Freunds adjuvant alone is antiatherogenic in apoE-deficient mice and specific immunization against TNFalpha confers no additional benefit

Immunomodulation therapy of diabetes by oral administration of a surfactin lipopeptide in NOD mice

Type 1 diabetes mellitus (T1DM) is considered an autoimmune disease, which can be attenuated by modulation of immune pathway from Th1- to Th2-type through vaccination. WH1fungin surfactin is a Bacillus-produced natural immunomodulator. NOD mice were orally treated with 5mg/kg or 25mg/kg WH1fungin once a week for total 4 weeks. After the final administration, the diabetes incidence and the anti-inflammatory roles of WH1fungin were investigated by immunohistochemistry, FACS and ELISA. The results showed oral WH1fungin obviously resulted in a WH1fungin-unspecific suppression of T1DM. Diabetes incidence was significantly reduced when compared to phosphate buffered saline (PBS) control. Mice in the control group began to be onset of diabetes at week 15, following with an increased mortality from week 16 to 28. At the end of observation, the diabetes incidence reached to 81% at week 30, while only 25% in WH1fungin groups. The splenocytes assay showed oral WH1fungin could suppress T cells proliferation, down-regulate amounts of activated CD8(+) T cells with the production of tumor necrosis factor (TNF)-α and interferon (IFN)-γ, and increase CD4(+)CD25(+)FOXP3(+) regulator T cells (Tregs). The serum assay revealed oral WH1fungin down-regulated TNF-α and IgG2a but increased interleukin (IL)-10 and IgG1 in mice. All of these data showed oral WH1fungin tended to switch the immune response from Th1- to Th2-type. The further surveys revealed that less IFN-γ but more transfer growth factor (TGF)-β were found in the islets of mice with oral WH1fungin when compared to that in the control group. As a result, the normal islet architecture and slight inflammatory cells infiltration was observed with a slight insulitis in the oral WH1fungin groups. These results demonstrate that oral WH1fungin might be a novel therapeutic approach for the prevention of T1DM.

Safety and efficacy trial of adipose-tissue derived oral preparation V-6 Immunitor (V-6): results of open-label, two-month, follow-up study

Background

Chronic inflammations, atherosclerosis and obesity, are major risk factors for cardiovascular diseases. Immune modulation of the inflammatory response has shown promise in animal models of atherogenesis and metabolic disease. Tableted dietary supplement, V-6, containing pooled antigens derived from pig adipose tissue has been administered daily to 12 volunteers for 2 months.

Results

No significant changes were observed in liver ALT and AST enzymes, i.e., 28 vs 23.8 IU and 22.6 vs 24.8 IU, with p = 0.07 and p = 0.49, respectively. Creatinine decreased; 0.88 vs 0.84 mg/dL (p = 0.05) while BUN moved upward; 14.5 vs 17.5 mg/dL (p = 0.01), but both values remained within normal range. Blood glucose remained within normal range; 96.1 vs 101.1 mg/dL (p = 0.04). Complete blood cell analysis has not revealed any change except slight increase in hemoglobin; 13.13 to 13.96 g/dL (p = 0.0002); hematocrit and red blood cells count 40.3 to 42.3% (p = 0.02) and 5.15 to 5.35 × 10⁶ cells/mm³ (p = 0.03) respectively. Blood pressure systolic and diastolic values were not affected, i.e., 116.1 vs 116.3 (p = 0.12) and 76.8 vs 76.6 (p = 0.99). Body weight and body mass index (BMI) remained same; 66.4 vs 66.3 kg (p = 0.47) and 25.7 vs 25.6 kg/m² (p = 0.2). Body fat deposit indices, such as abdomen; mid-arm; and thigh circumferences declined by 3.5 cm (p = 0.008); 1.2 cm (p = 0.004); and 3.0 cm (p = 0.0007) respectively. The total cholesterol and LDL levels did not change; 195.5 vs 195.1 (-0.2%; p = 0.8) and 113.4 vs 120.3 (6.1%; p = 0.08) respectively. Triglycerides have been reduced but not statistically significant; 168.1 vs 118 mg/dL (-29.8%; p = 0.2). In contrast, HDL content had risen by 29.7% from 39.4 to 51.1 mg/dL in all 12 patients (p = 0.000003). TG/HDL ratio - a marker of insulin resistance - was reduced from 4.78 to 2.56 (-46.5%; p = 0.04).

Conclusions

These results demonstrate that V-6 is safe and has a potential as an anti-atherogenic and overweight/obesity immune intervention.

Experimental immunotherapeutic approaches for atherosclerosis

Therapeutic options in atherosclerosis have largely been limited to the control of risk factors, such as hypercholesterolemia, hypertension, or diabetes. However, atherosclerosis is a chronic inflammatory disease in which dyslipidemia and inflammation are equally involved in disease pathogenesis. Moreover, abundant epidemiological and experimental evidence point to an important modulatory role of innate and adaptive immunity in atherogenesis, providing novel therapeutic targets for this disease. Indeed, there is now accumulating data in animal models demonstrating the potential for immunotherapeutic approaches to treat atherosclerosis. These include both general and antigen-specific ways of modulating immune functions, and they show great promise for the development of alternative and/or adjuvant therapies for atherosclerosis.

Effect of immunization against ox-LDL with two different antigens on formation and development of atherosclerosis

Background

Several studies were pointed to oxidized LDL (ox-LDL) as one of the main immunogenes which have important roles in primary lesions of atherosclerosis. In this study, by immunization against ox-LDL with two different antigens in an animal model (rabbit) and consideration of its effect on two different dietary regimens; we tried to clear relation between immune system and atherosclerosis.

Methods

LDL was isolated from hypercholesterolemic rabbits plasma and oxidized with MDA or Cu⁺⁺. Rabbits were divided to three groups and immunized with MDA-LDL or Cu-LDL or phosphate-buffer (PBS) as a control group. Immunization was repeated after 2, 4, 6, and 8 weeks and concentration of antibodies against ox-LDL was measured in each stage. After immunization, rabbits in each group were divided to two subgroups based on the dietary regimen (fed normal or high cholesterol diet). At the beginning and the end of the study, biochemical factors were measured. Also, fatty streaks in aorta and left and right coronary arteries evaluated.

Results

Immunization with Cu²⁺-LDL and MDA-LDL induced statistically significant antibodies against ox-LDL. In hypercholesterolemic rabbits immunized with MDA-LDL the level of cholesterol, LDL-cholesterol, triglyceride, fasting blood sugar and fatty streak lesions in aorta and right coronary arteries were significantly decreased as compared with non-immunized high-cholesterol group. Immunization with Cu²⁺-LDL in hypercholesterolemic rabbits significantly decreased triglyceride, fasting blood sugar, cholesterol and CRP. No significant differences were detected in the fatty streak lesions in this group as compared with non-immunized high-cholesterol diet. In groups under normal diet immunized with MDA-LDL or Cu²⁺-LDL no significant effect on biochemical factors and atherosclerotic lesions were observed.

Conclusion

This study indicates that although the effect of produced antibodies in several methods and different dietary regimens is different, immunization against ox-LDL is antiatherogenic.

Immunomodulation of the inflammatory response in atherosclerosis

PURPOSE OF REVIEW

Cardiovascular disease, as manifested in the formation of atherosclerotic lesions, can be described as a chronic inflammatory autoimmune-like disease that proceeds in the context of enhanced plasma lipid levels. Modulation of the immune response may therefore form a valuable therapy in addition to standardized cholesterol and blood pressure-lowering therapies. The purpose of this review is to describe a number of recent approaches to immunomodulate atherosclerosis: immunization against mediators involved in atherosclerosis, such as cytokines and modified low-density lipoprotein; intervention in cytokine pathways; intervention in co-stimulatory pathways; activation of regulatory T cells; and modulation of natural killer T cells.

RECENT FINDINGS

The most recent findings point to an important role for regulatory T cells in atherosclerotic lesion formation. The function of the regulatory T cells is modulated by chemokines and by co-stimulatory pathways, whereas the function of these cells can be strongly upregulated by anti-CD3 treatment and tolerance induction.

SUMMARY

In the near future the first exponents of this approach, such as immunization and enhancement of the function of regulatory T cells, may enter the first phase of clinical trials, and may ultimately add to the current therapies in atherosclerosis.

Atheroprotective effect of adjuvants in apolipoprotein E knockout mice

Strategies aimed at treating atherosclerosis by immunization protocols are emerging. Such protocols commonly use adjuvants as non-specific stimulators of immune responses. However, adjuvants are known to modify various disease processes. The aim of this study was to determine whether adjuvants alter the development of atherosclerosis. We performed immunization protocols in apolipoprotein E knockout mice (E degrees ) following chronic administration schedules commonly employed in experimental atherosclerosis. Our results point out a dramatic effect of several adjuvants on the development of atherosclerosis; three of the four adjuvants tested reduced lesion size. The Alum adjuvant, which is the adjuvant currently used in most vaccination protocols in humans, displayed a strong atheroprotective effect. Mechanisms accounting for atheroprotective effect of Freund's adjuvants included their capacity to increase both Th2 responses and anti-MDA-LDL IgM titers, and/or to impose atheroprotective lipoprotein profiles. The present study indicates that adjuvants have potent atheromodulating capabilities, and thus, implies that the choice of adjuvant is crucial in long-term immunization protocols in experimental atherosclerosis.

The TNF alpha converting enzyme (TACE/ADAM17) is expressed in the atherosclerotic lesions of apolipoprotein E-deficient mice: possible contribution to elevated plasma levels of soluble TNF alpha receptors

TNF alpha converting enzyme (TACE) critically regulates the inflammatory processes as it releases from the cell surface several transmembrane proteins, including TNFalpha (TNF) and its receptors TNFR1 and TNFR2. We investigated the expression of TACE in atherosclerotic lesions of apolipoproteinE-deficient (apoE (-/-)) mice. Five-week-old apoE(-/-) male mice were fed a high-fat diet and examined at 5, 10, 15 and 25 weeks of age. A group of wild-type C57BL/6 mice (WT) fed the high-fat diet for 25 weeks was included. In apoE(-/-) mice, lesions progressed with time in both aortic sinus and arch, in which TACE immunostaining also increased particularly between 5 and 15 weeks. TACE expression was also observed in human atherosclerotic plaques. The plasma levels of soluble TNFR1 and TNFR2 rose with atherosclerosis. In the 25-week-old WT mice, no lesions were observed and the plasma levels of TNFRs were 17% of those of age-matched apoE(-/-) mice. Incubated aortas of 25-week-old apoE(-/-) mice released much higher amounts of sTNF and sTNFRs than did aortas of 5-week-old apoE(-/-) mice or 25-week-old WT mice. Active TACE was expressed at the surface of macrophages isolated from apoE(-/-) mice. In conclusion, TACE expression is associated with lesions in atherosclerosis-prone sites. Our data suggest that atherosclerotic lesions-expressing TACE may contribute to the elevated levels of circulating sTNFRs.

Regulatory T cell responses: potential role in the control of atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis is an inflammatory disease of the arterial wall where both innate and adaptive Th1-driven immunoinflammatory responses contribute to disease development. Th2-related responses have been shown to be either protective or pathogenic. Thus, it is unclear whether immunoregulatory activity can modulate disease development.

RECENT FINDINGS

Novel subtypes of T cells, called the regulatory T cells, have been shown recently to play a critical role in the maintenance of immunological tolerance against self and non-self antigens and prevent the development of various immunoinflammatory diseases. Preliminary studies suggest a potential role for this type of regulatory T cell response in atherosclerosis.

SUMMARY

Here we present a novel view of the immunoinflammatory response in atherosclerosis where natural and/or adaptive regulatory T cell responses modulate both Th1 and Th2 pathogenic responses and play a central role in counteracting disease initiation and progression.

Blockade of Interleukin-12 Function by Protein Vaccination Attenuates Atherosclerosis

Background— Interleukin-12 (IL-12) has been identified as a key inducer of a type 1 T-helper cell cytokine pattern, which is thought to contribute to the development of atherosclerosis. We sought to study the role of IL-12 in atherosclerosis by inhibition of IL-12 using a newly developed vaccination technique that fully blocks the action of IL-12.

Methods and Results— LDL receptor–deficient (LDLr −/− ) mice were vaccinated against IL-12 by 5 intramuscular injections of IL-12–PADRE complex in combination with adjuvant oil-in-water emulsion (low dose)/MPL/QS21 every 2 weeks. Two weeks thereafter, atherogenesis was initiated in the carotid artery by perivascular placement of silicone elastomer collars. IL-12 vaccination resulted in the induction of anti–IL-12 antibodies that functionally blocked the action of IL-12 as determined in an IL-12 bioassay. Blockade of IL-12 by vaccination of LDLr −/− mice resulted in significantly reduced (68.5%; P <0.01) atherogenesis compared with control mice without a change in serum cholesterol levels. IL-12 vaccination also resulted in a significant decrease in intima/media ratios (66.7%; P <0.01) and in the degree of stenosis (57.8%; P <0.01). On IL-12 vaccination, smooth muscle cell and collagen content in the neointima increased 2.8-fold ( P <0.01) and 4.2-fold ( P <0.01), respectively.

Conclusions— Functional blockade of endogenous IL-12 by vaccination resulted in a significant 68.5% reduction in atherogenesis in LDLr −/− mice. Vaccination against IL-12 also improved plaque stability, from which we conclude that the blockade of IL-12 by vaccination may be considered a promising new strategy in the treatment of atherosclerosis.

Lesion Development and Response to Immunization Reveal a Complex Role for CD4 in Atherosclerosis

Atherosclerosis is a complex disease, bearing many of the characteristics of a chronic inflammatory process. Both cellular and humoral immune responses may be involved in the disease development. Oxidized low-density lipoprotein (oxLDL) is suggested to be an autoantigen in atherosclerosis. A protective effect against atherosclerosis has been demonstrated in animals immunized with oxLDL. Such a protection is associated with elevation of T cell–dependent IgG antibodies against oxLDL. In addition, it has been shown that immunization with Freund adjuvant alone also confers protection against development of atherosclerosis. We therefore hypothesized that CD4+ T cells are critical in the development of atherosclerosis and that they are involved in protective immune reactions after immunization. The development of atherosclerosis was studied in apolipoprotein E knockout (apoE KO) mice and CD4/apoE double knockout (dKO) mice that were immunized with either oxLDL in Freund adjuvant or adjuvant alone, or left untreated. Our results show that (1) the absence of CD4+ cells in apoE KO mice leads to reduced atherosclerosis, indicating that CD4+ cells constitute a major proatherogenic cell population, and (2) the atheroprotective effect of LDL immunization does not depend on CD4+ cells, whereas (3) the atheroprotective effect of adjuvant injection is CD4-dependent. These findings demonstrate complex roles of immune cell-cell interactions in the regulation of the atherosclerotic process and point to several possible targets in the treatment and prevention of atherosclerosis.

Immunomodulation of atherosclerosis: implications for vaccine development

A number of studies have shown activation of the immune system throughout various stages of atherosclerosis. Recent observations have suggested that activation of immune responses may promote atherosclerosis on one hand by inducing and perpetuating arterial inflammation, whereas on the other hand, selective activation of certain immune functions may inhibit atherosclerosis and arterial inflammation. These observations suggest the possibility that selective suppression of proatherogenic immune responses or selective activation of antiatherogenic immune responses may provide new approaches for atherosclerosis prevention and treatment. Several antigens activating immune responses affecting development of atherosclerosis have been identified. These immune responses may be modulated by presenting the antigens together with different types of adjuvants as well as through the route of administration. In this review, we summarize recent experimental studies using immunomodulatory approaches for treatment of atherosclerosis.

Induction of a regulatory T cell type 1 response reduces the development of atherosclerosis in apolipoprotein E-knockout mice

BACKGROUND

T helper type 1 (Th1) response plays a permissive role in atherosclerosis. We hypothesized that adoptive transfer of a novel subtype of T lymphocytes called regulatory T cells type 1 (Tr1) would inhibit Th1 responses by inducing a bystander immune suppression and therefore limit the development of atherosclerosis.

METHODS AND RESULTS

Clones of ovalbumin (OVA)-specific Tr1 cells expanded in vitro were administered intraperitoneally (106 cells per mouse) with their cognate antigen (50 microg of OVA subcutaneously in complete Freund's adjuvant [CFA]) to female apolipoprotein E-knockout mice. A group of mice received only (OVA/CFA) immunization without Tr1 cells. Two other control groups received no immunization and were injected with either Tr1 cells or saline. After 9 weeks of treatment, mice injected with (OVA/CFA)+OVA-specific Tr1 cells showed a significant decrease in Th1 responses, as revealed by a decrease in OVA-specific IgG2a serum levels (P<0.0001), a decrease in the production of interferon-gamma (P<0.001), and an increase in interleukin-10 production (P<0.001) by cultured spleen and lymph T cells compared with controls. In addition, cytokine production by concanavalin A-stimulated spleen cells showed a clear switch to a regulatory immune response in mice treated with (OVA/CFA)+Tr1. This was associated with a significant reduction in atherosclerotic lesion size in both the thoracic aorta and aortic sinus of mice treated with (OVA/CFA)+Tr1 compared with controls (P=0.002 to P<0.0001). Plaques of mice injected with (OVA/CFA)+Tr1 showed significantly lower accumulation of macrophages and T cells than plaques of control mice.

CONCLUSIONS

Tr1-type regulatory immune response reduces the development of experimental atherosclerosis.

Pneumococcal vaccination decreases atherosclerotic lesion formation: molecular mimicry between Streptococcus pneumoniae and oxidized LDL

During the progression of atherosclerosis, autoantibodies are induced to epitopes of oxidized low-density lipoprotein (oxLDL) and active immunization of hypercholesterolemic mice with oxLDL ameliorates atherogenesis. We unexpectedly found that many autoantibodies to oxLDL derived from 'naive' atherosclerotic mice share complete genetic and structural identity with antibodies from the classic anti-phosphorylcholine B-cell clone, T15, which protect against common infectious pathogens, including pneumococci. To investigate whether in vivo exposure to pneumococci can affect atherogenesis, we immunized Ldlr(-/-) mice with Streptococcus pneumoniae. This induced high circulating levels of oxLDL-specific IgM and a persistent expansion of oxLDL-specific T15 IgM-secreting B cells primarily in the spleen, which were cross-reactive with pneumococcal determinants. Pneumococcal immunization decreased the extent of atherosclerosis, and plasma from these mice had an enhanced capacity to block the binding of oxLDL to macrophages. These studies show molecular mimicry between epitopes of oxLDL and S. pneumoniae and indicate that these immune responses can have beneficial effects.