Metachronous Esophageal Ulcers after Immune-mediated Colitis Due to Immune Checkpoint Inhibitor Therapy: A Case Report and Literature Review.

Although cases of gastrointestinal toxicity of pembrolizumab have been reported, cases of acute immune-mediated colitis accompanied with metachronous esophageal disorders (esophagitis and ulcer) are rare. We herein report a case of acute colitis and metachronous esophageal ulcers due to an immune-related adverse event following concomitant pembrolizumab chemotherapy for lung adenocarcinoma. To our knowledge, there have so far been no reports of cases in which both acute immune-mediated colitis and metachronous esophageal ulcers developed. We therefore report the details of this case along with a review of the pertinent literature.

Large-cell neuroendocrine carcinoma arising from a gastritis cystica polyposa.

Gastritis cystica polyposa is a polypoid lesion that arises from the gastric mucosa at the gastrojejunal anastomotic site and is characterized by cystic dilation of the gastric glands. A 78-year-old man who underwent distal gastrectomy for a gastric ulcer with Billroth II reconstruction approximately 40 years previously, exhibited a gastritis cystica polyposa at the anastomotic site. Ulceration was observed on an annual endoscopic examination. Endoscopic ultrasonography revealed a submucosal hypoechoic mass with multiple cystic lesions. Gastrectomy was performed and histological examination revealed a large-cell neuroendocrine carcinoma with cystic dilation of the gastric glands. Here, we report the first case of a large-cell neuroendocrine carcinoma arising from a gastritis cystica polyposa. Endoscopic ultrasonography was effective at diagnosing a submucosal hypoechoic mass with cystic dilation of the gastric glands.

Characterization of polystyrene-binding peptides (PS-tags) for site-specific immobilization of proteins.

In this study, we characterized polystyrene-binding peptides (PS-tags) that possess a specific binding affinity for hydrophilic polystyrene (phi-PS) plates. Both the FITC-labeled PS19-1 (RAFIASRRIKRP) and PS19-6 (RIIIRRIRR) peptides showed strong binding affinity for commercially available hydrophilic, but not hydrophobic, PS plates in the presence of the non-ionic surfactant Tween 20. The dissociation constants (K(d)) of the PS19-1 and PS19-6 peptides for the hydrophilic PS-A plate were 169 and 86 nM, respectively, and the K(d) of both peptides increased with the concentration of NaCl or urea. Based on adsorption yield and residual activity of glutathione S-transferase (GST) after fusion with the PS19-6 peptide or its variants, it was found that the basic amino acid in the PS-tags, i.e., Arg was essential for the strong binding affinity of PS-tags in both the peptide and peptide-fused protein forms The aliphatic amino acids in PS19-6 and PS19-6L, such as Ile or Leu, were also effective. Thus, a series of PS-tags that possess this unusual feature, especially the peptides PS19-6 (RIIIRRIRR) and PS19-6L (RLLLRRLRR), are potential candidate affinity peptide tags for site-specific immobilization of proteins onto hydrophilic PS plates, which show potential as solid supports for protein-based biochips.

Direct immobilization of functional single-chain variable fragment antibodies (scFvs) onto a polystyrene plate by genetic fusion of a polystyrene-binding peptide (PS-tag).

Single-chain Fv antibodies (scFv) genetically fused with polystyrene-binding peptides (PS-tags, (PS19-1; RAFIASRRIRRP, PS19-6; RIIIRRIRR)) were generated by recombinant Escherichia coli for direct and site-specific immobilization of scFv on polystyrene supports with high antigen-binding activity. PS-tag-fused scFvs (scFv-PS-tags) specific for human C-reactive protein (CRP) were successfully over-expressed as an inclusion body and were refolded using the batch-dilution method. When scFv-PS-tags were immobilized on a hydrophilic PS (phi-PS) plate in the presence of Tween 20, they showed high antigen-binding activity comparable to, or greater than, that of a whole monoclonal antibody (mAb) on a hydrophobic PS (pho-PS) plate, which has been the exclusive method for enzyme-linked immunosorbent assay (ELISA). Furthermore, when a scFv-PS-tag was used as a ligand antibody in one- and two-step ELISA, the assay time was reduced without loss of sensitivity. These results indicate that strong and specific attachment of PS-tags onto the phi-PS surface prevented scFv conformational changes and consequently, the high antigen-binding activities of scFvs were preserved. Nearly identical results were obtained by use of PS-tag-fused scFvs with different VH/VL pairs. Therefore, a variety of scFvs could be functionalized onto phi-PS plates by genetic fusion of PS-tags. ScFv-PS-tags, which possess high antigen-binding activity on the phi-PS plate, are more useful ligand antibodies than whole mAbs. Thus, scFv-PS-tags are applicable in both clinical diagnosis and proteomic research.