The preventive effects of incomplete Freund’s adjuvant and other vehicles on the development of adjuvant‐induced arthritis in Lewis rats

Abstract

SUMMARYThe present study showed a novel finding that the development of adjuvant-induced arthritis (AA) in Lewis rats was completely prevented by incomplete Freund's adjuvant (IFA) injected 21 or 28 days before complete Freund's adjuvant (CFA) challenge. Hexadecane also completely prevented AA and squalane, methyl oleate and pristane moderately prevented AA, though pristane by itself induced mild arthritis in two out of five rats. Concanavalin A-stimulated lymph node cells (LNCs) isolated from AA rats were able to adoptively transfer the severe polyarthritis to all the naive recipients or even to the IFA pretreated recipients with earlier onset and more rapid progression than those of AA. The LNCs from the donors who had been pretreated with IFA and subsequently challenged with CFA could induce mild arthritis in only two out of eight naive recipients, whereas all the recipients who were challenged with CFA immediately after intravenous injection of these LNCs developed significantly less severe arthritis. However, the LNCs from IFA-pretreated donors failed to prevent AA. According to the T helper type 1 ( Th1)/Th2 paradigm, it was suggested that the adjuvant-active vehicles such as IFA, hexadecane, squalane, methyl oleate and pristane, can affect and deviate the Th1/Th2 balance of immune responses in host. CFA could promote the propagation of Th2 cells rather than Th1 cells in these vehiclepretreated rats through as yet undetermined mechanisms, eventually resulting in the prevention of AA. Finally, we discussed a regulatory role of adjuvant vehicles for induction and suppression of AA.

Balance of Th1/Th2 Cytokines Associated with the Preventive Effect of Incomplete Freund's Adjuvant on the Development of Adjuvant Arthritis in LEW Rats

“…As shown in Figure 1, we confirmed our previous report [19] that a single intradermal injection of CFA could induce severe arthritis in all the rats and the pretreatment of IFA could completely prevent the development of AA in all the rats. Total RNA was extracted from the LNCs of individual rats, reverse transcribed, cDNA was amplified using specific rat primers and the PCR products were subjected to gel electrophoresis stained with ethidium bromide.…”

“…The present findings, therefore, suggest that increased expression of IL-4 mRNA and reduced expression of IL-2 mRNA ( Figure 2, lane 3; Figure 3, lane 2) may play an important regulatory role for the induction of OIA in LEW rats after IFA immunization. Our previous findings [19] suggested that IFA immunization by itself was not enough to stimulate the Th1 and Th2 cells to induce or prevent AA in LEW rats, while subsequent CFA challenge in the IFA pretreated rats stimulated Th2 cells rather than Th1 cells, resulting in the prevention of AA. Taken altogether, the present study suggests that the increased mRNA expression of IL-4 and the markedly reduced mRNA expression of TNF-and IL-2 are responsible for the prevention of AA in the IFA pretreated and subsequently CFA challenged LEW rats, through the balance of Th2 over Th1 cytokines.…”

“…Alternatively, the preventive effect of IFA on AA in LEW rats can be explained by the regulatory T cells. It is possible that IFA induces inflammation [19] resulting in the upregulation of self heat shock protein (hsp60) [31] and that the regulatory T cells which can respond to both self hsp60 and mycobacterial hsp65 in CFA are activated to prevent AA, through mechanisms which are still unknown [32,33].…”

“…We reported earlier that pretreatment with IFA 28 days before CFA challenge could completely prevent the development of AA in LEW rats and suggested the possible regulatory role of Th2 cells in Th1 mediated AA [19]. In order to understand the role of Th1 and Th2 cytokines in the induction or prevention of AA and OIA, we have studied the mRNA expression of IFN-and IL-2 (Th1 type cytokines), IL-4 and IL-5 (Th2 type cytokines) and TNF-(pro-inflammatory cytokine) in the inguinal lymph node cells (ILNCs) of LEW, DA and F1 (LEW×DA) rats by reverse transcriptase-polymerase chain reaction (RT-PCR).…”

Inhibition of Histone Deacetylase Suppresses Osteoclastogenesis and Bone Destruction by Inducing IFN-β Production

“…AA was induced as described by Zhang et al (36). Briefly, CFA, emulsion of H37Ra in incomplete adjuvant (10 mg/ml), was prepared.…”