Limits...
Mycobacterium tuberculosis-infected human monocytes down-regulate microglial MMP-2 secretion in CNS tuberculosis via TNFα, NFκB, p38 and caspase 8 dependent pathways.

Green JA, Dholakia S, Janczar K, Ong CW, Moores R, Fry J, Elkington PT, Roncaroli F, Friedland JS - J Neuroinflammation (2011)

Bottom Line: Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01).In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05).Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01).

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Infectious Diseases and Immunity and the Imperial College Wellcome Trust Centre for Clinical Tropical Medicine, Hammersmith Campus, Imperial College London, London, W12 0NN, UK. justin.green@imperial.ac.uk

ABSTRACT
Tuberculosis (TB) of the central nervous system (CNS) is a deadly disease characterized by extensive tissue destruction, driven by molecules such as Matrix Metalloproteinase-2 (MMP-2) which targets CNS-specific substrates. In a simplified cellular model of CNS TB, we demonstrated that conditioned medium from Mycobacterium tuberculosis-infected primary human monocytes (CoMTb), but not direct infection, unexpectedly down-regulates constitutive microglial MMP-2 gene expression and secretion by 72.8% at 24 hours, sustained up to 96 hours (P < 0.01), dependent upon TNF-α. In human CNS TB brain biopsies but not controls the p38 pathway was activated in microglia/macrophages. Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01). In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05). Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01). Caspase 8 restored MMP-2 secretion to basal levels. However, this caspase-dependent regulation of MMP-2 was independent of p38 and NFκB pathways; p38 phosphorylation was increased and p50/p65 NFκB nuclear trafficking unaffected by caspase 8 inhibition. In summary, suppression of microglial MMP-2 secretion by M.tb-infected monocyte-dependent networks paradoxically involves the pro-inflammatory mediators TNF-α, p38 MAP kinase and NFκB in addition to a novel caspase 8-dependent pathway.

Show MeSH

Related in: MedlinePlus

Microglia are likely to express phosphorylated p38 in patients with CNS TB. Brain biopsies from five patients with CNS TB were stained. (A) H&E stained section of cerebellar cortex shows typical TB necrotizing granulomas (original magnification 10×). (B) Iba1 (a microglial/macrophage marker) staining confirms a florid microglial and macrophage infiltrate in the TB granuloma (original magnification 20×). (C) p38 immunoreactivity is almost exclusively expressed in the nucleus of microglial cells (original magnification 40×). (D) Iba-1 staining in microglia denoted by arrows with rectangle denoting area enlarged for (E) (original magnification 20×) (E) corresponding p38 positive microglia with characteristic nuclear shape enlarged from rectangle in (D) (original magnification 40×). For immunostaining (B - E) areas of immunoreactivity appear as brown against the blue counterstain. (F) Omission of the primary antibody in CNS TB biopsy demonstrates no immunoreactivity (original magnification 20×).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3113956&req=5

Figure 4: Microglia are likely to express phosphorylated p38 in patients with CNS TB. Brain biopsies from five patients with CNS TB were stained. (A) H&E stained section of cerebellar cortex shows typical TB necrotizing granulomas (original magnification 10×). (B) Iba1 (a microglial/macrophage marker) staining confirms a florid microglial and macrophage infiltrate in the TB granuloma (original magnification 20×). (C) p38 immunoreactivity is almost exclusively expressed in the nucleus of microglial cells (original magnification 40×). (D) Iba-1 staining in microglia denoted by arrows with rectangle denoting area enlarged for (E) (original magnification 20×) (E) corresponding p38 positive microglia with characteristic nuclear shape enlarged from rectangle in (D) (original magnification 40×). For immunostaining (B - E) areas of immunoreactivity appear as brown against the blue counterstain. (F) Omission of the primary antibody in CNS TB biopsy demonstrates no immunoreactivity (original magnification 20×).

Mentions: Since p38 appeared to have a potentially key role in CoMTb-induced MMP-2 suppression, the expression of microglial phospho-p38 in five CNS TB brain biopsies was investigated for the first time in human brain sections. Microglial cells appeared to be immunoreactive for phosphorylated p38 (Figure 4). Specifically nuclei were more immunoreactive for phosphorylated p38 than cytoplasm. Negative control brains and relevant methodological negative controls, including omission of primary antibody, did not demonstrate any p38 immunoreactivity further strengthening these novel data.


Mycobacterium tuberculosis-infected human monocytes down-regulate microglial MMP-2 secretion in CNS tuberculosis via TNFα, NFκB, p38 and caspase 8 dependent pathways.

Green JA, Dholakia S, Janczar K, Ong CW, Moores R, Fry J, Elkington PT, Roncaroli F, Friedland JS - J Neuroinflammation (2011)

Microglia are likely to express phosphorylated p38 in patients with CNS TB. Brain biopsies from five patients with CNS TB were stained. (A) H&E stained section of cerebellar cortex shows typical TB necrotizing granulomas (original magnification 10×). (B) Iba1 (a microglial/macrophage marker) staining confirms a florid microglial and macrophage infiltrate in the TB granuloma (original magnification 20×). (C) p38 immunoreactivity is almost exclusively expressed in the nucleus of microglial cells (original magnification 40×). (D) Iba-1 staining in microglia denoted by arrows with rectangle denoting area enlarged for (E) (original magnification 20×) (E) corresponding p38 positive microglia with characteristic nuclear shape enlarged from rectangle in (D) (original magnification 40×). For immunostaining (B - E) areas of immunoreactivity appear as brown against the blue counterstain. (F) Omission of the primary antibody in CNS TB biopsy demonstrates no immunoreactivity (original magnification 20×).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3113956&req=5

Figure 4: Microglia are likely to express phosphorylated p38 in patients with CNS TB. Brain biopsies from five patients with CNS TB were stained. (A) H&E stained section of cerebellar cortex shows typical TB necrotizing granulomas (original magnification 10×). (B) Iba1 (a microglial/macrophage marker) staining confirms a florid microglial and macrophage infiltrate in the TB granuloma (original magnification 20×). (C) p38 immunoreactivity is almost exclusively expressed in the nucleus of microglial cells (original magnification 40×). (D) Iba-1 staining in microglia denoted by arrows with rectangle denoting area enlarged for (E) (original magnification 20×) (E) corresponding p38 positive microglia with characteristic nuclear shape enlarged from rectangle in (D) (original magnification 40×). For immunostaining (B - E) areas of immunoreactivity appear as brown against the blue counterstain. (F) Omission of the primary antibody in CNS TB biopsy demonstrates no immunoreactivity (original magnification 20×).
Mentions: Since p38 appeared to have a potentially key role in CoMTb-induced MMP-2 suppression, the expression of microglial phospho-p38 in five CNS TB brain biopsies was investigated for the first time in human brain sections. Microglial cells appeared to be immunoreactive for phosphorylated p38 (Figure 4). Specifically nuclei were more immunoreactive for phosphorylated p38 than cytoplasm. Negative control brains and relevant methodological negative controls, including omission of primary antibody, did not demonstrate any p38 immunoreactivity further strengthening these novel data.

Bottom Line: Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01).In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05).Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01).

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Infectious Diseases and Immunity and the Imperial College Wellcome Trust Centre for Clinical Tropical Medicine, Hammersmith Campus, Imperial College London, London, W12 0NN, UK. justin.green@imperial.ac.uk

ABSTRACT
Tuberculosis (TB) of the central nervous system (CNS) is a deadly disease characterized by extensive tissue destruction, driven by molecules such as Matrix Metalloproteinase-2 (MMP-2) which targets CNS-specific substrates. In a simplified cellular model of CNS TB, we demonstrated that conditioned medium from Mycobacterium tuberculosis-infected primary human monocytes (CoMTb), but not direct infection, unexpectedly down-regulates constitutive microglial MMP-2 gene expression and secretion by 72.8% at 24 hours, sustained up to 96 hours (P < 0.01), dependent upon TNF-α. In human CNS TB brain biopsies but not controls the p38 pathway was activated in microglia/macrophages. Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01). In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05). Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01). Caspase 8 restored MMP-2 secretion to basal levels. However, this caspase-dependent regulation of MMP-2 was independent of p38 and NFκB pathways; p38 phosphorylation was increased and p50/p65 NFκB nuclear trafficking unaffected by caspase 8 inhibition. In summary, suppression of microglial MMP-2 secretion by M.tb-infected monocyte-dependent networks paradoxically involves the pro-inflammatory mediators TNF-α, p38 MAP kinase and NFκB in addition to a novel caspase 8-dependent pathway.

Show MeSH
Related in: MedlinePlus