Novel therapeutic approach by culture filtrate of Cryptococcus neoformans var. gattii (CneF) in experimental immune complex glomerulonephritis

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.

Ameliorative effects of arctiin from Arctium lappa on experimental glomerulonephritis in rats

Membranous glomerulonephritis (MGN) remains the most common cause of adult-onset nephrotic syndrome in the world and up to 40% of untreated patients will progress to end-stage renal disease. Although the treatment of MGN with immunosuppressants or steroid hormones can attenuate the deterioration of renal function, numerous treatment-related complications have also been established. In this study, the ameliorative effects of arctiin, a natural compound isolated from the fruits of Arctium lappa, on rat glomerulonephritis induced by cationic bovine serum albumin (cBSA) were determined. After oral administration of arctiin (30, 60, 120 mg/kgd) for three weeks, the levels of serum creatinine (Scr) and blood urea nitrogen (BUN) and 24-h urine protein content markedly decreased, while endogenous creatinine clearance rate (ECcr) significantly increased. The parameters of renal lesion, hypercellularity, infiltration of polymorphonuclear leukocyte (PMN), fibrinoid necrosis, focal and segmental proliferation and interstitial infiltration, were reversed. In addition, we observed that arctiin evidently reduced the levels of malondialdehyde (MDA) and pro-inflammatory cytokines including interleukin-6 (IL-6) and tumor necrosis factor (TNF-alpha), suppressed nuclear factor-kappaB p65 (NF-kappaB) DNA binding activity, and enhanced superoxide dismutase (SOD) activity. These findings suggest that the ameliorative effects of arctiin on glomerulonephritis is carried out mainly by suppression of NF-kappaB activation and nuclear translocation and the decreases in the levels of these pro-inflammatory cytokines, while SOD is involved in the inhibitory pathway of NF-kappaB activation. Arctiin has favorable potency for the development of an inhibitory agent of NF-kappaB and further application to clinical treatment of glomerulonephritis, though clinical studies are required.

Treatment of experimental immune complex glomerulonephritis by sodium alginate

We have studied the therapeutic efficacy of the sodium alginate in experimental immune complex glomerulonephritis. Bovine serum albumin (BSA) nephritis was induced in rats by a subcutaneous immunization and daily intravenous administration of BSA. Sodium alginate at two different doses (25 and 50 mg/kg) was administered intraperitoneally at regular 72-h intervals for 6 weeks. Onset of treatment was day 42. Urinary protein was measured weekly and serum anti-BSA antibody was assessed by ELISA method at different intervals. Animals were euthanized at the 12th experimental week and blood samples and kidney specimens were obtained. BUN, serum creatinine and serum cholesterol and triglyceride were measured at the time of sacrifice. Kidney specimens were processed for light and immunofluorescent microscopic examination. The tolerability and inhibitory effect of LVA on matrix metalloproteinase 2 (MMP-2) were tested using WEHI-164 cell line and zymography method. Results of this experiment showed that treatment with sodium alginate could significantly reduce the urinary protein excretion and serum creatinine in treated rats vs. nontreated controls. Anti-BSA antibody titers were lower in treated rats than in controls at the 12th week post-immunization. There was no significant difference in the level of BUN and serum lipids between two groups. Whereas, glomerular hypercellularity, PMN infiltration and glomerular deposition of BSA were less intense in treated rats vs. controls. Moreover, in vitro examinations revealed that treatment with LVA, as a very safe agent could diminish MMP-2 activity. These results suggest that treatment with sodium alginate as a new immunosuppressive agent can reduce proteinuria, inhibit MMP-2 activity and suppress the antibody production as well as the development of glomerular lesions in a rat model of immune complex glomerulonephritis.

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.

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.