G-protein-coupled receptors (GPCRs), among various cell surface proteins, are essential targets in the fields of basic science and drug discovery. The discovery and development of modulators for the receptors have provided deep insights into the mechanism of action of receptors and have led to a new therapeutic option for human diseases. Although various modulators against GPCRs have been developed to date, the identification of new modulators for GPCRs remains a challenge due to several technical problems and limitations. To overcome this situation, a variety of strategies have been developed by several modalities, including nucleic acid aptamers, which are emerging as unique molecules isolated by a repetitive selection process against various types of targets from an enormous combinatorial library. This review summarized the achievements in the development of aptamers targeting GPCRs, and discussed their isolation methods and the diverse functional features of aptamers against GPCRs.

We investigated a possible alteration in the ability of neutrophils to produce active oxygen species in streptozotocin (STZ)-induced diabetic rats. The production of Superoxide of the neutrophils was assessed by luminol-dependent chemiluminescence (LDCL) after the stimulation by opsonized zymosan. Four days after STZ (60 mg/kg, ip) injection, blood glucose level increased by 399 ± 9 mg/dl and the LDCL activity was significantly reduced in diabetic rats (control group: 5.12±1.53 KC/min²/10⁶ cells, STZ group: 1.10±0.07 KC/ min²/10⁶ cells, p<0.01). At Day 17, blood glucose level was maintained high (598 ±8 mg/dl) and the LDCL activity (1.01 ± 0.39 KC/min²/10⁶ cells) was almost at the same level as that of diabetic rats at Day 4. Subcutaneous injection of insulin for 10 consecutive days increased the LDCL activity of diabetic rats in a dose-dependent manner (vehicle: 0.82±0.27 KC/ min²/10⁶ cells, 0.04 U/day: 1.61 ±0.09 KC/min²/10⁶ cells, 0.40 U/day: 1.99±0.47 KC/min²/10⁶ cells, 4.00 U/day: 3.33 ±0.43 KC/min²/10⁶ cells). The data obtained herein indicate that an increased susceptibility to bacterial infection in diabetic rats results from impaired neutrophil function to produce active oxygen species.

Transforming growth factor β (TGF-β) is a multifunctional cytokine that plays crucial pathophysiological roles in various diseases, such as cancer and fibrosis. However, the disease modulation by targeting TGF-β1 isoform remains to be established, regardless of several studies employed with limited antibodies. Here, we developed an RNA aptamer to human active TGF-β1, named APT-β1, and characterized its properties in vitro and in vivo. APT-β1 bound to human and mouse active TGF-β1 proteins with high affinity and specificity and strongly inhibited TGF-β1-induced downstream signaling and cell morphology with 50% inhibition concentration (IC50) values at picomolar concentrations. In a xenograft mouse model of non-small cell lung cancer, APT-β1 alone showed no appreciable effect on tumor growth, while it greatly enhanced the anti-tumor effect of gefitinib, an approved tyrosine kinase inhibitor. These findings strongly suggest that the anti-TGF-β1 medication may be a promising cancer therapy to suppress repopulation of lung cancer in combination with certain anti-cancer drugs, such as gefitinib.

Nucleic acid aptamers are a promising drug modality, whereas the generation of virus-neutralizing aptamers has remained difficult due to the lack of a robust system for targeting the viral particles of interest. Here, we took advantage of our latest platform technology of Systematic Evolution of Ligands by EXponential enrichment (SELEX) with virus-like particles (VLPs) and targeted chikungunya virus (CHIKV) as a model, the pathogenic reemerging virus with an unmet need for control. The identified aptamer against CHIKV-VLPs, Apt#1, and its truncated derivatives showed neutralizing activity with nanomolar IC50 values in a cell-based assay system using a pseudoviral particle of CHIKV (CHIKVpp). An antiviral-based chemical genetics approach revealed significant competition of Apt#1 with suramin, a reported interactant with domain A of the E2 envelope protein (E2DA), in both CHIKVpp and surface plasmon resonance (SPR) analyses, predicting E2DA to be the Apt#1 interface. In addition, Apt#1 interfered with the attachment of CHIKVpp, collectively suggesting its property as an attachment inhibitor via E2DA of CHIKV. Thus, the generation of the VLP-targeted aptamers proved to contribute to anti-CHIKV strategies and confirmed the utility of the platform as a novel and viable option for the development of neutralizing agents against viral particles of interest. IMPORTANCE: Our latest SELEX technology using VLPs has generated aptamers that bind the native conformation of the incorporated envelope protein and achieve the virus binding and neutralizing effects. Indeed, the aptamer-probed target E2DA is a representative neutralization site on the surface of the viral particle, validating the utility of the VLP-driven procedure. Simultaneously, the enhanced antiviral effects of the aptamer in combination with approved drugs using the CHIKVpp assay with human cells indicated potential therapeutic strategies that are expected to help address unmet needs in CHIKV control. The robust affinity of the aptamer to viral particles demonstrated by SPR analysis can also lead to conjugates with antivirals as guiding molecules and aptasensors for diagnostic tools. Overall, our VLP-based method provided anti-CHIKV as well as a versatile platform applicable to other emerging and reemerging viruses, in preparation for outbreaks with the need for rapid development of antiviral strategies as next-generation theranostics.

A total of 2, 277 non-typhoidal Salmonella strains consisting of 1, 807 domestic strains and 470 imported strains isolated from sporadic cases during 1995-1999 in Tokyo, were examined regarding their serovar-distibution and their drug-resistance. The serological typing results showed that the domestic strains were classified into 17 0-groups and 99 serovars, and the imported strains were classified into 12 O-groups and 58 serovars. Among the serovars identified, Salmonella serovar Enteritidis (S. Enteritidis), S. Thompson, S. Hadar, S. Infantis, S. Typhimurium, and S. Litchfield were predominant in the domestic strains, whereas S. Enteritidis, S. Anatum, S. Hadar, and S. Weltevreden were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 34.0% of the domestic strains and 33.0% of the imported strains were resistant to any of the drugs examined. The serovars of a high resistant rate during this period were S. Blockley (100%), S. Hadar (96.6%), S. Typhimurium (63.6%), and S. Enteritidis (622%) in the domestic strains and S. Blockley (100%), S. Hadar (97.1%), S. Rissen (88.9%), S. Emek (83.3%), S. Panama (83.3%), and S. Typhimurium (77.8%) in the imported strains. Drug-resistance patterns of the resistant isolates varied to 60 types. Prevalent patterns recognized were SM, TC·ESM, TC, TC·SM·KM·ST, TC·SM·KM, and CP·TC·SM·ABPC in the domestic strains and TC·SM, TC, NA, TC·SM·KM·NA, and TC·SM·NA in the imported strains.