4+ T cells from mice splenocytes were monitored by flow cytometry. Mice with CIA at weeks 1, 2, and 4 after intra-articular injection of AdmIL-18BP/mIL-4 showed significantly increased serum concentrations of IL-4 and IL-10 (P<0.01 at all time points) but greatly decreased serum concentrations� of IFN-g, TNF-a, and IL-18 (P<0.01 at all time points) compared to both the control adenovirus and phosphate�-buffered saline control groups. The percentage of IFN-g-producing� CD4+ T cells was significantly decreased in response� to local AdmIL-18BP/mIL-4 treatment. The percentage� of IL-4-producing CD4+ T cells increased significantly� at 1 week after local injection of AdmIL-18BP/mIL-4 then returned to normal by week 4. These data indicated� the significant modifying effects on the Th1/Th2 imbalance in murine CIA produced by local overexpression of IL-18BP and IL-4. Combination treatment with IL-18BP and IL-4 is a promising potential therapy for rheumatoid arthritis.

 

Keywords������� interleukin-18 binding protein; interleukin-4; gene therapy; rheumatoid arthritis

 

 

A critical advance in cellular immunology has been the discovery of functionally distinct T-cell subsets, T-helper1 (Th1) and T-helper2 (Th2), separated on the basis of their cytokine expression. Th1 cells mainly secrete g-interferon (IFN-g), interleukin (IL)-2, and tumor necrosis factor-a (TNF-a), whereas Th2 cells generally produce IL-4, IL-5, and IL-10. The balance of Th1 and Th2 subsets is implicated� in the regulation of many immune responses [1]. Th1 cytokines have been linked to the pathogenesis of auto�immune diseases, including animal models [2,3], in which a T-cell response against an unknown self-antigen might play a role. In contrast, the Th2-like cytokines IL-4 and IL-10 down-regulate inflammation in these models [4].

IL-4 is a pleiotropic cytokine that plays a number of important roles, including the regulation of inflammation [5]. IL-4 acts as an autocrine growth factor promoting the differentiation of naive T cells to Th2 cells. It also inhibits the differentiation of naive T cells to Th1 as well as cytokine production by Th1 cells [6]. IL-18 is a cytokine with powerful� Th1-promoting activity in synergy with IL-12 [7]. IL-18 induces proliferation, up-regulates IL-2 receptor antagonist (IL-2Ra) expression, and promotes IFN-g, TNF-a, and granulocyte-macrophage colony-stimulating factor� (GM-CSF) production by Th1 clones [8]. Data indicate that IL-18 is capable of promoting a severe, erosive inflammatory� polyarthropathy in a murine model of inflammatory� arthritis. An IL-18 binding protein (IL-18BP) is a member of a novel family of soluble proteins that also includes several poxvirus-encoded putative proteins. It is constitutively expressed in lymphoid tissues and can bind to IL-18, thus blocking its biological activity and limiting the contribution of IL-18 to Th1 responses [9].

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by chronic synovitis of multiple joints normally� leading to destruction of joint cartilage and erosion� of bone. The Th1 and Th2 cytokine balance has attracted great interest as it is hypothesized that the degree of polarization� and heterogeneity of T-cell lymphocytes could be important to the initiation and perpetuation of synovial inflammation [10]. Using highly sensitive techniques, several� investigators have found a preferential activation of Th1 cells in rheumatoid synovium, suggesting that Th1, rather than Th2, cytokines are involved in the pathogenesis� of the disease [11].

Bypassing the initiating factors in RA and manipulating the cytokine balance might be an effective therapeutic means by which chronic inflammation can be managed [12]. It is promising for the combination of RA treatment with gene therapy as a means for agent delivery, making the appropriate selection of candidate therapeutic proteins essential� [13-15].

In the present study, we constructed a recombinant adenoviral vector containing a murine IL-18BP (mIL-18BP) and murine IL-4 (mIL-4) fusion gene (AdmIL-18BP/mIL-4). We used this adenoviral gene therapy in murine collagen�-induced arthritis (CIA), an autoimmune� model of RA, to increase the expression of IL-18BP and IL-4 in inflamed joints. We postulated that adenovirally-produced IL-4 and IL-18BP could significantly down-regulate the production of the Th1 cytokines, thus modulating the Th1/Th2 balance� in established CIA. Results� of this investigation could support� the feasibility of AdmIL-18BP/mIL-4 gene therapy in the treatment of RA.

 

Materials and Methods

 

Animals

Male DBA-1/BOM mice were purchased from the Sipper BK Experimental Animal Company (Shanghai, China). The mice were housed in filter-top cages, and were given free access to water and food. The mice were immunized at the age of 10-12 weeks.

 

Recombinant adenoviral vectors

The recombinant replication-deficient adenoviral vector containing mIL-18BP and mIL-4 fusion cDNA (AdmIL-18BP/mIL-4) was prepared and the virus was purified as follows. The two cDNA from mIL-18BP and mIL-4 were cloned by RT-PCR from total RNA obtained from mouse splenocytes, then connected by a linker [(Gly-Gly-Gly-Gly-Ser)3]. To ensure the correct nucleotide sequence, the entire cDNA was subsequently sequenced. The fusion cDNA of mIL-18BP and mIL-4 was inserted into the p-Shuttle-CMV vector (Stratagene, La Jolla, USA). The recombinant� replication-deficient adenovirus AdmIL-18BP/mIL-4 was generated by homologous recombination after electrotransforming BJ5183-AD-1 Electroporation Competent� Cells (pre-transformed with pAdEasy-1 adenoviral� vector backbone for 3-fold improvement of recombinant� adenovirus production) (Stratagene) with p-Shuttle-CMV-mIL-18BP/mIL-4. p-Shuttle-CMV-LacZ (Stratagene) was used as a control vector. High titers of recombinant adenoviruses were amplified in adenoviral E1-transformed human embryonic kidney 293 cells (Stratagene). Purification of the virus was accomplished using cesium chloride density ultracentrifugation followed by dialysis, and the viral titer (pfu/ml) was determined by plaque assay in 293 cells as described previously [16].

 

Functional analysis of AdmIL-18BP/mIL-4

Synovial fibroblasts of mice with CIA were isolated as previously described [17]. One million synovial fibroblasts seeded in a 6 cm culture dish were infected with AdmIL-18BP/mIL-4 or a control adenovirus (AdLacZ) at a multiplicity of infection of 100. After incubation at 37 �C in 5% CO2 for 30 min, the supernatants were replaced with RPMI 1640 complete medium (supplemented with 10% fetal calf serum, 100 U/ml penicillin, 50 mg/ml streptomycin, and 2 mM glutamine). Supernatant were collected at specified time points and analyzed for IL-4 release by ELISA (R&D Systems, Minneapolis, USA).

Synovial fibroblasts transfected or not transfected were collected and lysed by the addition of a lysis buffer consisting� of 20 mM Tris-HCl (pH 7.5), 150 mM NaCl, 1 mM Na2EDTA, 1 mM EGTA, 1% Triton X-100, 1% NP-40, 2.5 mM sodium� pyrophosphate, 1 mM b-glycero��phosphate, 1 mM leupeptin and 1 mM phenylmethylsulphonyl fluoride� for 30 min at 4 �C. Cellular proteins (40 mg/sample) were subjected to Western blot analysis using primary antibody specific to IL-18BP (R&D Systems) followed by horseradish peroxidase-conjugated secondary antibody. The reaction was visualized with enhanced chemiluminescence reagents and the signal was captured on X-ray film.

 

Induction of collagen-induced arthritis

Bovine type II collagen was prepared according to the method of Miller and Rhodes [18], diluted in 0.05 M acetic� acid to a concentration of 2 mg/ml, and emulsified in an equal volume of Freund complete adjuvant (2 mg/ml Mycobacterium tuberculosis, strain H37Ra; Difco Laboratories, Detroit, USA). The mice were immunized intradermally at the base of the tail with 100 ml of emulsion� (100 mg collagen). On day 21, mice were given an intra�peritoneal booster injection of 100 mg type II collagen dissolved� in phosphate-buffered saline (PBS) (pH 7.4). Arthritis� onset typically occurred by day 25-28.

 

Assessment of arthritis

Mice were examined for the visual appearance of arthritis in peripheral joints, and assigned a severity score (arthritis score) as previously described [19]. Mice were considered� arthritic when significant changes in redness and/or swelling� were noted in digits or in other parts of the paws. At later time points, ankylosis was also included in the arthritis score. The clinical severity of arthritis was graded on a scale of 0-2 for each paw, according to changes in redness and swelling: 0, no changes; 0.5, slight; 1.0, moderate; 1.5, marked; and 2.0, maximal swelling and redness, and eventually ankylosis. Arthritis score (mean�SD) was expressed as the cumulative value for all paws, with a maximum of 8 and expressed as a percentage� of the initial score at the beginning of treatment.

 

Treatment of CIA with mIL-18BP/mIL-4 co-expressing� recombinant adenovirus vector

To evaluate the effects of AdmIL-18BP/mIL-4 to Th1 and Th2 cytokine responses on established CIA, mice with CIA were selected with similar arthritis scores at day 28 and divided into three groups. Thereafter, intra-articular injections in the right knee joint of mice were carried out with 107 pfu/6 ml of either the mIL-18BP and mIL-4 fusion� expressing recombinant adenovirus vector (AdmIL-18BP/mIL-4), or a control replication-defective recombinant adenovirus vector (AdLacZ), or with PBS. At weeks 1, 2, and 4 after the intra-articular injection of the viral vector, mice serum was collected for the examination of Th1/Th2 cytokines. Mice splenocytes were isolated for the measurement� of IFN-g-expressing and IL-4-expressing CD4+ T cells.

 

Measurement of Th1/Th2 cytokines in serum

At weeks 1, 2, and 4 after the intra-articular injection of the viral vector, six mice from each group were bled and killed by cervical dislocation. The serum levels of TNF-a, IFN-g, IL-4, IL-10, and IL-18 were measured by ELISA using commercially available kits (R&D Systems).

 

Measurement of IFN-g-expressing and IL-4-expressing� CD4+ T cells

At weeks 1, 2, and 4 after the intra-articular injection of the viral vector, viable mice splenocytes were isolated from the various animal groups (six mice from each group). The cells were washed with PBS, then resuspended in RPMI 1640 culture medium (2106 cells/ml). They were stimulated with phorbol 12-myristate 13-acetate (Sigma, St Louis, USA) and ionomycin (Sigma) for 5 h at 37 �C in 5% CO2 at final concentrations of 25 ng/ml and 1 mg/ml. Monensin (Sigma) with a final concentration of 1.7 mg/ml was also added into the culture to block the intracellular cytokine transport processes for the final 4 h of the 5 h activation period. After stimulation, the cells were washed and incubated for 15 min with allophycocyanin-conjugated rat anti-mouse CD4 antibody (Caltag Laboratories, Burlingame, USA), then fixed and permeabilized using the Fix & Perm cell permeabilization kit (Scandic, Vienna, Austria). During permeabilization, the cells were incubated with fluorescein-isothiocyanate (FITC)-conjugated rat anti-mouse IFN-g (Caltag Laboratories) and phycoerythrin� (PE)-conjugated rat anti-mouse IL-4 (Caltag Laboratories) antibodies for 15 min. Isotype-matched controls rat IgG1-FITC and rat IgG1-PE were used to assess non-specific binding. Following a final washing step, the cells were resuspended in 500 ml PBS and subjected to flow cytometry. All incubations were carried out at room temperature� in the dark. The labeled cells were analyzed by FACSCalibur four-color flow cytometry (Becton Dickinson Immunocytometry Systems, San Jose, USA) using CellQuest software (Becton Dickinson). The cytometer� was calibrated with CaliBRITE beads (Becton Dickinson) using FACSComp software (Becton Dickinson) and with QC-4 beads according to the manufacturer's recommendations (Flow Cytometry Standards, San Juan, Puerto Rico). For the purpose of analysis, 50,000 events were acquired because the IFN-g-producing cells were expected to be present at low frequencies. T-helper cells were selected using a forward and side scatter gate for lymphocytes in combination with a gate on CD4+ cells. This specific cell population was then analyzed for intra�cellular cytokines using dual color dot plots of cytokine IFN-g FITC or IL-4 PE versus CD4+ allophycocyanin. Non-specific staining and autofluorescence were determined by the isotype-matched controls.

 

Statistical analysis

Data were expressed as the mean�SD. Differences were determined by one-way ANOVA with Bonferroni multiple comparison tests and Student t-test. Differences were accepted as significant when P<0.05.

 

Results

 

IL-4 expression in synovial fibroblasts infected with AdmIL-18BP/mIL-4

In order to establish the function of AdmIL-18BP/mIL-4, synovial fibroblasts of mice with CIA were isolated and infected with AdmIL-18BP/mIL-4 or a control adenovirus, AdLacZ. Two hours after being infected, IL-4 was released� in a conditioned medium of mouse synovial fibroblast cultures. As shown by ELISA [Fig. 1(A)], strong IL-4 production was observed at 72 h, beginning at a concentration of 47.6 ng/ml, followed by a steady increase. One week after being infected, the expression of IL-4 reached a peak concentration of 76.4 ng/ml. No detectable levels of IL-4 were found in the culture supernatants of synovial fibroblasts infected with AdLacZ or pure synovial fibroblasts (data not shown).

 

IL-18BP protein expression in synovial fibroblasts infected� with AdmIL-18BP/mIL-4

As there is presently no commercially available ELISA kit for the measurement of IL-18BP, IL-18BP protein expression in synovial fibroblast lysates was measured by Western� blot analysis [Fig. 1(B)]. These experiments suggested that the recombinant adenoviral vector AdmIL-18BP/mIL-4 is very effective in vitro.

 

Regulatory effects on Th1 and Th2 cytokine expression in serum after AdmIL-18BP/mIL-4 therapy

In order to examine the effects of AdmIL-18BP/mIL-4 on Th1 and Th2 serum cytokines, mice with CIA were bled and killed at weeks 1, 2, and 4 following intra-articular injection of AdmIL-18BP/mIL-4, AdLacZ, or PBS. Serum cytokines were detected by ELISA. As shown in Fig. 2, mice with CIA at weeks 1, 2, and 4 after injection of AdmIL-18BP/mIL-4 showed significantly increased mean serum concentrations of IL-4 and IL-10 (P<0.01 at all time points) but greatly decreased mean serum concentrations of IFN-g and TNF-a (P<0.01 at all time points) compared with the control groups that had received either AdLacZ or PBS. At weeks 1, 2, and 4 following injection of AdmIL-18BP/mIL-4, the serum concentrations of IL-4 and IL-10 were 2.3, 2.3, and 2.1 times higher and 2.2, 2.0, and 2.3 times higher, respectively, than those in mice that had received AdLacZ. However, the serum concentrations of IFN-g and TNF-a at 1, 2, and 4 weeks following the injection of AdmIL-18BP/mIL-4 were only 53%, 45%, 42% and 47%, 41%, and 40%, respectively, of the levels found in mice that had received AdLacZ. In addition, there were no significant differences in the serum concentrations of the four cytokines between the two control groups at any time points.

The results of serum levels of IL-18 at weeks 1, 2, and 4 following injection of AdmIL-18BP/mIL-4 are shown in Fig. 3. The serum levels of IL-18 at weeks 1, 2, and 4 following injection of AdmIL-18BP/mIL-4 were decreased by 45%, 53%, and 63%, respectively, compared to the serum levels found in mice that had received AdLacZ (P<0.01 at all time points). The serum levels of IL-18 were the same in both control groups (P>0.05 at all time points).

 

Effects of AdmIL-18BP/mIL-4 on IFN-g-producing and IL-4-producing CD4+ T cells

At weeks 1, 2, and 4 after intra-articular injection of AdmIL-18BP/mIL-4, viable mice splenocytes were isolated� from six mice from each group. IFN-g-producing and IL-4-producing CD4+ T cells were investigated by flow cytometry. Results are shown in Fig. 4.

When CD4+ T cells were analyzed 1 week after injection� of AdmIL-18BP/mIL-4 [Fig. 5(A)], the percentage of IFN-g-positive CD4+ T cells (7.03%�2.05%) was lower than that after injection of AdLacZ (17.10%�3.74%, P<0.01) or PBS (10.74%�3.92%, P<0.05). However, the difference was not significant (P>0.05) when compared to the normal group (4.58%1.43%). At weeks 2 and 4 after injection of AdmIL-18BP/mIL-4, the percentage of IFN-g-positive CD4+ T cells was 5.28%�2.29% and 3.99%�0.91%, respectively. However, at these different time points, no significant difference in the percentage of IFN-g-positive CD4+ T cells was noticed in the therapy group or in either of the control groups. As shown in Fig. 5(B), 1 week after injection of AdmIL-18BP/mIL-4, the percentage of IL-4-positive CD4+ T cells (47.56%�6.14%) was higher than after injection of AdLacZ (32.98%�10.00%, P<0.05) or PBS (14.27%�2.68%, P<0.01). This then decreased gradually. By weeks 2 and 4 after injection of AdmIL-18BP/mIL-4, the percentage of IL-4-positive CD4+ T cells was 9.56%�2.72% and 6.99%�1.37%, respectively. At week 4, when the therapy group was compared� to the normal group (5.58%�1.95%), the percentage� of IL-4-positive CD4+ T cells showed no significant� difference (P>0.05), nor was there any significant� difference for either of the control groups.

 

Discussion

 

Treatment of RA requires therapeutic measures over a prolonged period, therefore gene therapy has been considered� to be an interesting approach that might have advantages over conventional therapies that use soluble receptor, antagonizing protein, or blocking antibodies. Indeed, gene therapy has been proven to be useful in various� animal models of arthritis [20]. In the present study we constructed a recombinant adenoviral vector containing� the mIL-18BP and mIL-4 fusion gene (AdmIL-18BP/mIL-4). We evaluated the effect of IL-18BP/IL-14 gene therapy on modifying the immune response in murine CIA and identified possible pathways mediating this process in vivo. We found significantly increased serum levels of IL-4 and IL-10 but greatly reduced serum levels of IFN-g and TNF-a after intra-articular injection of AdmIL-18BP/mIL-4 in murine CIA.

It is now generally accepted that TNF-a plays a key role in the inflammation and joint damage that occurs in RA [21]. TNF-a controls in part the production of IL-1 and other pro-inflammatory cytokines, including IL-6 and IL-8. Furthermore, it increases the expression of adhesion� molecules, chemokines, prostaglandin E2, and matrix metalloproteinases. The importance of TNF-a in RA has been established by several experimental and clinical observations� [21,22]. TNF-a blockade after the onset of disease resulted in amelioration of clinical symptoms and prevention of joint destruction. TNF-a has been shown to be pivotal in the pathogenesis and progression of the disease and has been successfully targeted in the treatment� of RA patients [23].

The production of IL-10 is one of the anti-inflammatory� mechanisms used to control a dysregulated immune response� in reaction to the activity of pro-inflammatory cytokines in RA patients. IL-10 can suppress TNF-a and IL-1 production by activated macrophages and can enhance� the production of TNF inhibitors, acting as a potent anti-inflammatory cytokine [24].

Some investigations of IL-4 treatment in murine CIA focused on synovial and cartilage destruction. In this model, IL-4 displayed marked protection against cartilage and bone erosion, and promoted tissue repair [25]. The mechanisms of action of endogenous and exogenous IL-4 on inflammation� in vivo are not clear. Previous studies suggest� that a possible explanation for the tissue-protective effect of IL-4 might be its immunoregulatory ability to play a critical role in the Th2 reaction and to modulate the IL-1- and TNF-a-mediated inflammatory responses [26]. IL-1 has also been proven to be a critical cytokine involved in synovitis in RA [27]. In the RA synovium, an imbalance in this system exists because the relative levels of production� of IL-1Ra are not adequate to effectively block the pro-inflammatory effects of IL-1 [28]. Some studies revealed� that IL-4 treatment in animal models and in RA patients can enhance levels of IL-1Ra or suppress levels of IL-1b [29]. Recently, it was shown in rat adjuvant-induced arthritis� that IL-4 gene delivery resulted in anti-angiogenic effects in vitro and in vivo. IL-4 reduced synovial tissue vascularization through angiostatic effects, mediated inhibition� of angiogenesis by an association with altered pro- and anti-angiogenic cytokines. This study implied that IL-4 gene therapy might be a useful approach to the reduction� of neovascularization in arthritis [30].

We also found the serum levels of IL-18 were significantly down-regulated in response to local AdmIL-18BP/mIL-4 treatment in murine CIA. IL-18, initially described as an IFN-g-inducing factor, is a pro-inflammatory cytokine that plays an important role in the Th1-type immune� response through the induction of IFN-g synthesis� in T cells and natural killer cells, T-cell proliferation, and cytokine production [31]. Significant levels of expression of IL-18 have been shown previously in the synovium of RA patients [32]. In vivo observations further support a pro-inflammatory role in articular inflammation. Thus, IL-18 can replace the requirement for Freund's complete adjuvant to induce arthritis in collagen-immunized DBA/1 mice [33]. Using adenoviral delivery of IL-18 and TNF-a/IL-1 deficient mice, Joosten and colleagues subsequently showed that, although IL-18-induced joint inflammation is independent of IL-1, cartilage degradation requires IL-18 induced IL-1b production [34]. Furthermore, they suggested� that TNF is partly involved in IL-18-induced joint swelling and influx of inflammatory cells, but that cartilage proteoglycan loss occurs independent of TNF. These findings indicate that IL-18, in contrast to TNF, contributes through distinct pathways to joint inflammation� and cartilage destruction. IL-18-deficient DBA/1 mice have a reduced incidence and severity of CIA associated with amelioration of articular damage [35]. IL-18BP, a constitu�tively expressed and secreted protein, has been identified� [9]. IL-18BP binds IL-18 with high affinity (400 pM) and blocks its biological activity at a 1:1 molar ratio [36]. Such a naturally occurring molecule represents an interesting inhibitor for testing in experimental models of disease. IL-18 is an early signal leading to Th1 cytokine responses that are essential for the cytotoxic T cell response. Therefore, IL-18BP could modulate one of the earliest phases of the Th1 immune response. Moreover, local overexpression of IL-18 binding protein C by adenoviral delivery also ameliorates articular destruction [37]. Therefore, the therapeutic use of IL-18BP might modulate the cytokine balance, ameliorating established arthritis.

The investigation of intracellular cytokine profiles is not influenced by the soluble cytokine receptors or inhibitors in serum or plasma. Hence, we analyzed IFN-g-producing and IL-4-producing CD4+ T cells by flow cytometry. A previous study showed that the mean percentage of IFN-g-producing CD4+ T cells in patients with RA was almost 4-fold higher than the number of IL-4-producing CD4+ T cells [38]. We showed that the mean percentage of IFN-g-producing CD4+ T cells in murine CIA was significantly� decreased and seemed to reach a normal level after injection of AdmIL-18BP/mIL-4, whereas the mean percentage of IL-4-producing CD4+ T cells was remarkably� increased at week 1, then reduced to a normal group level at week 4. Our data show for the first time the marked effect of modifying Th1/Th2 imbalance in murine CIA after local AdmIL-18BP/mIL-4 gene therapy.

RA is a systemic disease and its joint manifestation depends, at least in part, on systemic immune dysfunction. The significant modificatory effects on Th1/Th2 imbalance� in murine CIA after local AdmIL-18BP/mIL-4 gene therapy support the view that combination treatment with IL-18BP and IL-4 is a promising therapeutic target for RA if overexpressed locally.

 

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