The role of mucins in mucositis.

PURPOSE OF REVIEW: Alimentary mucositis is a severe dose limiting side effect of chemotherapy and radiotherapy. Mucin expression and secretion are associated with mucositis. This article aims to review current studies involving mucin and mucositis. RECENT FINDINGS: Mucins have been shown to alter mucositis severity and key targets associated with mucositis. First, interventions increasing mucin content has been associated with reduce damage associated with mucositis. Second, mucins have also been shown to protect microbiota from radiation-induced damage. Finally, mucins have also been shown to be involved in lumen epithelial barrier interactions altering signalling for cell proliferation, motility, and the inhibition of apoptosis. SUMMARY: The current studies suggest that mucin expression prior to and during mucositis may be very important in reducing the severity of mucositis and further research into the area is warranted.

GlyCAM1 negatively regulates monocyte entry into the optic nerve head and contributes to radiation-based protection in glaucoma.

BACKGROUND: We previously reported a profound long-term neuroprotection subsequent to a single radiation-therapy in the DBA/2J mouse model of glaucoma. This neuroprotection prevents entry of monocyte-like immune cells into the optic nerve head during glaucoma. Gene expression studies in radiation-treated mice implicated Glycam1 in this protection. Glycam1 encodes a proteoglycan ligand for L-selectin and is an excellent candidate to modulate immune cell entry into the eye. Here, we experimentally test the hypothesis that radiation-induced over-expression of Glycam1 is a key component of the neuroprotection. METHODS: We generated a null allele of Glycam1 on a DBA/2J background. Gene and protein expression of Glycam1, monocyte entry into the optic nerve head, retinal ganglion cell death, and axon loss in the optic nerve were assessed. RESULTS: Radiation therapy potently inhibits monocyte entry into the optic nerve head and prevents retinal ganglion cell death and axon loss. DBA/2J mice carrying a null allele of Glycam1 show increased monocyte entry and increased retinal ganglion cell death and axon loss following radiation therapy, but the majority of optic nerves were still protected by radiation therapy. CONCLUSIONS: Although GlyCAM1 is an L-selectin ligand, its roles in immunity are not yet fully defined. The current study demonstrates a partial role for GlyCAM1 in radiation-mediated protection. Furthermore, our results clearly show that GlyCAM1 levels modulate immune cell entry from the vasculature into neural tissues. As Glycam1 deficiency has a more profound effect on cell entry than on neurodegeneration, further experiments are needed to precisely define the role of monocyte entry in DBA/2J glaucoma. Nevertheless, GlyCAM1's function as a negative regulator of extravasation may lead to novel therapeutic strategies for an array of common conditions involving inflammation.

Measuring short-term gamma-irradiation effects on mouse salivary gland function using a new saliva collection device.

A restraining device was designed specifically for the collection of whole saliva from mice without using anesthesia. As the procedure does not involve surgical cannulation of the salivary glands, saliva can be collected from the same mouse at different times. The time between the injection of a secretory stimulant (pilocarpine) and the appearance of saliva in the mouth (lag time) was 100.5 +/-8.5 s (mean+/-S.E.M., n=10) for control mice. The volume of saliva collected in the first 5 min was three times greater than that collected between 15 and 20 min. The average flow rate for a collection period of 15 min was 16.7 +/-1.8 microl/min (n=10). The flow rate was decreased 50% (P<0.005) whereas the lag time was increased more than 300% (P<0.05) at 24 h after irradiation. The concentrations of a 23.5-kDa protein and a mucin were decreased after irradiation whereas there was no significant effect on the concentration of amylase or peroxidase.

Radiation inactivation of human intestinal mucin: determination of the size of the functional antigenic unit.

Previously we have shown that the major antigenic determinant of human intestinal mucin is associated with its glycopeptide monomers and not the 118 kDa 'link' component. In the present study, the size and nature of the functional unit containing the antigenic determinant has been assessed by radiation inactivation and immunological assays. Increasing doses of radiation led to a monoexponential decay in antigenic reactivity due to a progressive loss of antigenic determinants. From three independent mucin preparations, a value of 78500 +/- 7000 was determined for the Mr of the functional antigenic unit. Prolonged pronase digestion of native mucin released large degraded glycopeptide monomers containing all the mucin carbohydrate, and low molecular weight peptides. The antigenicity of the glycopeptides decreased with digestion but could not be recovered in the peptide fractions, suggesting that determinants were released and destroyed by the enzyme. Treatment of native mucin with trifluoromethanesulphonic acid caused a major loss of carbohydrate (approx. 70%), but the protein component was unchanged in amino acid profile and remained antigenic. Subsequent thiol reduction, however, abolished the antigenicity of the deglycosylated mucin. We conclude that antigenicity is associated with a non-glycosylated segment of the peptide backbone of the glycopeptides and that a large functional unit of Mr 78500 which is stabilized by disulphide bonds is important for full antigenic activity.

[The influence of artificial infrared radiation and microwaves upon mucopolysaccharides, protamine sulphate, and mucin in virus-infected organ cultures (author's transl)]. / Einfluss von künstlich erzeugten Infrarotstrahlen und Mikrowellen auf Mucopolysaccharide, Protaminsulfat und Mucin in virus-infizierten Organkulturen.

Infrared radiation and 1-2 micron microwaves influenced the infectivity of Newcastle Disease Virus (NDV) upon chick embryo tracheal tissue in such a way that the expected destruction of ciliated epithelium turned out to be incomplete or did not take place at all, respectively. Due to the fact that direct damaging of viruses following such radiation was not shown and that it was our intention to arrange the experimental set-up as if natural rhinolaryngeal conditions had induced the infection of the mucous membrane of the respiratory tract a study was performed in order to establish the radiation influence on mediator substances involved in the virus infection of mucous membranes. The mucopolysaccharides, chondroitine sulphate and hyaluronic acid, as well as mucin served as models; in addition protamine sulphate was used for reasons of comparison. The influence of the above substances upon NDV-infection in organ cultures and the effect of electromagnetic waves upon such influence were studied. By choosing a virus concentration of 10(-8)/ml on chick embryo tracheal tissue it was established that the application of infrared radiation (Osram Siccatherm Infrared Radiator,- 1-2 micron) and cm-waves (Klystron Raytheon Comp. Mass. USA, - 1.35 cm) for a length of 10 min. inhibited Newcastle Disease Virus (NDV) infectivity. The suspension fluid was treated with infrared and the tissue with cm-waves. Previous experiments revealed that direct radiation influence upon viruses cannot be taken for granted which is why the agents, chondroitine sulphate (polyanion) 5-10 microgram/ml, and hyaluronic acid (polyanion) 10-50 microgram/ml, were used in order to study such influence upon NDV-infected tracheal mucous membrane. In addition, protamine sulphate (polycation), 5-10 microgram/ml, and mucin were used. All the above mentioned substances influenced viral infectivity in organ cultures-expressed in terms of quotients: quotient 1 means no influence on the motility of the ciliated mucous membrane cells and quotient 0.01 means the complete destruction of the cells. Chondroitine sulphate inhibited strong but promoted weak virus infectivity, hyaluronic acid inhibited strong virus infectivity, protamine sulphate inhibited strong but promoted weak virus infectivity and mucin promoted weak virus infectivity in accordance with the used virus concentrations (Table 2). Under the influence of infrared radiation the mediator substances exercised a different influence upon viral infectivity: 25 times out of 32 experiments chondroitine sulphate was inhibited and hyaluronic acid increased in 8 out of 12 experiments (Table 2). The influence of protamine sulphate on viral infectivity was found to be increased 39 times and inhibited 14 times out of 54 experiments, mucin was inhibited 6 times. Furthermore, it is to be added that additional radiation with cm-waves increased the influence of infrared radiation (Table 1)...