Gl-NETs—Uniform But Also Diverse

In the 100 years since the term Karzinoid was first coined by Siegfried Oberndorfer to describe gastrointestinal tumors that resembled carcinomas but pursued a relatively indolent course, these tumors have captured the attention, not only of internists, surgeons, endocrinologists, and pathologists but of biochemists, physiologists, geneticists, and molecular biologists as well. Initially thought to be limited to the gut, these tumors were soon found to arise in a variety of other organs as well. With the gradual evolution of the concept of a dispersed neuroendocrine cell system and the recognition that it was made up of a galaxy of at least 20 or so functionally distinct cell types (each of which could potentially give rise to a specific type of tumor, each of which could in turn be endocrinologically functional or silent), came the realization that carcinoids should perhaps be considered as a family of neoplasms that, despite sharing certain commonalities, can however, show significant heterogeneity among themselves in some of their other features. While it may seem that our knowledge of this fascinating group of tumors has improved significantly, a closer look reveals that we may have just begun to scratch the surface.     

Critical care 24 × 7: But,why is critical nutrition interrupted?

Background and Aims:

Adequate nutritional support is crucial in prevention and treatment of malnutrition in critically ill-patients. Despite the intention to provide appropriate enteral nutrition (EN), meeting the full nutritional requirements can be a challenge due to interruptions. This study was undertaken to determine the cause and duration of interruptions in EN.

Materials and Methods:

Patients admitted to a multidisciplinary critical care unit (CCU) of a tertiary care hospital from September 2010 to January 2011 and who received EN for a period >24 h were included in this observational, prospective study. A total of 327 patients were included, for a total of 857 patient-days. Reasons and duration of EN interruptions were recorded and categorized under four groups-procedures inside CCU, procedures outside CCU, gastrointestinal (GI) symptoms and others.

Results:

Procedure inside CCU accounted for 55.9% of the interruptions while GI symptoms for 24.2%. Although it is commonly perceived that procedures outside CCU are the most common reason for interruption, this contributed only to 18.4% individually; ventilation-related procedures were the most frequent cause (40.25%), followed by nasogastric tube aspirations (15.28%). Although GI bleed is often considered a reason to hold enteral feed, it was one of the least common reasons (1%) in our study. Interruption of 2-6 h was more frequent (43%) and most of this (67.1%) was related to “procedures inside CCU”.

Conclusion:

Awareness of reasons for EN interruptions will aid to modify protocol and minimize interruptions during procedures in CCU to reach nutrition goals.     

Transgenic Overexpression of Interleukin-1β Induces Persistent Lymphangiogenesis But Not Angiogenesis in Mouse Airways

These studies used bi-transgenic Clara cell secretory protein (CCSP)/IL-1β mice that conditionally overexpress IL-1β in Clara cells to determine whether IL-1β can promote angiogenesis and lymphangiogenesis in airways. Doxycycline treatment induced rapid, abundant, and reversible IL-1β production, influx of neutrophils and macrophages, and conspicuous and persistent lymphangiogenesis, but surprisingly no angiogenesis. Gene profiling showed many up-regulated genes, including chemokines (Cxcl1, Ccl7), cytokines (tumor necrosis factor α, IL-1β, and lymphotoxin-β), and leukocyte genes (S100A9, Aif1/Iba1). Newly formed lymphatics persisted after IL-1β overexpression was stopped. Further studies examined how IL1R1 receptor activation by IL-1β induced lymphangiogenesis. Inactivation of vascular endothelial growth factor (VEGF)-C and VEGF-D by adeno-associated viral vector-mediated soluble VEGFR-3 (VEGF-C/D Trap) completely blocked lymphangiogenesis, showing its dependence on VEGFR-3 ligands. Consistent with this mechanism, VEGF-C immunoreactivity was present in some Aif1/Iba1-immunoreactive macrophages. Because neutrophils contribute to IL-1β–induced lung remodeling in newborn mice, we examined their potential role in lymphangiogenesis. Triple-transgenic CCSP/IL-1β/CXCR2^−/− mice had the usual IL-1β-mediated lymphangiogenesis but no neutrophil recruitment, suggesting that neutrophils are not essential. IL1R1 immunoreactivity was found on some epithelial basal cells and neuroendocrine cells, suggesting that these cells are targets of IL-1β, but was not detected on lymphatics, blood vessels, or leukocytes. We conclude that lymphangiogenesis triggered by IL-1β overexpression in mouse airways is driven by VEGF-C/D from macrophages, but not neutrophils, recruited by chemokines from epithelial cells that express IL1R1.CME Accreditation Statement: This activity (“ASIP 2013 AJP CME Program in Pathogenesis”) has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Society for Clinical Pathology (ASCP) and the American Society for Investigative Pathology (ASIP). ASCP is accredited by the ACCME to provide continuing medical education for physicians.The ASCP designates this journal-based CME activity (“ASIP 2013 AJP CME Program in Pathogenesis”) for a maximum of 48 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.CME Disclosures: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.IL-1β is a key inflammatory cytokine found in many pathologic conditions and is responsible for triggering multiple downstream inflammatory pathways.¹ Inhibiting IL-1 signaling by neutralizing antibodies or by blocking IL1R1 receptors is effective in treating inflammation in numerous pathologic conditions.² However, IL-1β can be a two-edged sword. Depending on the context, IL-1β is responsible for deleterious effects by amplifying inflammation and also for protective effects, for example, by activating the immune system during infection.³IL-1β has a main role in the remodeling of many tissues, including the airways and lungs. Overexpression of IL-1β in adult mouse airways and lungs results in pulmonary inflammation and the recruitment of inflammatory cells, including neutrophils, enlargement of distal airspaces, and the induction of mucous metaplasia and airway fibrosis.⁴ In neonatal mice, overexpression of IL-1β results in the disruption of lung development characteristic of bronchopulmonary dysplasia,^5,6 and this effect is mediated in part by integrins.^7,8 Furthermore, in addition to its known effects on remodeling of many tissue types, IL-1β has been reported to induce angiogenesis in several experimental models and in human diseases, including the eye, arthritic joints, and tumors, mediated in part by recruitment of leukocytes that release other inflammatory mediators.^9–14Blood vessels and lymphatics of airways show a wide repertoire of responses to different inflammatory stimuli. Various patterns of blood vessel enlargement and angiogenic sprouting are found in mice with chronic airway inflammation.^15–17 For the most part, the cellular and molecular mediators that drive vascular changes are still poorly understood, but numerous cytokines and chemokines, including IL-1β, are up-regulated in Mycoplasma pulmonis infection.^17–20 M. pulmonis-infected mice also show profound lymphangiogenesis, mediated by vascular endothelial growth factor receptor (VEGFR)-3 signaling.²¹ Because IL-1β can activate NF-κB pathways to up-regulate vascular endothelial growth factor (VEGF)-C and -D, ligands for VEGFR-3,^22,23 IL-1β could also be a candidate for driving lymphangiogenesis. IL-1β is also known to up-regulate VEGF-C in vitro, a VEGFR-3 ligand that can drive lymphangiogenesis.²⁴ However, it has been difficult to dissect the effects of individual cytokines in bacterial infection, and the effects of IL-1β alone in airways have not been examined.With this background, we took advantage of bi-transgenic (CCSP/IL-1β) mice in which IL-1β is overexpressed in airways by the rat Clara cell secretory protein (CCSP) promoter in a doxycycline (Dox)-inducible fashion.⁴ This model permitted us to study the effects of overexpression of IL-1β alone on lymphangiogenesis and angiogenesis.The goal of this study was to determine whether selective overexpression of IL-1β in adult mouse airways would induce growth or remodeling of blood vessels or lymphatic vessels and to determine the involved cells and molecules. We also sought to learn if vessel remodeling persisted after IL-1β was turned off and if VEGFR-3 signaling drove the lymphangiogenesis. To approach these issues, we stained blood vessels and lymphatics immunohistochemically in whole mounts of tracheas from CCSP/IL-1β mice treated with Dox. We also used immunohistochemistry to identify airway cells that stained for IL1R1. Because IL-1β induced leukocyte influx, including abundant neutrophils, we tested whether neutrophils were essential for the effects of IL-1β on lymphatic vessels by examining lymphangiogenesis in CXCR2^−/− mice crossed to CCSP/IL-1β mice.We found that overexpression of IL-1β in mouse airways produced neutrophil and macrophage influx, expression of inflammatory cytokines and chemokines, and long-lasting lymphangiogenesis, but not angiogenesis. IL1R1 receptors were abundant on epithelial basal cells and neuroendocrine cells, but not on lymphatics. Inactivation of VEGFR-3 ligands by soluble VEGFR-3 (VEGF-C/D Trap) from an adeno-associated viral (AAV) vector completely blocked the lymphangiogenesis, indicative of the necessity of VEGFR-3 ligands, VEGF-C and/or VEGF-D. VEGF-C immunoreactivity was present in some recruited macrophages, but the lymphangiogenesis did not require the influx of neutrophils.     

Macrophages assemble! But do they need IL‐4R during schistosomiasis?

Helminth infections are a global health burden in humans and livestock and are considered to be a major evolutionary driver of type 2 immunity (orchestrated by type 2 cytokines, e.g., IL‐4 and IL‐13). Upon infection, helminths cause substantial damage to mucosal tissues as they migrate within the host and elicit crucial protective immune mechanisms. Macrophages, essential innate cells, are known to adopt a specific activation status (termed M(IL‐4)) in type 2 cytokine environments. Yet, the role of these macrophages in mediating protective immune/wound healing responses to helminths is unclear. Furthermore, macrophage subsets can be very heterogenous (linked to their differing cellular origins) and the relative role of these subsets in the context of M(IL‐4) activation to helminth infection is unknown. An article by Rolot et al. in this issue of the European Journal of Immunology [Eur. J. Immunol. 2019. 49: 1067–1081] uses a variety of transgenic murine strains to revise our understanding of the complexity of how these subsets undergo M(IL‐4) activation and participate in wound healing responses in helminth infection. Here we highlight that consideration of different macrophage subsets in mucosal tissues is essential when evaluating the functional role of M(IL‐4) macrophages.     

Interleukin-1β Inhibits Glutamate Release in Hippocampus of Young,But Not Aged,Rats

The proinflammatory cytokine, interleukin-1, is synthesized in neuronal and glial cells and is released in response to stress/injury. IL-1 exerts profound effects on the central nervous system, which include an inhibitory effect on synaptic activity in hippocampus, a brain area expressing a high density of IL-1 receptors. We report that IL-1β has an inhibitory effect on KCl-stimulated release of glutamate and KCl-stimulated [⁴⁵Ca] influx in synaptosomes prepared from hippocampus of 4-month-old rats. These effects were inhibited by the endogenous receptor antagonist, IL-1ra, and by the phospholipase A₂ (PLA₂) inhibitor, quinacrine, suggesting that IL-1 receptor activation is coupled to PLA₂. An inhibitory effect of IL-1β on protein kinase C activity was also observed. KCl-induced calcium-dependent release and calcium influx, and protein kinase C activity were significantly decreased in hippocampal synaptosomes prepared from 22-month-old compared to 4-month-old animals. In contrast to the inhibitory effect of IL-1β in synaptosomes prepared from young adult animals, no effect was observed on release, calcium influx, or protein kinase C activity in synaptosomes prepared from aged animals. We report that there is an age-related increase in expression of IL-1β in hippocampus and propose that this change may underlie the attenuated responses to IL-1β in hippocampus of aged animals.     

Ligand–Histone H1 Conjugates: Increased Solubility of DNA Complexes, But No Enhanced Transfection Activity

We introduced galactose and a short RGD sequence as ligands into H1 histone to target the asialoglycoprotein receptor or integrins on cells expressing these receptors. The efficiency of the gene transfer mediated by galactosylated H1 histone was strongly affected by the transfection conditions. Galactosylation of H1 led to an increase of the basic H1-mediated gene transfer activity only, when H1 itself did not develop its optimal transfection activity. Under other conditions any specific gene transfer mediated by the asialoglycoprotein receptor was covered by the high transfection efficiency of H1 itself. Similar results of a marginal increase in the transfection efficiency were obtained by conjugates of a short RGD sequence and H1. This unexpected failure in the receptor specificity of both conjugates could be due to the unspecific cell-binding capacity of the H1 moiety and to increasing solubility of the complexes as shown by gel shift and solubility measurements.     

A Bactericidal Cecropin-A Peptide with a Stabilized α-Helical Structure Possess an Increased Killing Capacity But No Proinflammatory Activity

Antibacterial peptides are part of the innate immune system in a variety of different species including humans. Some of these peptides have also been shown to have effects on immune competent cells such as professional phagocytes. We have recently shown that a cecropin-like peptide from Helicobacter pylori, Hp(2–20), in addition to being bactericidal possesses proinflammatory effects and can recruit and activate neutrophils as well as monocytes. It is well established that cecropins have the ability to adopt amphipathic α-helices, which is thought to be required for their bactericidal activity. In this study we show the same structural requirements for Hp(2–20). Breaking the helical structure of Hp(2–20) reduced the antibacterial effect and abolished its proinflammatory activity. A C-terminal truncated cecropin A peptide that highly resembles Hp(2–20) failed to activate neutrophils and computer-based structural simulations revealed a difference between the two peptides in the stability of their helical structures. A hybrid peptide with amino acid substitutions stabilizing the α-helical structure of the truncated cecropin A peptide did not introduce any proinflammatory activity; the bactericidal activity was, however, increased. We thus conclude that the proinflammatory effect of Hp(2–20) is a unique sequence-specific feature of the peptide and the ability to adopt a stable amphipathic helix is a necessary but not sufficient criterion for the functional dualism of the peptide.     

ABCB1 Allele Polymorphism Is Associated with Virological Efficacy in Naïve HIV-Infected Patients on HAART Containing Nonboosted PIs But Not Boosted PIs

Abstract

Objective: To assess the effect of the multidrug resistance-1 single nucleotide polymorphism (ABCB1 SNP) C3435T in exon 26 on the virological responses to first-line protease inhibitor (PI)-containing HAART regimens. Method: A cohort of 182 HIV-infected patients with a PI-containing HAART regimen initiated from 1997 to 2004 was enrolled. Time to the first indetectable viral load (VL) was determined in patients with the CC, CT, or TT genotype. Results: There were 37%, 44%, and 19% of patients who had the CC, CT and TT genotypes, respectively. The median estimated times to VL indetectability in the CC, CT, and TT groups were respectively 5.9, 3.9, and 4.8 months (p = .06). In patients on a non-boosted PI regimen, ABCB1 genotype was associated with time to VL indetectability that was shorter in patients with the CT than CC genotype (CT vs. CC, hazard ratio [HR] = 0.62, p = .02; TT vs. CC, HR = 0.72, p = .21). This association was not found in patients with first-generation boosted PI-containing regimens and especially not with second-generation boosted PI-containing regimens. Conclusion: Our results show that the ABCB1 SNP in exon 26 is associated with virological efficacy in HIV-infected patients treated with non-boosted PI-containing regimens but not with those containing boosted PIs, particularly of the second generation.     

Serum IgG2 Concentration Is Associated with Gm-Allotypes of IgG2 But Not with the R131H Polymorphism of Human Fcγ Receptor Type IIa

Serum concentrations of immunoglobulins IgG, IgG1, and IgG2 were determined in 62 Finnish subjects who were also typed for Gm(n) allele of IgG2 and R131 and H131 alleles of the Fc receptor IIa. Statistically significant G2m-allotype-associated differences in serum concentrations of IgG2 were found; the mean concentration of IgG2 was high in Gm(n)-positive homozygotes (3.9 g/liter) and low in Gm(n)-negative individuals (2.6 g/liter; P = 0.0036), which is in accordance with previous reports. Contrary to an earlier report, no statistically significant R131/H131-allotype-associated differences were found in serum concentrations of IgG2, not even in the case where the IgG2 concentration was calculated relative to the IgG1 or IgG concentration (IgG2/IgG1 or IgG2/IgG). The gene frequencies of R131 and H131 alleles were 0.516 and 0.484, respectively, which did not differ significantly from those reported earlier for Finnish or other Caucasian populations.