p38 regulates the tumor suppressor PDCD4 via the TSC-mTORC1 pathway.

Programmed cell death protein 4 (PDCD4) exerts critical functions as tumor suppressor and in immune cells to regulate inflammatory processes. The phosphoinositide 3-kinase (PI3K) promotes degradation of PDCD4 via mammalian target of rapamycin complex 1 (mTORC1). However, additional pathways that may regulate PDCD4 expression are largely ill-defined.

Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression.

The aggregation of hypertrophic macrophages constitutes the basis of all granulomatous diseases, such as tuberculosis or sarcoidosis, and is decisive for disease pathogenesis. However, macrophage-intrinsic pathways driving granuloma initiation and maintenance remain elusive. We found that activation of the metabolic checkpoint kinase mTORC1 in macrophages by deletion of the gene encoding tuberous sclerosis 2 (Tsc2) was sufficient to induce hypertrophy and proliferation, resulting in excessive granuloma formation in vivo.

Lysis gradient centrifugation: a flexible method for the isolation of nuclei from primary cells.

The isolation of nuclei from eukaryotic cells is essential for studying the composition and the dynamic changes of the nuclear proteome to gain insight into the mechanisms of gene expression and cell signalling. Primary cells are particularly challenging for standard nuclear isolation protocols due to low protein content, sample degradation, or nuclear clumping. Here, we describe a rapid and flexible protocol for the isolation of clean and intact nuclei, which results in the recovery of 90-95 % highly pure nuclei.

Immune responses of macrophages and dendritic cells regulated by mTOR signalling.

The innate myeloid immune system is a complex network of cells that protect against disease by identifying and killing pathogens and tumour cells, but it is also implicated in homoeostatic mechanisms such as tissue remodelling and wound healing. Myeloid phagocytes such as monocytes, macrophages or dendritic cells are at the basis of controlling these immune responses in all tissues of the body. In the present review, we summarize recent studies demonstrating that mTOR [mammalian (or mechanistic) target of rapamycin] regulates innate immune reactions in macrophages and dendritic cells.

p38α senses environmental stress to control innate immune responses via mechanistic target of rapamycin.

The MAPK p38α senses environmental stressors and orchestrates inflammatory and immunomodulatory reactions. However, the molecular mechanism how p38α controls immunomodulatory responses in myeloid cells remains elusive. We found that in monocytes and macrophages, p38α activated the mechanistic target of rapamycin (mTOR) pathway in vitro and in vivo.

Serum amyloid A in uremic HDL promotes inflammation.

Uremia impairs the atheroprotective properties of HDL, but the mechanisms underlying why this occurs are unknown. Here, we observed that HDL isolated from healthy individuals inhibited the production of inflammatory cytokines by peripheral monocytes stimulated with a Toll-like receptor 2 agonist. In contrast, HDL isolated from the majority of patients with ESRD did not show this anti-inflammatory property; many HDL samples even promoted the production of inflammatory cytokines.

Rapid isolation of nuclei from living immune cells by a single centrifugation through a multifunctional lysis gradient.

Due to their low protein content and limited nuclear detergent stability, primary human immune cells such as monocytes or T lymphocytes represent a great challenge for standard nuclear isolation protocols. Nuclei clumping during the multiple centrifugation steps or contamination of isolated nuclei with cytoplasmic proteins due to membrane lysis is a frequently observed problem. Here we describe a versatile and novel method for the isolation of clean and intact nuclei from primary human monocytes, which can be applied for virtually any cell type.

Inhibition of mTOR blocks the anti-inflammatory effects of glucocorticoids in myeloid immune cells.

A central role for the mammalian target of rapamycin (mTOR) in innate immunity has been recently defined by its ability to limit proinflammatory mediators. Although glucocorticoids (GCs) exert potent anti-inflammatory effects in innate immune cells, it is currently unknown whether the mTOR pathway interferes with GC signaling. Here we show that inhibition of mTOR with rapamycin or Torin1 prevented the anti-inflammatory potency of GC both in human monocytes and myeloid dendritic cells.