Neutrophils Promote Mycobacterial Trehalose Dimycolate-Induced Lung Inflammation via the Mincle Pathway

Trehalose 6,6'-dimycolate (TDM), a cord factor of Mycobacterium tuberculosis (Mtb), is an important regulator of immune responses during Mtb infections. Macrophages recognize TDM through the Mincle receptor and initiate TDM-induced inflammatory responses, leading to lung granuloma formation. Although various immune cells are recruited to lung granulomas, the roles of other immune cells, especially during the initial process of TDM-induced inflammation, are not clear. In this study, Mincle signaling on neutrophils played an important role in TDM-induced lung inflammation by promoting adhesion and innate immune responses. Neutrophils were recruited during the early stage of lung inflammation following TDM-induced granuloma formation. Mincle expression on neutrophils was required for infiltration of TDM-challenged sites in a granuloma model induced by TDM-coated-beads. TDM-induced Mincle signaling on neutrophils increased cell adherence by enhancing F-actin polymerization and CD11b/CD18 surface expression. The TDM-induced effects were dependent on Src, Syk, and MAPK/ERK kinases (MEK). Moreover, coactivation of the Mincle and TLR2 pathways by TDM and Pam3CSK4 treatment synergistically induced CD11b/CD18 surface expression, reactive oxygen species, and TNFα production by neutrophils. These synergistically-enhanced immune responses correlated with the degree of Mincle expression on neutrophil surfaces. The physiological relevance of the Mincle-mediated anti-TDM immune response was confirmed by defective immune responses in Mincle⁻/⁻ mice upon aerosol infections with Mtb. Mincle-mutant mice had higher inflammation levels and mycobacterial loads than WT mice. Neutrophil depletion with anti-Ly6G antibody caused a reduction in IL-6 and monocyte chemotactic protein-1 expression upon TDM treatment, and reduced levels of immune cell recruitment during the initial stage of infection. These findings suggest a new role of Mincle signaling on neutrophils during anti-mycobacterial responses.

Histopathological features and expression profiles of cytokines, chemokines and SOCS family proteins in trehalose 6,6'-dimycolate-induced granulomatous lesions

OBJECTIVE AND DESIGN

The objective of this paper is to elucidate the factors contributing to the development and regression of trehalose 6,6'-dimycolate (TDM)-induced model of tuberculous granulomatous lesions.

MATERIALS AND TREATMENT

BALB/c mice were twice injected i.p. with a 100 μl of w/o/w emulsion (100 μg of TDM, 3.2 μl of Freund's incomplete adjuvant, 3.2 μl of PBS, and 93.6 μl of saline containing 0.2% Tween 20) at a 1 week interval. The mice were killed at days 0, 3, 7, 14, or 21 after the last injection. Three mice were used per group.

METHODS

We examined histopathological changes of the lesions and defined the expression levels of cytokines and suppressor of cytokine signaling (SOCS) family proteins by real-time PCR.

RESULTS

The levels of inflammatory cytokine, such as TNF-α and IL-1β, paralleled with the size of the lesions and the levels of TGF-β and SOCS-3 were high at regression phase.

DISCUSSION

Our results demonstrated that both the down-regulation of inflammatory cytokines and up-regulation of TGF-β and SOCS-3 are crucial for histopathological changes including alteration in the sizes of the lesions and changes in inflammatory cell populations.

Evaluation of somatic and reproductive immunotoxic effects of the porcine zona pellucida vaccination

Immunological, immunocytochemical and fertility analyses were performed to determine the potential toxic side effects of porcine zona pellucida (pZP) vaccinations on target animals, including horses and dogs. The study was designed to determine the effect of antibodies, raised against highly purified pZP, on somatic tissues. Immunocytochemical studies performed with fixed tissues showed that rabbit anti-pZP antiserum did not crossreact with brain, heart, lung, kidney, liver, bladder, stomach, small intestine, large intestine, muscle, skin, spleen, pancreas, or lymph node of either the dog or horse. To determine the effect or oral intake on nontarget animals, female rabbits were fed a contraceptive vaccine containing pZP glycoproteins and the synthetic trehalose dicorynomycolate in drakeol (S-TDCM) adjuvant. Enzyme-linked immunoadsorbent assay (LISA) analyses showed that rabbits fed with the adjuvanted pZP proteins did not develop circulating anti-pZP IgG antibodies that crossreacted with pZP. Furthermore, fertility studies performed on rabbits fed with adjuvanted pZP revealed no significant differences in the number of embryos or stage of the embryos produced between the treated and control animals. Results of these studies suggest that the pZP vaccine delivered to dogs or horses in field studies have no recognizable somatic tissue effects. Moreover, there were no side effects on nontarget animals should they eat the vaccine. This substantiates field trials results about the safety of the pZP immunocontraceptive vaccine.

Production and partial characterization of antibody to cord factor (trehalose 6,6'-dimycolate) in mice

Antibody production against the trehalose 6,6'-dimycolate (TDM, cord factor) of Rhodococcus ruber, a non-pathogenic species of the Actinomycetales group, was investigated in mice by repeated intraperitoneal injection of TDM in water-in-oil-in-water micelles without carrier protein. The antigenic TDM was isolated and purified chromatographically from the chloroform-methanol extractable lipids of R. ruber. The hydrophobic moiety of this TDM was composed of two molecules of monoenoic or dienoic alpha-mycolic acids with a carbon chain length ranging from C44 to C48 centering at C46. To detect the antibody, an enzyme-linked immunosorbent assay (ELISA) system was employed using plastic plates coated with TDM. The antibody reacted against the TDM of R. ruber. The antibody was reactive in similar fashion against glycosyl monomycolates differing in the carbohydrate moiety, such as that of glucose mycolate (GM) and mannose mycolate (MM), obtained from R. ruber. Moreover, the antibody reacted against mycolic acid methyl ester itself when it was used as the antigen in ELISA, and trehalose did not absorb the antibody to TDM or inhibit the reaction. These results indicate that the epitope of TDM recognized by the antibody is mycolic acid, an extremely hydrophobic part of the molecule. Next, we prepared monoclonal anti-TDM antibody (moAb) in mice myeloma cells to examine its biological activities and the role of humoral immunity in mycobacterial infection. MoAb reacted against the TDM, glycosyl mycolate, and mycolic acid methyl ester in ELISA in the same manner as our polyclonal antibody did. The administration of moAb suppressed granuloma formation in the lungs, spleen, and liver induced by TDM and inhibited the production of interleukin-1 (IL-1) and chemotactic factor, which is reported to precede granuloma formation.

Kinetics of organ-associated natural killer cells and intermediate CD3 cells during pulmonary and hepatic granulomatous inflammation induced by mycobacterial cord factor

We investigated here the kinetics of natural killer (NK) cells and extrathymic T cells, which include intermediate CD3 cells and gamma delta T cells, in the cord factor-induced granulomatous inflammation of the lungs and liver. In Balb/c mice, pulmonary inflammation elevated the proportion of NK cells and that of extrathymic T cells to mononuclear cells in the lungs. C3H/He mice exhibited shorter-term inflammation of the lungs than Balb/c mice and accordingly showed a smaller increase in the proportions of pulmonary NK cells and intermediate CD3 cells. In the liver of Balb/c mice, hepatic NK cells increased as well with the granulomatous changes, while intermediate CD3 cells exhibited a transient decrease before they increased. The present study has demonstrated that granulomatous inflammation is accompanied by the increase of lung-associated NK cells and extrathymic T cells and that there exists a difference between these two mouse strains in the induction of these lymphocyte subsets by cord factor.

Comparison of the effects of five adjuvants on the antibody response to influenza virus antigen in guinea pigs

Five adjuvants were tested for their effect on the immune response in guinea pigs to the hemagglutinin antigen of influenza virus strain B/Panama. Vaccines containing 924 micrograms of hemagglutinin antigen/ml were prepared at high and low doses of Freund's complete and incomplete adjuvants, Syntex adjuvant, RIBI's adjuvant, TiterMax adjuvant, and aluminum phosphate adjuvant. Responses to these vaccines were compared with those to a control vaccine containing influenza virus B/Panama hemagglutinin antigen and saline. On day 28, vaccines containing the following adjuvant doses had significantly higher titers than the titer for the control: Freund adjuvants at high and low doses, RIBI at high dose, TiterMax at high and low doses, and aluminum phosphate at high dose. On day 42, vaccines containing the following adjuvant doses had significantly higher titers than that for the control: Freund adjuvants at high and low doses, RIBI at high dose, TiterMax at high dose, and aluminum phosphate at high dose. Freund adjuvants at high and low doses, RIBI adjuvant at high dose, and aluminum phosphate at high dose caused significantly greater swelling at the inoculation site than did the control vaccine. TiterMax adjuvant at high and low doses, and aluminum phosphate at low dose caused minor swelling at the inoculation site, but it was not significantly different from the swelling caused by the control vaccine. Syntex adjuvant at high and low doses, RIBI at low dose, and control (saline/antigen) at high and low doses caused no swelling after inoculation. Overall, the high dose of adjuvants caused greater tissue swelling than did the low dose of adjuvants.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of several adjuvants as alternatives to the use of Freund's adjuvant in rabbits

In three experiments we evaluated several types of adjuvants as an alternative to Freund's adjuvant (FA). In the first experiment three adjuvant preparations (a water-in-oil emulsion (Specol), a combination preparation of monophosphoryl lipid A + trehalose dimycolate + cell wall skeleton and a non-ionic block polymer surfactant (TiterMax)) were evaluated. The adjuvants were combined with three different types of weak immunogenic antigens (synthetic peptide, glycolipid and particulate antigen) and administered following the intramuscular and subcutaneous route. The evaluation was based on clinical, pathological and immunological parameters. The animals did not appear to be severely or chronically impaired by the experiment. After injection of the RIBI adjuvant, side effects of the same severity as with FA were induced, while low antibody titers were produced. TiterMax caused few side effects, while antibody responses were very low. In comparing Specol and FA, Specol had far fewer adverse effects than FA. However, Specol had immunostimulating properties of the same level as FA. In the second experiment, the effect of injected volume of FA on side effects and antibody titer was studied. Immunization of rabbits with a total of 0.5 ml FA at different sites does not seem to increase the immune response when compared with the immune response seen after injection of 0.5 ml FA at one site. However side effects were seen in all the animals. In the third experiment, the side effects following intradermal (i.d.) injection of the adjuvants were studied. After i.d. injection of FA or RIBI, undesirable effects were found. No side effects occurred after i.d. injection of Specol or TiterMax. From the studies it is concluded that Specol is an alternative to FA for hyperactivation of the immune response in rabbits.

Extravascular coagulation and fibrinolysis in murine lung inflammation induced by the mycobacterial cord factor trehalose-6,6'-dimycolate

Diffuse pulmonary inflammation in interstitial lung diseases is associated with increased coagulation in the extravascular spaces of the lung. We hypothesized that conditions favoring coagulation over fibrinolysis in the lung are related to inflammation. Pulmonary coagulation and fibrinolysis were studied in two strains of mice susceptible or resistant to the development of lung inflammation in response to the mycobacterial cell wall glycolipid trehalose-6,6'-dimycolate (TDM). Susceptible animals treated with TDM intravenously develop well-organized collections of mononuclear cells in the lung parenchyma referred to as granulomas in this report. More granulomas were found in the susceptible ICR mice than in the resistant A/J mice after intravenous administration of TDM (7 +/- 1 granulomas/mm2 versus 1 +/- 0.3 granulomas/mm2, p = 0.005). Granuloma formation was associated with increased lung procoagulant activity (PCA) measured in bronchoalveolar lavage (BAL) cell lysates from susceptible mice. In contrast, TDM-resistant A/J mice challenged with TDM did not have a significant BAL cell PCA response, but expressed several-fold greater levels of lung BAL fluid plasminogen activator activity (PAA) than ICR mice. To examine the role of coagulation in the TDM pulmonary inflammatory response, susceptible C57Bl/10SnJ mice were anticoagulated by oral administration of warfarin prior to challenge of TDM; these mice developed fewer pulmonary granulomas than TDM-treated mice without warfarin treatment (2.6 +/- 0.5 granulomas/mm2 versus 6.5 +/- 0.8 granulomas/mm2, p < 0.001) but had similar BAL cell PCA and lung inflammatory changes as measured by lung weights and BAL cellularity.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Freund's and Ribi adjuvants for inducing antibodies to the synthetic antigen (TG)-AL in rabbits

Antibody responses and health parameters were compared in rabbits immunized with a synthetic polypeptide antigen, [L-Tyr,L-Glu,DL-Ala]-poly-L-lysine ((TG)-AL), in Freund's (FA) or Ribi (RA) adjuvants. Rabbits, 12 weeks old, of both sexes, were inoculated with 0.5 ml divided between two intramuscular (i.m.) sites. Eight received FA and antigen (50 micrograms); eight RA and antigen, eight PBS and antigen; four FA and PBS; four RA and PBS, and four PBS. Identical booster inoculations were made 21 days later, except that incomplete FA was substituted for complete FA. Rabbits were monitored until euthanasia and necropsy 7 weeks after the primary inoculation. Sera, obtained weekly, were analyzed for immunoglobulins using an enzyme immunoassay. Only rabbits given antigen with adjuvant produced high titered antibodies. Mean optical density values for immunoglobulin (Ig)M were greater the week after the booster in the group given FA. IgG values were similar for both adjuvant/antigen groups the week after the booster, but thereafter decreased in rabbits given RA. Antisera from rabbits given antigen with FA had greater avidity for the antigen than that from rabbits given antigen with RA, however, the difference was not significant (p greater than 0.05). Rabbits inoculated with FA and antigen had high serum creatinine kinase levels the day after inoculation, showed evidence of discomfort, and extensive granulomatous inflammation at the inoculation sites. Lesions were minimal to mild in rabbits given antigen with RA and PBS with either adjuvant. While RA did not result in adverse side effects, the IgG response to (TG)-AL with RA was transient compared to FA.

Pathogenesis of trehalose dimycolate-induced interstitial pneumonitis. IV. Evidence against roles for immunoglobulins and the complement system

We showed previously that trehalose dimycolate (TDM) in oil administered intraperitoneally into susceptible mice produced interstitial and hemorrhagic pneumonitis by the seventh day after injection and that mature T cells are necessary for the production of these lesions. TDM has been reported to activate complement and to be chemotactic for macrophages in vitro. Accordingly, we looked for involvement of humoral mechanisms in the pathogenesis of TDM-induced pneumonitis. Genetically C5-deficient B10D2/oSn mice developed pulmonary lesions just as well as C5-sufficient mice. No activation of C3 occurred in the plasma of TDM-treated mice as determined by crossed immunoelectrophoresis. Some splitting of C3 occurred in bronchoalveolar lavage fluids, but this was similar in control and experimental mice. By immunofluorescence microscopy, there was no deposition of C3 or immunoglobulins (Ig) along the alveolar membranes. These findings and our published data provide additional evidence that TDM-induced interstitial inflammation in mice is exclusively a T-lymphocyte-dependent process.

Enhancement of in vitro and in vivo antitumor activity by cord factor (6-6'-dimycolate of trehalose) administered suspended in saline

The antitumor activity of trehalose-6,6'-dimycolate (TDM) dispersed in saline was studied in vitro and in vivo. In vitro, macrophages from TDM-treated mice entirely abolish, even at a 1.25:1 effector/target cell ratio, the (3H)TdR incorporation of P815 mastocytoma cells to the culture in which they were added. In vivo, the number of P815 cells harvested 10 days after their injection into TDM-treated mice was reduced by a factor higher than 50. The slopes of the radiolabel elimination of TDM-treated mice injected with 10(7) 125I-UdR-labelled L1210 leukemic cells were greater than those of untreated controls. The interest of such a compound which seems to be one of the active structures responsible for the antitumor activity of BCG is its efficiency when administered dispersed in saline.