Dimethyl dioctadecyl ammonium bromide (DDA)-induced arthritis in rats: a model of experimental arthritis

Evaluation of mRNA lipoplexes prepared using modified ethanol injection method as a tumour vaccine

We have previously demonstrated that messenger RNA (mRNA) lipoplexes composed of N-hexadecyl-N,N-dimethylhexadecan-1-aminium bromide (DC-1-16), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and polyethylene glycol-cholesteryl ether (PEG-Chol) exhibited high protein expression in the lungs and spleen of mice after intravenous injection and induced high levels of antigen-specific IgG1 upon immunisation. In this study, we optimised PEG modification in mRNA lipoplexes to reduce mRNA accumulation in the lungs and evaluated the suppression of tumour growth in mice bearing mouse lymphoma E.G7-ovalbumin (OVA) tumours by immunising them with an intravenous injection of OVA mRNA lipoplexes. PEGylation of mRNA lipoplexes with 3 mol% PEG-Chol (LP-DC-1-16-3PCL) prevented agglutination of erythrocytes and reduced accumulation in the lungs. Intravenous injection of LP-DC-1-16-3PCL lipoplexes containing OVA mRNA into mice induced high levels of anti-OVA IgG1 (83,000 mU/mL) in serum, and exhibited a high cytotoxic activity (97%) against E.G7-OVA cells by the splenocytes of mice. Furthermore, immunisation with LP-DC-1-16-3PCL lipoplexes containing OVA mRNA suppressed E.G7-OVA tumour growth compared to control mRNA. Based on these results, LP-DC-1-16-3PCL lipoplexes may be an effective mRNA vaccine for inducing antibody- and cytotoxic cell-mediated immune responses to tumours through intravenous injection.

Transplantation of IL‑1β siRNA‑modified bone marrow mesenchymal stem cells ameliorates type II collagen‑induced rheumatoid arthritis in rats

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes erosion of articular cartilage and bone and has adverse effects on both patients and livestock animals. The aim of the present study was to investigate the role of interleukin-1β (IL-1β) in the pathogenesis of RA, and to further determine whether injection of IL-1β small interfering RNA (siRNA) or transplantation of IL-1β siRNA + bone marrow mesenchymal stem cells (BMSCs) can ameliorate RA in rats. A collagen-induced arthritis (CIA) rat model was established by injecting type II collagen for 4 weeks. Next, CIA rats were randomly divided into three groups and injected or transplanted with PBS, IL-1β siRNA and IL-1β siRNA + BMSCs for another 4 weeks. The CIA rat model was successfully established, as demonstrated by the higher toe swelling value, thymus and spleen/body weight, immobility time and serum IL-1β concentration, as well as lower body weight, climbing time and mRNA expression of programmed death-1 (PD-1), transforming growth factor-β1 (TGF-β1) and forkhead box protein 3 (Foxp3) in the spleen, compared with control rats. Furthermore, histopathology results demonstrated that joint swelling and redness were observed in the knee joints of CIA rats. H&E results revealed that CIA rats presented erosive destruction of the bone and ulceration of the articular cartilage. In addition, in vitro results demonstrated that IL-1β expression was successfully silenced after IL-1β siRNA transfection in lipopolysaccharide-stimulated BMSCs. When compared with the results of PBS rats, both IL-1β siRNA injection and IL-1β siRNA + BMSC transplantation significantly increased the body weight, climbing time and mRNA expression of PD-1, TGF-β1 and Foxp3 in the spleen, while significantly reduced the immobility time and serum IL-1β concentration. In addition, when compared with that of IL-1β siRNA injection, IL-1β siRNA + BMSC transplantation exhibited markedly higher therapeutic efficacy against CIA. These results demonstrated that higher IL-1β contributed to the pathogenesis of CIA, and that IL-1β siRNA injection ameliorated CIA, while its combination with BMSCs exerted synergistic effects, which may be beneficial against RA.

Heat shock protein 65-reactive T cells are involved in the pathogenesis of non-antigenic dimethyl dioctadecyl ammonium bromide-induced arthritis

Dimethyl dioctadecyl ammonium bromide (DDA) (C(38)H(80)NBr) is a nonantigenic lipoid material. DDA-induced arthritis (DIA) in the Lewis (LEW) (RT.1(l)) rat is a new experimental model for human rheumatoid arthritis (RA). DIA is a T cell-mediated autoimmune disease. However, the precise self/foreign Ags associated with the disease process in DIA are not yet known. We observed that LEW rats with DIA spontaneously raised a vigorous T cell response both to 65-kDa self (rat) heat shock protein (Rhsp65) and mycobacterial hsp65 (Bhsp65), but not to another arthritis-related Ag, bovine collagen type II. The T cell response to Rhsp65 was focused predominantly on determinant regions 120-134 and 213-227 of the self protein. Interestingly, pretreatment of adult LEW rats using either a mixture of peptides 120-134 and 213-227 of Rhsp65 or a low nonarthritogenic dose of DDA induced protection against subsequent DIA. Intriguingly, the protection induced by the latter was associated with spontaneous priming of T cells specific for peptide 213-227 of Rhsp65. Similarly, LEW rats neonatally tolerized against either Rhsp65 or Bhsp65 were significantly protected from subsequently induced DIA at adult stage, showing the disease-modulating attribute of the hsp65-specific T cells. Taken together, the above findings demonstrate that the hsp65-directed T cell repertoire is of significance in the pathogenesis of autoimmune arthritis induced by nonantigenic DDA. Like other animal models of RA involving hsp65, these first insights into the disease-associated Ags in the DIA model would pave the way for further understanding of the immunological aspects of induction and regulation of RA.

Matrix metalloproteinases as targets for the immune system during experimental arthritis

Novel therapies for rheumatoid arthritis aiming at intervention in the inflammatory process by manipulation of autoreactive T and B lymphocytes receive major interest. However, the development of such therapies is largely hampered by the lack of knowledge of self-Ags recognized during the disease process. Recently, we predicted putative T cell self-epitopes based on a computer search profile. In the present study, the predicted self-epitopes were tested for T cell recognition in two experimental arthritis models, and their arthritogenic capacity was analyzed. Fourteen of n = 51 predicted self-epitopes were recognized during experimental arthritis of which six were able to actively induce arthritis. Interestingly, three of these six peptides were derived from matrix metalloproteinases (MMP), and only T cells responsive to MMP-derived epitopes were able to passively transfer arthritis to naive rats. Moreover, we demonstrate the presence of Abs to MMP-3 during the course of adjuvant arthritis. Together these data indicate that MMPs play a pivotal role as target for T and B cells during the development of inflammatory arthritis. This finding sheds new light on the pathophysiological role of MMPs during arthritis and opens novel possibilities for Ag-specific immunotherapy.

Achievement of a synergistic adjuvant effect on arthritis induction by activation of innate immunity and forcing the immune response toward the Th1 phenotype

OBJECTIVE

To apply and analyze the mechanisms of action of dimethyldioctadecylammonium bromide (DDA), a powerful adjuvant that does not have the side effects of the conventionally used Freund's adjuvants, in proteoglycan-induced arthritis (PGIA) and collagen-induced arthritis (CIA).

METHODS

PGIA and CIA were generated using standard immunization protocols with cartilage proteoglycan aggrecan (PG) or human type II collagen (CII) emulsified with Freund's complete adjuvant (CFA), and compared with PGIA and CIA generated using immunization protocols in which the same antigens were used in combination with the adjuvant DDA. Immune responses to immunizing and self PGs and CII, and the incidence, severity, and onset of arthritis were monitored throughout the experiments. In addition, a new, inexpensive, and powerful method of inducing arthritis using crude cartilage extracts is described.

RESULTS

A significantly reduced onset period and a more severe arthritis were achieved in BALB/c mice immunized with cartilage PGs in DDA. PGs from bovine, ovine, and porcine cartilage, which otherwise have no effect or have only a subarthritogenic effect, and crude extracts of human osteoarthritic cartilage induced a 100% incidence with a very high arthritis score in BALB/c mice. The overall immune responses to either CII or PG were similar in antigen/CFA-immunized and antigen/DDA-immunized animals, but the Th1/Th2 balance shifted significantly toward a Th1 bias in DDA-injected animals with either PGIA or CIA.

CONCLUSION

DDA, which was first used in autoimmune models, is a potent nonirritant adjuvant, which eliminates all undesired side effects of the Freund's adjuvants. DDA exerts a strong stimulatory effect via the activation of nonspecific (innate) immunity and forces the immune regulation toward Th1 dominance. These lines of evidence also suggest the possibility that seemingly innocuous compounds may exert an adjuvant effect in humans and may create the pathophysiologic basis of autoimmunity in susceptible individuals via the activation/stimulation of innate immunity.

The immunogenicity and protective efficacy of bovine herpesvirus 1 glycoprotein D plus Emulsigen are increased by formulation with CpG oligodeoxynucleotides

The immunogenicity and protective efficacy of a bovine herpesvirus 1 (BHV-1) subunit vaccine formulated with Emulsigen (Em) and a synthetic oligodeoxynucleotide containing unmethylated CpG dinucleotides (CpG ODN) was determined in cattle. A truncated, secreted version of BHV-1 glycoprotein D (tgD) formulated with Em and CpG ODN at concentrations of 25, 2.5, or 0.25 mg/dose produced a more balanced immune response, higher levels of virus neutralizing antibodies, and greater protection after BHV-1 challenge compared to tgD adjuvanted with either Em or CpG ODN alone. In contrast, tgD formulated with Em and either 25 mg of a non-CpG ODN or another immunostimulatory compound, dimethyl dioctadecyl ammonium bromide, induced similar immunity and protection compared to tgD formulated with Em alone, a finding which confirms the immunostimulatory effect of ODN to be CpG motif mediated. Our results demonstrate the ability of CpG ODN to induce a strong and balanced immune response in a target species.