Paola Zaccone

Elevated serum levels of interleukin-12 in chronic progressive multiple sclerosis.

The serum levels of the heterodimeric cytokine IL-12 were measured by solid-phase ELISA in a group of healthy subjects, multiple sclerosis (MS) patients with secondary chronic progressive course of the disease and patients suffering from other neurological diseases (OND). Serum levels of IL-12 higher than 5 pg/ml (limit of sensitivity of the assay) were only found in 2/30 (6.7%) of the healthy subjects and none of the 8 subjects with OND. In contrast, IL-12 was found in the majority of CPMS patients sera (10/15, 66.7%) with values ranging between 5.5 and 18.6 pg/ml. These results are suggestive for an up-regulated production of IL-12 in CPMS.

Prevention of Spontaneous Autoimmune Diabetes in Diabetes-Prone BB Rats by Prophylactic Treatment with Antirat Interferon-γ Antibody

The role of endogenous interferon-γ (IFNγ) in the development of insulin-dependent diabetes mellitus (IDDM) in diabetes-prone BB rats was evaluated. Several groups of these animals were treated under different experimental conditions with a purified polyclonal antibody (Ab), antirat IFNγ. The results show that when administered at doses of 100 or 200 μg/week from the 30/33th until the 105th day of age, the anti-IFNγ Ab reversibly reduced the incidence of IDDM compared to that in control rats treated with either irrelevant rabbit IgG or PBS. Moreover, when given up to the 105th day of age, these doses of anti-IFNγ Abs exerted comparable preventive effects regardless of whether application started as early as within 24 h after birth or at the end of the prediabetic period (e.g. 70/75 days). In contrast, under none of the above experimental conditions did larger doses of anti-IFNγ Ab (500 μg or 1 mg/week) exert antidiabetogenic effects in the BB rats. Apparently, this was due to the exuberant production of n...

Blood levels of transforming growth factor‐beta 1 (TGF‐β1) are elevated in both relapsing remitting and chronic progressive multiple sclerosis (MS) patients and are further augmented by treatment with interferon‐beta 1b (IFN‐β1b)

The serum levels of TGF‐β1, measured by solid‐phase ELISA, were determined to be significantly augmented in patients with both relapsing remitting (RR) and secondary chronic progressive (CP) MS compared with sex‐ and age‐matched healthy controls. Moreover, in RR MS patients, the blood levels of the cytokine were further augmented either during relapses or, in a rapid but reversible fashion, by s.c. injection with 8 million International Units (MIU) IFN‐β1b. Because TGF‐β1 possesses multiple anti‐inflammatory activities, we hypothesize that the increase in its circulating levels in RR and CP MS patients might represent an endogenous anti‐inflammatory mechanism aimed at counteracting ongoing immunoinflammatory events, and that IFN‐β may further potentiate this natural defensive apparatus.

Dichotomic effects of IFN-γ on the development of systemic lupus erythematosus-like syndrome in MRL-lpr/lpr mice

Systemic lupus erythematosus (SLE)‐prone female MRL‐lpru2009/u2009lpr (MRL‐lpr) mice were treated with mouse or rat IFN‐γ under different experimental conditions, both prophylactically in 6‐ to 8 week‐old animals and therapeutically in 12‐ to 18‐week‐old SLE‐affected mice. It was found that IFN‐γ heterogeneously modulated the course of the disease in MRL‐lpr mice. When administered prophylactically, IFN‐γ favorably modulated the histological, serological and clinical signs of the disease. Relative to untreated or PBS‐treated control animals, the MRL‐lpr mice which received IFN γ were virtually free of inflammatory infiltration of the kidneys and the lungs, had lower levels of azotemia with reduction of both circulating IgG1, IgG2a and IgG3 and anti‐double strand (ds) and single strand (ss) DNA antibodies, milder skin vasculitis, significantly reduced enlargment of their lymph nodes and lower weight of the spleens. IFN‐γ also lowered the rate of mortality of MRL‐lpr mice. In contrast to these findings, therapeutically administered IFN‐γ worsened the course of the disease in MRL‐lpr mice, which exhibited increased proteinuria, higher levels of IgG2a and IgG3 and anti‐ds and ‐ss DNA antibodies, more aggressive nephritis and died at an earlier age than PBS‐treated control mice. The dichotomic effect of IFN‐γ on disease manifestation in MRL‐lpr mice offers new insights into the complex role of this cytokine in the regulation of systemic autoimmunity such as SLE.

Paradoxical Antidiabetogenic Effect of γ-Interferon in DP-BB Rats

Previous studies have shown that anti-γ-interferon (IFN-γ) antibody reduces the frequency of autoimmune IDDM in the DP-BB rat. We tested the effects of systemically administered recombinant rat IFN-γ in both DP-BB and DR-BB rats. Unexpectedly, IFN-γ markedly reduced the incidence of IDDM as compared with control rats when administered six times per week at a dosage of 280,000 U between ages 30-35 to 105 days or ages 60-64 to 105 days. A lower dosage (28,000 U on alternate days) was also protective when administered to DP-BB rats between birth and age 60 days. However, long-lasting protection against IDDM development over the 1-year study period was achieved only by the highest dosage of IFN-γ administered from age 30 to 105 days. Ex vivo production of tumor necrosis factor-a from splenic lymphoid cells (SLCs) and peritoneal macrophages of the rats treated with IFN-γ was comparable with that of controls; however, SLCs from the IFN-γ-treated animals secreted lower amounts of IFN-γ after stimulation with concanavalin A. IFN-γ treatment also markedly reduced the frequency of phenotypically activated SLC-expressing class II antigens and interleukin-2 receptor. Finally, in agreement with the observed antidiabetogenic effects, exogenously administered IFN-γ induced neither insulitis nor IDDM development in DR-BB rats, a subline of DP-BB rats in which autoimmune diabetes rarely occurs spontaneously but can be induced by administration of polyinosinic-polycytidilic acid.

The involvement of IL-12 in murine experimentally induced autoimmune thyroid disease

Experimental autoimmune thyroid disease (EAT) can be induced experimentally in mice following immunization with mouse thyroglobulin (mTg) and the adjuvants lipopolysaccharide (LPS) or complete Freunds adjuvant (CFA). EAT can also be transferred to naive recipients by CD4+ T cells from mTg‐primed mice. Here we demonstrate a role for IL‐12 in the development of EAT by the ability of neutralizing antibody to IL‐12 to reduce disease severity and by the lack of significant levels of thyroid infiltration in IL‐12p40‐deficient mice following immunization with mTg and CFA. A single injection of 300u2004ng IL‐12 at the time of initial immunization with mTg and LPS was able to increase the degree of thyroid infiltration. These data are all consistent with EAT being a Th1‐mediated disease. Conversely, however, administration of IL‐12 over a prolonged period markedly inhibited the induction of EAT by mTg and CFA and, if given to recipients, inhibited the transfer of EAT by mTg‐primed lymphnode cells. The development of an autoantibody response to mTg was also inhibited when IL‐12 was administered throughout the experimental period, suggesting that sustained exposure to IL‐12 can be immunosuppressive.

The Role of Regulatory T Cell Defects in Type I Diabetes and the Potential of these Cells for Therapy

Type I diabetes is increasing in incidence in developed countries [1]. Diabetes arises from a breakdown of tolerance to islet antigens, resulting in T cell-driven destruction of the islet cells and concomitant hyperglycemia. In this review, we explore whether this loss of tolerance results in part from a defect in the action of regulatory T cells. We draw on both human data and that obtained from NOD mice, the murine model of autoimmune diabetes. Although insulin-based therapies have been highly successful in treating diabetes, the complications of long-term hyperglycemia are still major causes of morbidity and mortality. Accordingly, we also discuss whether treatment with regulatory T cells is a viable method for restoring long-term tolerance to self-antigens in recently diagnosed or pre-diabetic individuals. Regulatory T cell therapy offers many potential advantages, including a specific and lasting dampening of inflammation. However, some significant hurdles would have to be overcome before it could become an established treatment.

Endogenous interleukin-12 only plays a key pathogenetic role in non-obese diabetic mouse diabetes during the very early stages of the disease

A rat monoclonal antibody (mAb) that neutralizes mouse interleukin‐12 (IL‐12) was administered to female non‐obese diabetic (NOD) mice of different ages to dismantle the role of endogenous IL‐12 in murine autoimmune diabetogenesis. Thisu2003mAb was effective in preventing clinical, but not histological signs of spontaneous diabetes when treatment was started early in life at the age of 4 weeks and consecutively continued for 10 weeks. Delaying commencement of anti‐IL‐12u2003mAb prophylaxis until the age of 18 weeks, when NOD mice suffer from advanced insulitis, was ineffective. Anti‐IL‐12u2003mAb did not influence the course of the accelerated model of diabetes induced by cyclophosphamide. These data prove that the pathogenetic role of endogenous IL‐12 in NOD mouse diabetes is restricted to the very early diabetogenic events presumably occurring prior to insulitis development.

Prevention by rolipram of concanavalin A-induced T-cell-dependent hepatitis in mice

Rolipram is a type IV phosphodiesterase inhibitor endowed with powerful immunomodulatory properties. In this study, we evaluated the effects of this drug on the development of the T-cell-mediated hepatitis inducible in mice by concanavalin A. The results indicated that prophylactic treatment with either 5 or 10 mg/kg rolipram injected intraperitoneally 24 h and 1 h prior to intravenous (i.v.) challenge with 20 mg/kg concanavalin A successfully ameliorated serological and histological signs of liver damage, so that the treated mice showed lower transaminase levels in the plasma and milder mononuclear cell infiltration of the liver as compared to vehicle-treated controls. Moreover, this effect was associated with profound modifications of circulating levels of cytokines released after concanavalin A injection, with the blood levels of interferon-gamma and tumor necrosis factor-alpha being significantly lower and those of interleukin-10 higher than those of the control mice. In particular, the increased blood levels of interleukin-10 might play an important role in the anti-hepatitic effects of rolipram as coadministering this compound with anti-interleukin-10 monoclonal antibody significantly reduced its anti-inflammatory action. These results suggest that rolipram may be useful in the clinical setting for the treatment of cell-mediated immunoinflammatory diseases such as immunoinflammatory hepatitis.

The Effects of Thymopentin on the Development of SLE‐Like Syndrome in the MRL/lpr‐lpr Mouse

Thymopentin (TP‐5) is a synthetic pentapeptide that corresponds to the active 32–36 amino acid sequence of the thymic hormone thymopoietin, of which it retains all the immunomodulatory properties. In this study, we have evaluated the effects of long term prophylactic treatment with TP‐5 on the clinical, immunological and histological parameters of the SLE‐like syndrome that spontaneously occurs in MRL/lpr‐lpr (MRL‐lpr) mice. TP‐5., administered (s. c.) to these mice at the doses of 1, 10 and 100mg/kg. was given daily, five times a week, from the 9th to the 26th weeks of life. The prophylactic treatment with TP‐5 prolonged in a clear dose‐dependent fashion the lifespan of MRL‐lpr mice as compared with PBS‐treated control mice, and the effect reached statistical significance at the doses of 10 and 100mg/kg. In parallel ex vivo studies., this chnical effect was associated with multiple profound modifications of the immune system including: (i) the reduction of the spontaneous and Con A‐induced release of interleukin‐4 (IL‐4); (ii) the increased secretion of interferon‐γ (IFN‐γ) and IL‐6 upon polyclonal mitogenic stimulation, and (iii) the amelioration of the defective Con A‐induced lympho‐proliferative response. In contrast, although the drug diminished the severity of proteinuHa in MRL‐lpr mice, it neither reduced histological signs of lupus nephritis nor diminished the serum titres of antinative DNA and anti‐histone autoantibodies. These results indicate that TP‐5 displayed powerful immunomodulatory activities in a well known model of human SLE.