HMGB1 and leukocyte migration during trauma and sterile inflammation.

HMGB1 is a nuclear protein that is released or secreted following trauma or severe cellular stress. Extracellular HMGB1 triggers inflammation and recruits leukocytes to the site of tissue damage. We review recent evidence that the ability of HMGB1 to recruit leukocytes may be entirely due to the formation of a heterocomplex with the homeostatic chemokine CXCL12.

Mutually exclusive redox forms of HMGB1 promote cell recruitment or proinflammatory cytokine release.

Tissue damage causes inflammation, by recruiting leukocytes and activating them to release proinflammatory mediators. We show that high-mobility group box 1 protein (HMGB1) orchestrates both processes by switching among mutually exclusive redox states. Reduced cysteines make HMGB1 a chemoattractant, whereas a disulfide bond makes it a proinflammatory cytokine and further cysteine oxidation to sulfonates by reactive oxygen species abrogates both activities.

Possible mechanisms involved in chemokine synergy fine tuning the inflammatory response.

The arrest and directed migration of leukocytes during homeostasis, tumour development and inflammation is orchestrated by a multitude of chemokines, which govern leukocyte migratory activities. Immune cells are particularly adept at adjusting rapidly to changes within the environment by migration in response to chemokines. The confrontation of leukocytes with different combination of chemokines that are concomitantly produced under physiological or pathological conditions in vivo is complex.

HMGB1 promotes recruitment of inflammatory cells to damaged tissues by forming a complex with CXCL12 and signaling via CXCR4.

After tissue damage, inflammatory cells infiltrate the tissue and release proinflammatory cytokines. HMGB1 (high mobility group box 1), a nuclear protein released by necrotic and severely stressed cells, promotes cytokine release via its interaction with the TLR4 (Toll-like receptor 4) receptor and cell migration via an unknown mechanism. We show that HMGB1-induced recruitment of inflammatory cells depends on CXCL12.

Perivascular expression of CXCL9 and CXCL12 in primary central nervous system lymphoma: T-cell infiltration and positioning of malignant B cells.

Primary central nervous system lymphomas (PCNSL) are aggressive malignancies confined to the CNS, mostly of diffuse large B-cell histotype. Despite improved understanding of the malignant B cells, little is known on the tumor microenvironment and on the response of the adaptive immunity against PCNSL. We investigated the phenotype of tumor infiltrating lymphocytes (TILs), and the expression of chemokines that could affect malignant B cells and trafficking of TILs.

Synergy-inducing chemokines enhance CCR2 ligand activities on monocytes.

The migration of monocytes to sites of inflammation is largely determined by their response to chemokines. Although the chemokine specificities and expression patterns of chemokine receptors are well defined, it is still a matter of debate how cells integrate the messages provided by different chemokines that are concomitantly produced in physiological or pathological situations in vivo. We present evidence for one regulatory mechanism of human monocyte trafficking.