Macrophage re-programming by JAK inhibitors relies on MAFB.

Monocyte-derived macrophages play a key pathogenic role in inflammatory diseases. In the case of rheumatoid arthritis (RA), the presence of specific synovial tissue-infiltrating macrophage subsets is associated with either active disease or inflammation resolution. JAK inhibitors (JAKi) are the first targeted synthetic disease-modifying antirheumatic drugs (tsDMARD) approved for treatment of RA with comparable efficacy to biologics. However, the effects of JAKi on macrophage specification and differentiation are currently unknown. We have analyzed the transcriptional and functional effects of JAKi on human peripheral blood monocyte subsets from RA patients and on the differentiation of monocyte-derived macrophages promoted by granulocyte-macrophage colony-stimulating factor (GM-CSF), a factor that drives the development and pathogenesis of RA. We now report that JAKi Upadacitinib restores the balance of peripheral blood monocyte subsets in RA patients and skewed macrophages towards the acquisition of an anti-inflammatory transcriptional and functional profile in a dose-dependent manner. Upadacitinib-treated macrophages showed a strong positive enrichment of the genes that define synovial macrophages associated to homeostasis/inflammation resolution. Specifically, Upadacitinib-treated macrophages exhibited significantly elevated expression of MAFB and MAFB-regulated genes, elevated inhibitory phosphorylation of GSK3ß, and higher phagocytic activity and showed an anti-inflammatory cytokine profile upon activation by pathogenic stimuli. These outcomes were also shared by macrophages exposed to other JAKi (baricitinib, tofacitinib), but not in the presence of the TYK2 inhibitor deucravacitinib. As a whole, our results indicate that JAKi promote macrophage re-programming towards the acquisition of a more anti-inflammatory/pro-resolution profile, an effect that correlates with the ability of JAKi to enhance MAFB expression.

[Pathogenesis and Targeted Treatment Progress of Splenomegaly in Primary Myelofibrosis--Review].

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm with splenomegaly as the major clinical manifestation, which is commonly considered to be linked to splenic extramedullary hematopoiesis. Alteration of CXCL12/CXCR4 pathway can lead to the migration of hematopoietic stem cells and hematopoietic progenitor cells from bone marrow to spleen which results in splenic extramedullary hematopoiesis. In addition, low GATA1 expression and the abnormal secretion of cytokines were found to be significantly associated with splenomegaly. With the application of JAK1/2 inhibitors in clinical, the symptoms of splenomegaly have been significantly improved in PMF patients. This article will review the pathogenesis and targeted treatment progress of splenomegaly in PMF.

A transcriptomic analysis of the effects of macrophage polarization and endotoxin tolerance on the response to Salmonella.

Salmonella is an intracellular pathogen causing significant morbidity and mortality. Its ability to grow inside macrophages is important to virulence, and is dependent on the activation state of the macrophages. Classically activated M1 macrophages are non-permissive for Salmonella growth, while alternatively activated M2 macrophages are permissive for Salmonella growth. Here we showed that endotoxin-primed macrophages (MEP), such as those associated with sepsis, showed similar levels of Salmonella resistance to M1 macrophages after 2 hr of intracellular infection, but at the 4 hr and 24 hr time points were susceptible like M2 macrophages. To understand this mechanistically, transcriptomic sequencing, RNA-Seq, was performed. This showed that M1 and MEP macrophages that had not been exposed to Salmonella, demonstrated a process termed here as primed activation, in expressing relatively higher levels of particular anti-infective genes and pathways, including the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway. In contrast, in M2 macrophages these genes and pathways were largely expressed only in response to infection. Conversely, in response to infection, M1 macrophages, but not MEP macrophages, modulated additional genes known to be associated with susceptibility to Salmonella infection, possibly contributing to the differences in resistance at later time points. Application of the JAK inhibitor Ruxolitinib before infection reduced resistance in M1 macrophages, supporting the importance of early JAK-STAT signalling in M1 resistance to Salmonella.

Impact of JAK/STAT inhibitors on human monocyte-derived-macrophages stimulated by cigarette smoke extract and lipopolysaccharide.

The main risk factor for chronic obstructive pulmonary disease (COPD) is cigarette smoke (CS). It can alter many immune cells functions such as phagocytosis, efferocytosis and cytokine production. Cytokines play a role in the orchestration of inflammation in COPD. The JAK/STAT pathways are among the most important signalling components of cytokines. The objective of this work was to investigate the role of the JAK/STAT pathway with regard to cytokine release and microsphere uptake capacity (to minimize the non-specific scavenging) in human monocyte-derived-macrophages (MDMs). The MDMs were stimulated by cigarette smoke extract (CSE) alone or in combination with lipopolysaccharide (LPS). CSE alone was not associated with significant changes in the cytokine, with the exception of IL-8/CXCL8 production. However, CSE disturbed cytokine production in LPS-stimulated MDMs. CSE increase CXCL-8 and CCL2 release in LPS-stimulated monocyte-derived macrophages and suppressed the production of IL-6 and CXCL1 in these cells. CSE also decreased microsphere uptake capacity by MDMs. Then, CSE + LPS-stimulated MDMs were treated with two different JAK inhibitors. AG490 (specific inhibitor of JAK2) and ruxolitinib (inhibitor of JAK1 and JAK2). JAK/STAT inhibitors, particularly ruxolitinib, attenuated in cytokine production without completely inhibiting when compared with dexamethasone. On the other hand, the cells exposed to dexamethasone are nearly unable to capture the microspheres, while both JAK inhibitors do not affect the uptake capacity. In summary, our results showed the versatility of ruxolitinib which might bring a better balance disturbance of cytokine release and uptake capacity. The information regarding the distinctive effect of JAK/STAT inhibitors may be useful in the development of novel treatments for COPD.

PK, PD, and interactions: the new scenario with JAK inhibitors and S1P receptor modulators, two classes of small molecule drugs, in IBD.

INTRODUCTION: Inflammatory bowel diseases (IBDs) are immune-mediated chronic inflammatory disorders of the gastrointestinal tract whose pathogenesis is not yet fully understood. Despite the advent of biological agents, there are still unmet needs for IBD patients, due to suboptimal rate of sustained remission achieved. Small molecule drugs (SMDs), the next generation of selective drugs in IBD, show promising results in ongoing trials. AREAS COVERED: We describe the pharmacodynamics and pharmacokinetic features of novel SMDs and their main differences with biologic agents. EXPERT OPINION: Small molecule drugs are a promising class of drugs for the treatment of ulcerative colitis and Crohn's disease with good results in inducing and maintaining remission. Hence, over the next few years physicians will have numerous options of small molecule drugs for the treatment of patients with IBD. This group of drugs are potentially easier to use over biological agents due to pharmacokinetic features such as oral administration, short half-life, high volume of distribution, and lack of immunogenicity. On the other hand, drug-drug interactions can happen with small-molecule drugs, principally due to competitive metabolic and clearance mechanisms.