N-Acetylglucosamine Induces White to Opaque Switching, a Mating Prerequisite in Candida albicans

To mate, the fungal pathogen Candida albicans must undergo homozygosis at the mating-type locus and then switch from the white to opaque phenotype. Paradoxically, opaque cells were found to be unstable at physiological temperature, suggesting that mating had little chance of occurring in the host, the main niche of C. albicans. Recently, however, it was demonstrated that high levels of CO2, equivalent to those found in the host gastrointestinal tract and select tissues, induced the white to opaque switch at physiological temperature, providing a possible resolution to the paradox. Here, we demonstrate that a second signal, N-acetylglucosamine (GlcNAc), a monosaccharide produced primarily by gastrointestinal tract bacteria, also serves as a potent inducer of white to opaque switching and functions primarily through the Ras1/cAMP pathway and phosphorylated Wor1, the gene product of the master switch locus. Our results therefore suggest that signals produced by bacterial co-members of the gastrointestinal tract microbiota regulate switching and therefore mating of C. albicans

Treatment of ocular allergies:nonpharmacologic, pharmacologic and immunotherapy

Ocular allergy is a significant and growing issue worldwide but for many patients, it is often not differentiated from systemic conditions, such as hay fever. Management of seasonal and perennial allergic conjunctivitis is often poor. Management is principally through avoidance measures (blocking or hygiene), nonpharmaceutical (such as artificial tears and cold compresses) and pharmaceutical (such as topical antihistamines and prophylactic mast cell stabilizers). Vernal and atopic keratoconjunctivitis are more severe and generally need treatment with NSAIDs, steroids and immunomodulators. Giant papillary conjunctivitis can be related to allergy but also is often contact lens related and in such cases can be managed by a period of abstinence and replacement of the lens or a change in lens material and/or design. Immunotherapy can be efficacious in severe, persistent cases of contact lens or allergic conjunctivitis

Etanercept treatment in the endotoxin-induced uveitis of rats

This study was conducted to investigate therapeutic value of a soluble tumor necrosis factor-alpha (TNF-alpha) receptor, etanercept, in a rat model of endotoxin-induced uveitis (EIU). Forty-two inbred male Lewis rats were divided into seven equal groups. 200 mug of Escherichia coli 055:1355 lipopolysaccharide, (LPS) was injected in one hind footpad of the Groups 2, 3, 4, 5, 6, and 7 rats. Group 5, 6, and 7 rats also received subcutaneous etanercept 24 hr prior to LPS injection at a dose of 0(.)4 mg kg(-1). Group 1 rats were used as controls. Eight, 24, and 48 hr after treatment clinical uvetis scores (miosis, iris hyperemia, and hypopyon) were assessed by a masked observer and the rats were euthanized. Neutrophil leukocytes, CD8 +, CD4 +, and CD45RO + cells in the anterior uveal tissue were counted either after hematoxylin-eosin or monoclonal antibody staining. TNF-alpha. levels were also measured in the aqueous humor samples by an ELISA method. Etanercept treatment significantly improved clinical uveitis scores at all examination points compared to the LPS injected animals. The improvement was almost complete expect for the miosis score, since no significant difference was detected between the controls and LPS + Etanercept treated animals at all examination points. Cell counts were also at significantly lower levels in LPS + Etanercept treated animals at all examination points, except for CD8 + and CD45RO + cell counts at 24 hr examination point. There was no significant difference between the controls and LPS + Etanercept treated animals at all examination points as with CD4 + and CD45RO + cell counts at 48 hr. Our data showed that etanercept had a definite effect on the treatment of EIU. Further studies should clarify its efficacy on clinical uveitis conditions. (C) 2004 Elsevier Ltd. All rights reserved

Immunohistochemical analysis of orbital connective tissue specimens of patients with active graves ophthalmopathy

Purpose: To explore the immune mechanism of Graves ophthalmopathy (GO) by analyzing infiltrating cells in orbital connective tissue (OCT) specimens of patients with active GO using immunohistochemical methods. Methods: Five OCT specimens obtained from patients with active GO and five control specimens obtained from forensic cadavers who died from nonmedical reasons were stained with anti-CD3, CD4, CD8, CD45RO, HLA-Dr, CD25, and TNF-alpha monoclonal antibodies. Positively stained cells were counted and results were interpreted as cell counts/mm(2). Four of five GO patients had never been treated with any immunomodulating therapy. Only one had received oral prednisolone prior to tissue sampling, but this treatment had ceased 5 months before surgery. Results: The retro-orbital tissue specimens obtained from forensic cadavers did not show any significant positive staining for any monoclonal antibody tested. However, the specimens from GO patients showed positively stained means of 36.66 +/- 4.61 HLA- Dr(+), 12.8 +/- 3.42 CD8(+), 11.8 +/- 1.78 CD4(+), 16.6 +/- 1.81 CD3(+), 21.2 +/- 3.12 CD45RO(+), 10.4 +/- 2.07 TNF-alpha(+), 7.2 +/- 1.48 CD25(+), 3.2 +/- 1.09 CD4(+) CD8(+), 4.6 +/- 1.67 CD4(+) CD45RO(+), 2.8 +/- 0.83 CD8(+) CD45RO(+), 1.6 +/- 0.89 CD4(+) CD25(+), and 1.8 +/- 1 0.83 CD8(+) CD25(+) cells/ mm(2). Conclusions: Our study supports that most of the infiltrating lymphocytic cells in the active stage of GO are T cells, and a significant proportion of them are CD45RO+ cells. Infiltration of OCT by HLA- Dr+, CD25+, and TNF-alpha cells suggests that Th1-type immune reaction with the interference of proinflammatory cytokine(s) (TNF-alpha) may be important in the pathogenesis of disease. Further studies are needed to understand the disease pathogenesis and may provide a scientific basis for future treatment alternatives for the disease (e. g., anticytokine treatment)