A novel CNS-homing peptide for targeting neuroinflammatory lesions in experimental autoimmune encephalomyelitis.

Using phage peptide library screening, we identified peptide-encoding phages that selectively home to the inflamed central nervous system (CNS) of mice with experimental autoimmune encephalomyelitis (EAE), a model of human multiple sclerosis (MS). A phage peptide display library encoding cyclic 9-amino-acid random peptides was first screened ex-vivo for binding to the CNS tissue of EAE mice, followed by in vivo screening in the diseased mice. Phage insert sequences that were present at a higher frequency in the CNS of EAE mice than in the normal (control) mice were identified by DNA sequencing. One of the phages selected in this manner, denoted as MS-1, was shown to selectively recognize CNS tissue in EAE mice. Individually cloned phages with this insert preferentially homed to EAE CNS after an intravenous injection. Similarly, systemically-administered fluorescence-labeled synthetic MS-1 peptide showed selective accumulation in the spinal cord of EAE mice. We suggest that peptide MS-1 might be useful for targeted drug delivery to CNS in EAE/MS.

Peptide-targeted liposomal delivery of dexamethasone for arthritis therapy.

Aim: Rheumatoid arthritis is an autoimmune disease affecting the joints. Antiarthritic drugs are given systemically, thereby exposing various healthy organs to these drugs, resulting in adverse reactions. Accordingly, there is an urgent need for targeted drug delivery methods for inflamed joints. Materials & methods: We developed a liposomal drug delivery system using a novel peptide ligand (CKPFDRALC) named ART-2, which homes to the inflamed joints when injected intravenously to rats with adjuvant-induced arthritis. Results: The ART-2-coated liposomes encapsulating an antiarthritic drug, dexamethasone (DEX), were more effective in inhibiting arthritis progression than control-DEX liposomes or free DEX, despite a comparable safety profile. Conclusion: Peptide-targeted therapy has advantages over conventional drug delivery and can be adapted for rheumatoid arthritis therapy.

Cytokine-modulating strategies and newer cytokine targets for arthritis therapy.

Cytokines are the key mediators of inflammation in the course of autoimmune arthritis and other immune-mediated diseases. Uncontrolled production of the pro-inflammatory cytokines such as interferon-γ (IFN-γ), tumor necrosis factor α (TNFα), interleukin-6 (IL-6), and IL-17 can promote autoimmune pathology, whereas anti-inflammatory cytokines including IL-4, IL-10, and IL-27 can help control inflammation and tissue damage. The pro-inflammatory cytokines are the prime targets of the strategies to control rheumatoid arthritis (RA). For example, the neutralization of TNFα, either by engineered anti-cytokine antibodies or by soluble cytokine receptors as decoys, has proven successful in the treatment of RA. The activity of pro-inflammatory cytokines can also be downregulated either by using specific siRNA to inhibit the expression of a particular cytokine or by using small molecule inhibitors of cytokine signaling. Furthermore, the use of anti-inflammatory cytokines or cytokine antagonists delivered via gene therapy has proven to be an effective approach to regulate autoimmunity. Unexpectedly, under certain conditions, TNFα, IFN-γ, and few other cytokines can display anti-inflammatory activities. Increasing awareness of this phenomenon might help develop appropriate regimens to harness or avoid this effect. Furthermore, the relatively newer cytokines such as IL-32, IL-34 and IL-35 are being investigated for their potential role in the pathogenesis and treatment of arthritis.

In vivo imaging of myocardial cell death using a peptide probe and assessment of long-term heart function.

During acute myocardial infarction (AMI), both apoptosis and necrosis of myocardial cells could occur and lead to left ventricular (LV) functional decline. Here we determined whether in vivo imaging signals of myocardial cell death by ApoPep-1 (CQRPPR), a peptide probe that binds to apoptotic and necrotic cells through histone H1, at an early stage after AMI showed correlation with the long-term heart function. AMI was induced using a rat model of ischemia and reperfusion (I/R) injury. Fluorescence-labeled ApoPep-1 was administered by intravenous injection into rats 2h after reperfusion. Ex vivo imaging of hearts isolated 2h after peptide injection showed higher levels of near-infrared fluorescence (NIRF) signals at hearts of I/R rats than those of sham-operated rats. The fluorescent peptide was rapidly cleared from the blood and did not bind to red and white blood cells. Localization of fluorescent ApoPep-1 at the area of cell death was demonstrated by co-staining of myocardial tissue with TUNEL. The intensity of in vivo NIRF imaging signals by homing of ApoPep-1 to injured myocardium of I/R rats obtained 2h after peptide injection (equivalent to 4h after injury) showed strong and moderate correlation with the change in the LV ejection fractions (r(2)=0.82) and the size of the fibrotic area (r(2)=0.64), respectively, observed at four weeks after injury. These results suggest that ApoPep-1-mediated in vivo imaging signals of myocardial cell death, including both apoptosis and necrosis, at an early stage of AMI could be a potential biomarker for assessment of long-term outcome of heart function.

Enhanced delivery of T cells to tumor after chemotherapy using membrane-anchored, apoptosis-targeted peptide.

Chemotherapy-induced apoptosis of tumor cells enhances the antigen presentation and sensitizes tumor cells to T cell-mediated cytotoxicity. Here we harnessed the apoptosis of tumor cells as a homing signal for the delivery of T cells to tumor. Jurkat T cells were anchored with ApoPep-1, an apoptosis-targeted peptide ligand, using the biocompatible anchor for membrane (BAM), an oleyl acid derivative. The ApoPep-1-BAM conjugate was efficiently anchored to cell membrane, while little anchoring was obtained with ApoPep-1 alone. The retention period of the ApoPep-1-BAM conjugate on cell membrane was approximately 80 and 40 min in the absence and presence of serum, respectively. ApoPep-1 was resistant to degradation in serum until 2h. The apoptosis-targeted T cells that were anchored with the ApoPep-1-BAM preferentially bound to apoptotic tumor cells over living cells. When intravenously injected into tumor-bearing mice, the number of apoptosis-targeted T cells and in vivo fluorescence signals by the homing of the cells to doxorubicin-treated tumor were higher than those of untargeted T cells. Accumulation of apoptosis-targeted T cells at other organs such as liver was not detected. These results suggest that the chemotherapy-induced apoptosis and subsequent enhancement of T cell delivery to tumor by the membrane anchoring of the apoptosis-targeted peptide could be a novel strategy for cancer immunotherapy.

Surface immobilization of MEPE peptide onto HA/ß-TCP ceramic particles enhances bone regeneration and remodeling.

Calcium phosphate ceramics have been widely used as scaffolds for bone regeneration. Here, to improve the osteogenic potential of hydroxyapatite/ß-tricalcium phosphate (HA/ß-TCP) and to apply the bioactive peptide in situ, matrix extracellular phosphoglycoprotein (MEPE) peptide, which has been shown to stimulate osteoblast differentiation, was covalently and directionally immobilized on HA/ß-TCP particles. The free-hydroxyl groups on the surface of the HA/ß-TCP particles were sequentially conjugated with APTES, PEG-(SS)(2), and the synthetic MEPE peptide. Using FTIR and XPS, immobilization of the MEPE peptide on the HA/ß-TCP was confirmed. Implantation of the MEPE peptide-immobilized HA/ß-TCP into calvarial defect and subsequent analyses using a micro CT and histology showed significant bone regeneration and increased bone area (9.89-fold) as compared to that of unmodified HA/ß-TCP. Moreover, tartrate-resistant acid phosphatase-positive osteoclasts were observed in regenerated bone by the MEPE peptide-immobilized HA/ß-TCP, indicating that the bones newly formed by the MEPE peptide-immobilized HA/ß-TCP are actively remodeled by osteoclasts. Therefore, our data demonstrate that MEPE peptide immobilization onto the HA/ß-TCP surface stimulates bone regeneration associated with physiological bone remodeling.

Secretome analysis of human BMSCs and identification of SMOC1 as an important ECM protein in osteoblast differentiation.

Extracellular matrix proteins have been implicated in the regulation of osteoblast differentiation of bone marrow derived mesenchymal stem cells (BMSCs) through paracrine or autocrine mechanisms. In the current study, we analyzed the secretory protein profiles of BMSCs grown in osteogenic medium (OSM) and identified SPARC-related modular calcium-binding protein 1 (SMOC1), a member of the SPARC family, as a regulator of osteoblast differentiation of BMSCs. BMSCs with high and low osteogenic potential were grouped and stimulated with OSM, after which conditioned medium was collected and analyzed by LC-MS/MS. We identified 410 proteins, 64 of which were selectively secreted by high osteogenic potential BMSCs. Of these 64 secreted proteins, we selected extracellular matrix proteins for validation in BMSCs undergoing osteoblast differentiation and found that SMOC1 is highly expressed and secreted in BMSCs stimulated with OSM. To examine the role of SMOC1 in osteoblast differentiation, we analyzed the effect of SMOC1 knockdown and overexpression using shRNAs and wild-type cDNA, respectively. Knockdown of SMOC1 significantly inhibited mineralization and the expression of osteoblast differentiation markers, while overexpression of SMOC1 substantially increased the expression of osteoblast differentiation-related genes. Thus, validation of secretome profiling data identified SMOC1 as a putative regulator of osteoblast differentiation of BMSCs.