Culture filtrate of Cryptococcus neoformans var. gattii (CneF) as a novel anti-inflammatory compound in the treatment of experimental septic arthritis

The Immunomodulatory Effect of Trichophyton Rubrum Exoantigens in the Treatment of Experimental Septic Arthritis

Background:

Understanding the nature and function of fungal exoantigens might lead to novel approaches in the treatment and prophylaxis of some infectious diseases. Septic arthritis represents a serious problem for medicine due to the high incidence rate and severe complications.

Objective:

The present study aimed at assessing the immunomodulatory effects of Trichophyton rubrum culture filtrate as a novel compound in experimental septic arthritis.

Method:

The septic arthritis was haematogenously induced in Sprague-Dawley rats by a single intravenous injection of 10⁹ colony forming units of the human clinical isolate Staphylococcus aureus producing toxic shock syndrome toxin-1. Trichophyton rubrum culture filtrate at two different doses 20 and 40 mg/kg was administered intraperituneally two days after bacterial inoculation in the treatment groups and concurrently with the appearance of clinical signs in the patient groups. The administration of Trichophyton rubrum solution was continued every other day for 10 injections.

Results:

The clinical evaluation showed that Trichophyton rubrum-treated rats were significantly protected from disease development compared with untreated controls. This finding was correlated with results of radiological evaluation of the involved joints. Although, the inflammatory cell infiltration, cartilage/bone destruction and synovial hypertrophy had been decreased in the treatment groups in comparison with arthritic controls however, the histological changes were not significant in these two groups.

Conclusion:

It is possible that Trichophyton rubrum antigens may play a role in modulating the immune responses and would be efficient in septic arthritis treatment.

Design of a New Line in Treatment of Experimental Rheumatoid Arthritis by Artesunate

This study was aimed to evaluate the therapeutic potency of a new antimalarial drug, artesunate, in an experimental model of rheumatoid arthritis. Collagen-induced arthritis (CIA) was induced in Lewis rats.The intraperitoneally administration of artesunate (ARS) and methotrexate (MTX) were started on day 25 postimmunization and continued until final assessment on day 35. During this period, clinical examination was intermittent. The anticollagen type II antibody (CII Ab) and nitric oxide synthesis were measured. The paws and kness were then removed for histopathology and radiography assay. The biocompatibility of ARS and MTX were assessed using fibrosarcoma cell line. Our results showed that i.p. injection of artesunate to arthritic rats induced a significant reduction in paw edema. This beneficial effect was associated with a significant decrease in anti-CII antibody response compared with untreated rats. Histopathological assessment showed reduced inflammatory cells infiltrate in joints of treated rats, and tissue edema and bone erosion in the paws were markedly reduced following ARS therapy. Moreover, our radiographic results paralleled histological findings. Cytotoxicity analysis of ARS showed greater tolerability compared with MTX. Treatment with ARS significantly diminished nitric oxide formation in treated rats compared with untreated controls. Our findings revealed the therapeutic efficacy of artesunate in experimental rheumatoid arthritis compared with a choice drug (methotrexate). This result may recommend it as a second-line drug in the treatment of rheumatoid arthritis.

Artemether: A New Therapeutic Strategy in Experimental Rheumatoid Arthritis

The current research was designed to determine the effect of artemether in treatment of experimental rheumatoid arthritis. Collagen-induced arthritis was induced in Lewis rats. The intramusculary administration of artemether (ART) and intraperitoneally injection of methotrexate (MTX) were started on day 25 postimmunization and continued until final assessment on day 35. During this period, clinical examination was taken intermittently. The anticollagen type II antibody (CII Ab) and nitric oxide synthesis were measured. The paws and kness were then removed for histopathology and radiography assay. The biocompatibility of ART and MTX were assessed using fibrosarcoma cell line. Data showed that i.m. injection of ART to arthritic rats induced a significant reduction in paw edema. This beneficial effect was associated with a significant decrease in anti-CII antibody response compared with untreated rats. Histopathological assessment showed a reduced inflammatory cell infiltrate in joints of treated rats; tissue edema, and bone erosion in the paws were markedly reduced following ART therapy. Furthermore, our radiography results paralleled our histological findings. Cytotoxicity analysis of ART showed greater tolerability compared with MTX. Treatment with ART significantly diminished NO formation in treated rats compared with nontreated controls. Our data shed light on the therapeutic efficacy of artemether in experimental rheumatoid arthritis compared with a choice drug (methotrexate), and it may be offered as a second-line drug in treatment of rheumatoid arthritis.

Cryptococcus neoformans capsular glucuronoxylomannan induces expression of fas ligand in macrophages

The major component of capsular material of Cryptococcus neoformans is glucuronoxylomannnan (GXM), a polysaccharide that exhibits potent immunosuppressive properties in vitro and in vivo. The results reported here show that 1) soluble purified GXM induces a prompt, long-lasting, and potent up-regulation of Fas ligand (FasL) on macrophages, 2) the up-regulation of FasL is related to induced synthesis and increased mobilization to the cellular surface, 3) this effect is largely mediated by interaction between GXM and TLR4, 4) FasL up-regulation occurs exclusively in GXM-loaded macrophages, 5) macrophages that show up-regulation of FasL induce apoptosis of activated T cells expressing Fas and Jurkat cells that constitutively express Fas, and 6) anti-Fas Abs rescue T cells from apoptosis induced by GXM. Collectively our results reveal novel aspects of the immunoregulatory properties of GXM and suggest that this nontoxic soluble compound could be used to dampen the immune response, to promote or accelerate the death receptor, and to fix FasL expression in a TLR/ligand-dependent manner. In the present study, we delineate potential new therapeutic applications for GXM that exploit death receptors as key molecular targets in regulating cell-mediated cytotoxicity, immune homeostasis, and the immunopathology of diseases.

Glucuronoxylomannan, the major capsular polysaccharide of Cryptococcus neoformans, inhibits the progression of group B streptococcal arthritis

Glucuronoxylomannan (GXM), the principal constituent of the Cryptococcus neoformans capsule, modulates the inflammatory response of human monocytes in vitro. Here we examine the efficacy of GXM as a novel anti-inflammatory compound for use against experimental septic arthritis. Arthritis was induced in mice by the intravenous injection of 8 x 10(6) CFU of type IV group B streptococcus (GBS). GXM was administered intravenously in different doses (50, 100, or 200 microg/mouse) 1 day before and 1 day after bacterial inoculation. GXM treatment markedly decreased the incidence and severity of articular lesions. Histological findings showed limited periarticular inflammation in the joints of GXM-treated mice, confirming the clinical observations. The amelioration of arthritis was associated with a significant reduction in the local production of interleukin-6 (IL-6), IL-1beta, macrophage inflammatory protein 1alpha (MIP-1alpha), and MIP-2 and an increase in systemic IL-10 levels. Moreover, peritoneal macrophages derived from GXM-treated mice and stimulated in vitro with heat-inactivated GBS showed a similar pattern of cytokine production. The present study provides evidence for the modulation of the inflammatory response by GXM in vivo and suggests a potential therapeutic use for this compound in pathologies involving inflammatory processes.

Tolerability and anti-inflammatory effects of glucuronoxylomannan in collagen-induced arthritis

This investigation was planned to assess the therapeutic efficacy of glucuronoxylomannan (GXM) in collagen-induced arthritis (CIA). GXM was isolated from culture filtrate of Cryptococcus neoformans var. gattii, serotype C. CIA was induced by the immunization of Dark Agouti rats with bovine type II collagen in incomplete Freund's adjuvant. GXM solution at two doses, 25 and 50 mg/kg, was administered intraperitoneally. Onset of i.p. injections of GXM to prevention and treatment groups was days 0 and 10 postimmunization, respectively. The WEHI-164 cell line was used for assaying tolerability, matrix metalloproteinase type 2 (MMP-2) activity and apoptosis. MMP-2 activity was assessed using zymography. For assessment of apoptosis, the terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling method was used. The results of this experiment showed that the treatment of CIA with GXM at a dose of 50 mg/kg could suppress disease development both prophylactically and therapeutically. This beneficial effect of GXM was associated with a significant decrease in the anti-CII antibody response compared with untreated rats. Moreover, GXM therapy could diminish MMP-2 activity, but it had no notable effect on apoptosis. GXM also showed a high tolerability compared with certain steroidal and non-steroidal anti-inflammatory drugs. We conclude that GXM suppresses the development of disease in CIA and it could be recommended as a new immunosuppressive and anti-inflammatory agent for further investigations.

Cryptococcal capsular glucuronoxylomannan reduces ischaemia-related neutrophil influx

BACKGROUND

The capsular polysaccharide glucuronoxylomannan (GXM) of Cryptococcus neoformans interferes with the chemotaxis and transendothelial migration of neutrophils. Intravenous administration of purified GXM has been shown to reduce the influx of inflammatory cells in an animal model of bacterial infection. Here we show that isolated GXM can also interfere with neutrophil migration in a model of inflammation not related to infection. We assessed the effects of intravenous GXM on neutrophil infiltration in a rat model of myocardial ischaemia, where neutrophil infiltration has been shown to contribute to postischaemic reperfusion injury.

MATERIALS AND METHODS

Rats were subjected to coronary artery ligation followed by a 3-h reperfusion period. Myeloperoxidase-activity was measured in the ischaemic tissues as a marker of neutrophil infiltration.

RESULTS

Intravenous administration of GXM markedly reduced the influx of neutrophils in the ischaemic myocardium as measured by a 65% reduction of tissue MPO activity. This reduction of MPO activity was clearly correlated to the serum concentration of GXM. As complement activation by GXM was minimal at the doses applied in vivo, it is unlikely that generation of chemotactic C5a in the circulation by GXM caused the observed reduction in leucocyte migration.

CONCLUSION

Purified cryptococcal GXM has the ability to reduce neutrophil influx even outside the scope of infection.

Cryptococcal glucuronoxylomannan interferes with neutrophil rolling on the endothelium

The major capsular polysaccharide glucuronoxylomannan (GXM) of the pathogenic fungus Cryptococcus neoformans has been associated with depression of a variety of immunological host responses. For one, GXM has been shown to interfere with the migration of phagocytes to sites of inflammation by interference with both chemokinesis and leucocyte adhesion to the endothelium. We reported previously that GXM blocks the firm adhesion of neutrophils (PMNs) to endothelium in a static adhesion model, most probably by interfering with E-selectin binding pathways. Using a flow model, we now demonstrate that GXM also interferes with the initial rolling phase of PMN adhesion to endothelium (40% decrease) as well as to E-selectin-transfected CHO cells (43% inhibition). Furthermore, we show that CD14 and TLR4, which are known receptors for GXM, mediate this interference with PMN rolling. However, thus far, we are not able to identify the ligand of E-selectin on the surface of PMNs that is specifically affected by GXM. In conclusion, cryptococcal GXM interferes with both rolling and fixed binding of neutrophils on the endothelium, providing a novel means of contributing to the absence of neutrophil infiltration observed in cryptococcal infections.

Metabolites released by Cryptococcus neoformans var. neoformans and var. gattii differentially affect human neutrophil function

Differences in the ability of Cryptococcus neoformans var. neoformans (CNVN) and var. gattii (CNVG) to establish localized lesions in the lungs of healthy humans remain unexplained. In this study, CNVG infection in a rat model was characterized by early neutrophil invasion into lung tissue, but phagocytosis of cryptococci was not observed. The chemical composition of non-enzymic components secreted by one strain of each variety (heat-inactivated supernatants from CNVN and CNVG, termed vns and vgs, respectively) were compared, using magnetic resonance spectroscopy. Effects on human neutrophil viability and functions at both pH 5.5 and 7.0 were investigated, as the pH of cryptococcomas was found to be 5.4-5.6 in vivo. The supernatants were similar in composition, although metabolites in vns were generally present in higher concentrations. In addition, vgs contained two novel metabolites-acetoin and dihydroxyacetone. Polyphosphate was observed in cells from both varieties and may be a source of extracellular inorganic phosphate. Superoxide production in the presence of phorbol ester was enhanced by treatment with vns and decreased by vgs. At pH 5.5, vns caused high levels of necrosis in neutrophils, as well as increased adhesion/migration through A549 lung epithelial cell monolayers. Individual supernatant components such as polyols, acetoin, dihydroxyacetone, and gamma-aminobutyric acid exhibited both pro- and anti-inflammatory properties. Overall, we found that vgs was potentially less pro-inflammatory than vns. Inhibition of neutrophil function by products of CNVG may promote survival of extracellular organisms, and local multiplication to form cryptococcomas.