Antimicrobial Properties of Chitosan-Modified Cotton Fabric Treated with Aldehydes and Zinc Oxide Particles

Chitosan is a natural biopolymer with a proven ability to impart textile materials with antimicrobial properties when loaded onto them. The mechanism of its bacteriological activity depends on the contact between the positive and negative charges of the amino groups located on the surface of the microbes. Unfortunately, the type of microorganisms and pH influence this action-shortcomings that can be avoided by chitosan modification and by loading its film with substances possessing antimicrobial properties. In this study, chitosan was modified with benzaldehyde and crosslinked with glutaraldehyde to form a film on the surface of cotton fabric (CB). Also, another material was obtained by including zinc oxide particles (CBZ) synthesized in situ into the chitosan coating. The performed analyses (contact angle measurement, optical and scanning electron microscopy, FTIR, XRD, and thermal analysis) evidenced the modification of the cotton fabric and the alteration of the film properties after zinc oxide inclusion. A comparison of the antimicrobial properties of the new CB with materials prepared with chitosan without benzaldehyde from our previous study verified the influence of the hydrophobicity and surface roughness of the fabric surface on the enhancement of antimicrobial activity. The microbial growth inhibition increased in the following order: fungal strain Candida lipolytica >Gram-positive bacteria Bacillus cereus >Gram-negative bacteria Pseudomonas aeruginosa. The samples containing zinc oxide particles completely inhibited the growth of all three model strains. The virucidal activity of the CB was higher against human adenovirus serotype 5 (HAdV-5) than against human respiratory syncytial virus (HRSV-S2) after 60 min of exposure. The CBZ displayed higher virucidal activity with a Δlog of 0.9 against both viruses.

[Stable disease or complete response? : A critical evaluation of the radiologic response to immune checkpoint blockade in advanced melanoma]

BACKGROUND

Rating the response of melanoma to immune checkpoint blockade (ICB) by conventional CT proves to be difficult, since response patterns and kinetics differ from the classical responses seen with other therapies. Hence, immune-related response criteria were developed. However, they are mainly based on the alteration of the diameter of lesions over time but do not include metabolic activity.

OBJECTIVE

The aim of this study was to search for additional criteria to improve the interpretation of the radiologic images of patients with metastatic melanoma after ICB.

MATERIALS AND METHODS

We retrospectively analysed 7 patients with metastatic melanoma over a period of 13-41 months after treatment with ICB using contrast enhanced CT scans from the neck region to the lower abdomen and compared the results in the follow ups with ¹⁸F-FDG PET/CT.

RESULTS

Metastatic lesions in 5 of 7 patients rated as stable disease (SD) in CT staging showed no metabolic activity in ¹⁸F-FDG PET/CT. The size of these lesions did not increase or show metabolic activity in the further follow-up, even after discontinuation of ICB. In contrast, tumor lesions in the other 2 patients rated as SD in CT staging showed metabolic activity in ¹⁸F-FDG PET/CT. These tumor lesions expanded significantly in the further course of the disease.

CONCLUSION

In addition to the size of a tumor lesion, its metabolic activity adds important information regarding treatment response. Thus, we propose that the metabolic activity assessed with ¹⁸F-FDG-PET/CT should be included in the immune response criteria. No FDG uptake in a lesion should be rated as inactive tumor rather than SD and further treatment may not be required.

The proportion of circulating CD45RO+CD8+ memory T cells is correlated with clinical response in melanoma patients treated with ipilimumab

BACKGROUND

Immune checkpoint blockade (ICB) has been a breakthrough in the treatment of metastatic melanoma. But with only about 20-40% long-term responders and severe side-effects in about 12-17%, finding predictive markers for treatment response is of great interest.

METHODS

We prospectively assessed clinical data, haematologic parameters and freshly isolated peripheral blood mononuclear cells of 30 patients treated with ipilimumab (n = 21) and pembrolizumab (n = 9) prior to the first 4 cycles with ICB and before the first tumour assessment.

RESULTS

We discovered that the baseline levels of CD45RO⁺CD8⁺ T cells significantly differed among the patients. Thirteen (43%) of our patients had normal baseline levels of CD45RO⁺CD8⁺ T cells, whereas 17 (57%) patients were low on CD45RO⁺CD8⁺ T cells. The baseline levels of CD45RO⁺CD8⁺ T cells correlated significantly with the response to ipilimumab but not pembrolizumab. Patients with baseline levels of lower/equal 25% of CD45RO⁺CD8⁺ T cells did not respond to treatment with ipilimumab. Phenotyping the CD8⁺ T cells in patients treated with ipilimumab revealed an activated HLA-DR⁺CD25^- phenotype, implying antigen non-specific stimulation. The levels of the HLA-DR⁺CD25^-CD8⁺ T cells were significantly higher in patients with a normal baseline of CD45RO⁺CD8⁺ T cells and even increased significantly during treatment. Furthermore, proliferation of melanoma antigen recognized by T cells 1 (MART-1)-specific CD8⁺ T cells was not observed. Patients with normal baseline levels of CD45RO⁺CD8⁺ T cells showed a significant longer overall survival when treated with ipilimumab but not pembrolizumab.

CONCLUSION

Patients with normal baseline levels of CD45RO⁺CD8⁺ T cells respond significantly more frequently to treatment with ipilimumab and the CD8⁺ T cells appear to be antigen non-specifically activated. The baseline level of CD45RO⁺CD8⁺ T cells represents a promising factor as biomarker for the prediction of the response to ipilimumab.