Presence Of Pro-inflammatory Mediators Research Articles

The Anorexigenic Peptide, Nesfatin-1, Dampens the B Cell Response to Receptor Mediated Stimulation

Obesity is an inflammatory condition marked by an increase in the accumulation of dysregulated B cells in adipose tissue (AT). These dysregulated B cells secrete pro-inflammatory mediators, cytokines and antibodies, that interfere with the normal function of the AT and contribute to the development of insulin resistance. Furthermore, depletion of the B cell compartment in a murine model has been shown to attenuate the metabolic aberrations associated with obesity. These data emphasize a clear role for B cell contribution to the comorbidities associated with obesity; however, the mechanism(s) regulating their accumulation and function are unknown. Therefore, discovery of targets that normalize the interaction between B cells and adipocytes has the potential to significantly reduce the burden of the inflammatory comorbidities of obesity that lead to metabolic disorders. Nesfatin-1 is a peptide hormone that is cleaved from the nucleobindin 2 (NUCB2) precursor along with two other peptides, nesfatin-2,3. Nesfatin-1 was originally described based on its anorexigenic effects in vivo, however recent reports have documented its anti-inflammatory activity. When NUCB2 is genetically deleted, there is a resultant increase in the presence of pro-inflammatory mediators in subcutaneous white AT (WAT). This is intriguing because humans with obesity have reduced serum nesfatin-1 in addition to low-grade chronic inflammation in WAT. However, the underlying mechanisms of how nesfatin-1 exerts its effects and its sites of action within the immune system have not been fully elucidated. In this study, we sought to determine a mechanism by which this peptide might directly interact with the immune system starting with a human B cell line, Raji. Here, we show that nesfatin-1 directly inhibits lipopolysaccharide (LPS) and B cell receptor (BCR) stimulated B cell proliferation while also protecting from inflammatory cell death. Furthermore, nesfatin-1 prevented stimulation induced secretion of pro-inflammatory mediators IgM and TNFa. Finally, we show that this effect is likely mediated via nesfatin-1’s ability to inhibit inflammatory pathway activation in this B cell line. Taken together, this work highlights a novel action of nesfatin-1 to directly bind to and inhibit B cell responses. These fundamental studies will serve as a springboard for the future development of nesfatin-1-based therapeutics for the treatment of obesity-associated inflammation, thus enabling potential new preventative strategies for forestalling the development of inflammation associated diseases, such as T2D. Saint Louis University. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Porphyromonas gingivalis Conditioned Medium Induces Amyloidogenic Processing of the Amyloid-β Protein Precursor upon in vitro Infection of SH-SY5Y Cells

Background:Cleavage of the amyloid-β protein precursor (AβPP) mediated by host secretase enzymes, releases several fragments including amyloid-β (Aβ40 and Aβ42).Objective:To determine if Porphyromonas gingivalis conditioned medium cleaved AβPP to release Aβ40 and Aβ42.Methods:The SH-SY5Y cell line was challenged, in vitro, with P. gingivalis (Pg381) conditioned medium in the presence/absence of cytokines. The cells and their supernatants were assessed for AβPP cleavage fragments by immunoblotting and transmission electron microscopy.Results:Western blotting of the cell lysates with the anti-AβPP C-terminal antibody demonstrated variable molecular weight bands corresponding to full length and fragmented AβPP in lanes treated with the following factors: Tryptic soy broth (TSB), Pg381, IL-6, Pg381 + IL-1β, and Pg381 + TNF-α. The low molecular weight bands corresponding to the C99 dimerized fragment were observed in the Pg381 and interlukin-6 (IL-6) treated groups and were significantly more intense in the presence of Pg381 with either IL-6 or TNF-α. Bands corresponding to the dimerized C83 fragment were observed with cells treated with TNF-α alone and with Pg381 combined with IL-1β or IL-6 or TNF-α. The anti-Aβ antibody detected statistically significant Aβ40 and Aβ42, levels when these two Aβ species were pooled across test samples and compared to the untreated group. Electron microscopic examination of the supernatants demonstrated insoluble Aβ40 and Aβ42.Conclusion:These observations strongly imply that AβPP is an infection responsive protein cleaved via the amyloidogenic pathway on exposure to conditioned medium and in the presence of pro-inflammatory mediators.

6-Shogaol (enexasogoal) treatment improves experimental knee osteoarthritis exerting a pleiotropic effect over immune innate signalling responses in chondrocytes.

The pathogenesis of osteoarthritis implicates a low-grade inflammation associated to the innate immune system activation. Toll like receptor (TLR) stimulation triggers the release of inflammatory mediators, which aggravate osteoarthritis. We studied the preventive effect of 6-shogaol, a potential TLR4 inhibitor, on the treatment of experimental knee osteoarthritis. Osteoarthritis was induced in C57BL6 mice by surgical section of the medial meniscotibial ligament, which received 6-shogaol for eight weeks. Cartilage damage, inflammatory mediator presence and disease markers were assessed in joint tissues by immunohistochemistry. Computational modelling was used to predict binding modes of 6-shogaol into the TLR4/MD2 receptor and its permeability across cellular membranes. Employing LPS-stimulated chondrocytes and MAPK assay, we elucidated 6-shogaol action mechanisms. 6-Shogaol treatment prevented articular cartilage lesions, synovitis and the presence of pro-inflammatory mediators, and disease markers in osteoarthritis animals. Molecular modelling studies predicted 6-shogaol interaction with the TLR4/MD-2 heterodimer in an antagonist conformation through its binding into the MD-2 pocket. In cell culture, we confirmed that 6-shogaol reduced LPS-induced TLR4 inflammatory signalling pathways. Besides, MAPK assay demonstrated that 6-shogaol directly inhibits the ERK1/2 phosphorylation activity. 6-Shogaol evoked a preventive action on cartilage and synovial inflammation in osteoarthritis mice. 6-shogaol effect may take place not only by hindering the interaction between TLR4 ligands and the TLR4/MD-2 complex in chondrocytes, but also through inhibition of ERK phosphorylation, implying a pleiotropic effect on different mediators activated during osteoarthritis, which proposes it as an attractive drug for osteoarthritis treatments.

Capsaicin and TRPV1 Channels in the Cardiovascular System: The Role of Inflammation.

Capsaicin is a potent agonist of the Transient Receptor Potential Vanilloid type 1 (TRPV1) channel and is a common component found in the fruits of the genus Capsicum plants, which have been known to humanity and consumed in food for approximately 7000–9000 years. The fruits of Capsicum plants, such as chili pepper, have been long recognized for their high nutritional value. Additionally, capsaicin itself has been proposed to exhibit vasodilatory, antimicrobial, anti-cancer, and antinociceptive properties. However, a growing body of evidence reveals a vasoconstrictory potential of capsaicin acting via the vascular TRPV1 channel and suggests that unnecessary high consumption of capsaicin may cause severe consequences, including vasospasm and myocardial infarction in people with underlying inflammatory conditions. This review focuses on vascular TRPV1 channels that are endogenously expressed in both vascular smooth muscle and endothelial cells and emphasizes the role of inflammation in sensitizing the TRPV1 channel to capsaicin activation. Tilting the balance between the beneficial vasodilatory action of capsaicin and its unwanted vasoconstrictive effects may precipitate adverse outcomes such as vasospasm and myocardial infarction, especially in the presence of proinflammatory mediators.

P.124: Withaferin A Prevents Inflammatory Phenotype in Cultured Islets

Introduction: Islets undergo enormous ischemic, and mechanical stress throughout clinical isolation steps which affect the quality of processed islets available for transplantation. Isolated islets produce pro-inflammatory cytokines and chemokines that are further exacerbated during culture. Transplantation of islets with a strong pro-inflammatory phenotype may induce the activation of IBMIR and affect overall transplant outcomes. Strategies to improve the outcome of isolation and protection of islets from pro-inflammatory gene activation is an unmet requirement. Here, we sought to investigate the protective/anti-inflammatory effect of Withaferin A: a plant-derived inhibitor of Nuclear Factor Kappa B (NFκB). Methods: A bisected split lobe isolation technique was adopted where the head and tail were isolated subsequently with a control or WA-treated (2µM) medium during isolation. WA was added in the isolation solutions including preservation media, Collagenase, Recombination Media, Wash Buffer, and also in islet culture media. The islets isolated from (+/-) WA treatment during isolation was analyzed for the viability, function, and intracellular pro-inflammatory cytokine expression. Western blots were performed to study the activation of transcription factors and stress-regulated genes post-culture. Exosomes were isolated and the presence of pro-inflammatory mediators was examined. Results: Islet damage was reduced in the WA-treated group as shown by miRNA 375 release. No significant difference in the isolation outcomes such as yield, purity, and viability of islets between WA and the control group was seen. The purity of islets post-culture was better maintained in the WA treated group, compared to the control group (Figure 1). No difference in viability and insulin secretion was observed post-culture in the two groups. The western blotting of WA-cultured islets (at 24 and 48H) showed a significant reduction in the activation of p65 NFκB (P-s536) and P-IκBα (P-s32). Interestingly, WA treatment also synergistically reduced the activation of PERK (P-T982) and IRE1 mediated ER stress signals compared to the non-WA treated cultured islets. There was a significant reduction in the intracellular mRNA expression (Tissue factor, MCP1, and IL-8) and subsequent exosomal content of pro-inflammatory mediators (IP-10, IL-6, and IL-2) in the WA treated cultured islets (24 and 48H) compared to non-WA treated islets. Conclusion: Withaferin A treatment prevented islet damage during isolation and also prevented the generation of a proinflammatory phenotype in islets post-culture. The study proposes a novel protective strategy to control islet inflammation during isolation and peritransplant steps which may improve the functional outcomes of transplantation.

Treatment-associated hemolysis in Kawasaki disease: association with blood-group antibody titers in IVIG products

AbstractHemolytic anemia resulting from IV Immunoglobulin (IVIG) treatment can be a serious complication, especially for those with underlying conditions with a high level of inflammation and after administration of high IVIG dosages, such as Kawasaki disease (KD), a multisystem vasculitis affecting young children. This hemolysis is caused by antibodies against blood groups A and B, but the precise mechanism for hemolysis is not known. We performed a single center, partly retrospective, partly prospective study of a cohort of 581 patients who received IVIG for treatment of KD from 2006 to 2013. Factors associated with hemolysis were identified through univariable and multivariable logistic regression. Six IVIG preparations were assayed for their hemolytic effect with serological and cellular assays to clarify the mechanism of red cell destruction. During the study period, a sudden increase in the incidence of hemolysis was observed, which coincided with the introduction of new IVIG preparations in North America that contained relatively high titers of anti-A and anti-B. These blood-group–specific antibodies were of the immunoglobulin G2 (IgG2) subclass and resulted in phagocytosis by monocyte-derived macrophages in an FcγRIIa-dependent manner. Phagocytosis was increased in the presence of proinflammatory mediators that mimicked the inflammatory state of KD. An increased frequency of severe hemolysis following IVIG administration was caused by ABO blood-group–specific IgG2 antibodies leading to FcγRIIa-dependent clearance of erythrocytes. This increase in adverse events necessitates a reconsideration of the criteria for maximum titer (1:64) of anti-A and anti-B in IVIG preparations.

Investigation of Extracellular Matrix Protein Expression Dynamics Using Murine Models of Systemic Inflammation.

Extracellular matrix (ECM) proteins form the structural support for migration of leukocytes and provide multiple signals to assist in their functions during inflammatory conditions. Presence of pro-inflammatory mediators in the tissues results in the remodelling of matrices which could modify the functions of extravasated leukocytes. Previous reports have shown changes in the expression of ECM proteins during local inflammatory responses. In this study, we have investigated the time- and tissue-specific expression profile of key ECM proteins in systemic inflammation using lipopolysaccharide (LPS)-induced endotoxemia and cecal ligation and puncture (CLP) mouse models. The results show that compared to naïve tissues, within 12h following CLP surgery, a 20-30-fold increase was observed in the expression of collagen-IV (Col-IV) transcripts in the mesentery tissues with a 2.4-fold increase in the protein by 24h. However, Western blot band intensities indicated that vimentin and fibrinogen were remarkably expressed in more quantity compared to Col-IV. Secondly, in CLP group of mice, fibrinogen showed 6-40-fold increase in mRNA level in various tissues with about 2-fold increase in the protein level compared to respective naïve tissues. Similar studies in the LPS-injected mice showed up to 2-3 fold increase in the expression of Col-IV, fibrinogen and vimentin at protein level in the lungs. In such animals, although similar pattern was observed for fibrinogen in kidney and liver tissues, the mesentery showed prominent changes in Col-IV and vimentin mRNA compared to CLP. Further, bioinformatics analysis showed multiple pathways which could be associated with vimentin, Col-IV and fibrinogen under inflammatory conditions both in human and mouse. The current study will help in better understanding of possible signalling from ECM proteins in inflammatory microenvironment and may contribute in development of cell adhesion-based therapeutics.

Secreted Factors From Intervertebral Disc Cells and Infiltrating Macrophages Promote Degenerated Intervertebral Disc Catabolism.

Rat nucleus pulposus (NP) cells or annulus fibrosus (AF) cells were stimulated with conditioned media of RAW 264.7 macrophages and vice versa under healthy culture conditions and in the presence of pro-inflammatory mediators. The gene expression of pro-inflammatory mediators, extracellular matrix (ECM)-modifying enzymes, and chemokines, which play important roles in intervertebral disc degeneration (IDD), was determined. To test whether the interaction between native disc cells and infiltrating macrophages accelerates inflammation state, disrupts matrix homeostasis, and promotes inflammatory cells infiltration. With macrophages infiltration, the disc resident cells would be inevitably exposed to macrophages. Macrophages have been shown to play pro-inflammatory role in the cellular interactions with disc cells under healthy culture conditions. However, the biologic interactions between macrophages and disc cells under degenerated disc inflammatory environment remain unknown. Murine Macrophages RAW 264.7 were cultured in the conditioned media of Rat AF or NP cells culture in the presence or absence of IL-1β stimulation. Similarly, Rat AF or NP cells were also cultured in the conditioned media of Murine Macrophages RAW 264.7 culture in the presence or absence of IFN-γ stimulation. The mRNA levels difference of pro-inflammatory genes, catabolic genes and chemokines genes for AF cells, NP cells and Macrophages RAW 264.7 were analyzed by qRT-PCR, respectively. Compared with serum-free media exposure, RAW 264.7 macrophages exposed to AF or NP cells conditioned media selectively modestly upregulated mRNA levels of the aforementioned cytokines. Exposure of RAW 264.7 macrophages to conditioned media from AF or NP cells with IL-1β stimulation dramatically increased mRNA levels of all the investigated cytokines. Similarly, compared with serum-free media exposure, AF or NP cells exposed to RAW 264.7 macrophages conditioned media selectively modestly upregulated mRNA levels of the aforementioned cytokines. Exposure of AF or NP cells to conditioned media from RAW 264.7 macrophages with IFN-γ stimulation dramatically increased mRNA levels of all the investigated cytokines. The biologic interactions between infiltrating macrophages and native disc cells under degenerated disc inflammatory environment lead to an increasingly severe inflammatory conditions, which may be a self-stimulated process from the macrophages infiltration occurrenceLevel of Evidence: 5.

Uncovering Cellular retinoic acid-binding protein 2 as a potential target for rheumatoid arthritis synovial hyperplasia

Rheumatoid arthritis (RA) is a systemic autoimmune disease including synovitis and synovial hyperplasia that contribute to joint destruction. Pivotal pathogenic mechanisms in this process are the dysregulated proliferation and apoptosis of fibroblast-like synoviocytes (FLS). Unfortunately, the mechanisms of FLS dysregulation are not completely elucidated. Here, we explored a new hypothesis based in the potent anti-proliferative and pro-apoptotic activity of retinoids in some types of cancer. Specifically, we investigated the role of retinoids and of the retinoic acid binding proteins, CRABP2 and FABP5, on the proliferation and apoptosis of FLS from RA by adding all-trans retinoic acid (ATRA) or silencing CRABP2 and FABP5. We showed an unconventional behaviour of RA FLS, which were relatively insensitive to ATRA. In effect, ATRA increased the resistance to apoptosis despite the high CRABP2/FABP5 ratio of RA FLS; and CRABP2 suppression sensitized RA FLS to Fas-induced apoptosis. This latter effect was associated with changes in expression of kinases, ASK1 up-regulation and ERK down-regulation, and increased phosphorylation of JNK. In addition, the potentiation of FLS apoptosis by CRABP2 silencing persisted in the presence of pro-inflammatory mediators, TNF e IL1β. Therefore, the results point to CRABP2 as a potential target to decrease synovial hyperplasia in RA.

Pulsed electromagnetic fields increase osteogenetic commitment of MSCs via the mTOR pathway in TNF-\u03b1 mediated inflammatory conditions: an in-vitro study

Pulsed electromagnetic fields (PEMFs) have been considered a potential treatment modality for fracture healing, however, the mechanism of their action remains unclear. Mammalian target of rapamycin (mTOR) signaling may affect osteoblast proliferation and differentiation. This study aimed to assess the osteogenic differentiation of mesenchymal stem cells (MSCs) under PEMF stimulation and the potential involvement of mTOR signaling pathway in this process. PEMFs were generated by a novel miniaturized electromagnetic device. Potential changes in the expression of mTOR pathway components, including receptors, ligands and nuclear target genes, and their correlation with osteogenic markers and transcription factors were analyzed. Involvement of the mTOR pathway in osteogenesis was also studied in the presence of proinflammatory mediators. PEMF exposure increased cell proliferation and adhesion and the osteogenic commitment of MSCs even in inflammatory conditions. Osteogenic-related genes were over-expressed following PEMF treatment. Our results confirm that PEMFs contribute to activation of the mTOR pathway via upregulation of the proteins AKT, MAPP kinase, and RRAGA, suggesting that activation of the mTOR pathway is required for PEMF-stimulated osteogenic differentiation. Our findings provide insights into how PEMFs influence osteogenic differentiation in normal and inflammatory environments.

Cyclic AMP is a key regulator of M1 to M2a phenotypic conversion of microglia in the presence of Th2 cytokines.

BackgroundMicroglia and macrophages play a central role in neuroinflammation. Pro-inflammatory cytokines trigger their conversion to a classically activated (M1) phenotype, sustaining inflammation and producing a cytotoxic environment. Conversely, anti-inflammatory cytokines polarize the cells towards an alternatively activated (M2), tissue reparative phenotype. Elucidation of the signal transduction pathways involved in M1 to M2 phenotypic conversion may provide insight into how the innate immune response can be harnessed during distinct phases of disease or injury to mediate neuroprotection and neurorepair.MethodsMicroglial cells (cell line and primary) were subjected to combined cyclic adenosine monophosphate (cyclic AMP) and IL-4, or either alone, in the presence of pro-inflammatory mediators, lipopolysaccharide (LPS), or tumor necrosis factor-α (TNF-α). Their effects on the expression of characteristic markers for M1 and M2 microglia were assessed. Similarly, the M1 and M2 phenotypes of microglia and macrophages within the lesion site were then evaluated following a contusive spinal cord injury (SCI) to the thoracic (T8) spinal cord of rats and mice when the agents were administered systemically.ResultsIt was demonstrated that cyclic AMP functions synergistically with IL-4 to promote M1 to M2 conversion of microglia in culture. The combination of cyclic AMP and IL-4, but neither alone, induced an Arg-1+/iNOS−cell phenotype with concomitant expression of other M2-specific markers including TG2 and RELM-α. M2-converted microglia showed ameliorated production of pro-inflammatory cytokines (TNF-α and IP-10) and reactive oxygen species, with no alteration in phagocytic properties. M2a conversion required protein kinase A (PKA), but not the exchange protein directly activated by cyclic AMP (EPAC). Systemic delivery of cyclic AMP and IL-4 after experimental SCI also promoted a significant M1 to M2a phenotypic change in microglia and macrophage population dynamics in the lesion.ConclusionsUsing primary microglia, microglial cell lines, and experimental models of CNS injury, we demonstrate that cyclic AMP levels are a critical determinant in M1–M2 polarization. High levels of cyclic AMP promoted an Arg-1+ M2a phenotype when microglia were activated with pro-inflammatory stimuli and Th2 cytokines. Th2 cytokines or cyclic AMP independently did not promote these changes. Phenotypic conversion of microglia provides a powerful new therapeutic approach for altering the balance of cytotoxic to reparative microglia in a diversity of neurological diseases and injury.

Soluble factors from the notochordal-rich intervertebral disc inhibit endothelial cell invasion and vessel formation in the presence and absence of pro-inflammatory cytokines

Chronic low back pain can be associated with the pathological ingrowth of blood vessels and nerves into intervertebral discs (IVDs). The notochord patterns the IVD during development and is a source of anti-angiogenic soluble factors such as Noggin and Chondroitin sulfate (CS). These factors may form the basis for a new minimally invasive strategy to target angiogenesis in the IVD. To examine the anti-angiogenic potential of soluble factors from notochordal cells (NCs) and candidates Noggin and CS under healthy culture conditions and in the presence of pro-inflammatory mediators. NC conditioned media (NCCM) was generated from porcine NC-rich nucleus pulposus tissue. To assess the effects of NCCM, CS and Noggin on angiogenesis, cell invasion and tubular formation assays were performed using human umbilical vein endothelial cells (HUVECs) ± tumor necrosis factor alpha (TNFα [10 ng/ml]). vascular endothelial growth factor (VEGF)-A, MMP-7, interleukin-6 (IL-6) and IL-8 mRNA levels were assessed using qRT-PCR. NCCM (10 & 100%), CS (10 and 100 μg) and Noggin (10 and 100 ng) significantly decreased cell invasion of HUVECs with and without TNFα. NCCM 10% and Noggin 10 ng inhibited tubular formation with and without TNFα and CS 100 μg inhibited tubules in Basal conditions whereas CS 10 μg inhibited tubules with TNFα. NCCM significantly decreased VEGF-A, MMP-7 and IL-6 mRNA levels in HUVECs with and without TNFα. CS and Noggin had no effects on gene expression. We provide the first evidence that soluble factors from NCs can inhibit angiogenesis by suppressing VEGF signaling. Notochordal-derived ligands are a promising minimally invasive strategy targeting neurovascular ingrowth and pain in the degenerated IVD.

Abstract 582: Inflammatory Cytokines Reduce Thrombin Activatable Fibrinolysis Inhibitor Protein Levels in HepG2 Cells via TTP-Mediated Destabilization of TAFI mRNA

Thrombin activatable fibrinolysis inhibitor (TAFI) is the zymogen form of a basic carboxypeptidase (TAFIa) with both anti-fibrinolytic and anti-inflammatory properties. The role of TAFI in inflammatory disease is multifaceted and involves both recognition of specific pro-inflammatory substrates by TAFIa as well as regulation of TAFI gene expression by inflammatory mediators. In this study we addressed the hypothesis that decreased TAFI levels observed in inflammation are due to destabilization of its mRNA via the A/U-rich responsive element binding protein tristetraprolin (TTP). TAFI protein levels were measured in conditioned medium of HepG2 cells with recently developed assay specific for TAFIa. Treatment of cells with pro-inflammatory cytokines TNFα, IL-6 in combination with IL-1β, or with bacterial lipopolysaccharide (LPS) decreased TAFI protein levels by approximately 2-fold over 24 to 48 hours of treatment. Conversely, treatment of HepG2 cells with the anti-inflammatory cytokine IL-10 increased TAFI protein levels by 2-fold at both 24 and 48 hour time points. We employed luciferase reporter gene studies using human TAFI promoter constructs and found no change in promoter activity with these treatments. We then hypothesized that changes in mRNA stability may be involved through binding of TTP to the TAFI 3’-UTR, as we recently characterized the role of TTP in mediating TAFI mRNA stability. Using constructs expressing β-globin fusion mRNAs containing the TAFI 3’-UTR, we found that TNFα, IL-6, IL-1β, and LPS reduce TAFI mRNA half-life by 30%. This effect appears to be dependent on TTP binding, since these cytokines did not alter the stability of a fusion transcript lacking the TTP binding site. IL-10 caused an increase in fusion transcript stability by 38%, an effect that was also observed when the TTP binding site was mutated. Using reporter constructs expressing fusion mRNA’s containing the luciferase coding region and the TAFI 3’-UTR, we found that translation rate remained unaffected with both pro- and anti-inflammatory treatments. In conclusion, destabilization of TAFI mRNA appears to be the main mechanism behind decreased TAFI protein levels observed in the presence of pro-inflammatory mediators.

THU0037 Immune complex-induced inhibition of osteoclastogenesis is mediated via activating, but not inhibitory FCGAMMA receptors on myeloid precursor cells

BackgroundRheumatoid arthritis is characterized by osteoclast-mediated bone loss. Co-stimulatory signalling via ITAM- and ITIM-coupled receptors is essential for osteoclast formation and function. The ITAM- and ITIM-coupled Fcγ receptors (FcγR) are...

Fish oil-based lipid emulsion in the treatment of parenteral nutrition-associated liver disease

Parenteral nutrition-associated liver disease (PNALD) is a major cause of morbidity and mortality in the parenteral nutrition-dependent population. Here, we review the most recent literature involving a fish oil-based lipid emulsion (FOLE) and its effects on PNALD. Vegetable oil-based lipid emulsions (VBLEs) contribute to PNALD. This may be due to parenteral phytosterols and/or the presence of pro-inflammatory mediators. Whereas a small reduction in the dose of VBLE does not appear to prevent PNALD, a significant reduction in the dose may reverse PNALD; however, it carries the risk of essential fatty acid deficiency. Furthermore, the impact of extreme lipid restriction on subsequent neurodevelopment is unknown. Combination lipid emulsions containing fish oil are associated with decreased bilirubin levels, though no studies compare these emulsions with the outcomes with FOLE alone. The utility of FOLE in the reversal of PNALD has been demonstrated and its administration does not lead to essential fatty acid deficiency. Furthermore, there is evidence that FOLE may prevent PNALD. FOLE appears to be an efficacious treatment to reverse PNALD. However, more studies are necessary to determine if FOLE might also be beneficial in the prevention of PNALD. Future studies should additionally focus on the preterm infant population, as they represent a major population requiring parenteral nutrition support for survival.

Immune complex-induced inhibition of osteoclastogenesis is mediated via activating but not inhibitory Fcγ receptors on myeloid precursor cells

ObjectiveTo investigate the role of Fcγ receptors (FcγRs) in osteoclastogenesis and osteoclast function.MethodsBone destruction was analysed in arthritic knee joints of several FcγR-knockout mouse strains. Unfractionated bone marrow cells were...

Activating FCγ RECEPTORS mediate immune complex-induced inhibition of osteoclastogenesis

BackgroundRheumatoid arthritis is characterised by osteoclast-mediated bone loss. Co-stimulatory signalling via ITAM- and ITIM-coupled receptors is essential for osteoclast formation and function. The ITAM- and ITIM-coupled Fcγ receptors (FcγR) play...

Infection, Inflammation, and Bone Regeneration: a Paradoxical Relationship

Various strategies have been developed to promote bone regeneration in the craniofacial region. Most of these interventions utilize implantable materials or devices. Infections resulting from colonization of these implants may result in local tissue destruction in a manner analogous to periodontitis. This destruction is mediated via the expression of various inflammatory mediators and tissue-destructive enzymes. Given the well-documented association among microbial biofilms, inflammatory mediators, and tissue destruction, it seems reasonable to assume that inflammation may interfere with bone healing and regeneration. Paradoxically, recent evidence also suggests that the presence of certain pro-inflammatory mediators is actually required for bone healing. Bone injury (e.g., subsequent to a fracture or surgical intervention) is followed by a choreographed cascade of events, some of which are dependent upon the presence of pro-inflammatory mediators. If inflammation resolves promptly, then proper bone healing may occur. However, if inflammation persists (which might occur in the presence of an infected implant or graft material), then the continued inflammatory response may result in suboptimal bone formation. Thus, the effect of a given mediator is dependent upon the temporal context in which it is expressed. Better understanding of this temporal sequence may be used to optimize regenerative outcomes.

Modulation of the response of rheumatoid arthritis synovial fibroblasts to proinflammatory stimulants with cyclic tensile strain

Although physical therapy has been shown to be an effective method for treatment of rheumatoid arthritis, a thorough investigation on the impact of mechanical signals upon the complex cytokine network associated with pathogenesis has not yet been conducted. In the current study, our research group investigated the effect of mechanical stimulation on primary and immortalized rheumatoid arthritis synovial fibroblasts (RASFs) through analysis of secreted proteins using multiplex immunoassay. Equibiaxial tensile strain was applied to 2D cultures grown on collagen-coated, flexible silicone membranes at a magnitude of 10% and a frequency of 0.5 Hz using the Flexcell System. After 24 h, supernatant was removed and assayed for the following cytokines: IL-1β, IL-6, IL-8, VEGF, FGF-2, GM-CSF, MCP-1, RANTES, TNF-α. The results were compared to unstimulated control groups. Mechanical stimulation alone only impacted secretion of IL-8 by primary RASFs. However, in the presence of proinflammatory mediators (TNF-α or IL-17), application of cyclic tensile strain increased secretion of a number of proteins by both primary and immortalized RASFs, although the responses were not analogous. In contrast, MCP-1 secretion was decreased when mechanical stimulation was applied in combination with IL-17 to primary cultures. In general, the study suggests that cyclic tensile strain can be used to modulate the effects of proinflammatory stimulants on RASFs; however, given the highly variable results, more research will be necessary to identify the pathways that are implicated in mechanotransduction.

Dysregulation of Arachodonic Acid Metabolism resulting from Aminosalicylate administration may cause Asthma Exacerbation in atopic patients with Inflammatory Bowel Disease

Aminosalicylates have been reported to be associated with respiratory side effects. Dyspnea, cough and pneumonitis have been well documented. Asthma has been speculated to be a potential adverse reaction of aminosalicylates because of the molecular similarity with aspirin. However, there have been no reported cases of asthma exacerbations occurring as a result of aminosalicylate administration. We report two cases of documented asthma occurrences, confirmed with medication rechallenge, resulting from mesalamine. Case 1: MO is a 28 year old woman with a history of asthma, not requiring chronic medications, and newly diagnosed terminal ileal and colonic Crohn's disease. She initially presented with a fever, abdominal pain and leukocytosis. Abdominal CT revealed an abscess adjacent to the ileum. Laparoscopic drainage and antibiotics resulted in abscess resolution and white count normalization. One week following mesalamine administration, MO reported dyspnea and wheezing similar to previous asthma exacerbations. Chest radiograph was normal. Self-discontinuation of mesalamine and albuterol resolved her symptoms. Two weeks later, mesalamine was restarted. The patient developed recurrent dyspnea and wheezing which resolved following mesalamine discontinuation. Case 2: CL is a 47 year old woman with a history of asthma not requiring chronic medications and colonic Crohn's disease. Initial presentation and subsequent exacerbations resulted in frequent hospitalizations and recurrent steroid administration. Treatment with mesalamine was reported to result in dyspnea and wheezing attributed to an asthma exacerbation. Chest radiograph was normal. Her respiratory symptoms were treated with albuterol and she self-discontinued her mesalamine. She subsequently transferred her care to our institution. She was restarted on mesalamine with development of dyspnea and wheezing which was attributed to an asthma exacerbation by her pulmonologist. Mesalamine was discontinued with resolution of her dyspnea. Asthma has been speculated to be an adverse reaction to aminosalicylates. However, there have been no documented cases of asthma occurring as a result of aminosalicylates. Given the similar molecular structures of aspirin and aminosalicylates, an imbalance in arachidonic acid metabolism can be a possible mechanism for asthma. The direct inhibition of the cyclooxygenase (COX1) pathway by aspirin leads to decreased prostaglandin E2 synthesis and uninhibited 5-lipoxygenase pathway resulting in increased leukotrienes. The presence of pro-inflammatory mediators may trigger bronchospasm in sensitive individuals. While aminosalicylates have been shown to inhibit prostaglandin and leukotriene formation, it can be speculated that they may stimulate prostaglandin production in certain concentrations which may rarely promote dysregulation of normal arachidonic acid metabolism. These cases illustrate that asthma exacerbation is a potential adverse reaction to mesalamine. Both patients had a history of asthma and in both cases the bronchospasm improved with discontinuation of mesalamine. Rechallenge with mesalamine resulted in recurrence of dyspnea and wheezing. The clinical evidence combined with the above proposed pathophysiology suggests that the previously speculated, but unreported complication of asthma from aminosalicylate treatment, can occur in predisposed individuals. Physicians should be aware of this potential adverse reaction to aminosalicylates to ensure optimal care.