Toxicologic Effects of an Oligodeoxynucleotide Phosphorothioate and Its Analogs Following Intravenous Administration in Rats

Abstract

The aim of the present study is to evaluate the in vivo toxicologic effects of a phosphorothioate oligodeoxynucleotide (PS oligo) and three of its analogs [PS oligo containing four methylphosphonate linkages at the 3' and 5'-ends (MBO 1), PS oligo containing four 2'-O-methylribonucleosides at both the 3'- and 5'-ends (MBO 2), and PS oligo containing an 8 bp loop region at the 3'-end (self-stabilized oligo)]. Oligodeoxynucleotides were administrated intravenously to male and female rats at doses of 3, 10, and 30 mg/kg/day for 14 days. Rats were killed on day 15, blood samples were collected for hematology and clinical chemistry determinations, and tissues, including lymph nodes, spleens, livers, and kidneys, were subjected to pathologic examinations. The toxicity profiles of the four oligodeoxynucleotides were very similar, but differed in magnitude. In terms of the severity of the abnormalities caused by the oligodeoxynucleotides, the order was MBO 2> PS oligo > self-stabilized oligo > MBO 1. Alterations in hematology parameters included thrombocytopenia, anemia, and neutropenia. Abnormalities in clinical chemistry parameters observed with PS oligo or MBO 2 were dose-dependent elevation of liver transaminases and reduction of the levels of alkaline phosphatase, albumin, and total protein. In addition, MBO 2 caused elevation of the total bilirubin level in male rats at the 30 mg/kg dose. No major alterations in hematology or clinical chemistry were observed in rats receiving MBO 1 or self-stabilized oligo. Dose-dependent enlargements of spleen, liver, and kidney were observed, especially in rats receiving PS oligo and MBO 2. Pathologic studies showed a generalized hyperplasia of the reticuloendothelial (RE) system in the tissues examined. Alterations in the spleen were mainly RE cell hyperplasia and hematopoietic cell proliferation. In addition to RE cell hyperplasia, lymph nodes showed necrosis, hepatocytes showed cytologic alterations and necrosis, and kidneys showed renal tubule regeneration. The severity of pathologic changes observed was oligodeoxynucleotide dependent, in the order of MBO 2 > PS oligo > self-stabilized oligo > MBO 1.

CpG oligodeoxynucleotide nanomedicines for the prophylaxis or treatment of cancers, infectious diseases, and allergies

“…Here, recent findings obtained from preclinical and clinical studies are introduced. Tables 1-3 present a summary of the results from preclinical 23 and complement activation, 24,25 and has been reported to cause thrombocytopenia, anemia, and neutropenia in rats 26 as well as induce arthritis in mice. 27 Thus, it is possible to avoid these adverse effects by using self-assembled CpG ODN nanomedicines, which are formed from natural phosphodiester CpG ODNs only.…”

“…To resolve these issues, research is under way on CpG ODN nanomedicines such as self-assembled CpG ODNs, protein/peptide-CpG ODN conjugates, and nanoparticleCpG ODN complexes. With CpG ODN nanomedicines, a high immunostimulatory effect can be expected even with natural phosphodiester CpG ODNs, which means it is possible to avoid the various associated adverse drug reactions [20][21][22][23][24][25][26][27][28] that were a concern with phosphorothioated CpG ODNs. Furthermore, the immunoreactivity of CpG ODN changes depending upon its formation of complexes with proteins (or peptides) or nanoparticles, [29][30][31] and ODNs without CpG can be made recognizable to TLR9.…”

Double-stranded phosphodiester cytosine-guanine oligodeoxynucleotide complexed with calcium phosphate as a potent vaccine adjuvant for activating cellular and Th1-type humoral immunities

“…33,34 Furthermore, a higher risk of adverse events was demonstrated in clinical trials using conventional CpG-B-PT. 47,48 To avoid this toxicity, CpG ODNs with a native PD backbone were developed.…”

“…Furthermore, adverse drug reactions associated with the artificial nuclease-resistant PT backbone of CpG-B have been reported. [33][34][35][36][37][38][39][40] In this study, we demonstrate that CpG-B composed of ss native PD backbone (ss CpG-B-PD) can more potently induce IFN-β than conventional CpG-B with ss PT backbone (ss CpG-B-PT) when complexed with a commercially available cationic liposome, and that double-stranded (ds) CpG-B-PD is a more effective IFN-β inducer than the ss CpG-B-PD. We also found that ds CpG-B-PD entrapped by calcium phosphate (CaP; low-crystalline apatite) formed from inexpensive ingredients (calcium chloride and monosodium phosphate) could induce antigen-specific CD8 + T cells and IgG2a antibody to a degree similar to or higher than ds CpG-B-PD complexed with a cationic liposome.…”

Antisense, RNAi, and gene silencing strategies for therapy: Mission possible or impossible?

“…As a result of this, these oligonucleotides were found to affect coagulation because they bind thrombin [11]. In addition to coagulopathies, the phosphorothioate modified oligonucleotides have a tendency to accumulate in the liver, and their administration leads to elevated transaminases, indicative of liver damage [12]. Although the effects are relatively modest, modified oligonucleotides have also been shown to stimulate the immune system [13].…”