2 research outputs found
CD14+ macrophages that accumulate in the colon of African AIDS patients express pro-inflammatory cytokines and are responsive to lipopolysaccharide
BACKGROUND : Intestinal macrophages are key regulators of inflammatory responses to the gut microbiome and play
a central role in maintaining tissue homeostasis and epithelial integrity. However, little is known about the role of
these cells in HIV infection, a disease fuelled by intestinal inflammation, a loss of epithelial barrier function and
increased microbial translocation (MT).
METHODS : Phenotypic and functional characterization of intestinal macrophages was performed for 23 African AIDS
patients with chronic diarrhea and/or weight loss and 11 HIV-negative Africans with and without inflammatory
bowel disease (IBD). AIDS patients were treated with cotrimoxazole for the prevention of opportunistic infections
(OIs). Macrophage phenotype was assessed by flow cytometry and immuno-histochemistry (IHC); production of
proinflammatory mediators by IHC and Qiagen PCR Arrays; in vitro secretion of cytokines by the Bio-Plex Suspension
Array System. Statistical analyses were performed using Spearman’s correlation and Wilcoxon matched-pair tests.
Results between groups were analyzed using the Kruskal-Wallis with Dunn’s post-test and the Mann–Whitney U tests.
RESULTS : None of the study participants had evidence of enteric co-infections as assessed by stool analysis and
histology. Compared to healthy HIV-negative controls, the colon of AIDS patients was highly inflamed with increased
infiltration of inflammatory cells and increased mRNA expression of proinflammatory cytokine (tumour necrosis factor
(TNF)-α, interleukin (IL)-1β, IFN-γ, and IL-18), chemokines (chemokine (C-C motif) ligand (CCL)2 and chemokine (C-X-C)
motif ligand (CXCL)10) and transcription factors (TNF receptor-associated factor (TRAF)6 and T-box (TXB)21). IHC
revealed significant co-localization of TNF-α and IL-1β with CD68+ cells. As in IBD, HIV was associated with a marked
increase in macrophages expressing innate response receptors including CD14, the co-receptor for lipopolysaccharide
(LPS). The frequency of CD14+ macrophages correlated positively with plasma LPS, a marker of MT. Total unfractionated
mucosal mononuclear cells (MMC) isolated from the colon of AIDS patients, but not MMC depleted of CD14+ cells, secreted increased levels of proinflammatory cytokines ex vivo in response to LPS
CONCLUSIONS : Intestinal macrophages, in the absence of overt OIs, play an important role in driving persistentinflammation in HIV patients with late-stage disease and diarrhea. These results suggest intensified treatmentstrategies that target inflammatory processes in intestinal macrophages may be highly beneficial in restoringthe epithelial barrier and limiting MT in HIV-infected patients.This research and selected researchers (EC, TR, PM, SM and CS) were funded
in part by a grant from the Delegation of the European Union to South
Africa: “Drug Resistance Surveillance and Treatment Monitoring Network for
the Public Sector HIV Antiretroviral Treatment Programme in the Free State –
Sante 2007/147-790” and by a grant from the National Research Council of
South Africa, Unlocking the Future 61509.http://www.biomedcentral.com/bmcinfectdisam201
Activated intestinal macrophages in patients with cirrhosis release NO and IL- 6 that may disrupt intestinal barrier function
BACKGROUND & AIMS : Bacterial infections commonly occur in
decompensated cirrhosis resulting from bacterial translocation
from the intestine. We studied the role of intestinal macrophages
and the epithelial barrier in cirrhosis.
METHODS : Forty-four patients with NASH/ASH cirrhosis (decompensated
n = 29, compensated n = 15) and nineteen controls
undergoing endoscopy were recruited. Serum was obtained and
LPS and LBP levels determined. Intestinal macrophages were
characterized by flow cytometry, immunohistochemistry, and
nitric oxide (NO) production measured in supernatant of cultured
duodenal samples. Quantitative RT-PCR was performed on duodenal
biopsies assessing 84 inflammatory genes. Protein levels
of cytokines/chemokines were assessed in serum and supernatant.
The duodenal wall was assessed by electron microscopy,
tight junction protein expression determined by RT-PCR, immunohistochemistry,
and Western blot and, functional analysis
performed by transepithelial resistance measurement and permeability
studies.RESULTS : Increased plasma LPS, LBP levels and higher numbers of
duodenal CD33+/CD14+/Trem-1+ macrophages, synthesizing iNOS
and secreting NO were present in decompensated cirrhosis.
Upregulation of IL-8, CCL2, CCL13 at the transcriptional level,
and increased IL-8, and IL-6 were detected in supernatant and
serum in cirrhosis. IL-6 and IL-8 co-localised with iNOS+ and
CD68+, but not with CD11c+ cells. Electron microscopy demonstrated
an intact epithelial barrier. Increased Claudin-2 was
detected by Western blot and immunohistochemistry, while
decreased transepithelial resistance and increased duodenal permeability
were detected in decompensated cirrhosis.
CONCLUSIONS : Our study shows the presence of activated CD14+-
Trem-1+iNOS+ intestinal macrophages, releasing IL-6, NO, and
increased intestinal permeability in patients with cirrhosis, suggesting
that these cells may produce factors capable of enhancing
permeability to bacterial products.http://www.journals.elsevier.com/journal-of-hepatologyhb201