Macrophage differentiation and function in health and disease

Granulomatous inflammatory reaction in human gastric adenocarcinomas: a light and electron microscopy study

Granuloma is a focal, compact collection of inflammatory cells in which mononuclear phagocytes predominate. The authors report 9 cases of papillary-tubular gastric adenocarcinomas characterized by mature granulomas associated with recent microhemorrhages. Mature granulomas were composed of foamy, CD68-positive histiocytes with occasional giant cells. Hemosiderin-containing macrophages were present in the tumor stroma, suggesting phagocytosis of erythrocytes. Under electron microscopy, mature (nonepithelioid) granulomas and clusters containing 1 macrophage and 1-3 eosinophils were found. This study provides morphological examples of skewed type II macrophage infiltration in gastric adenocarcinomas that is involved in scavenging activity, particularly erythrophagocytosis, formation of mature (nonepithelioid granulomas), and heterotypic aggregation with eosinophils.

Tyrosine kinases as targets for the treatment of rheumatoid arthritis

As critical regulators of numerous cell signaling pathways, tyrosine kinases are implicated in the pathogenesis of several diseases, including rheumatoid arthritis (RA). In the absence of disease, synoviocytes produce factors that provide nutrition and lubrication for the surrounding cartilage tissue; few cellular infiltrates are seen in the synovium. In RA, however, macrophages, neutrophils, T cells and B cells infiltrate the synovium and produce cytokines, chemokines and degradative enzymes that promote inflammation and joint destruction. In addition, the synovial lining expands owing to the proliferation of synoviocytes and infiltration of inflammatory cells to form a pannus, which invades the surrounding bone and cartilage. Many of these cell responses are regulated by tyrosine kinases that operate in specific signaling pathways, and inhibition of a number of these kinases might be expected to provide benefit in RA.

Alterations in cellular proteome and secretome upon differentiation from monocyte to macrophage by treatment with phorbol myristate acetate: insights into biological processes

Monocyte and macrophage are mainly involved in immune response and inflammatory processes. Monocytes circulate in the bloodstream and migrate to various tissues where they can differentiate to macrophages. However, the molecular basis of biological processes involved in this cellular differentiation remains ambiguous. This study was to investigate alterations in cellular and secreted proteins after this differentiation phase. Macrophage was differentiated from U937 human monocytic cell line by treatment with 100 ng/ml phorbol myristate acetate (PMA) for 48 h. Cellular and secreted proteins extracted from PMA-treated cells (macrophages) were compared with those of untreated cells (monocytes) using 2-DE (n=5 gels/condition; stained with Deep Purple fluorescence dye). Quantitative intensity analysis revealed 81 and 67 protein spots whose levels were significantly altered in cellular proteome and secretome. These proteins were subsequently identified by Q-TOF MS and/or MS/MS analyses. The altered levels of cellular elongation factor-2 (EF-2) and secreted alpha-tubulin were confirmed by Western blot analysis. Global protein network analysis demonstrated that these altered proteins were involved in cell death, lipid metabolism, cell morphology, cellular movement, and protein folding. Our data may provide some insights into molecular mechanisms of biological processes upon differentiation from monocytes to macrophages.

Molecular cloning and characterization of macrophage migration inhibitory factor from small abalone Haliotis diversicolor supertexta

The macrophage migration inhibitory factor (mif) cDNA and its genome were cloned from small abalone Haliotis diversicolor supertexta. Small abalone mif (samif) was originally identified from an expressed sequence tag (EST) fragment from a normalized cDNA library. It's 5' untranslated region (UTR) was obtained by 5' rapid amplification of cDNA end (RACE) techniques and its genomic DNA was cloned by PCR. The full-length cDNA of samif was of 535 bp, consisting of a 5'-terminal UTR of 49 bp, an open reading frame of 384 bp and a 3'-terminal UTR of 102 bp. The deduced protein was composed of 128 amino acids, with an estimated molecular mass of 14.0 kDa and a predicted pI of 6.90. The full-length samif genomic DNA comprises 3238 bp, containing three exons and two introns. Real time quantitative PCR analysis revealed that samif gene is constitutively expressed in 6 selected tissues, and its expression level in hepatopancreas is higher than that in the other tissues (p < 0.01). Samif expression level in the hepatopancreas at 24 and 48 h after Vibrio parahaemolyticus injection was upregulated significantly (p < 0.01), but there was no significant change after exposure to tributyltin (TBT) (p > 0.05).

Gene expression profiling in neutrophils from children with polyarticular juvenile idiopathic arthritis

OBJECTIVE

We have previously reported a defect in neutrophil activation in children with polyarticular juvenile idiopathic arthritis (JIA). The current study was undertaken to determine whether gene expression abnormalities persist in JIA in remission and to use systems biology analysis to elucidate pathologic pathways in polyarticular JIA.

METHODS

We performed gene expression profiling on neutrophils from children with polyarticular JIA. Children were grouped according to disease status. We studied 14 children with active disease who were taking medication, 8 children with clinical remission of disease who were taking medication (CRM status), and 6 children with clinical remission of disease who were not taking medication (CR status). We also studied 13 healthy children whose age ranges overlapped those of the patients.

RESULTS

Neutrophil abnormalities persisted in children with polyarticular JIA even after disease remission was achieved. Children with active disease and those with CRM status showed no differences in expression of specific genes, although they could be separated on cluster analysis. A comparison of children with CR status and healthy control children revealed networks of pro- and antiinflammatory genes that suggested that remission is a state of homeostasis and balance rather than a return to normal immune function. Furthermore, gene overexpression in patients with CR status supports the hypothesis that neutrophils play a role in regulating adaptive immunity in this disease.

CONCLUSION

Neutrophil gene profiling in polyarticular JIA suggests important roles for neutrophils in disease pathogenesis. These findings suggest the presence of complex interactions between innate and adaptive immunity, that are not easily modeled in conventional, linear, reductionist systems.

Macrophage differentiation increases expression of the ascorbate transporter (SVCT2)

To determine whether macrophage differentiation involves increased uptake of vitamin C, or ascorbic acid, we assessed the expression and function of its transporter SVCT2 during phorbol ester-induced differentiation of human-derived THP-1 monocytes. Induction of THP-1 monocyte differentiation by phorbol 12-myristate 13-acetate (PMA) markedly increased SVCT2 mRNA, protein, and function. When ascorbate was present during PMA-induced differentiation, the increase in SVCT2 protein expression was inhibited, but differentiation was enhanced. PMA-induced SVCT2 protein expression was blocked by inhibitors of protein kinase C (PKC), with most of the affect due to the PKCbetaI and betaII isoforms. Activation of MEK/ERK was sustained up to 48 h after PMA treatment, and the inhibitors completely blocked PMA-stimulated SVCT2 protein expression, indicating an exclusive role for the classical MAP kinase pathway. However, inhibitors of NF-kappaB activation, NADPH oxidase inhibitors, and several antioxidants also partially prevented SVCT2 induction, suggesting diverse distal routes for control of SVCT2 transcription. Both known promoters for the SVCT2 were involved in these effects. In conclusion, PMA-induced monocyte-macrophage differentiation is enhanced by ascorbate and associated with increased expression and function of the SVCT2 protein through a pathway involving sustained activation of PKCbetaI/II, MAP kinase, NADPH oxidase, and NF-kappaB.

Neuroimmune regulation in immunocompetence, acute illness, and healing

Adaptive immunocompetence is maintained by growth hormone (GH), prolactin (PRL), and vasopressin (VP). Innate or natural immunocompetence depends on cytokines, hormones (especially of the hypothalamus-pituitary-adrenal axis), and catecholamines. The acute phase response (APR, or acute febrile illness) is an emergency defense reaction whereby the adaptive, T cell-dependent, immune reactions are suppressed and the innate immune function is dramatically amplified. Infection and various forms of injury induce APR. Cytokines [interleukin (IL)-1beta, tumor necrosis factor-alpha, and IL-6] stimulate corticotropin-releasing hormone (CRH) and VP secretion and cause a "sympathetic outflow." Colony-stimulating factors activate leukocytes. CRH is a powerful activator of the pituitary adrenocortical axis and elevates glucocorticoid (GC) levels. Cytokines, GCs, and catecholamines play fundamental roles in the amplification of natural immune defense mechanisms. VP supports the APR at this stage. However, VP remains active and is elevated for a longer period than is CRH. VP, but not CRH, is elevated during chronic inflammatory diseases. VP controls adaptive immune function and stimulates adrenocorticotropic hormone (ACTH) and PRL secretion. PRL maintains the function of the thymus and of the T cell-dependent adaptive immune system. The ACTH-adrenal axis stimulates natural immunity and of suppressor/regulatory T cells, which suppress the adaptive immune system. VP also has a direct effect on lymphoid cells, the significance of which remains to be elucidated. It is suggested that VP regulates the process of recovery from acute illness.

Oxidation-dependent maturation and survival of explanted blood monocytes via Bcl-2 up-regulation

Monocytes isolated and cultured according to standard procedures from the blood of 22 healthy donors display an activation process, monitored as adhesion and increased exposure of CD11. Starting from very early time points, monocytes undergo a deep redox modulation, i.e., they increase reactive oxygen species (ROS) formation and decrease glutathione content; at the same time, the anti-apoptotic protein Bcl-2 is substantially up-regulated. The cause-effect relationship between these parameters was investigated. On the one side, pharmacological glutathione depletion with BSO further increases ROS formation and Bcl-2 levels. On the other side, scavenging of ROS by Trolox prevents Bcl-2 up-regulation. Two lipoxygenase (LOX) inhibitors (CAPE or AA861) prevent ROS increase and, accordingly, also prevent Bcl-2 up-regulation. All this evidence supports the redox-sensitivity of Bcl-2 regulation. Trolox, CAPE and AA861, i.e., all treatments that abolish ROS increase and prevent Bcl-2 up-regulation, increase the rate of cell loss, whereas BSO, increasing Bcl-2, reduces cell loss and induces chemo-resistance. Thus, explanted healthy monocytes seem to undergo an oxidation-dependent maturation implying increased survival via Bcl-2 up-regulation, perhaps mimicking physiological activation.