Macrophage Inhibitory Factor Research Articles

Brain immune interactions and air pollution: macrophage inhibitory factor (MIF), prion cellular protein (PrPC), Interleukin-6 (IL-6), interleukin 1 receptor antagonist (IL-1Ra), and interleukin-2 (IL-2) in cerebrospinal fluid and MIF in serum differentiate urban children exposed to severe vs. low air pollution

Brain immune interactions and air pollution: macrophage inhibitory factor (MIF), prion cellular protein (PrPC), Interleukin-6 (IL-6), interleukin 1 receptor antagonist (IL-1Ra), and interleukin-2 (IL-2) in cerebrospinal fluid and MIF in serum differentiate urban children exposed to severe vs. low air pollution

Plasma cytokines and markers of endothelial activation increase after packed red blood cell transfusion in the preterm infant

Transfusion of packed red blood cells (PRBCs) saves lives in the neonatal critical care setting and is one of the most common interventions in the preterm infant. The number and volume of PRBC transfusions are associated with several major neonatal morbidities, although a direct causal link between transfusion and major neonatal morbidity is still to be proven. Transfusion-related immunomodulation (TRIM) may underlie these adverse outcomes, yet it has received little attention in the high-risk preterm infant. One transfusion event was studied in infants ≤28 wk gestation between 2 and 6 wk postnatal age (n = 28). Plasma inflammatory cytokines and markers of endothelial activation were measured in the infants before and 2-4 h after transfusion, as well as in the donor pack. Median (range) age at transfusion was 18 (14-39) days with the pretransfusion hemoglobin level at 9.8 (7.4-10.2) g/dl. Interleukin (IL)-1β (P = 0.01), IL-8 (P = <0.001), tumor necrosis factor-α (P = 0.008), and monocyte chemoattractant protein (P = 0.01) were increased after transfusion. A similar elevation in markers of endothelial activation was seen after transfusion with increased plasma macrophage inhibitory factor (P = 0.005) and soluble intracellular adhesion molecule-1 (P = <0.001). Production of inflammatory cytokines and immunoactivation of the endothelium observed after the transfusion of PRBCs in the preterm infant may be a manifestation of TRIM. The implications of this emerging phenomenon within the preterm neonatal population warrant further investigation.

Candidate gene case-control and functional study shows macrophage inhibitory factor (MIF) polymorphism is associated with cutaneous leishmaniasis

American tegumentary leishmaniasis (ATL) is an infectious disease caused mostly by Leishmania(Viannia)braziliensis in Southeast Brazil. The clinical manifestations are vast, ranging from asymptomatic to severe mucosal leishmaniasis (ML). It has been suggested that variation of the pathogen does not fully explain the response spectrum and the variability of clinical manifestations. Previous data have shown that host genetics also play a role in disease outcome. Herein, we have tested the association of TNF, IL10, IL12 and MIF single nucleotide polymorphisms (SNPs) using a case-control study design including 110 cutaneous leishmaniasis (CL) patients and 682 healthy subjects. The genotype–phenotype correlation was also assessed using leishmania antigens to stimulate peripheral blood mononuclear cells obtained from cured CL patients. Results demonstrated that the MIF −173C allele is associated with leishmaniasis outcome and also with lower levels of MIF in culture supernatants. Also, the TNF −308AA genotype was statistically increased among leishmaniasis patients. The results showed here suggest that the lower levels of MIF produced by MIF −173C carriers could influence the host–Leishmania interaction, favoring infection and disease progression. On the other hand, high TNF levels can contribute to tissue damage, consequently leading to skin lesions.

Tumor Microenvironment Macrophage Inhibitory Factor Directs the Accumulation of Interleukin-17-producing Tumor-infiltrating Lymphocytes and Predicts Favorable Survival in Nasopharyngeal Carcinoma Patients

The accumulation of an intratumoral CD4(+) interleukin-17-producing subset (Th17) of tumor-infiltrating lymphocytes (TILs) is a general characteristic in many cancers. The relationship between the percentage of Th17 cells and clinical prognosis differs among cancers. The mechanism responsible for the increasing percentage of such cells in NPC is still unknown, as is their biological function. Here, our data showed an increase of Th17 cells in tumor tissues relative to their numbers in normal nasopharynx tissues or in the matched peripheral blood of NPC patients. Th17 cells in tumor tissue produced more IFNγ than did those in the peripheral blood of matched NPC patients and healthy controls. We observed high levels of CD154, G-CSF, CXCL1, IL-6, IL-8, and macrophage inhibitory factor (MIF) out of 36 cytokines examined in tumor tissue cultures. MIF promoted the generation and recruitment of Th17 cells mediated by NPC tumor cells in vitro; this promoting effect was mainly dependent on the mammalian target of rapamycin pathway and was mediated by the MIF-CXCR4 axis. Finally, the expression level of MIF in tumor cells and in TILs was positively correlated in NPC tumor tissues, and the frequency of MIF-positive TILs was positively correlated with NPC patient clinical outcomes. Taken together, our findings illustrate that tumor-derived MIF can affect patient prognosis, which might be related to the increase of Th17 cells in the NPC tumor microenvironment.

Neuroprotective Effects of Sulforaphane after Contusive Spinal Cord Injury

Traumatic spinal cord injury (SCI) leads to oxidative stress, calcium mobilization, glutamate toxicity, the release of proinflammatory factors, and depletion of reduced glutathione (GSH) at the site of injury. Induction of the Keap1/Nrf2/ARE pathway can alleviate neurotoxicity by protecting against GSH depletion, oxidation, intracellular calcium overload, mitochondrial dysfunction, and excitotoxicity. Sulforaphane (SF), an isothiocyanate derived from broccoli, is a potent naturally-occurring inducer of the Keap1/Nrf2/ARE pathway, leading to upregulation of genes encoding cytoprotective proteins such as NAD(P)H: quinone oxidoreductase 1, and GSH-regulatory enzymes. Additionally, SF can attenuate inflammation by inhibiting the nuclear factor-κB (NF-κB) pathway, and the enzymatic activity of the proinflammatory cytokine macrophage inhibitory factor (MIF). Our study examined systemic administration of SF in a rat model of contusion SCI, in an effort to utilize its indirect antioxidant and anti-inflammatory properties to decrease secondary injury. Two doses of SF (10 or 50 mg/kg) were administered at 10 min and 72 h after contusion SCI. SF (50 mg/kg) treatment resulted in both acute and long-term beneficial effects, including upregulation of the phase 2 antioxidant response at the injury site, decreased mRNA levels of inflammatory cytokines (i.e., MMP-9) in the injured spinal cord, inactivation of urinary MIF tautomerase activity, enhanced hindlimb locomotor function, and an increased number of serotonergic axons caudal to the lesion site. These findings demonstrate that SF provides neuroprotective effects in the spinal cord after injury, and could be a candidate for therapy of SCI.

Candidate Genes Expression Profile Associated with Antidepressants Response in the GENDEP Study: Differentiating between Baseline ‘Predictors’ and Longitudinal ‘Targets’

To improve the ‘personalized-medicine' approach to the treatment of depression, we need to identify biomarkers that, assessed before starting treatment, predict future response to antidepressants (‘predictors'), as well as biomarkers that are targeted by antidepressants and change longitudinally during the treatment (‘targets'). In this study, we tested the leukocyte mRNA expression levels of genes belonging to glucocorticoid receptor (GR) function (FKBP-4, FKBP-5, and GR), inflammation (interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-7, IL-8, IL-10, macrophage inhibiting factor (MIF), and tumor necrosis factor (TNF)-α), and neuroplasticity (brain-derived neurotrophic factor (BDNF), p11 and VGF), in healthy controls (n=34) and depressed patients (n=74), before and after 8 weeks of treatment with escitalopram or nortriptyline, as part of the Genome-based Therapeutic Drugs for Depression study. Non-responders had higher baseline mRNA levels of IL-1β (+33%), MIF (+48%), and TNF-α (+39%). Antidepressants reduced the levels of IL-1β (−6%) and MIF (−24%), and increased the levels of GR (+5%) and p11 (+8%), but these changes were not associated with treatment response. In contrast, successful antidepressant response was associated with a reduction in the levels of IL-6 (−9%) and of FKBP5 (−11%), and with an increase in the levels of BDNF (+48%) and VGF (+20%)—that is, response was associated with changes in genes that did not predict, at the baseline, the response. Our findings indicate a dissociation between ‘predictors' and ‘targets' of antidepressant responders. Indeed, while higher levels of proinflammatory cytokines predict lack of future response to antidepressants, changes in inflammation associated with antidepressant response are not reflected by all cytokines at the same time. In contrast, modulation of the GR complex and of neuroplasticity is needed to observe a therapeutic antidepressant effect.

Macrophage migration inhibitory factor and DJ-1 in gastric cancer: differences between high-incidence and low-incidence areas

Background:There is a need for sensitive and specific blood-borne markers for the detection of gastric cancer. Raised serum macrophage inhibitory factor (MIF) levels have been proposed as a marker for gastric cancer diagnosis but, to date, studies have only encompassed patients from high-incidence areas.Methods:We have compared the serum concentration of MIF in a large cohort of UK and Japanese gastric cancer patients, together with appropriate control subjects (age and gender matched). Carcinoembryonic antigen and H. pylori IgG were also measured, as was DJ-1, a novel candidate protein biomarker identified by analysis of gastric cancer cell line secretomes.Results:Marked elevations of the serum concentration of MIF and DJ-1 were seen in Japanese patients with gastric cancer compared with Japanese controls, a trend not seen in the UK cohort. These results could not be accounted for by differences in age, disease stage or H. pylori status.Conclusion:In regions of high, but not low incidence of gastric cancer, both MIF and DJ-1 have elevated serum concentrations in gastric cancer patients, compared with controls. This suggests that differing mechanisms of disease pathogenesis may be at play in high- and low-incidence regions.

Mumps virus inhibits migration of primary human macrophages toward a chemokine gradient through a TNF-alpha dependent mechanism

Macrophages are an important cell type for regulation of immunity, and can play key roles in virus pathogenesis. Here we address the effect of infection of primary human macrophages with the related paramyxoviruses Parainfluenza virus 5 (PIV5) and Mumps virus (MuV). Monocyte-derived macrophages infected with PIV5 or MuV showed very little cytopathic effect, but were found to be defective in migration toward a gradient of chemokines such as macrophage colony stimulating factor (MCSF) and vascular endothelial growth factor (VEGF). For MuV infection, the inhibition of migration required live virus infection, but was not caused by a loss of chemokine receptors on the surface of infected cells. MuV-mediated inhibition of macrophage chemotaxis was through a soluble factor released from infected cells. MuV infection enhanced secretion of TNF-α, but not macrophage inhibitory factor (MIF). Antibody inhibition and add-back experiments demonstrated that TNF-α was both necessary and sufficient for MuV-mediate chemotaxis inhibition.

Role of Microparticles as Messengers Enhancing Stem Cell Activity After Genetic Engineering

Despite significant therapeutic advances over several decades, myocardial infarction remains the most common cause of death worldwide. In this context, cell-based therapy was considered a promising novel strategy for regeneration of healthy, functionally integrated, myocardial tissue. Unfortunately, the clinical trials using cell-based therapy did not always confirm the preclinical experimental results.1,2 Therefore, in the last decade, the efforts were focused on studying the complex molecular and cellular mechanisms contributing to improved myocardial remodeling and function after stem cell transplantation.3 Article, see p 312 Because cell-based therapy has been proposed, various cell types were tested in transplantation experiments.4–10 Among all, autologous bone marrow-derived CD34+ stem cells demonstrate a major benefit, showing favorable impact on angiogenic growth, without the toxicity and inflammatory response observed in nonautologous cell-based therapy.11,12 However, insufficient number of donor stem cells, low cell viability, and inefficient expansion techniques limit the effects of this therapy. In this regard, overexpressing angiogenic growth factors in transplanted cells has been reported to be beneficial by attenuating myocardial ischemia and preserving the heart function.13–17 In this issue of Circulation Research , Mackie et al investigate the mechanisms of preserving the heart function after transplantation of CD34+ cells overexpressing sonic hedgehog (Shh) protein, a well-established angiogenic factor.18 After …

Coculture with hematopoietic stem cells protects cardiomyocytes against apoptosis via paracrine activation of AKT

BackgroundPrevious experimental studies concluded that stem cells (SC) may exert their beneficial effects on the ischemic heart by paracrine activation of antiapoptotic pathways. In order to identify potential cardioprotective mediators, we performed a systematic analysis of the differential gene expression of hematopoietic SC after coculture with cardiomyocytes (CM).MethodsAfter 48 h of coculture with neonatal rat ventricular CM (NRVCM), two consecutive cell sorting steps generated a highly purified population of conditioned murine hematopoietic SC (>99%). Next, a genome-wide microarray analysis of cocultured vs. monocultured hematopoietic SC derived from three independent experiments was performed. The analysis of differentially expressed genes was focused on products that are secretable and/or membrane-bound and potentially involved in antiapoptotic signalling.ResultsWe found CCL-12, Macrophage Inhibitory Factor, Fibronectin and connexin 40 significantly upregulated in our coculture model. An ELISA of cell culture supernatants was performed to confirm secretion of candidate genes and showed that coculture supernatants revealed markedly higher CCL-12 concentrations. Moreover, we stimulated NRVCM with concentrated coculture supernatants which resulted in a significant reduction of apoptosis compared to monoculture-derived supernatant. Mechanistically, NRVCMs stimulated with coculture supernatants showed a higher level of AKT-phosphorylation, consistent with enhanced antiapoptotic signaling.ConclusionIn summary, our results show that the interaction between hematopoietic SC and NRVCM led to a modified gene expression and induction of antiapoptotic pathways. These findings may thus at least in part explain the cardioprotective effects of hematopoietic SC.

Decidual cells as target for Macrophage Inhibitory Migration Factor (MIF): receptors and signaling pathways associated responses

Decidual cells as target for Macrophage Inhibitory Migration Factor (MIF): receptors and signaling pathways associated responses

Macrophage inhibitory factor (MIF) in the nucleus of tract solitary (NTS) improves baroreflex function in spontaneously hypertensive rats (SHR)

SHR have impaired baroreflex function. Previously we demonstrated that increased expression of MIF in the NTS of SHR can reduce resting mean arterial pressure (MAP). Thus, in this study we investigated whether MIF over expression in the NTS of SHR can alter baroreflex function. Male SHR (9 weeks old) or normotensive (NT) control rats were injected at 5 sites in the NTS with (1×109 gc in 150 nl) adenoassociated viruses for over expression of MIF or eGFP. Thirty days after the microinjections the femoral artery and vein were cannulated under anesthesia to measure MAP and heart rate (HR), and to perform drug infusions in awake animals the next day. During the experiment, we used phenylephrine to elicit a pressor response (5 μg/kg) and sodium nitroprusside (30 μg/kg) to produce a depressor response, and analyzed the HR reflex response to each 10 mmHg change in MAP. The results showed that the SHR‐eGFP group exhibited a significant impairment of the baroreflex compared with the NT‐eGFP rats, as expected. Further, the SHR‐MIF rats exhibited improvement in the baroreflex curves as to tachycardia (1/slope: − 2.4 ± 0.38) and bradycardia responses (1/slope: −3 ± 0.28) when compared to SHR‐eGFP rats (1/slope bradycardia: −1.1 ± 0.28; tachycardia: −1.2 ± 0.72). The results showed that MIF over expression in the NTS improves the cardiac baroreflex in SHR, helping to decrease the MAP in these animals.Supported by: CNPq, FAPESP, NIH

Changes in macrophage inhibitory factor and liver injury in rats with severe acute pancreatitis during pregnancy

Objective To observe the levels of serum macrophage migration inhibitory factor (MIF) and the expression of MIF mRNA in the liver tissue and the liver injury of pregnant rats with severe acute pancreatitis.Methods Pregnant SD rats were randomly divided into pregnancy group and SAP group.Non-pregnant female rats were randomly divided into sham operation group (SO group) and SAP group.Rats were killed at 3rd,6th and 12th h,respectively.Liver function levels,serum MIF,and liver tissue pathological changes were observed.The expression of MIF mRNA was assayed by semi-quantitative reverse transcription-polymersse chain reaction (RT-PCR).Results Liver function levels and the levels of serum MIF [3 h:( 12.46 ±3.66) vs (6.17 ±2.29) μg/L; 6 h:( 14.02 ±3.19) vs (8.32 ±3.51 ) μg/L;12 h:(13.81 ±3.72) vs (8.53 ±2.46) μg/L,P＜0.01 ] at each time point were higher significantly in SAP group of pregnant rats than those in SAP group.Histological scores of the liver at 3rd,and 6th h were higher significantly in SAP group of pregnant rats than in SAP group.The expression of MIF mRNA of the liver at 3rd,and 6th h was higher significantly in SAP group of pregnant rats than that in SAP group (3 h:0.58±0.12vs0.37±0.10,P＜0.01;6h:0.55±0.11 vs0.41±0.12,P＜0.0S).Conclusion The pancreatitis and liver injury occurring in pregnant rats are more acute and more severe.MIF may be one of the mechanisms in the pathogenesis of liver injury in SAP.Serum MIF concentrations of pregnant rats and expression of liver MIF mRNA are increased rapidly in early stage of disease,which may be one of the reasons in acute and severe onset of SAP in pregnant rats. Key words: Pregnancy; Severe pancreatitis; Liver; Macrophage migration inhibitory factors

Role of Obesity and Lipotoxicity in the Development of Nonalcoholic Steatohepatitis: Pathophysiology and Clinical Implications

As obesity reaches epidemic proportions, nonalcoholic fatty liver disease (NAFLD) is becoming a frequent cause of patient referral to gastroenterologists. There is a close link between dysfunctional adipose tissue in NAFLD and common conditions such as metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. This review focuses on the pathophysiology of interactions between adipose tissue and target organs in obesity and the resulting clinical implications for the management of nonalcoholic steatohepatitis. The release of fatty acids from dysfunctional and insulin-resistant adipocytes results in lipotoxicity, caused by the accumulation of triglyceride-derived toxic metabolites in ectopic tissues (liver, muscle, pancreatic beta cells) and subsequent activation of inflammatory pathways, cellular dysfunction, and lipoapoptosis. The cross talk between dysfunctional adipocytes and the liver involves multiple cell populations, including macrophages and other immune cells, that in concert promote the development of lipotoxic liver disease, a term that more accurately describes the pathophysiology of nonalcoholic steatohepatitis. At the clinical level, adipose tissue insulin resistance contributes to type 2 diabetes mellitus and cardiovascular disease. Treatments that rescue the liver from lipotoxicity by restoring adipose tissue insulin sensitivity (eg, significant weight loss, exercise, thiazolidinediones) or preventing activation of inflammatory pathways and oxidative stress (ie, vitamin E, thiazolidinediones) hold promise in the treatment of NAFLD, although their long-term safety and efficacy remain to be established. Better understanding of pathways that link dysregulated adipose tissue, metabolic dysfunction, and liver lipotoxicity will result in improvements in the clinical management of these challenging patients.

Overexpression of extracellular superoxide dismutase has a protective role against hyperoxia‐induced brain injury in neonatal mice

There is increasing evidence that hyperoxia, particularly at the time of birth, may result in neurological injury, in particular to the susceptible vasculature of these tissues. This study was aimed at determining whether overexpression of extracellular superoxide dismutase (EC-SOD) is protective against brain injury induced by hyperoxia. Transgenic (TG) mice (with an extra copy of the human extracellular superoxide dismutase gene) and wild-type (WT) neonate mice were exposed to hyperoxia (95% of F(i) o(2) ) for 7 days after birth versus the control group in room air. Brain positron emission tomography (PET) scanning with fludeoxyglucose (FDG) isotope uptake was performed after exposure. To assess apoptosis induced by hyperoxia exposure, caspase 3 ELISA and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were performed. Quantitative western blot for the following inflammatory markers was performed: glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, macrophage-inhibiting factor, and phospho-AMP-activated protein kinase. PET scanning with FDG isotope uptake showed significantly higher uptake in the WT hyperoxia neonate brain group (0.14 ± 0.03) than in both the TG group (0.09 ± 0.01) and the control group (0.08 ± 0.02) (P< 0.05). Histopathological investigation showed more apoptosis and dead neurons in hippocampus and cerebellum brain sections of WT neonate mice after exposure to hyperoxia than in TG mice; this finding was also confirmed by TUNEL staining. The caspase 3 assay confirmed the finding of more apoptosis in WT hyperoxia neonates (0.814 ± 0.112) than in the TG hyperoxic group (0.579 ± 0.144) (P < 0.05); this finding was also confirmed by TUNEL staining. Quantitative western blotting for the inflammatory and metabolic markers showed significantly higher expression in the WT group than in the TG and control groups. Thus, overexpression of EC-SOD in the neonate brain offers significant protection against hyperoxia-induced brain damage.

Biomarker of bone destruction

Patients with rheumatoid arthritis (RA) often have progression of bone destruction owing to chronic inflammation. Treatment for bone destruction is still insufficient in these patients although goal of treatment has become remission since biologics have been used widely. It is shown that collagen cross-linked C-peptide (CTX- I ) and tartrate-resistant acid phosphatase (TRACP) have correlated with bone destruction in patients with RA, in addition, evidence of new biomarker such as hepatocyte growth factor and macrophage inhibitory factor have been accumulated recently. These biomarkers may help evaluation of bone quality clinically.

Changes in macrophage inhibitory factor correlate with changes in bone mineral density in glucocorticoid-treated patients with rheumatoid arthritis

To investigate whether changes in bone density and turnover are associated with changes in inflammatory mediators in RA patients treated with glucocorticoids (GCs) upon vitamin D treatment in comparison with alendronate treatment. RA patients (n = 40) on long-term oral GC treatment received either alfacalcidol or alendronate. At baseline and after 18 months, we measured cytokines capable of antagonizing GCs [macrophage migration inhibitory factor (MIF), IL-13 and IL-7], cytokines causing T-cell differentiation (IL-6, IL-7, IL-12, IL-10 and IL-23) and cytokines produced by effector T cells (IFN-γ, IL-4, IL-17, IL-22). Associations of cytokine profiles with bone markers and BMD changes of the lumbar spine were explored using multiple regression analyses that corrected for study medication and risk factors of osteoporosis (gender, age, cumulative/change in GC dose). Alendronate, unlike alfacalcidol, increased BMD changes in the lumbar spine. Most cytokines were below detection limits. MIF and IL-23 were detectable in almost all samples; neither alfacalcidol nor alendronate significantly influenced serum concentrations of these cytokines. Interestingly, changes in MIF correlated positively with changes in BMD of the lumber spine (Pearson's correlation = 0.31), and in multivariate analysis adjusting for treatment, age and change in GC dose (P = 0.022). During GC treatment, changes in the GC-antagonist MIF were positively correlated with changes in BMD, which could mean MIF has bone-protecting capacities in patients suffering from GC-induced bone destruction. Further studies need to validate the importance of these findings.

Adipose tissue‐derived adiponectin expression is significantly associated with increased post operative mortality in horses undergoing emergency abdominal surgery

Adipose tissue is an important source of inflammatory cytokines (adipokines) and adiposity has been identified as having a significant effect on human morbidity and mortality. Obesity is also an emerging welfare problem in the UK horse population, but the role that it plays in secondary diseases is unclear. To examine the expression of inflammation-related adipokine genes in retroperitoneal adipose tissue of horses undergoing emergency abdominal surgery and to explore associations with adiposity and post operative survival. Retroperitoneal adipose tissue samples were obtained from 76 horses undergoing emergency abdominal surgery. Real-time PCR was used to measure gene expression for leptin, adiponectin, tumour necrosis factor-alpha, macrophage chemoattractant protein-1, macrophage inhibitory factor, serum amyloid A, haptoglobin and interleukin-1. Multivariate patterns of adipokine expression were explored with principal component analysis (PCA), whilst univariable associations with post operative survival were tested in a Cox proportional hazards model. Leptin gene expression was higher in overweight and obese horses than in lean animals. Expression of mRNA encoding adiponectin mRNA in visceral adipose tissue was positively associated with increased post operative mortality (hazard ratio 1.31, 95% CI 1.05-1.65). However, PCA did not demonstrate multivariable patterns of adipokine gene expression from visceral adipose tissue associated with body mass index or with survival. In horses presented with acute intestinal disease, increased adiponectin gene expression from retroperitoneal adipose tissue is associated with an increased risk of mortality. Obesity assessed by BMI had no association with increased post operative mortality in horses with primary gastrointestinal disease. Further study is warranted on the expression and effects of adipokines, particularly adiponectin, and correlation with postoperative outcome.

Protein Kinase C and NF-κB–Dependent CD4 Downregulation in Macrophages Induced by T Cell-Derived Soluble Factors: Consequences for HIV-1 Infection

Upon activation, CD4(+) T cells release cytokines, chemokines, and other soluble factors that influence the kinetics of HIV-1 replication in macrophages (M). In this article, we show that activation of human primary T cells suppresses the early stages of HIV-1 replication in human primary Mφ by downregulating the main cellular receptor for the virus CD4. The secreted factors responsible for this effect have a molecular mass greater than conventional cytokines, are independent of Th1 or Th2 polarization, and are not IFN-γ, IL-16, RANTES, or macrophage inhibitory factor, as revealed by cytokine array analysis and neutralization assays. CD4 downregulation is entirely posttranslational and involves serine phosphorylation of CD4 and its targeting to an intracellular compartment destined for acidification and degradation. CD4 downregulation is dependent on the activities of both protein kinase C and NF-κB as well as the proteasomes. Using high-resolution liquid chromatography-tandem mass spectrometry analysis in conjugation with label-free protein quantitation software, we found that proteins that promote Mφ adherence and spreading, such as attractin, fibronectin, and galectin-3-binding protein, were significantly overrepresented in the activated T cell supernatant fractions. These results reveal the existence of previously unreported anti-HIV-1 proteins, released by activated T cells that downregulate CD4 expression, and are of fundamental importance to understand the kinetics of HIV infection in vivo.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature