Popliteal lymph node responses to acetone and ethanol differ from those induced by streptozotocin

Abstract

The popliteal lymph node (PLN) assay was proposed to detect the potential of immunotoxicants for inducing systemic autoimmune-like reactions, but also xenobiotics that are sensitizing or exert immunostimulatory properties. Results on over 100 chemicals, mostly pharmaceuticals, are available with the PLN assay and show many correlations between rodent data and the clinical experience. A major issue is that the mechanisms involved have not been fully elucidated. In order to provide mechanistic clues to improve the predictability of the PLN assay, the effects of streptozotocin (STZ) were compared to those of ethanol and acetone in normal C57Bl/6 mice as well as mice depleted in CD4+ or CD8+ T-cells by treatment with specific monoclonal antibodies. STZ, ethanol and acetone gave similar positive responses in normal mice. Neither CD4+ nor CD8+ T-cell depletion influenced the PLN responses to ethanol or acetone, whereas CD8+ in contrast to CD4+ T-cell depletion abolished the response to STZ. There was an increase in the production of IL-6 and IFN-gamma mRNAs measured by RT-PCR in STZ-, but not in ethanol- or acetone-treated normal mice. The production of TNFalpha, IL-1alpha, IL-1beta, IL-2R and IL-12 mRNAs was increased whatever the treatment, but increases were 2- to 3-fold greater after STZ than ethanol or acetone. These results suggest that PLN responses to primary irritants such as ethanol and acetone essentially reflect non-specific inflammation, whereas PLN responses to an autoimmunogenic compound such as STZ involve CD8+ T lymphocytes and the production of IFN-gamma and IL-6. These findings may prove useful to improve the predictability of the PLN assay.

Mast Cell Degranulation Breaks Peripheral Tolerance

“…Mice were treated with inflammatory doses of the Toll-like receptor (TLR) 4 agonist, LPS; the TLR9 agonist, CpG-ODN 1826; Complete Freund's Adjuvant (CFA) or an agonistic αCD40 antibody. Finally, local, chemical-induced Th2-biased inflammation was induced using acetone/dibutylphthalate/FITC applied directly onto the graft(16-18). No acute rejection was observed in any of the groups tested except for the tolerant mice administered αCD40 antibody, as previously reported(19).…”

Effect of cerebrocrast, a new long‐acting compound on blood glucose and insulin levels in rats when administered before and after STZ‐induced diabetes mellitus

“…1,2 The formation of cytokines plays an important role in pancreatic beta cell destruction in the onset as well as in long-standing IDDM, [3][4][5] [6][7][8] and in animals with induced diabetes by the autoimmunogenic compound streptozotocin (STZ). [9][10][11][12] It is known that STZ in animals evokes formation of several cytokines such as IL-1b, TNF-a, IL-6, 9 the increase of inducible nitric oxide synthase (iNOS), and subsequent synthesis of the oxygen free radicals, NO, and peroxynitrite anion. 10,11,[13][14][15][16] Peroxynitrite is a strong oxidant and cytotoxic mediator that modulates mitochondrial respiration and leads to extensive morphological damage of b-cells, DNA fragmentation, 12,15,17,18 decreased glucose oxidation, impaired glucoseinsulin secretion and impaired proinsulin biosynthesis.…”

Popliteal lymph node assay: facts and perspectives

“…In mice, streptozotocin induced a dramatic increase in interferon-γ (IFN-γ ) mRNA production that correlated with WI and CI increases, whereas there was no change in the production of interleukin 4 (IL-4) mRNA (Choquet-Kastylevsky et al, 2000a). Subsequently, streptozotocin was shown to induce a marked increase in the production of IL-6, IFN-γ, tumous neurosis factor alpha (TNF-α), IL-1α, IL-1β, IL-2R and IL-12 mRNA (Choquet-Kastylevsky et al, 2000b), whereas neither ethanol nor acetone induced changes in the production of IL-6 and IFN-γ mRNA (Choquet-Kastylevsky and Descotes, 2004). In addition, increases in the production of TNF-α, IL-1α, IL-1β, IL-2R and IL-12 mRNA were two to three times lower in mice treated with acetone or ethanol than with streptozotocin.…”

“…To date, positive responses in the direct PLNA are more likely to reflect varied mechanisms, even though T lymphocytes often have been suggested to play a pivotal role (Klinkhammer et al, 1988;Ewens et al, 1999;Tuschl et al, 2002). Indeed, PLN responses can be induced also by macrophage activation (Weirich et al, 1996) or non-specific inflammatory responses (Krzystyniak et al, 1995;Choquet-Kastylevsky and Descotes, 2004), although rarely. As long as no elucidation of the underlying mechanism(s) is available, the search for endpoints other than WI and CI to assess better the relevance of a positive response to a given compound in the PLNA is difficult, if at all possible.…”

“…Subsequently, false-positive PLN responses to imipramine (Choquet-Kastylevsky et al, 2002), acetone and ethanol (Choquet-Kastylevsky and Descotes, 2004) were shown to reflect primary irritation using this experimental procedure. Indeed, false-positive PLN responses to imipramine, acetone or ethanol were observed in normal mice and in mice depleted in either CD4…”