Efficacy of intra-articular polynucleotides associated with hyaluronic acid vs hyaluronic acid alone in the treatment of knee osteoarthritis: A systematic review and meta-analysis of randomized clinical trial

BACKGROUND

The reduced range of motion and pain are the most characteristic clinical features of osteoarthritis (OA). Hyaluronic acid (HA), which is one of the infiltrative therapies for OA treatment, and polynucleotides (PNs), which is a DNA-derived macromolecule favored cell growth and collagen production, are an ongoing debate in clinical effectiveness.

METHODS

We plan to perform a systematic review and meta-analysis of randomized clinical trial to evaluate efficacy of intra-articular polynucleotides associated with hyaluronic acid versus hyaluronic acid alone in the treatment of knee osteoarthritis. We will search PubMed, EMBASE, Cochrane Library using a comprehensive strategy. The related conference proceedings and reference lists of the included studies will also be checked to identify additional studies. Two reviewers will screen retrieved records, extract information and assess the risk of bias independently. Stata v15.1 software will be used to conduct data synthesis.

RESULTS

This study will be submitted to a peer-reviewed journal for publication.

CONCLUSION

We hope it will provide a relatively comprehensive reference for clinical practice and future relevant clinical trials.

ETHICS AND DISSEMINATION

Ethics approval and patient consent are not required, as this study is a systematic review and meta-analysis.

PROSPERO REGISTRATION NUMBER

CRD42020167678.

Effect of multiple intra-articular injections of polynucleotides on treatment of intractable knee osteoarthritis: A case report

RATIONALE

Knee osteoarthritis (KOA) is a chronic joint degenerative disease. Intra-articular injection (IAI) of hyaluronic acid (HA) is widely used to treat KOA. However, some HA injections have no effect at all. Polynucleotides (PN) are recently noted as a valid substitute for HA.

PATIENT CONCERNS

A 61-year-old female was admitted to the pain center with symptoms of pain over the knee and warmth feeling with stiffness in the left knee. The patient reported chronic severe pain in the left knee area despite 6 times IAI of HA. She had past medical history of breast cancer and thyroid cancer.

DIAGNOSES

She was diagnosed as having KOA.

INTERVENTIONS

Ultrasound-guided IAI of PN was carried out 3 times in 3 weeks.

OUTCOMES

She was followed-up for more than 5 months with good improvement in intractable knee pain without any adverse event.

LESSONS

IAI of PN is an efficient therapeutic option for KOA treatment if HA injection is unsuccessful.

Synthetic nanocarriers for the delivery of polynucleotides to the eye

This review is a comprehensive analysis of the progress made so far on the delivery of polynucleotide-based therapeutics to the eye, using synthetic nanocarriers. Attention has been addressed to the capacity of different nanocarriers for the specific delivery of polynucleotides to both, the anterior and posterior segments of the eye, with emphasis on their ability to (i) improve the transport of polynucleotides across the different eye barriers; (ii) promote their intracellular penetration into the target cells; (iii) protect them against degradation and, (iv) deliver them in a long-term fashion way. Overall, the conclusion is that despite the advantages that nanotechnology may offer to the area of ocular polynucleotide-based therapies (especially AS-ODN and siRNA delivery), the knowledge disclosed so far is still limited. This fact underlines the necessity of more fundamental and product-oriented research for making the way of the said nanotherapies towards clinical translation.

Chitosans for delivery of nucleic acids

Alternatives to efficient viral vectors in gene therapy are desired because of their poor safety profiles. Chitosan is a promising non-viral nucleotide delivery vector because of its biocompatibility, biodegradability, low immunogenicity and ease of manufacturing. Since the transfection efficiency of chitosan polyplexes is relatively low compared to viral counterparts, there is an impetus to gain a better understanding of the structure-performance relationship. Recent progress in preparation and characterisation has enabled coupling analysis of chitosans structural parameters that has led to increased TE by tailoring of chitosan's structure. In this review, we summarize the recent advances that have lead to a more rational design of chitosan polyplexes. We present an integrated review of all major areas of chitosan-based transfection, including preparation, chitosan and polyplexes physicochemical characterisation, in vitro and in vivo assessment. In each, we present the obstacles to efficient transfection and the strategies adopted over time to surmount these impediments.

Intrarticular treatment of osteoartropaty knee with polynucleotides: a pilot study with medium-term follow-up

Knee osteoarthritis is a major cause of disability in the elderly. Many therapies are nowadays available, ranging from non-pharmacologic to pharmacological approaches like visco-supplementation, oral supplements or topical treatments, but a flawless treatment is still to be found. Visco-supplementation represents a valid treatment option for reducing pain associated with knee osteoarthritis and improving function in the affected joint. Many literature data report on the efficacy and safety profiles of hyaluronic acid in knee osteoarthritis, however the efficacy of intra-articular hyaluronic acid remains controversial, in fact while several clinical trials claimed a disease-modifying effect for hyaluronic acid, subsequent meta-analyses have cast doubts on this fact. The ideal intra-articular treatment for osteoarthritis should not only provide a mechanical protection of the cartilage surface, but also restore condrocytes’ homeostasis by restoring the physiological articular micro-environment and supplying nutrients. In this perspective an innovative medical product made up of polynucleotides (Condrotide) has been developed. The aim of this study is to test the 2-months efficacy in pain relief and improving function of intra-articular injections of Condrotide in patients with knee osteoarthritis or with grade III or IV chondropathy. Ninety-five subjects (33 men, 62 women), aged between 53 and 80, were included between May 2011 to July 2012. All subjects received intra-articular injections of Condrotide and were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS), the NRS scale for pain assessment, the measurement of the range of motion (R.O.M.). In all subjects a significant improvement was found in KOOS score after 60 days. The mean global NRS pain decreased in both groups and there was also a R.O.M. improvement. These results show that the intra-articular administration of nucleotides in subjects with both severe knee arthritis and chondropathy can be recommended since is able to reverse in the short and medium term symptoms and function with a significant improvement in quality of life.

Cellular delivery of polynucleotides by cationic cyclodextrin polyrotaxanes

Cationic polyrotaxanes, obtained by temperature activated threading of cationic cyclodextrin derivatives onto water-soluble cationic polymers (ionenes), form metastable nanometric polyplexes with pDNA and combinations of siRNA with pDNA. Because of their low toxicity, the polyrotaxane polyplexes constitute a very interesting system for the transfection of polynucleotides into mammalian cells. The complexation of Cy3-labeled siRNA within the polyplexes was demonstrated by fluorescence correlation spectroscopy. The uptake of the polyplexes (red) was imaged by confocal fluorescence microscopy using the A549 cell line as a model (blue: nuclei, green: membranes). The results prove the potential of polyrotaxanes for further investigations involving knocking down genes of therapeutic interest.

Identification and molecular cloning of Atlantic cod (Gadus morhua) activating transcription factor 3 (ATF3) transcript and its induction in spleen following intraperitoneal polyriboinosinic polyribocytidylic acid injection

Activating transcription factor 3 (ATF3) participates in cellular processes to adapt to various extra- and intra-cellular changes including the modulation of immunity to prevent uncontrolled immune responses to pathogens. In teleost fishes, the involvement of ATF3 in immune response has not been documented. In this study, the putative Atlantic cod (Gadus morhua) ATF3 transcript was identified by performing rapid amplification of cDNA ends (RACE) based on unknown expressed sequence tags (ESTs) that are potentially inducible by polyriboinosinic polyribocytidylic acid (pIC, a synthetic double-stranded RNA viral mimic) in Atlantic cod. ATF3-like ESTs were the most abundant unknown transcript (i.e. lacking significant BLAST hits) generated from a previously constructed cDNA library enriched for pIC inducible transcripts in Atlantic cod spleen. The full-length cDNA of cod ATF3 consists of 2329 nucleotides with an open reading frame (ORF) of 735 bp encoding 244 amino acids. The deduced amino acid sequence of Atlantic cod ATF3 shares over 45% identity with its putative orthologs from other vertebrates. In addition, the presence of a conserved basic region leucine zipper (bZIP) domain in the deduced Atlantic cod ATF3-like protein further supports its identity as an ATF3 homolog. In the spleen of Atlantic cod challenged with intraperitoneal (IP) injections of pIC, the time-course transcript expression of ATF3 was studied using quantitative reverse transcription-polymerase chain reaction (QPCR). At 6 h following the pIC injection, the relative expression level of ATF3 mRNA was significantly up-regulated in comparison to a pre-injected control (61.9-fold) and its time-matched saline-injected control (97.3-fold). At 24 h following the pIC injection, the mRNA expression level of cod ATF3 had subsided and was no longer significantly different from its pre-injected control, but significantly higher (1.88-fold) than its time-matched saline-injected control. Collectively, these results suggest that ATF3 may be involved in the modulation of innate anti-viral response in Atlantic cod.

Efficacy of intra-articular polynucleotides in the treatment of knee osteoarthritis: a randomized, double-blind clinical trial

This randomized, double-blind clinical trial was conducted over 16 weeks to assess the efficacy and safety profile of intra-articular polynucleotides gel injections in the treatment of knee osteoarthritis associated with persistent knee pain. 60 patients were enrolled and randomized to receive intra-articular polynucleotides (n = 30) or hyaluronan (n = 30); patients received five weekly intra-articular knee injections and the follow-up period was 3 months after the end of treatment. Primary endpoint was to determine polynucleotides (PN) efficacy in reducing knee pain at the end of the study, over baseline value and over standard hyaluronan viscosupplementation (HA). Pain levels were measured using a 0-10 cm Visual Analogue Scale (VAS). Secondary endpoints included Knee Osteoarthritis Outcome Score (KOOS), NSAIDs consumption, crackling during movement and articular mobility limitation. The mean global VAS pain decreased from 5.7 + or - 1.9 cm (T0) to 1.9 + or - 1.5 cm (T16) in polynucleotide group and from 4.9 + or - 2.0 cm (T0) to 2.1 + or - 1.4 cm (T16) in hyaluronan group. The reduction in pain was statistically significant for both groups. KOOS increases from baseline values were statistically significant in both groups. No significant adverse events were reported. These findings suggest that intra-articular polynucleotides can be a valid alternative to traditional hyaluronan supplementation for the treatment of knee osteoarthritis.

Nanoparticulate systems for polynucleotide delivery

Nanotechnology has tremendously influenced gene therapy research in recent years. Nanometer-size systems have been extensively investigated for delivering genes at both local and systemic levels. These systems offer several advantages in terms of tissue penetrability, cellular uptake, systemic circulation, and cell targeting as compared to larger systems. They can protect the polynucleotide from a variety of degradative and destabilizing factors and enhance delivery efficiency to the cells. A variety of polymeric and non-polymeric nanoparticles have been investigated in an effort to maximize the delivery efficiency while minimizing the toxic effects. This article provides a review on the most commonly used nanoparticulate systems for gene delivery. We have discussed frequently used polymers, such as, polyethyleneimine, poly (lactide-co-glycolide), chitosan, as well as non-polymeric materials such as cationic lipids and metallic nanoparticles. The advantages and limitations of each system have been elaborated.

Retinoic acid and polyriboinosinic:polyribocytidylic acid stimulate robust anti-tetanus antibody production while differentially regulating type 1/type 2 cytokines and lymphocyte populations

Retinoic acid (RA), a bioactive retinoid, and polyriboinosinic:polyribocytidylic acid (PIC) are known to promote immunity in vitamin A-deficient animals. In this study, we hypothesized that RA, PIC, and the combination can provide significant immunoadjuvant activity even in the vitamin A-adequate state. Six-week-old C57BL/6 mice were immunized with tetanus toxoid (TT) and treated with RA and/or PIC at priming in three independent studies of short and long duration. RA and PIC differentially regulated both primary and secondary anti-TT IgG isotypes, whereas the combination of RA + PIC stimulated the highest level of anti-TT IgG production and, concomitantly, a ratio of IgG1 to IgG2a similar to that of the control group. The regulation of Ab response was strongly associated with type 1/type 2 cytokine gene expression. Whereas RA reduced type 1 cytokines (IFN-gamma and IL-12), PIC enhanced both type 1 and type 2 cytokines (IL-4 and IL-12) and cytokine-related transcription factors. Despite the presence of PIC, the IL-4:IFN-gamma ratio was significantly elevated by RA. In addition, RA and/or PIC modulated NK/NKT cell populations and the level of expression of the costimulatory molecules CD80/CD86, evident 3 days after priming. Notably, the NKT:NK and CD80:CD86 ratios were correlated with the IL-4:IFN-gamma ratio, indicative of multiple converging modes of regulation. Overall, RA, PIC, and RA + PIC rapidly and differentially shaped the anti-tetanus Ig response. The robust, durable, and proportionate increase in all anti-TT IgG isotypes induced by RA + PIC suggests that this combination is promising as a means to enhance the Ab response to TT and similar vaccines.

Lactose-appended schizophyllan is a potential candidate as a hepatocyte-targeted antisense carrier

A schizophyllan (beta-1,3-glucan) derivative carrying lactose-appendages prepared by reductive amination can form stable macromolecular complexes with polynucleotides, shows excellent affinity with a lactose-binding lectin, and effectively mediates gene transfection into hepatocytes.

Atelocollagen for protein and gene delivery

Recent progress in recombinant gene technology and cell culture technology has made it possible to use protein and polynucleotides as effective drugs. However, because of their short half-lives in the body and the necessity of delivering to target site, those substances do not always exhibit good potency as expected. Therefore, delivery systems of such drugs are important research subjects in the field of pharmacology, and to prolong the effect of these drugs, many studies are being conducted to control the release of proteins and polynucleotides from various carrier materials. Collagen is one of the most useful carrier materials for this purpose. In this article, we report on the controlled release of protein drugs using collagen, focusing on a new drug delivery system (DDS), the Minipellet, as our basic technology. Then we introduce our recent work about gene therapy using collagen-based DDS. Basic formulation study showed that collagen DDS protects DNA degradation from both chemical cleavage and enzymatic digestion. A single injection of collagen DDS containing plasmid DNA produced physiologically significant levels of gene-encoding proteins in the local site and systemic circulation of animals and resulted in prolonged biological effects. These results suggest that collagen DDS containing plasmid DNA may enhance the clinical potency of plasmid-based gene transfer, facilitating a more effective and long-term use of naked plasmid vectors for gene therapy. Also, variety kinds of application of collagen DDS for gene therapy using adenovirus vector, antisense DNA and DNA vaccine, will be discussed.

SEREX analysis for tumor antigen identification in a mouse model of adenocarcinoma

Evaluation of immunotherapy strategies in mouse models of carcinoma is hampered by the limited number of known murine tumor antigens (Ags). Although tumor Ags can be identified based on cytotoxic T-cell activation, this approach is not readily accomplished for many tumor types. We applied an alternative strategy based on a humoral immune response, SEREX, to the identification of tumor Ags in the murine colon adenocarcinoma cell line MC38. Immunization of syngeneic C57BL/6 mice with MC38 cells by three different methods induced a protective immune response with concomitant production of anti-MC38 antibodies. Immunoscreening of an MC38-derived expression library resulted in the identification of the endogenous ecotropic leukemia virus envelope (env) protein and the murine ATRX protein as candidate tumor Ags. Northern blot analysis demonstrated high levels of expression of the env transcript in MC38 cells and in several other murine tumor cell lines, whereas expression in normal colonic epithelium was absent. ATRX was found to be variably expressed in tumor cell lines and in normal tissue. Further analysis of the expressed env sequence indicated that it represents a nonmutated tumor Ag. Polynucleotide immunization with DNA encoding the env polypeptide resulted in strong and specific antibody responses to this self Ag in all immunized mice. Thus, SEREX offers a rapid means of identifying tumor Ags in murine cancer models.

Polynucleotide immunization of nonhuman primates against carcinoembryonic antigen

In preparation for a Phase I trial of DNA immunization against carcinoembryonic antigen (CEA) in patients with colorectal carcinoma, we have produced a single plasmid DNA encoding CEA and hepatitis B surface antigen (HBsAg) under transcriptional regulatory control of two separate cytomegalovirus promoters within separate eukaryotic expression cassettes, designated pCEA/HBsAg. Hepatitis B surface antigen was included to provide an internal positive control for the efficacy of this immunization strategy without regard to the issue of breaking tolerance to a self-antigen. In the present work, we sought to examine the immunogenicity of this plasmid in a nonhuman primate model with close phylogenetic relationship to humans. Groups of pig-tailed macaques were immunized with pCEA/ HBsAg by i.m. injection or particle bombardment of the skin according to a dose and schedule thought to be optimal for the respective technique of DNA immunization. Both administration techniques produced humoral and lympho-proliferative responses of comparable magnitude. However, delayed type hypersensitivity to CEA and CEA-specific interleukin-2 release were observed only in the i.m. group, suggesting a qualitative difference in the character of the immune response elicited by the two techniques of DNA immunization. The antibody responses to CEA and HBsAg were surprisingly persistent in that all immunized animals maintained moderate antibody titers against both antigens for more than 15 months after the last boost. No toxicity was observed during 2 years of follow-up, including no measurable levels of anti-DNA antibody. This antitumor immunization strategy is presently being examined in patients with metastatic colorectal carcinoma using pCEA/HBsAg administered by i.m. injection.

Polynucleotide-mediated immunization therapy of cancer

The novel observations that intramuscular injection of plasmid DNA preparations could result in myocyte gene expression and induce immune responses to encoded immunogens has generated intense interest in the form of gene therapy. This phenomena can occur with both DNA and RNA reagents, and can be used in immune protection (vaccine) or therapy strategies. Immunization with DNA plasmids has generated protective immunity to a wide variety of pathogens and tumor cells in murine animal models. Immune response has occurred in a broad range of animal species following intramuscular injection of plasmid DNA encoding various immunogens as well as following other routes of administration (intravenous, intradermal, etc). The mechanisms responsible for induction of the immune response are as yet unclear, but responses include antibody production, T-cell proliferation, lymphokine release, generation of cytolytic T cells, and delayed hypersensitivity reactions. Plasmid DNA production and purification methods are relatively easy to standardize, and dual expressing plasmids allow incorporation of immune enhancement molecules or second immunogens. Plasmid DNA encoding nontransforming tumor-associated antigens are in development with a National Institutes of Health-approved protocol for carcinoembryonic antigen in colorectal cancer patients. Transforming tumor-associated antigens (eg, HER2/neu) may be approached with RNA or replicative RNA constructs for immunization. The efficacy of this immune approach will soon be examined in clinical trials in patients with cancer and the acquired immunodeficiency syndrome.

[The passive transfer by Drosophila spermatozoa of exogenous DNA molecules or synthetic polynucleotides into fertilizable eggs]

Experiments on mutation induction in Drosophila melanogaster by injections of exogenous DNAs or a synthetic polyribonucleotide solutions into the hemolymph of the male demonstrated that Drosophila spermatozoa were able to transfer passively molecules of these mutagens into fertilized eggs. This induced mutations in both paternal and maternal chromosomes in offspring.

A new cationic liposome encapsulating genetic material. A potential delivery system for polynucleotides

The endeavour to enhance gene therapy has led to increased research on the development of simple, efficient and safe delivery systems. This study deals with the use of an artificial cationic lipid on the encapsulation of genetic material in liposomes. The addition of a biologically degradable cationic phospholipid, dipalmitoyl-L-alpha-phosphatidylethanolamine covalently coupled to L-lysine, in a standard liposome formulation allowed us to obtain vesicles with high entrapment of various polynucleotides. Polynucleotide degradation by nucleases is markedly prevented by these liposomes. The preparations were stable in both culture medium and human plasma. This latter finding is consistent with the weak binding of plasma proteins on the liposome surface. The efficiency of this new delivery system was demonstrated in antiviral assays. Finally, these liposomes displayed a relatively low cellular toxicity. All these findings indicate that these cationic vesicles are very suitable for genetic material vehiculation.

Pilot study of the efficacy of a thrombin inhibitor for use during cardiopulmonary bypass

Heparin is normally used for anticoagulation during cardiopulmonary bypass (CPB), but its use is contraindicated in patients with a history of heparin-induced thrombocytopenia, heparin-provoked thrombosis, or both. Heparin therapy can also be ineffective due to heparin resistance. A short-acting, oligonucleotide-based thrombin inhibitor (thrombin aptamer) may potentially serve as a substitute for heparin in these and other clinical situations. We tested a novel thrombin aptamer in a canine CPB pilot study to determine its anticoagulant efficacy, the resultant changes in coagulation variables, and the aptamer's clearance mechanisms and pharmacokinetics. Seven dogs were studied initially: Four received varied doses of the aptamer (to establish the pharmacokinetic profile) and 3 received heparin. Subsequently, 4 other dogs underwent CPB, receiving a constant infusion of the aptamer before CPB (to characterize the baseline coagulation status), with partial CPB and hemodilution, during 60 minutes of total CPB, and, finally, after a 2-hour recovery period. At a 0.5 mg.kg-1.min-1 dose, the activated clotting time rose with aptamer infusion from 106 +/- 12 seconds to 187 +/- 8 seconds (+/- 1 standard deviation) (p = 0.014), increased further with hemodilution (to 259 +/- 41 seconds; p = 0.017), and was even more prolonged during total CPB (> 1,500 seconds; p < 0.001). This later increase in the activated clotting time paralleled a rise in the plasma concentration of the thrombin aptamer during total CPB, as determined by high-performance liquid chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of natural killer cytotoxicity by long-term treatment with double-stranded polynucleotides without induction of hyporesponsiveness

Treatment of Wistar/AG rats with a single i.p. injection of 1 mg/kg of synthetic double-stranded polynucleotides, either polyadenylic-polyuridylic acid (rAn.rUn), or a mismatched analogue of polyinosinic-polycytidylic acid (rIn.r(C12U)n), enhanced the cytotoxicity of natural killer (NK) cells among peripheral blood leukocytes and lung intracapillary leukocytes (LICL). The enhancement reached a peak 24 h after treatment and returned to control values after 4 days. In rats given repeated injections of double-stranded polynucleotides (2 per week), the NK cytotoxicity expressed by LICL reached more than ten times (in lytic units) the control levels between day 8, after 3 injections, and day 360, after 100 injections. No hyporesponsiveness was observed. Moreover, NK activity was frequently and significantly higher in rats given multiple injections than in those given a single injection. In rats with experimentally induced P77 lung fibrohistiocytoma colonies, repeated injections of rIn.r(C12U)n stimulated NK activity and reduced the number of metastatic nodules from 172 to 19. The same significant reduction (from 172 to 27) was also observed in animals given repeated injections of rAn.rUn. However, with two models of spontaneous metastases, significant reduction in lung metastases (M37 bronchioloalveolar carcinoma) or lack of effect (S4T19 rhabdomyosarcoma) were observed.

Continued studies on the adjuvancy effect of natural and synthetic double-stranded RNA preparations with inactivated Newcastle disease vaccines in fowls

The adjuvant effect of the natural ds-RNA, BRL 5907, with inactivated Newcastle disease vaccines was confirmed using different oil-based formulations and could be given either as single injections or separately at adjacent sites. A minimum dose level of 0-04 mg BRL 5907 per bird was required for a significant enhancement of antibody levels following vaccination. While the synthetic ds-RNA Poly IC gave a similar response to that observed with BRL 5907, no significant effects could be detected with two other natural ds-RNA materials.

Enhancing activity of synthetic polynucleotides on the induction of anti-hapten antibody response

The enhancing activity of synthetic polynucleotides on the secondary anti-hapten antibody response was studied by using an adoptive transfer system of hapten-primed cells in mice. Hapten-primed B cells were effectively stimulated to produce anti-hapten antibody on challenge with hapten—heterologous carrier in the presence of an appropriate dose of polynucleotides. The enhancing activity of polynucleotides was most effective when administered at the same time as the second antigen and the activity was consistently observed either when these agents were administered in vivo or when hapten-primed cells were treated in vitro with the second antigen and these agents. Polynucleotides enhanced mainly the development of 7S plaque-forming cells (PFC) rather than 19S PFC. The enhancing effect of polynucleotides was not observed in hapten-primed cells from ATS-treated mice, but it was restored by the addition of non-primed lymph node cells or thymus-derived spleen cells from lethally irradiated mice reconstituted with thymocytes.

These results clearly indicate that polynucleotides enhance the anti-hapten antibody response of hapten-primed B cells to the hapten—heterologous carrier through activation of non-primed T cells specific for the heterologous carrier and do not directly affect hapten-primed B cells. The mechanism of the stimulation of T cells by polynucleotides is discussed.

Regulation of the immune system by synthetic polynucleotides. V. Effect on cell-associated immunoglobulin receptors and immunological memory

Addition of polyadenylic-polyuridylic acid in complex form (poly A:U) without antigen to a suspension of spleen cells obtained from BALB/Aj mice primed 6 wk previously with human gamma-globulin (HGG) resulted in an immediate fourfold increase over background number of anti-HGG rosette-forming cells (RFC). Culture of similar cells in the presence of puromycin for 1-6 hr before poly A:U did not significantly reduce the response. Continued culture of primed spleen cells in the presence of poly A:U, resulted in a decrease of RFC to background levels within an hour followed by an increase again 6 hr later. This later increase in RFC was inhibited by addition of puromycin to the culture medium. The nonspecific stimulation by poly A:U of antibody production by primed spleen cells also was induced in vivo. Increases in splenic RFC were detectable 6 hr after intravenous injection of poly A:U alone, without antigen, into primed mice. The response peaked at 18 hr and had dissipated completely within 3 days. A second injection of poly A:U 24 hr or later after the first injection resulted in a second response, similar to the first with respect to kinetics and intensity. Rosette formation by poly A:U-stimulated cells could not be inhibited by mitotic poisons, but was inhibited by treatment of the cells with goat anti-mouse gamma-globulin serum, suggesting that the antibody involved was a 7S gamma-globulin. The decrease in RFC induced by culture of primed cells for 1 hr in poly A:U paralleled a decrease in secondary responsiveness of the cells to antigen. This poly A:U-induced inhibition of secondary responsiveness could be reversed by suspending the treated cells in supernatant fluids derived from poly A:U-stimulated cultures. The reversal was specific in that supernatant fluids removed from bovine serum albumin (BSA)-primed cells by poly A:U did not stimulate the response of HGG-primed cells to HGG. However supernatant fluids from BSA-primed cells caused the production of anti-HGG RFC if BSA rather than HGG was used as triggering antigen. The active factor in the supernatant fluids appeared to be a 7S gamma-globulin since activity was lost after 45 min incubation of the supernatant fluids in the presence of goat anti-mouse 7S gamma-globulin serum.

Dose responsiveness and variation among inbred strains of mice in production of interferon after treatment with poly (I)-poly (C) (poly-D-lysine) complexes

Poly-d-lysine forms a stochiometric complex with poly(I) . poly(C) which has a higher T(m) (83 C in 0.15 m NaCl) than the uncomplexed double-stranded polyribo-nucleotide (63 C). The complex was superior to poly(I) . poly(C) alone as an interferon inducer in vivo. Significant serum interferon titers were attained in Swiss mice during a 24-hr period after intraperitoneal injection of 10 to 300 mug of poly(I) . poly(C) [1.0 poly-d-lysine] complex, at concentrations of 100 to 1,000 mug/ml. The serum interferon responses (average and maximum titers) of a series of inbred strains of mice to a single intraperitoneal injection of 100 mug of complex decreased in the order: Swiss > DBA/2 > C3H > BALB/c > CF-1 > AKR, C57Bl/6, NZB > SJL > NZW and varied by a factor of approximately 100 from the most to the least responsive.

Antiviral activity of polyribocytidylic acid in cells primed with polyriboinosinic acid

Separate administration of polyribocytidylic acid [poly(rC)] and polyriboinosinic acid [poly(rI)] to cell cultures in vitro resulted in an antiviral activity identical to or greater than that resulting from addition of the poly(rI) * poly(rC) complex. Priming of cells with poly(rI), followed by treatment with poly(rC), gave a consistently greater antiviral activity than poly(rI) * poly(rC) itself. This priming effect was obtained in several cell cultures challenged with different viruses. In vivo, the antiviral activity of poly(rI) * poly(rC) was only partially restored if poly(rI) and poly(rC) were injected separately; prior injection of poly(rI) proved superior in restoring this antiviral activity as compared to prior injection of poly(rC).

Antibody formation: reduced responses after administration of excessive amounts of nonspecific stimulators

Enhancement of antibody formation in vitro and in vivo by poly(A.U), cyclic AMP, dibutyryl cyclic AMP, or any one of these agents in combination with theophylline or caffeine, is usually limited to certain dose ranges. High doses of these nonspecific stimulators can produce less or no enhancement, or may actually inhibit antibody formation. Such dose-response relationships may be pertinent to an understanding of phenomena of specific immunological nonresponsiveness and certain types of antigenic competition.

Effect of poly I: C on experimental respiratory infection in hamsters

The interferon inducer double-stranded polyinosinic acid and polycytidylic acid (poly I:C) was studied in hamsters experimentally infected with parainfluenza 3 virus. Upper intranasal, deep intranasal, or intraperitoneal treatment of hamsters with poly I:C (100 mug/100- to 120-g animal) 24 hr before an upper respiratory infection significantly reduced the virus yields taken 28 hr after infection. Deep intranasal and intraperitoneal treatment with poly I:C greatly decreased the virus titers in the lungs, as measured 48 hr after a deep lung infection with parainfluenza 3 virus; however, the upper respiratory poly I:C treatment was ineffective.

Role of adrenal cortical function in toxicity of polyriboinosinic-polyribocytidylic acid and its component homopolymers

Adrenalectomized rats are 1000 times more sensitive to lethal effects of the double-stranded complex polyriboinosinic.polyribocytidylic acid than intact rats. They are protected from such lethal effects by corticosterone. The complex can rapidly induce diffuse, severe necrosis of villous epithelium in small intestine without damage in crypts. Injection of the individual homopolymers, polyriboinosinic acid and polyribocytidylic acid, separately but in rapid succession is at least as lethal as injection of the complex.