Plasma cells (PCs) are the final B-cell differentiation stage. Recent evidence reveals relevant functional differences within the PC compartment. In rodents, early PCs formed in secondary lymphoid tissues show enhanced apoptosis and short life span, whereas PCs present in a final destination organ, such as the bone marrow (BM), have reached a stable prolonged survival state. BM PCs arrive at this organ as a circulating precursor whose cellular nature remains uncertain. An initial aim of this study was to characterize this circulating cell. We hypothesized that antibody-secreting cells detectable in the human blood after immunization might be a candidate precursor. These cells were obtained from the blood of volunteers immunized 6 days earlier with tetanus toxoid (tet), and they were unambiguously identified as PCs, as demonstrated by their expression of the CD38^h phenotype, by morphology, by immunoglobulin (Ig) intracytoplasmic staining, and by IgG-tet–secreting capacity in vitro. In addition, by using the common CD38^h feature, human PCs from tonsil (as a possible source of early PCs), from blood from tet-immunized donors (as the putative precursors of BM PCs), and from BM (as a deposit organ) have been purified and their phenotypes compared. The results show that a variety of differentiation molecules, proteins involved in the control of apoptosis, the B-cell transcription factors, positive regulatory domain I-binding factor 1/B lymphocyte-induced maturation protein 1 and B cell–specific activating protein and, at least partially, the chemokine receptor CXCR4 were expressed by human PCs following a gradient of increasing maturity in the direction: tonsil→blood→BM. However, PCs from these different organs showed a local pattern of adhesion molecule expression. These observations are discussed in light of the complex physiology of the human PC compartment.

Pancreatic β-cell homeostasis is a balance between programmed cell death (apoptosis) and regeneration. Although autoimmune diabetes mellitus type 1 (DM1) is the most-studied cause of β-cell mass loss by pro-inflammatory cytokine-induced apoptosis, influences of a pro-inflammatory environment on β-cell regenerative response have been poorly studied. In this study, we assess the anti-proliferative effect of pro-inflammatory cytokines and glucose concentration on rat pancreatic β cells and the potential protective role of glucagon-like peptide (GLP-1). Apoptotic and proliferating islet cells were stained using the DeadEnd Fluorimetric TUNEL System and 5-bromo-2′-deoxyuridine label respectively, in the presence–absence of varying concentrations of glucose, pro-inflammatory cytokines, and GLP-1. The potential signaling pathways involved were evaluated by western blot. Considerable anti-proliferative effects of pro-inflammatory cytokines interleukin (IL)-1β, interferon (IFN)-γ, and tumour necrosis factor-α (TNF-α) were observed. The effects were synergistic and independent of glucose concentration, and appeared to be mediated by the inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activation, the signaling pathway involved in β-cell replication. GLP-1 completely reversed the cytokine-induced inhibition of ERK phosphorylation and increased β-cell proliferation threefold in cytokine-treated cultures. While pro-inflammatory cytokines reduced islet cell ERK1/2 activation and β-cell proliferation in pancreatic islet culture, GLP-1 was capable of reversing this effect. These data suggest a possible pharmacological application of GLP-1 in the treatment of early stage DM1, to prevent the loss of pancreatic β cells as well as to delay the development of overt diabetes.

Oxidative stress and inflammation have been postulated as underlying mechanisms for the development of obesity-related insulin resistance. This association however, remains elusive especially in childhood. We sought to investigate this relation by measuring oxidative stress and antioxidant response biomarkers, before and during an oral glucose tolerance test (OGTT), in different biological samples from obese children. 24 children were recruited for the study, (18 obese and 6 controls). After OGTT, the obese group was subdivided in two, according to whether or not carbohydrate metabolic impairment (Ob.IR+, Ob.IR-; respectively) was found. Different biomarkers were analyzed after fasting (T = 0) and during an OGTT (T = 60 and 120 min). Lipoperoxides were measured in plasma, erythrocytes, and urine; while advanced glycation end products were determined in plasma, and redox status (GSH/GSSG ratio) in erythrocytes. We found marked differences in the characterization of the oxidative status in urine and erythrocytes, and in the dynamics of the antioxidant response during OGTT. Specifically, Ob.IR+ children show increased oxidative stress, deficient antioxidant response and a significant imbalance in redox status, in comparison to controls and Ob.IR- children. Obese children with insulin resistance show increased levels of oxidative stress biomarkers, and a stunted antioxidant response to an OGTT leading to increased oxidative stress after a single glucose load, as detected in erythrocytes, but not in plasma. We propose erythrocytes as sensors of early and acute changes in oxidative stress associated with insulin resistance in childhood obesity. This is a pilot study, performed with a limited sample size, so data should be interpreted with caution until reproduced.

The analytical bias introduced by most of the commonly used techniques in metabolomics considerably hinders the simultaneous detection of all metabolites present in complex biological samples. In order to solve this limitation, the combination of complementary approaches is emerging in recent years as the most suitable strategy in order to maximize metabolite coverage. This review article presents a general overview of the most important analytical techniques usually employed in metabolomics: nuclear magnetic resonance, mass spectrometry and hybrid approaches. Furthermore, we emphasize the potential of integrating various tools in the form of metabolomic multi-platforms in order to get a deeper metabolome characterization, for which a revision of the existing literature in this field is provided. This review is not intended to be exhaustive but, rather, to give a practical and concise guide to readers not familiar with analytical chemistry on the considerations to account for the proper selection of the technique to be used in a metabolomic experiment in biomedical research.

Background and aims: Large numbers of plasma cells (PC) localise in the intestinal lamina propria (LP) where they play a critical role in the defence against pathogens. This study analyses the level of maturation reached by normal human colon LPPC in comparison with that of bone marrow (BM) PC. Methods: A technique was designed to purify LPPC by combining collagenase digestion of the mucosal layer and immunomagnetic selection of CD54⁺ LP cells. It provided highly purified PC, as demonstrated by morphology, CD38^h phenotype, and cytoplasmic IgA staining criteria. This procedure allowed comparison of in vitro functional capacities and a broad phenotypic analysis of BMPC and LPPC. Results: LPPC and BMPC exhibited identical expression of differentiation markers (CD19^−/+, CD20⁻, HLA-DR^low/−, VS38c^high), survival molecules (CD95 ^low/−, Bcl-2⁺), and B cell transcription factor profile, as well as similar in vitro Ig secreting kinetics (14 days) and lack of susceptibility to apoptosis by CD95 ligation. In contrast, they markedly differed in adhesion molecule expression, as LPPC showed higher levels of CD44 and CD21 and were α4β7⁺ whereas BMPC lacked this integrin and expressed higher levels of CD49d and CD31. Conclusion: These data indicate that PC at effector sites of the humoral response (BM and LP) show similar high differentiation, survival, and functional features but display a distinctive pattern of adhesion molecules, probably related to their respective homing locations.