Inhibition of TNF-alpha reduces transplant arteriosclerosis in a murine aortic transplant model

Cytokines in Lung Transplantation

Lung transplantation has developed significantly in recent years, but post-transplant care and patients' survival still need to be improved. Moreover, organ shortage urges novel modalities to improve the quality of unsuitable lungs. Cytokines, the chemical mediators of the immune system, might be used for diagnostic and therapeutic purposes in lung transplantation. Cytokine monitoring pre- and post-transplant could be applied to the prevention and early diagnosis of injurious inflammatory events including primary graft dysfunction, acute cellular rejection, bronchiolitis obliterans syndrome, restrictive allograft syndrome, and infections. In addition, preoperative cytokine removal, specific inhibition of proinflammatory cytokines, and enhancement of anti-inflammatory cytokines gene expression could be considered therapeutic options to improve lung allograft survival. Therefore, it is essential to describe the cytokines alteration during inflammatory events to gain a better insight into their role in developing the abovementioned complications. Herein, cytokine fluctuations in lung tissue, bronchoalveolar fluid, peripheral blood, and exhaled breath condensate in different phases of lung transplantation have been reviewed; besides, cytokine gene polymorphisms with clinical significance have been summarized.

PI3Kγ promotes vascular smooth muscle cell phenotypic modulation and transplant arteriosclerosis via a SOX9-dependent mechanism

Background

Transplant arteriosclerosis (TA) remains the major cause of chronic graft failure in solid organ transplantation. The phenotypic modulation of vascular smooth muscle cells (VSMCs) is a key event for the initiation and progression of neointimal formation and TA. This study aims to explore the role and underlying mechanism of phosphoinositide 3-kinases γ (PI3Kγ) in VSMC phenotypic modulation and TA.

Methods

The rat model of aortic transplantation was established to detect PI3Kγ expression and its role in neointimal formation and vascular remodeling in vivo. PI3Kγ shRNA transfection was employed to knockdown PI3Kγ gene. Aortic VSMCs was cultured and treated with TNF-α to explore the role and molecular mechanism of PI3Kγ in VSMC phenotypic modulation.

Findings

Activated PI3Kγ/p-Akt signaling was observed in aortic allografts and in TNF-α-treated VSMCs. Lentivirus-mediated shRNA transfection effectively inhibited PI3Kγ expression in medial VSMCs while restoring the expression of VSMC contractile genes, associated with impaired neointimal formation in aortic allografts. In cultured VSMCs, PI3Kγ blockade with pharmacological inhibitor or genetic knockdown markedly abrogated TNF-α-induced downregulation of VSMC contractile genes and increase in cellular proliferation and migration. Moreover, SOX9 located in nucleus competitively inhibited the interaction of Myocardin and SRF, while PI3Kγ inhibition robustly reduced SOX9 expression and its nuclear translocation and repaired the Myocardin/SRF association.

Interpretation

These results suggest that PI3Kγ plays a critical role in VSMC phenotypic modulation via a SOX9-dependent mechanism. Therefore, PI3Kγ in VSMCs may represent a promising therapeutic target for the treatment of TA.

Fund

National Natural Science Foundation of China.

A20 Haploinsufficiency Aggravates Transplant Arteriosclerosis in Mouse Vascular Allografts: Implications for Clinical Transplantation

BACKGROUND

Inflammation is central to the pathogenesis of transplant arteriosclerosis (TA). We questioned whether physiologic levels of anti-inflammatory A20 influence TA severity.

METHODS

We performed major histocompatibility complex mismatched aorta to carotid artery interposition grafts, using wild type (WT) or A20 heterozygote (HET) C57BL/6 (H-2) donors and BALB/c (H-2) recipients, and conversely BALB/c donors and WT/HET recipients. We analyzed aortic allografts by histology, immunohistochemistry, immunofluorescence, and gene profiling (quantitative real-time reverse-transcriptase polymerase chain reaction). We validated select in vivo A20 targets in human and mouse smooth muscle cell (SMC) cultures.

RESULTS

We noted significantly greater intimal hyperplasia in HET versus WT allografts, indicating aggravated TA. Inadequate upregulation of A20 in HET allografts after transplantation was associated with excessive NF-кB activation, gauged by higher levels of IkBα, p65, VCAM-1, ICAM-1, CXCL10, CCL2, TNF, and IL-6 (mostly localized to SMC). Correspondingly, cytokine-induced upregulation of TNF and IL-6 in human and mouse SMC cultures inversely correlated with A20 expression. Aggravated TA in HET versus WT allografts correlated with increased intimal SMC proliferation, and a higher number of infiltrating IFNγ and Granzyme B CD4 T cells and natural killer cells, and lower number of FoxP3 regulatory T cells. A20 haploinsufficiency in allograft recipients did not influence TA.

CONCLUSIONS

A20 haploinsufficiency in vascular allografts aggravates lesions of TA by exacerbating inflammation, SMC proliferation, and infiltration of pathogenic T cells. A20 single nucleotide polymorphisms associating with lower A20 expression or function in donors of vascularized allografts may inform risk and severity of TA, highlighting the clinical implications of our findings.

Synthesis of α-santonin derivatives for diminutive effect on T and B-cell proliferation and their structure activity relationships

A new library of 20 compounds from α-santonin was synthesized and tested against Con-A induced T-cell proliferation and LPS-induced B-cell proliferation via MTT assay. The study resulted in the identification of potent immunosuppressant molecules, which were further screened along with α-santonin for Tumor Necrosis Factor Alpha (TNF-α) inhibitory activity. One of the molecules (7) at 10 μM showed equipotency to that of dexamethasone (1 μM conc.) used as a standard. Structure activity relationships of the synthesized compounds along with our earlier reported α-santonin derivatives have been studied. Inferences from the modifications carried out at all the three sites of α-santonin have been elaborated. Computational study of the active compounds shows TNF-α protein as its preferable target rather than Inosine Monophosphate Dehydrogenase (IMPDH).

Topical infliximab for the suppression of wound healing following experimental glaucoma filtration surgery

Background

The purpose of this work was to look into the effects of infliximab on wound healing in experimental glaucoma filtration surgery and to compare the antifibrotic effects of this agent to that of mitomycin-C (MMC).

Methods

Twenty-eight male New Zealand White rabbits were randomly assigned to four groups, each including seven rabbits: control group, sham group, MMC group, and infliximab group. The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the MMC treatment group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the infliximab treatment group underwent trabeculectomy and one drop of 10 mg/mL infliximab was instilled four times a day for 14 days after surgery. On day 14 of the experiment, the operated and control eyes were enucleated and histologically and immunohistochemically analyzed.

Results

The mean fibroblast and mononuclear cell (MNC) numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β), and platelet-derived growth factor (PDGF) in the sham group were higher than those of the control group (P<0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β, and PDGF in the MMC and infliximab groups were statistically significantly lower than those of the sham group (P<0.01). The mean fibroblast and MNC numbers and the mean TGF-β, FGF-β, and PDGF immunostaining intensities of the MMC and infliximab groups were similar (P>0.05).

Conclusion

Our study suggests that topical infliximab effectively suppresses the subconjunctival wound healing response after experimental glaucoma filtration surgery, reducing the MNC and fibroblast numbers and immunostaining intensities of TGF-β, FGF-β, and PDGF.

Short-term TNF-alpha inhibition reduces short-term and long-term inflammatory changes post-ischemia/reperfusion in rat intestinal transplantation

BACKGROUND

Tumor necrosis factor (TNF)-α inhibition was shown to reduce ischemia/reperfusion injury (IRI) after intestinal transplantation (ITX). We studied the effects of different TNFα inhibitors on acute IRI and long-term inflammatory responses in experimental ITX.

METHODS

Orthotopic ITX was performed in an isogenic ischemia/reperfusion model in Lewis rats. The TNFα inhibition groups received infliximab post-reperfusion; etanercept pre-reperfusion and at postoperative days (POD) 1, 3, 5, and 7; or pentoxifylline pre-reperfusion and at POD 1 to 5. Tissue samples were taken from proximal and distal graft sections and mesenteric lymph nodes at 20 min, 12 hr, 7 day, and 6 months post-reperfusion for histopathology, immunohistology, terminal deoxyribosyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and real-time RT-PCR. Lung sections were stained for the myeloperoxidase assay.

RESULTS

TNFα inhibitors decreased inflammatory changes after IRI in all treatment groups. Infliximab significantly improved 7-day survival and reduced the histological and immunohistochemical signs of IRI, the numbers of graft-infiltrating T cells and ED1 monocytes and macrophages, and pulmonary neutrophil infiltration, and also enhanced the accumulation of cytoprotective markers. Graft injury was more prominent in the distal graft than in the proximal graft in all groups, regardless of TNFα inhibition.

CONCLUSION

Infliximab significantly reduced both acute IRI and, as with other TNFα inhibitors, long-term inflammatory responses after rat ITX. TNFα inhibition may help diminish chronic inflammatory long-term effects and avoid chronic allograft enteropathy.

G-protein coupled receptor 30 (GPR30): a novel regulator of endothelial inflammation

Estrogen, the female sex hormone, is known to exert anti-inflammatory and anti-atherogenic effects. Traditionally, estrogen effects were believed to be largely mediated through the classical estrogen receptors (ERs). However, there is increasing evidence that G-protein coupled receptor 30 (GPR30), a novel estrogen receptor, can mediate many estrogenic effects on the vasculature. Despite this, the localization and functional significance of GPR30 in the human vascular endothelium remains poorly understood. Given this background, we examined the subcellular location and potential anti-inflammatory roles of GPR30 using human umbilical vein endothelial cells as a model system. Inflammatory changes were induced by treatment with tumor necrosis factor (TNF), a pro-inflammatory cytokine involved in atherogenesis and many other inflammatory conditions. We found that GPR30 was located predominantly in the endothelial cell nuclei. Treatment with the selective GPR30 agonist G-1 partially attenuated the TNF induced upregulation of pro-inflammatory proteins such as intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). This effect was completely abolished by the selective GPR30 antagonist G-15, suggesting that it was indeed mediated in a GPR30 dependent manner. Interestingly, estrogen alone had no effects on TNF-treated endothelium. Concomitant activation of the classical ERs blocked the anti-inflammatory effects of G-1, indicating opposing effects of GPR30 and the classical ERs. Our findings demonstrate that endothelial GPR30 is a novel regulator of the inflammatory response which could be a potential therapeutic target against atherosclerosis and other inflammatory diseases.

Anti-LFA-1 or rapamycin overcome costimulation blockade-resistant rejection in sensitized bone marrow recipients

While costimulation blockade-based mixed chimerism protocols work well for inducing tolerance in rodents, translation to preclinical large animal/nonhuman primate models has been less successful. One recognized cause for these difficulties is the high frequency of alloreactive memory T cells (Tmem) found in the (pre)clinical setting as opposed to laboratory mice. In the present study, we therefore developed a murine bone marrow transplantation (BMT) model employing recipients harboring polyclonal donor-reactive Tmem without concomitant humoral sensitization. This model was then used to identify strategies to overcome this additional immune barrier. We found that B6 recipients that were enriched with 3 × 10(7) T cells isolated from B6 mice that had been previously grafted with Balb/c skin, rejected Balb/c BM despite costimulation blockade with anti-CD40L and CTLA4Ig (while recipients not enriched developed chimerism). Adjunctive short-term treatment of sensitized BMT recipients with rapamycin or anti-LFA-1 mAb was demonstrated to be effective in controlling Tmem in this model, leading to long-term mixed chimerism and donor-specific tolerance. Thus, rapamycin and anti-LFA-1 mAb are effective in overcoming the potent barrier that donor-reactive Tmem pose to the induction of mixed chimerism and tolerance despite costimulation blockade.

Tumor necrosis factor alpha inhibitors as immunomodulatory antirejection agents after intestinal transplantation

We reported the successful administration of infliximab for late-onset OKT3-resistant rejection in two patients, who presented persistent ulcerative inflammation of the ileal graft after intestinal transplantation (ITX). Based on this experience, the present study demonstrated our long-term experience with infliximab for different types of rejection-related and inflammatory allograft alterations. Infliximab administration (5 mg/kg body weight (BW)) was initiated at a mean of 18.2 ± 14.1 months after transplantation. The number of administrations per patient averaged 8.4 ± 6.7. Repeat dosing was timed according to clinical signs and graft histology in addition to serum-levels of tumor necrosis factor alpha (TNFα), lipopolysaccharide binding protein (LBP) and C-reactive protein (CRP). Infliximab was successful in the following patients: patients with late-onset OKT3- and steroid-refractory rejection who presented persistent ulcerative alterations of the ileal graft (n = 5), patients with ulcerative ileitis/anastomositis, who did not show typical histological rejection signs (n = 2), and one patient with early-onset OKT3-resistant rejection. Infliximab was not successful in one patient with early-onset OKT3-resistant rejection that was accompanied by treatment-refractory humoral rejection. In conclusion, infliximab can expand therapeutic options for late-onset OKT3- and steroid-refractory rejection and chronic inflammatory graft alterations in intestinal allograft recipients.

Characterization of golimumab, a human monoclonal antibody specific for human tumor necrosis factor α

We prepared and characterized golimumab (CNTO148), a human IgG1 tumor necrosis factor alpha (TNFα) antagonist monoclonal antibody chosen for clinical development based on its molecular properties. Golimumab was compared with infliximab, adalimumab and etanercept for affinity and in vitro TNFα neutralization. The affinity of golimumab for soluble human TNFα, as determined by surface plasmon resonance, was similar to that of etanercept (18 pM versus 11 pM), greater than that of infliximab (44 pM) and significantly greater than that of adalimumab (127 pM, p=0.018).  The concentration of golimumab necessary to neutralize TNFα-induced E-selectin expression on human endothelial cells by 50% was significantly less than those for infliximab (3.2 fold; p=0.017) and adalimumab (3.3-fold; p=0.008) and comparable to that for etanercept. The conformational stability of golimumab was greater than that of infliximab (primary melting temperature [Tm] 74.8 °C vs. 69.5 °C) as assessed by differential scanning calorimetry.  In addition, golimumab showed minimal aggregation over the intended shelf life when formulated as a high concentration liquid product (100 mg/mL) for subcutaneous administration.  In vivo, golimumab at doses of 1 and 10 mg/kg significantly delayed disease progression in a mouse model of human TNFα-induced arthritis when compared with untreated mice, while infliximab was effective only at 10 mg/kg. Golimumab also significantly reduced histological scores for arthritis severity and cartilage damage, as well as serum levels of pro-inflammatory cytokines and chemokines associated with arthritis. Thus, we have demonstrated that golimumab is a highly stable human monoclonal antibody with high affinity and capacity to neutralize human TNFα in vitro and in vivo.

Rheumatoid arthritis and renal light-chain deposition disease: long-term effectiveness of TNF-α blockade with etanercept

A 68-year-old woman diagnosed with erosive rheumatoid arthritis (RA) was treated with intramuscular methotrexate 15 mg weekly and oral prednisone 5 mg daily. A favorable outcome of 6 years was followed by RA flare and nephrotic syndrome (NS). Renal biopsy revealed non-amyloid light-chain deposition disease. Laboratory analysis and bone marrow biopsy excluded monoclonal protein and plasma cell dyscrasia. Addition of subcutaneous etanercept, 25 mg twice weekly allowed rapid control of both arthritis and NS. To date, after over 7-year follow-up, RA is in clinical remission, 24-h albuminuria is consistently below 0.5 g, and serum creatinine is 0.9 mg/dl.

Effect of selective inhibitors of inflammation on oral mucositis: preclinical studies

OBJECTIVE

Oral mucositis is a severe, dose-limiting side effect of radio(chemo)therapy for head and neck tumors. The epithelial radiation response (ulceration) is accompanied by inflammatory changes. Their interaction with the epithelial processes remains unclear. The present study was initiated to determine the effect of inhibition of TNF-alpha or COX-2 on the epithelial radiation response in the mouse tongue model.

METHODS

Daily fractionated irradiation was given with 5 x 3 Gy/week over one (days 0-4) or two weeks (days 0-4, 7-11). Each protocol was terminated by graded test doses (5 dose groups, 10 animals each) to a defined area of the lower tongue surface to generate full dose-effect curves for mucosal ulceration. A TNF-alpha inhibiting antibody (Infliximab) or a COX-2 inhibitor (Celecoxib) was administered.

RESULTS

No effect of Infliximab or Celecoxib was found in any of the protocols. Isoeffective doses for ulcer induction were unchanged. Also, the time course of the response was largely unaffected.

CONCLUSIONS

Inhibition of TNF-alpha or COX-2, two dominating inflammatory pathways, did not result in modulation of the response of oral epithelium during fractionated irradiation. This suggests that the inflammatory changes mediated through TNF-alpha or COX-2 are not relevant for the epithelial radiation response of oral mucosa.