In the first days of life, the newborns' intestinal microbiota develops simultaneously with the intestinal gut barrier and follows intestinal immunity. The mode of delivery shows significant impact on microbial development and, thus, the initiation of the tryptophan catabolism pathway. Further antibiotics (ATB) treatment of mothers before or during delivery affects the microbial and tryptophan metabolite composition of stool of the caesarean- and vaginal-delivered newborns. The determination of microbiome and levels of tryptophan microbial metabolites in meconium and stool can characterize intestinal colonization of a newborn. From 134 samples from the Central European Longitudinal Studies of Parents and Children: The Next Generation (CELSPAC: TNG) cohort study, 16S rRNA gene sequencing was performed, and microbial tryptophan metabolites were quantified using ultra-high-performance liquid chromatography with triple-quadrupole mass spectrometry. Microbial diversity and concentrations of tryptophan metabolites were significantly higher in stool compared to meconium. Treatment of mothers with ATB before or during delivery affects metabolite composition and microbial diversity in stool of vaginal- and caesarean-delivered newborns. Correlation of microbial and metabolite composition shows significant positive correlations of indol-3-lactic acid, N-acetyl-tryptophan and indol-3-acetic acid with Bifidobacterium, Bacteroides and Peptoclostridium. The positive effect of vaginal delivery on newborns' microbiome development is degraded when mother is treated with ATB before or during delivery. KEY POINTS: • Antibiotic treatment diminishes the positive effects of vaginal delivery. • Antibiotic treatment affects metabolite and microbial composition in newborns. • Bifidobacterium and Peptoclostridium could be the producer of indole-lactic acid.

• Keywords
• Caesarean delivery, Kynurenine, Microbiome, Stool, Tryptophan catabolites, Vaginal delivery,
• MeSH
• Anti-Bacterial Agents * MeSH
• Bifidobacterium metabolism   growth & development   MeSH
• Feces * microbiology   chemistry   MeSH
• Indoles metabolism   MeSH
• Indoleacetic Acids metabolism   MeSH
• Humans MeSH
• Longitudinal Studies MeSH
• Meconium * microbiology   chemistry   MeSH
• Infant, Newborn MeSH
• RNA, Ribosomal, 16S * genetics   MeSH
• Gastrointestinal Microbiome * drug effects   MeSH
• Tryptophan * metabolism   MeSH
• Chromatography, High Pressure Liquid MeSH
• Check Tag
• Humans MeSH
• Infant, Newborn MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• indole-3-lactic acid MeSH Browser
• indoleacetic acid MeSH Browser
• Indoles MeSH
• Indoleacetic Acids MeSH
• RNA, Ribosomal, 16S * MeSH
• Tryptophan * MeSH

National screening programs use dried blood specimens to detect metabolic disorders or aberrant protein functions that are not clinically evident in the neonatal period. Similarly, gut microbiota metabolites and immunological acute-phase proteins may reveal latent immune aberrations. Microbial metabolites interact with xenobiotic receptors (i.e., aryl hydrocarbon and pregnane-X) to maintain gastrointestinal tissue health, supported by acute-phase proteins, functioning as sensors of microbial immunomodulation and homeostasis. The delivery (vaginal or cesarean section) shapes the microbial colonization, which substantially modulates both the immune system's response and mucosal homeostasis. This study profiled microbial metabolites of the kynurenine and tryptophan pathway and acute-phase proteins in 134 neonatal dried blood specimens. We newly established neonatal blood levels of microbial xenobiotic receptors ligands (i.e., indole-3-aldehyde, indole-3-butyric acid, and indole-3-acetamide) on the second day of life. Furthermore, we observed diverse microbial metabolic profiles in neonates born vaginally and via cesarean section, potentially due to microbial immunomodulatory influence. In summary, these findings suggest the supportive role of human gut microbiota in developing and maintaining immune system homeostasis.

• Keywords
• acute-phase proteins, dried blood specimens, human gut microbiota, immunomodulation, tryptophan and kynurenine metabolism,
• Publication type
• Journal Article MeSH

The specificity of a diagnostic assay depends upon the purity of the biomolecules used as a probe. To get specific and accurate information of a disease, the use of synthetic peptides in diagnostics have increased in the last few decades, because of their high purity profile and ability to get modified chemically. The discovered peptide probes are used either in imaging diagnostics or in non-imaging diagnostics. In non-imaging diagnostics, techniques such as Enzyme-Linked Immunosorbent Assay (ELISA), lateral flow devices (i.e., point-of-care testing), or microarray or LC-MS/MS are used for direct analysis of biofluids. Among all, peptide-based ELISA is considered to be the most preferred technology platform. Similarly, peptides can also be used as probes for imaging techniques, such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET). The role of radiolabeled peptides, such as somatostatin receptors, interleukin 2 receptor, prostate specific membrane antigen, αβ3 integrin receptor, gastrin-releasing peptide, chemokine receptor 4, and urokinase-type plasminogen receptor, are well established tools for targeted molecular imaging ortumor receptor imaging. Low molecular weight peptides allow a rapid clearance from the blood and result in favorable target-to-non-target ratios. It also displays a good tissue penetration and non-immunogenicity. The only drawback of using peptides is their potential low metabolic stability. In this review article, we have discussed and evaluated the role of peptides in imaging and non-imaging diagnostics. The most popular non-imaging and imaging diagnostic platforms are discussed, categorized, and ranked, as per their scientific contribution on PUBMED. Moreover, the applicability of peptide-based diagnostics in deadly diseases, mainly COVID-19 and cancer, is also discussed in detail.

• Keywords
• ELISA, PET, SPECT, diagnostic, imaging diagnostic, microarray, non-imaging diagnostic, peptides,
• MeSH
• COVID-19 diagnosis   virology   MeSH
• Databases, Factual MeSH
• Enzyme-Linked Immunosorbent Assay methods   MeSH
• Tomography, Emission-Computed, Single-Photon methods   MeSH
• Humans MeSH
• Peptides analysis   MeSH
• Positron-Emission Tomography methods   MeSH
• Receptors, Somatostatin MeSH
• SARS-CoV-2 isolation & purification   MeSH
• Tandem Mass Spectrometry methods   MeSH
• COVID-19 Testing methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Peptides MeSH
• Receptors, Somatostatin MeSH

A proper internal standard choice is critical for accurate, precise, and reproducible mass spectrometry-based proteomics assays. Synthetic isotopically labeled (SIL) proteins are currently considered the gold standard. However, they are costly and challenging to obtain. An alternative approach uses SIL peptides or SIL "winged" peptides extended at C- or/and N-terminus with an amino acid sequence or a tag cleaved during enzymatic proteolysis. However, a consensus on the design of a winged peptide for absolute quantification is missing. In this study, we used human serum albumin as a model system to compare the quantitative performance of reference SIL protein with four different designs of SIL winged peptides: (i) commercially available SIL peptides with a proprietary trypsin cleavable tag at C-terminus, (ii) SIL peptides extended with five amino acid residues at C-terminus, (iii) SIL peptides extended with three and (iv) with five amino acid residues at both C- and N-termini. Our results demonstrate properties of various SIL extended peptides designs, e.g., water solubility and efficiency of trypsin enzymatic cleavage with primary influence on quantitative performance. SIL winged peptides extended with three amino acids at both C- and N-termini demonstrated optimal quantitative performance, equivalent to the SIL protein.

• MeSH
• Biological Assay methods   standards   MeSH
• Isotope Labeling MeSH
• Kinetics MeSH
• Protein Conformation MeSH
• Humans MeSH
• Peptides chemical synthesis   chemistry   MeSH
• Proteins analysis   chemistry   MeSH
• Proteolysis MeSH
• Proteomics methods   MeSH
• Reference Standards MeSH
• Solvents MeSH
• Solubility MeSH
• Amino Acid Sequence MeSH
• Trypsin metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Peptides MeSH
• Proteins MeSH
• Solvents MeSH
• Trypsin MeSH

An aberrant immune response developed early in life may trigger inflammatory bowel disease (IBD) and food allergies (e.g., celiac disease). Fecal levels of immune markers categorize an inflammatory response (e.g., food allergy, autoimmune) paralleled with the initial microbial colonization. The immunoaffinity assays are routinely applied to quantify circulating immune protein markers in blood/serum. However, a reliable, multiplex assay to quantify fecal levels of immune proteins is unavailable. We developed mass spectrometry assays to simultaneously quantify fecal calprotectin, myeloperoxidase, eosinophil-derived neurotoxin, eosinophil cationic protein, alpha-1-antitrypsin 1, and adaptive immunity effectors in 134 neonatal stool swabs. We optimized extraction and proteolytic protocol and validated the multiplex assay in terms of linearity of response (> 100; typically 0.04 to 14.77 µg/mg of total protein), coefficient of determination (R2; > 0.99), the limit of detection (LOD; 0.003 to 0.04 µg/mg of total protein), the limit of quantification (LOQ; 0.009 to 0.122 µg/mg of total protein) and robustness. The median CV of intra- and interday precision was 9.8% and 14.1%, respectively. We quantified breast milk-derived IGHA2 to differentiate meconium from feces samples and to detect the first food intake. An early life profiling of immune markers reflects disrupted intestinal homeostasis, and it is perhaps suitable for pre-symptomatic interception of IBD and food allergies.

• MeSH
• Biomarkers metabolism   MeSH
• Chemistry Techniques, Analytical methods   MeSH
• Feces chemistry   MeSH
• Mass Spectrometry methods   MeSH
• Inflammatory Bowel Diseases etiology   metabolism   MeSH
• Humans MeSH
• Infant, Newborn MeSH
• Specimen Handling methods   MeSH
• Food Hypersensitivity etiology   metabolism   MeSH
• Inflammation diagnosis   microbiology   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Infant, Newborn MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH

Lipids are secreted into milk as bilayer-coated structures: milk fat globules (MFGs). Adipophilin (ADRP) and perilipin 3 (TIP47) are associated with MFGs in human breast milk; however, the role of these proteins in milk lipid secretion is not fully understood. The study aimed to investigate levels of ADRP, TIP47 and total lipid content in human breast milk, their mutual correlations, and dynamics during lactation. Milk samples from 22 healthy lactating women (Caucasian, Central European) were collected at five time points during lactation (1-3, 12-14, 29-30, 88-90 and 178-180 days postpartum). Mass spectrometry-based method was used for quantification of ADRP and TIP47 in the samples. The gravimetric method was used to determine milk total lipid content. We observed distinctive trends in ADRP, TIP47 levels and lipid content in human breast milk during the first six months of lactation. We also found a significant association between lipid content and ADRP, lipid content and TIP47, and ADRP and TIP47 concentrations in breast milk at all sampling points. A mass spectrometry-based method was developed for quantifying ADRP and TIP47 in human breast milk. Strong mutual correlations were found between ADRP, TIP47 and total lipid content in human breast milk.

• MeSH
• Adult MeSH
• Glycolipids metabolism   MeSH
• Glycoproteins metabolism   MeSH
• Lactation metabolism   MeSH
• Humans MeSH
• Lipid Droplets MeSH
• Milk, Human metabolism   MeSH
• Perilipin-2 metabolism   MeSH
• Perilipin-3 metabolism   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Glycolipids MeSH
• Glycoproteins MeSH
• milk fat globule MeSH Browser
• Perilipin-2 MeSH
• Perilipin-3 MeSH