Serum lipopolysaccharide-binding protein and soluble CD14 are markers of disease activity in patients with Crohn's disease

Negative regulation of human mononuclear phagocyte function

At mucosal surfaces, phagocytes such as macrophages coexist with microbial communities; highly controlled regulation of these interactions is essential for immune homeostasis. Pattern-recognition receptors (PRRs) are critical in recognizing and responding to microbial products, and they are subject to negative regulation through various mechanisms, including downregulation of PRR-activating components or induction of inhibitors. Insights into these regulatory mechanisms have been gained through human genetic disease-association studies, in vivo mouse studies utilizing disease models or targeted gene perturbations, and in vitro and ex vivo human cellular studies examining phagocytic cell functions. Although mouse models provide an important approach to study macrophage regulation, human and mouse macrophages exhibit differences, which must be considered when extrapolating mouse findings to human physiology. This review discusses inhibitory regulation of PRR-induced macrophage functions and the consequences of dysregulation of these functions and highlights mechanisms that have a role in intestinal macrophages and in human macrophage studies.

Relevance of TNBS-colitis in rats: a methodological study with endoscopic, histologic and Transcriptomic [corrected] characterization and correlation to IBD

Background

Rectal instillation of trinitrobenzene sulphonic acid (TNBS) in ethanol is an established model for inflammatory bowel disease (IBD). We aimed to 1) set up a TNBS-colitis protocol resulting in an endoscopic and histologic picture resembling IBD, 2) study the correlation between endoscopic, histologic and gene expression alterations at different time points after colitis induction, and 3) compare rat and human IBD mucosal transcriptomic data to evaluate whether TNBS-colitis is an appropriate model of IBD.

Methodology/Principal Findings

Five female Sprague Daley rats received TNBS diluted in 50% ethanol (18 mg/0.6 ml) rectally. The rats underwent colonoscopy with biopsy at different time points. RNA was extracted from rat biopsies and microarray was performed. PCR and in situ hybridization (ISH) were done for validation of microarray results. Rat microarray profiles were compared to human IBD expression profiles (25 ulcerative colitis Endoscopic score demonstrated mild to moderate colitis after three and seven days, but declined after twelve days. Histologic changes corresponded with the endoscopic appearance. Over-represented Gene Ontology Biological Processes included: Cell Adhesion, Immune Response, Lipid Metabolic Process, and Tissue Regeneration. IL-1α, IL-1β, TLR2, TLR4, PRNP were all significantly up-regulated, while PPARγ was significantly down-regulated. Among genes with highest fold change (FC) were SPINK4, LBP, ADA, RETNLB and IL-1α. The highest concordance in differential expression between TNBS and IBD transcriptomes was three days after colitis induction. ISH and PCR results corresponded with the microarray data. The most concordantly expressed biologically relevant pathways included TNF signaling, Cell junction organization, and Interleukin-1 processing.

Conclusions/Significance

Endoscopy with biopsies in TNBS-colitis is useful to follow temporal changes of inflammation visually and histologically, and to acquire tissue for gene expression analyses. TNBS-colitis is an appropriate model to study specific biological processes in IBD.

Chronic immune activation in common variable immunodeficiency (CVID) is associated with elevated serum levels of soluble CD14 and CD25 but not endotoxaemia

Common variable immunodeficiency (CVID), the most frequent symptomatic immunoglobulin primary immunodeficiency, is associated with chronic T cell activation and reduced frequency of CD4(+) T cells. The underlying cause of immune activation in CVID is unknown. Microbial translocation indicated by elevated serum levels of lipopolysaccharide and soluble CD14 (sCD14) has been linked previously to systemic immune activation in human immunodeficiency virus/acquired immune deficiency syndrome (HIV-1/AIDS), alcoholic cirrhosis and other conditions. To address the mechanisms of chronic immune activation in CVID, we performed a detailed analysis of immune cell populations and serum levels of sCD14, soluble CD25 (sCD25), lipopolysaccharide and markers of liver function in 35 patients with CVID, 53 patients with selective immunoglobulin (Ig)A deficiency (IgAD) and 63 control healthy subjects. In CVID subjects, the concentration of serum sCD14 was increased significantly and correlated with the level of sCD25, C-reactive protein and the extent of T cell activation. Importantly, no increase in serum lipopolysaccharide concentration was observed in patients with CVID or IgAD. Collectively, the data presented suggest that chronic T cell activation in CVID is associated with elevated levels of sCD14 and sCD25, but not with systemic endotoxaemia, and suggest involvement of lipopolysaccharide-independent mechanisms of induction of sCD14 production.

Biomarkers of microbial translocation and macrophage activation: association with progression of subclinical atherosclerosis in HIV-1 infection

BACKGROUND

The relationships between soluble CD14 (sCD14), endotoxin (lipopolysaccharide [LPS]), and progression of atherosclerosis have not been defined in human immunodeficiency virus (HIV) infection.

METHODS

We retrospectively assessed serum sCD14 and LPS levels of 91 subjects in a prospective 3-year study of carotid artery intima-media thickness (CIMT) (AIDS Clinical Trials Group [ACTG] 5078), where subjects were enrolled as risk factor-controlled triads of HIV-uninfected (n = 36) and HIV-infected individuals with (n = 29) or without (n = 26) protease inhibitor (PI)-based therapy for ≥2 years. The primary end point was the yearly rate of change of CIMT (ΔCIMT).

RESULTS

In multivariate analysis of the HIV-infected subjects, each 1 µg/mL above the mean of baseline serum sCD14 corresponded to an additional 1.52 µm/y (95% confidence interval, .07-2.98; P = .04) in the ΔCIMT. Every 100 pg/mL above the mean of baseline serum LPS corresponded to an additional 0.49 µm/y (95% confidence interval, .18-.81; P = .003) in the ΔCIMT. However, in univariate analysis in the HIV-uninfected group sCD14 (P = .33) and LPS (P = .27) levels were not associated with higher ΔCIMT. HIV infection and PI therapy were not associated with baseline serum LPS and sCD14 levels (P > .1).

CONCLUSIONS

Our data are among the first to suggest that serum biomarkers of microbial translocation (LPS) and macrophage activation (sCD14) predict subclinical atherosclerosis progression in HIV-infected persons.

Association between CD14 gene C-260T polymorphism and inflammatory bowel disease: a meta-analysis

Background

The gene encoding CD14 has been proposed as an IBD-susceptibility gene with its polymorphism C-260T being widely evaluated, yet with conflicting results. The aim of this study was to investigate the association between this polymorphism and IBD by conducting a meta-analysis.

Methodology/Principal Findings

Seventeen articles met the inclusion criteria, which included a total of 18 case-control studies, including 1900 ulcerative colitis (UC) cases, 2535 Crohn's disease (CD) cases, and 4004 controls. Data were analyzed using STATA software. Overall, association between C-260T polymorphism and increased UC risk was significant in allelic comparison (odds ratio [OR]  = 1.21, 95% confidence interval [CI]: 1.02–1.43; P = 0.027), homozygote model (OR  = 1.44, 95% CI: 1.03–2.01; P = 0.033), as well as dominant model (OR  = 1.36, 95% CI: 1.06–1.75; P = 0.016). However, there was negative association between this polymorphism and CD risk across all genetic models. Subgroup analyses by ethnicity suggested the risk-conferring profiles of -260T allele and -260 TT genotype with UC in Asians, but not in Caucasians. There was a low probability of publication bias.

Conclusions/Significance

Expanding previous results of individual studies, our findings demonstrated that CD14 gene C-260T polymorphism might be a promising candidate marker in susceptibility to UC, especially in Asians.

High-sensitivity C-reactive protein for identification of disease phenotype, active disease, and clinical relapses in Crohn's disease: a marker for patient classification?

BACKGROUND

C-reactive protein (CRP) is a traditional nonspecific marker of inflammation, with Crohn's disease (CD) being associated with a strong CRP response. Thus far, no clear cutoff values have been determined. The authors' aim was to investigate whether high-sensitivity (hs)-CRP is useful for the identification disease phenotype, active disease, and relapse during follow-up, using a classification based on the hs-CRP value at diagnosis.

METHODS

In all, 260 well-characterized, unrelated, consecutive CD patients (male/female: 120/140; duration: 7.0 ± 6.1 years), with a complete clinical follow-up, were included. Hs-CRP, clinical activity according to the Harvey-Bradshaw Index, and clinical data (disease phenotype according to the Montreal Classification, extraintestinal manifestations, smoking habits, medical therapy, and surgical events) were prospectively collected between January 1, 2008 and June 1, 2010. Medical records prior to the prospective follow-up period were analyzed retrospectively.

RESULTS

In all, 32.3% of CD patients had normal hs-CRP at diagnosis. Elevated hs-CRP at diagnosis was associated with disease location (P = 0.002), noninflammatory disease behavior (P = 0.058), and a subsequent need for later azathioprine/biological therapy (P < 0.001 and P = 0.024), respectively. The accuracy of hs-CRP for identifying patients with active disease during prospective follow-up was good (area under the curve [AUC]: 0.82, cutoff: 10.7 mg/L). AUC was better in patients with an elevated hs-CRP at diagnosis (AUC: 0.92, cutoff: 10.3 mg/L). In Kaplan-Meier and Cox-regression analyses, hs-CRP was an independent predictor of 3- (P = 0.007) or 12-month (P = 0.001) clinical relapses for patients in remission who had elevated hs-CRP at diagnosis. In addition, perianal involvement (P = 0.01) was associated with the 12-month relapse frequency.

CONCLUSIONS

Our data suggest that hs-CRP positivity at diagnosis is associated with disease location and behavior, and in patients who are hs-CRP positive at diagnosis, is an accurate marker of disease activity and a predictor of short- and medium-term clinical flare-ups during follow-up.

Porphyromonas gingivalis LPS stimulates the expression of LPS-binding protein in human oral keratinocytes in vitro

LPS-binding protein (LBP) functions as a crucial molecule in innate immune responses to bacterial challenge. Our study has shown the expression of LBP in human gingiva and its significant association with periodontal health and disease. Porphyromonas gingivalis is a key pathogen of periodontal disease. P. gingivalis LPS as a main virulence factor is strongly involved in periodontal pathogenesis and it displays a significant lipid A structural heterogeneity. Currently, it remains unknown whether, and to what extent, the lipid A structural heterogeneity of P. gingivalis LPS affects LBP expression. The present study investigated the expression profile of LBP in human oral keratinocytes (HOKs) stimulated by two isoforms of P. gingivalis LPS [tetra- (LPS(1435/1449)) and penta-acylated (LPS(1690))] and Escherichia coli LPS, and the involvement of TLRs in LBP expression. The results showed that the expression of LBP mRNA and peptide was significantly up-regulated by P. gingivalis LPS(1690) and E. coli LPS, while P. gingivalis LPS(1435/1449) did not affect LBP expression. Blocking assay and siRNA gene silencing revealed that P. gingivalis LPS(1690)-induced LBP expression was through both TLR2 and TLR4. This in vitro study demonstrates that P. gingivalis LPS with a lipid A structural heterogeneity differentially modulates LBP expression in HOKs.

Oil composition of high-fat diet affects metabolic inflammation differently in connection with endotoxin receptors in mice

Low-grade inflammation observed in obesity is a risk factor for cardiovascular disease. Recent studies revealed that this would be linked to gut-derived endotoxemia during fat digestion in high-fat diets, but nothing is known about the effect of lipid composition. The study was designed to test the impact of oil composition of high-fat diets on endotoxin metabolism and inflammation in mice. C57/Bl6 mice were fed for 8 wk with chow or isocaloric isolipidic diets enriched with oils differing in fatty acid composition: milk fat, palm oil, rapeseed oil, or sunflower oil. In vitro, adipocytes (3T3-L1) were stimulated or not with lipopolysaccharide (LPS; endotoxin) and incubated with different fatty acids. In mice, the palm group presented the highest level of IL-6 in plasma (P < 0.01) together with the highest expression in adipose tissue of IL-1β and of LPS-sensing TLR4 and CD14 (P < 0.05). The higher inflammation in the palm group was correlated with a greater ratio of LPS-binding protein (LBP)/sCD14 in plasma (P < 0.05). The rapeseed group resulted in higher sCD14 than the palm group, which was associated with lower inflammation in both plasma and adipose tissue despite higher plasma endotoxemia. Taken together, our results reveal that the palm oil-based diet resulted in the most active transport of LPS toward tissues via high LBP and low sCD14 and the greatest inflammatory outcomes. In contrast, a rapeseed oil-based diet seemed to result in an endotoxin metabolism driven toward less inflammatory pathways. This shows that dietary fat composition can contribute to modulate the onset of low-grade inflammation through the quality of endotoxin receptors.

Microbial translocation across the GI tract

The lumen of the gastrointestinal (GI) tract is home to an enormous quantity of different bacterial species, our microbiota, that thrive in an often symbiotic relationship with the host. Given that the healthy host must regulate contact between the microbiota and its immune system to avoid overwhelming systemic immune activation, humans have evolved several mechanisms to attenuate systemic microbial translocation (MT) and its consequences. However, several diseases are associated with the failure of one or more of these mechanisms, with consequent immune activation and deleterious effects on health. Here, we discuss the mechanisms underlying MT, diseases associated with MT, and therapeutic interventions that aim to decrease it.

Early clinical remission and normalisation of CRP are the strongest predictors of efficacy, mucosal healing and dose escalation during the first year of adalimumab therapy in Crohn's disease

BACKGROUND

Adalimumab is a fully human monoclonal antibody targeting tumour necrosis factor with proven efficacy in the treatment of Crohn's disease (CD).

AIM

To investigate the predictors of medium-term clinical efficacy and mucosal healing during adalimumab therapy, in patients with CD, in specialised centres approved for biological therapy in Hungary.

METHODS

Data capture of the 201 CD patients was standardised and prospective (male/female: 112/89, median age: 33.0 years, duration: 8 years). Previous infliximab therapy had been administered in 48% of patients, concomitant steroids in 41%, azathioprine in 69% and combined therapy in 27% of patients.

RESULTS

Overall clinical response and remission rates at 24 weeks were 78% and 52%, respectively; at 52 weeks were 69% and 44%, respectively. Endoscopic improvement and healing were achieved in 43% and 24% of patients. In a logistic regression model, clinical efficacy and CRP at week 12, need for combined immunosuppression at induction, shorter disease duration and smoking were identified as independent predictors for 12-month clinical outcome, whereas CRP at week 12, clinical remission at week 24, inflammatory parameters and nonsmoking were associated to endoscopic improvement/healing. Intensification to weekly dosing was needed in 16% of patients. Parallel azathioprine therapy and clinical remission at week 12 were inversely associated with dose escalation.

CONCLUSIONS

Clinical efficacy and normalised CRP at week 12 (early deep clinical remission) are associated with medium-term clinical efficacy and mucosal healing during adalimumab therapy, whereas need for combined immunosuppression at induction and smoking status are predictors for non-response. Parallel azathioprine therapy may decrease the probability for dose escalation.

[Predictors of efficacy, mucosal healing and dose intensification during the first year of adalimumab therapy in patients with luminal and fistulizing Crohn's disease. National data from Hungary]

Adalimumab is a fully human monoclonal antibody targeting tumor necrosis factor with proven efficacy in the treatment of Crohn's disease in clinical trials. The aim of the present study was to investigate the predictors of medium term clinical efficacy and mucosal healing during adalimumab therapy in patients with Crohn's disease in specialized centers approved for biological therapy in Hungary.

METHODS

Data of 201 Crohn's disease patients were prospectively captured (male/female: 112/89, median age: 24 years, duration: 8 years). Previous infliximab therapy was given in 97 (48.3%) patients, concomitant steroids in 41.3% and azathioprine in 69.2% (combined: 26.4%) of patients.

RESULTS

Overall clinical response and remission rates at 24 and 52 weeks were 78% and 52%, and 69.4% and 44.4%, respectively. Endoscopic improvement and healing was achieved in 43.1% and 23.6%, respectively. In a logistic regression model, clinical efficacy and normalized C-reactive protein at week 12, need for combined immunosuppression at induction, shorter disease duration and smoking were identified as independent predictors for 12-month clinical outcome, while normalized C-reactive protein at week 12, clinical remission at week 24, frequency of previous relapses and smoking were associated to endoscopic improvement/healing. Dose intensification to weekly dosing was needed in 16.4%. Parallel azathioprine therapy and clinical remission at week 12 was inversely associated to dose escalation to weekly dosing.

CONCLUSION

Clinical efficacy and normalized C-reactive protein at week 12, need for combined immunosuppression, luminal disease and smoking are predictors for medium term clinical efficacy/mucosal healing during adalimumab therapy, while parallel azathioprine therapy may decrease the probability for dose escalation.

Cellular and molecular mechanisms in the two major forms of inflammatory bowel disease

The factors involved in the pathogenesis of Crohn's disease and ulcerative colitis, the two major types of inflammatory bowel disease (IBD) are summarized. Intestinal antigens composed of bacterial flora along with antigen presentation and impaired mucosal barrier have an important role in the initiation of IBD. The bacterial community may be modified by the use of antibiotics and probiotics. The dentritic cells recognize the antigens by cell surface Toll like receptor and the cytoplasmic CARD/NOD system. The balance between Th1/Th2/Th17 cell populations being the source of a variety of cytokines regulates the inflammatory mechanisms and the clearance of microbes. The intracellular killing and digestion, including autophagy, are important in the protection against microbes and their toxins. The homing process determines the location and distribution of the immune cells along the gut. All these players are potential targets of pharmacological manipulation of disease status.