Regulation of human dendritic cells by a novel specific nuclear factor-kappaB inhibitor, dehydroxymethylepoxyquinomicin

Dehydroxymethylepoxyquinomicin, a novel nuclear factor-κB inhibitor, prevents the development of cyclosporine A nephrotoxicity in a rat model

Background

Cyclosporine A (CsA) is an essential immunosuppressant in organ transplantation. However, its chronic nephrotoxicity is an obstacle to long allograft survival that has not been overcome. Nuclear factor-κB (NF-κB) is activated in the renal tissue in CsA nephropathy. In this study, we aimed to investigate the effect of the specific NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in a rat model of CsA nephrotoxicity.

Methods

We administered CsA (15 mg/kg) daily for 28 days to Sprague-Dawley rats that underwent 5/6 nephrectomy under a low-salt diet. We administered DHMEQ (8 mg/kg) simultaneously with CsA to the treatment group, daily for 28 days and evaluated its effect on CsA nephrotoxicity.

Results

DHMEQ significantly inhibited NF-κB activation and nuclear translocation due to CsA treatment. Elevated serum urea nitrogen and creatinine levels due to repeated CsA administration were significantly decreased by DHMEQ treatment (serum urea nitrogen in CsA + DHMEQ vs CsA vs control, 69 ± 6.4 vs 113.5 ± 8.8 vs 43.1 ± 1.1 mg/dL, respectively, p < 0.0001; serum creatinine in CsA + DHMEQ vs CsA vs control, 0.75 ± 0.02 vs 0.91 ± 0.02 vs 0.49 ± 0.02 mg/dL, respectively, p < 0.0001), and creatinine clearance was restored in the treatment group (CsA + DHMEQ vs CsA vs control, 2.57 ± 0.09 vs 1.94 ± 0.12 vs 4.61 ± 0.18 ml/min/kg, respectively, p < 0.0001). However, DHMEQ treatment did not alter the inhibitory effect of CsA on urinary protein secretion. The development of renal fibrosis due to chronic CsA nephrotoxicity was significantly inhibited by DHMEQ treatment (CsA + DHMEQ vs CsA vs control, 13.4 ± 7.1 vs 35.6 ± 18.4 vs 9.4 ± 5.4%, respectively, p < 0.0001), and these results reflected the results of renal functional assessment. DHMEQ treatment also had an inhibitory effect on the increased expression of chemokines, monocyte chemoattractant protein-1, and chemokine (c-c motif) ligand 5 due to repeated CsA administration, which inhibited the infiltration of macrophages and neutrophils into the renal tissue.

Conclusions

These findings suggest that DHMEQ treatment in combination therapy with CsA-based immunosuppression is beneficial to prevent the development of CsA-induced nephrotoxicity.

Dehydroxymethylepoxyquinomicin suppresses atopic dermatitis-like lesions in a stratum corneum-removed murine model through NF-κB inhibition

Background: Dehydroxymethylepoxyquinomicin (DHMEQ) is a specific and potent inhibitor of nuclear factor-kappa B (NF-κB) and has been shown to possess promising potential as an anti-inflammation including anti-atopic dermatitis (AD)-like skin lesions. Objective: To further evaluate the activity of DHMEQ in vivo modified AD-like lesion model in BALB/c mice and in vitro AD-like lesion cell model in human keratinocytes. Materials and methods: In this study, in vivo modified AD-like lesion model in BALB/c mice was chronically induced by the repetitive and alternative application of 2,4-dinitrochlorobenzene (DNCB) and oxazolone (OX) on ears, and stratum corneum of the ear skin was additionally stripped off with surgical tapes before each challenge with DNCB/OX. Moreover, in vitro AD-like lesion cell model in human keratinocytes (HaCaT) achieved by stimulating HaCaT cells with tumor necrosis factor (TNF)-α plus interferon (IFN)-γ was used to investigate mechanisms of the action. Results: The lesions derived from the stratum corneum-removed AD-like lesion model reaches to peak as well as DHMEQ arrives to its efficacy a week earlier than the data previously obtained from the common AD-like lesion model. Results showed that the drug reduced the ear thickness, epidermal thickness, mast cell infiltration, and gene expressions of interleukin (IL)-4, IL-13, and interferon (IFN)-γ in ear tissues. It significantly inhibited the expression of cytokines IL-6 and IL-1β, chemokines thymus and activation-regulated chemokine (TARC)/CCL17, and macrophage-derived chemokine (MDC)/CCL22 in the stimulated HaCaT cells. Discussion and conclusion: This study indicated that the action of DHMEQ's anti-AD like lesions might be related to its inhibition on NF-κB.

Efficacy of DHMEQ, a NF-κB inhibitor, in islet transplantation: II. Induction DHMEQ treatment ameliorates subsequent alloimmune responses and permits long-term islet allograft acceptance

BACKGROUND

Long-term graft deterioration remains a major obstacle in the success of pancreatic islet transplantation (PITx). Antigen-independent inflammatory and innate immune responses strengthen subsequent antigen-dependent immunity; further, activation of nuclear factor (NF)-κB plays a key role during these responses. In this study, we tested our hypothesis that, by the inhibition of NF-κB activation, the suppression of these early responses after PITx could facilitate graft acceptance.

METHODS

Full major histocompatibility complex (MHC)-mismatched BALB/c (H-2) mice islets were transplanted into streptozotocin-induced diabetic C57BL/6 (B6: H-2) mice. The NF-κB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) was administered for either 3 or 14 days after PITx. To some PITx recipients, tacrolimus was also administered. Islet allograft survival, alloimmune responses, and in vitro effects of DHMEQ on dendritic cells (DCs) were assessed.

RESULTS

With a vehicle treatment, 600 islet allografts were promptly rejected after PITx. In contrast, 3-day treatment with DHMEQ, followed by 2-week treatment with tacrolimus, allowed permanent acceptance of islet allografts. The endogenous danger-signaling molecule high mobility group complex 1 (HMGB1) was elevated in sera shortly after PITx, whereas DHMEQ administration abolished this elevation. DHMEQ suppressed HMGB1-driven cellular activation and proinflammatory cytokine secretion in mouse bone marrow-derived DCs and significantly reduced the capacity of DCs to prime allogeneic T-cell proliferation in vitro. Finally, the DHMEQ plus tacrolimus regimen reverted the diabetic state with only 300 islet allografts.

CONCLUSIONS

Inhibition of NF-κB activation by DHMEQ shortly after PITx suppresses HMGB1, which activates DCs and strengthens the magnitude of alloimmune responses; this permits long-term islet allograft acceptance, even in case of fewer islet allografts.

Immunosuppressive effects of DTCM-G, a novel inhibitor of the mTOR downstream signaling pathway

BACKGROUND

A newly developed compound, 3-[(dodecylthiocarbonyl)methyl]-glutarimide (DTCM-G), has been shown to inhibit nuclear translocation of c-Fos/c-Jun in a murine macrophage cell line. Herein, we studied the immunosuppressive properties and potency of DTCM-G.

METHODS

Using purified mouse T cells, the in vitro effects of DTCM-G on activation, cytokine production, proliferation, and cell cycle progression were assessed, and a possible molecular target of DTCM-G was investigated. In a BALB/c (H-2(d)) to C57BL/6 (H-2(d)) mouse heart transplantation model, transplant recipients were administered DTCM-G, a calcineurin inhibitor (tacrolimus), and a nuclear factor-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ). Treatment drugs were administered daily for 14 days after transplantation. Alloimmune responses were assessed in addition to graft survival time.

RESULTS

After anti-CD3+anti-CD28 monoclonal antibody stimulation, DTCM-G significantly suppressed proliferation, interferon-γ production, and cell cycle progression of activated T cells but not CD25 expression or interleukin-2 production. These effects were accompanied by inhibition of 70-kDa S6 protein kinase phosphorylation, a downstream kinase of the mammalian target of rapamycin. The addition of tacrolimus and DHMEQ to DTCM-G resulted in a robust inhibition of T-cell proliferation. In vivo combination therapy of DTCM-G plus either tacrolimus or DHMEQ significantly suppressed alloreactive interferon-γ-producing precursors and markedly prolonged cardiac allograft survival. Furthermore, combination of all three agents markedly inhibited alloimmune responses and permitted long-term cardiac allograft survival.

CONCLUSIONS

DTCM-G inhibits T cells by suppressing the downstream signal of mammalian target of rapamycin. DTCM-G in combination with tacrolimus and DHMEQ induces a strong immunosuppressive effect in vivo.

Contribution of double-stranded RNA and CPSF30 binding domains of influenza virus NS1 to the inhibition of type I interferon production and activation of human dendritic cells

The influenza virus nonstructural protein 1 (NS1) inhibits innate immunity by multiple mechanisms. We previously reported that NS1 is able to inhibit the production of type I interferon (IFN) and proinflammatory cytokines in human primary dendritic cells (DCs). Here, we used recombinant viruses expressing mutant NS1 from the A/Texas/36/91 and A/Puerto Rico/08/34 strains in order to analyze the contribution of different NS1 domains to its antagonist functions. We show that the polyadenylation stimulating factor 30 (CPSF30) binding function of the NS1 protein from A/Texas/36/91 influenza virus, which is absent in the A/Puerto Rico/08/34 strain, is essential for counteracting these innate immune events in DCs. However, the double-stranded RNA (dsRNA) binding domain, present in both strains, specifically inhibits the induction of type I IFN genes in infected DCs, while it is essential only for inhibition of type I IFN proteins and proinflammatory cytokine production in cells infected with influenza viruses lacking a functional CPSF30 binding domain, such as A/Puerto Rico/08/34.

Stimulation of dendritic cells with Helicobacter pylori vacuolating cytotoxin negatively regulates their maturation via the restoration of E2F1

Helicobacter pylori induces an infiltration of dendritic cells (DCs) into the infected gastric mucosa. Although DCs play an important role in the regulation of inflammation, the effects of H. pylori vacuolating cytotoxin (VacA) on DC maturation process have not yet been elucidated. The role of VacA in DC maturation following co-exposure to Escherichia coli lipopolysaccharide (LPS) was investigated. The treatment of immature DCs with LPS up-regulated the expression of surface molecules [e.g. CD40, CD80, CD86 and major histocompatibility complex (MHC) class II], as well as the production of cytokines [e.g. interleukin (IL)-1β, IL-12p70 and tumour necrosis gactor (TNF)-α] compared with those of unstimulated controls. Co-stimulation with H. pylori VacA significantly reduced the up-regulated DC maturation markers induced by LPS. In addition, VacA sustained the immature state of DCs with high endocytosis and low migratory capacity. The LPS-induced down-regulation of E2F1 expression in DCs was recovered by co-stimulation with VacA. Moreover, suppression of E2F1 by small interfering RNA resulted in a significant recovery of the inhibited DC maturation by VacA. In contrast, VacA did not affect nuclear factor (NF)-κB responses to LPS and the NF-κB signal was not associated with VacA-induced inhibition of DC maturation. These results suggest that the exposure of DCs to H. pylori VacA negatively regulates DC maturation via the restoration of E2F1. The immunomodulatory action of VacA on DCs may contribute to the ability of VacA-producing H. pylori to establish a persistent infection in the gastric mucosa.

Vaccine platforms combining circumsporozoite protein and potent immune modulators, rEA or EAT-2, paradoxically result in opposing immune responses

Background

Malaria greatly impacts the health and wellbeing of over half of the world's population. Promising malaria vaccine candidates have attempted to induce adaptive immune responses to Circumsporozoite (CS) protein. Despite the inclusion of potent adjuvants, these vaccines have limited protective efficacy. Conventional recombinant adenovirus (rAd) based vaccines expressing CS protein can induce CS protein specific immune responses, but these are essentially equivalent to those generated after use of the CS protein subunit based vaccines. In this study we combined the use of rAds expressing CS protein along with rAds expressing novel innate immune response modulating proteins in an attempt to significantly improve the induction of CS protein specific cell mediated immune (CMI) responses.

Methods and Findings

BALB/cJ mice were co-vaccinated with a rAd vectors expressing CS protein simultaneous with a rAd expressing either TLR agonist (rEA) or SLAM receptors adaptor protein (EAT-2). Paradoxically, expression of the TLR agonist uncovered a potent immunosuppressive activity inherent to the combined expression of the CS protein and rEA. Fortunately, use of the rAd vaccine expressing EAT-2 circumvented CS protein's suppressive activity, and generated a fivefold increase in the number of CS protein responsive, IFNγ secreting splenocytes, as well as increased the breadth of T cells responsive to peptides present in the CS protein. These improvements were positively correlated with the induction of a fourfold improvement in CS protein specific CTL functional activity in vivo.

Conclusion

Our results emphasize the need for caution when incorporating CS protein into malaria vaccine platforms expressing or containing other immunostimulatory compounds, as the immunological outcomes may be unanticipated and/or counter-productive. However, expressing the SLAM receptors derived signaling adaptor EAT-2 at the same time of vaccination with CS protein can overcome these concerns, as well as significantly improve the induction of malaria antigen specific adaptive immune responses in vivo.