Protein conjugates in tissue regeneration 3 (PCTR3) is a specialized pro-resolving mediator (SPM) synthesized from docosahexaenoic acid . DHA is oxidized to 16S,17S-epoxy-protectin, which is converted to PCTR1 by glutathione S-transferase and to PCTR2 and PCTR3 via peptidases. PCTR3 is found in infected mouse spleens and resolving exudate as well as isolated human spleen and septic plasma. It is also found in both M1 and M2 macrophages differentiated from isolated human monocytes.
Maresin conjugates in tissue regeneration 3 (MCTR3) is a specialized pro-resolving mediator (SPM) synthesized from docosahexaenoic acid in macrophages. DHA is oxidized to maresin 1 , which is converted to MCTR1 by glutathione S-transferase Mu 4 or leukotriene C4 synthase, then to MCTR2 by γ-glutamyl transferase, and to MCTR3 by dipeptidase. MCTR3 accelerates tissue regeneration in planaria (1 and 100 nM) approximately as potently as MCTR2 and more potently than MCTR1. Pretreatment with MCTR3 prior to E. coli administration in mice reduces neutrophil infiltration, shortens the inflammatory resolution period, and increases phagocytosis of E. coli by macrophages. When administered at a dose of 100 ng 12h post E. coli infection in a mouse model of peritonitis, MCTR3 selectively reduces the amount of the eicosanoids PGD2 , PGE2 , PGF2α , and TXB2 in the exudate.
Cortistatin-29 is a neuropeptide that is structurally similar to somatostatin-28. It is produced by cleavage of preprocortistatin to procortistatin, which is cleaved at dibasic amino acids to form cortistatin-29 and cortistatin-14 as well as other partial cleavage products. Cortistatin mRNA is expressed in the human brain and in interneurons of the rat hippocampus and cerebral cortex. Cortistatin-29 binds to somatostatin (SST) receptors with IC50 values of 2.8, 7.1, 0.2, 3, and 13.7 nM for SST1-5, respectively. Cortistatin-29 is found at similar levels as cortistatin-14 in mouse AtT20 cells but is secreted at a lower level. Cortistatin-29 corresponds to residues 85-112 of the rat peptide sequence.
Veldoreotide, also known as Somatoprim, is a unique somatostatin receptor subtypes 2-, 4- and 5-selective analogue which effectively reduces GH secretion in human GH-secreting pituitary adenomas, even in Octreotide non-responsive tumours.