Mitogenic lectins from Cephalosporium curvulum (CSL) and Aspergillus oryzae (AOL) mediate host-pathogen interactions leading to mycotic keratitis.

A core-fucose-specific lectin, CSL from Cephalosporium curvulum, has been reported earlier. Here we assign the role for CSL and another lectin AOL, from pathogenic fungus Aspergillus oryzae, in causing mycotic keratitis. CSL and AOL show strong binding to immortalized and primary human corneal epithelial cells (HCECs) which are inhibited by asialofetuin, confirming their glycan-mediated binding. CSL and AOL showed increase in viability at lower concentrations (0.07 µg/ml) whereas at higher concentrations (0.15 µg/ml and 0.30 µg/ml), have inhibitory effect on immortalized HCECs. Lectin-mediated effect was comparable with the effect induced by the Colony Forming Units (CFUs) of C. curvulum and A. oryzae. CFUs induced more than 1.5-fold increase in HCECs proliferation. Both lectins and fungal CFUs induce secretion of proinflammatory cytokines IL6 and IL8 implicated in ocular diseases. This was supported by upregulation of TLR2 and 4 by lectins as revealed by flow cytometry and RT-PCR. CSL and AOL mediate host-pathogen interactions leading to mycotic keratitis. The mechanism of pathogenesis is possibly initiated through surface binding of mycelia through the lectins to TLR2/4 followed by upregulation of proinflammatory cytokines IL6, IL8 and TLR2 and 4. Understanding the mechanism of pathogenesis is of clinical significance in designing and developing therapeutic strategy to control the infection.

Anticancer Studies of Aqueous Extract of Roots and Leaves of Pandanus Odoratissimus f. ferreus (Y. Kimura) Hatus: An In Vitro Approach.

A number of medicinal plant extracts are being used against various diseases in different systems of medicine such as Ayurveda, Unani, and Siddha, but only a few of them have been scientifically explored. The objective of the present study was to explore the dose-dependent in vitro anticancer effects of the extracts of Pandanus odoratissimus whose scientific documentation as an anticancer agent is lacking despite being used traditionally. The dried parts of roots and leaves were extracted with methanol (MEPO) and water (AEPO). The extracts were then subjected to in vitro cytotoxic and antimitotic screening by brine shrimp lethality assay and onion root tip method, respectively. Further, the behavior of the extracts on calu-6 (non-small cell lung cancer cell lines), PBMC (peripheral blood mononuclear cells) and WI (lung fibroblast cell lines) was studied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay followed by flow cytometric analysis on calu-6 cell lines. AEPO showed significant cytotoxic and antimitotic activities. It showed 100% lethality of brine shrimps at 80 µg/ml and an LC50 of 33.33 µg/ml, which was eightfold higher than that of synthetic standard podophyllotoxin (4.16 µg/ml). AEPO at 10 mg/ml concentration showed significant antimitotic activity by showing 3% mitotic index. which was more than that of standard cyclophosphamide with 4% mitotic index in comparison to control. There was a significant reduction in cell proliferation of calu-6 cells, ranging from 56 to 35%, after 24-48 h of treatment with 200 µg/ml (P < 0.001) of AEPO, while AEPO remained unaffected on PBMC and WI-38 cel lines. Cell cycle analysis revealed that AEPO at 50 µg/ml and 100 µg/ml significantly increased the number of cells in sub G0-G1 phase, indicating the cells entering in to apoptotic phase. These results suggest that aqueous extract of P. odoratissimus possesses better anticancer activity. The plant has the potential to be used in anticancer therapy, and this study scientifically validated the folklore use of this plant.

Sclerotium rolfsii lectin inhibits proliferation and induces apoptosis in human ovarian cancer cell line PA-1.

OBJECTIVES: Sclerotium rolfsii lectin (SRL), isolated from soil born phytopathogenic fungus Sclerotium rolfsii, exhibits exquisite binding specificity to the oncofoetal Thomsen-Friedenreich (Galß1,3GalNAcα-O-Ser/Thr, T or TF) antigen and associated glycans. In the present study, we report anti-proliferative activity of SRL and investigate underlying mechanisms of SRL-induced apoptosis, in the human ovarian cancer cell line PA-1. MATERIALS AND METHODS: SRL-induced anti-proliferative effects were determined using MTT assay and induction of apoptosis was determined by flow cytometry, confocal microscopy and western blot analysis. RESULTS: SRL inhibited population growth of PA-1 cells in a dose- and time-dependent manner with maximum inhibition (71.3 ± 1.9%) occurring at concentration of 50 µg/ml after 72 h incubation. Observed effects of SRL could be blocked by competing glycoproteins, asialomucin, mucin and fetuin. Treatment with SRL resulted in increase in hypodiploid cell population as determine by cell cycle analysis. Increase in numbers of annexin V-PI positive cells, and cleavage of PARP confirmed apoptosis-inducing activity of SRL. Involvement of caspases in SRL-mediated apoptosis was determined by cleavage of caspases-3, -8 and -9 in a time-dependent manner, thereby suggesting possible involvement of both intrinsic and extrinsic caspase-dependent pathways. CONCLUSION: The present study demonstrates anti-proliferative and apoptosis-inducing activity of SRL that can be exploited for potential application in ovarian cancer research.

X-ray sequence ambiguities of Sclerotium rolfsii lectin resolved by mass spectrometry.

X-ray crystallography, although a powerful technique for determining the three-dimensional structure of proteins, poses inherent problems in assigning the primary structure in residues Asp/Asn and Glu/Gln since these cannot be distinguished decisively in the electron density maps. In our recently published X-ray crystal structure of the Sclerotium rolfsii lectin (SRL) at 1.1 A resolution, amino acid sequence was initially deduced from the electron density map and residues Asp/Asn and Glu/Gln were assigned by considering their hydrogen bonding potential within their structural neighborhood. Attempts to verify the sequence by Edman sequencing were not successful as the N terminus of the protein was blocked. Mass spectrometry was applied to verify and resolve the ambiguities in the SRL X-ray crystal structure deduced sequence. From the Matrix assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI TOF-MS) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis of tryptic and chymotryptic peptides of SRL, we could confirm and correct the sequence at five locations with respect to Asp/Asn and Glu/Gln. Analysis data also confirmed the positions of Leu/Ile, Gln/Lys residues and the sequence covering 118 of the total 141 residues accounting to 83.68% of the earlier deduced sequence of SRL.

Carbohydrate specificity of a lectin isolated from the fungus Sclerotium rolfsii.

In order to investigate the functional roles of a phytopathogenic fungal lectin (SRL) isolated from the bodies of Sclerotium rolfsii, the binding properties of SRL were studied by enzyme linked lectinosorbent assay and by inhibition of SRL-glycan interaction. Among glycoproteins (gp) tested for binding, SRL reacted strongly with GalNAc alpha1-->4Ser/Thr (Tn) and/or Gal beta1-->3GalNAc alpha1-->(T(alpha)) containing gps: human T(alpha) and Tn glycophorin, asialo salivary gps, and asialofetuin, but its reactivity toward sialylated glycoproteins was reduced significantly. Of the sugar ligands tested for inhibition of SRL-asialofetuin binding, Thomsen-Friedenreich residue (T(alpha)) was the best, being 22.4 and 2.24 x 10(3) more active than GalNAc and Gal beta1--> residues, respectively. Other ligands tested were inactive. When the glycans used as inhibitors, T(alpha), and/or Tn containing gps, especially asialo PSM, asialo BSM, asialo OSM, active antifreeze gp, asialo glycophorin and Tn-glycophorin were very active, and 1.0 x 10(4) times more potent than GalNAc. From these results, it is clear that the combining site of SRL should be of a cavity type and recognizes only Tn and T(alpha) residues of glycans; it is suggested that T(alpha) and Tn glycotopes, which are present only in abnormal carbohydrate sequences of higher orders of mammal, are the most likely sites for phytopathogenic fungal attachment as an initial step of infection. The affinity of SRL for ligands can be ranked in decreasing order as follows: multivalent T(alpha) and Tn >> monomeric T(alpha) and Tn > GalNAc >>> II (Gal beta1-->4GlcNAc), L (Gal beta1-->4Glc), and Gal.