Little is known about mechanisms that drive the development of progressive multiple sclerosis (MS), although inflammatory factors, such as macrophage migration inhibitory factor (MIF), its homolog D-dopachrome tautomerase (D-DT), and their common receptor CD74 may contribute to disease worsening. Our findings demonstrate elevated MIF and D-DT levels in males with progressive disease compared with relapsing-remitting males (RRMS) and female MS subjects, with increased levels of CD74 in females vs. males with high MS disease severity. Furthermore, increased MIF and D-DT levels in males with progressive disease were significantly correlated with the presence of two high-expression promoter polymorphisms located in the gene, a -794CATT microsatellite repeat and a -173 G/C SNP. Conversely, mice lacking MIF or D-DT developed less-severe signs of experimental autoimmune encephalomyelitis, a murine model of MS, thus implicating both homologs as copathogenic contributors. These findings indicate that genetically controlled high MIF expression (and D-DT) promotes MS progression in males, suggesting that these two factors are sex-specific disease modifiers and raising the possibility that aggressive anti-MIF treatment of clinically isolated syndrome or RRMS males with a high-expresser genotype might slow or prevent the onset of progressive MS. Additionally, selective targeting of MIF:CD74 signaling might provide an effective, trackable therapeutic approach for MS subjects of both sexes.

Chemotherapy treatment negatively affects the nervous and immune systems and alters gastrointestinal function and microbial composition. Outside of the cancer field, alterations in commensal bacteria and immune function have been implicated in behavioral deficits; however, the extent to which intestinal changes are related to chemotherapy-associated behavioral comorbidities is not yet known. Thus, this study identified concurrent changes in behavior, central and peripheral immune activation, colon histology, and bacterial community structure in mice treated with paclitaxel chemotherapy. In paclitaxel-treated mice, increased fatigue and decreased cognitive performance occurred in parallel with reduced microglia immunoreactivity, increased circulating chemokine expression (CXCL1), as well as transient increases in pro-inflammatory cytokine/chemokine (Il-1β, Tnfα, Il-6, and Cxcl1) gene expression in the brain. Furthermore, mice treated with paclitaxel had altered colonic bacterial community composition and increased crypt depth. Relative abundances of multiple bacterial taxa were associated with paclitaxel-induced increases in colon mass, spleen mass, and microglia activation. Although microbial community composition was not directly related to available brain or behavioral measures, structural differences in colonic tissue were strongly related to microglia activation in the dentate gyrus and the prefrontal cortex. These data indicate that the chemotherapeutic paclitaxel concurrently affects the gut microbiome, colonic tissue integrity, microglia activation, and fatigue in female mice, thus identifying a novel relationship between colonic tissue integrity and behavioral responses that is not often assessed in studies of the brain-gut-microbiota axis.

Increasing scientific attention is focused on the gut-brain axis, including the ability of the gastrointestinal (GI) tract to modulate central nervous system function. Changes in the intestinal microbiome can influence affective-like behavior, cognitive performance, fatigue, and sleep in rodents and humans. Patients with cancer who are receiving chemotherapy experience similar negative behavioral changes and concurrent GI symptoms. These chemotherapy comorbidities can be long-lasting and may reduce patients' quality of life and motivation to comply with treatment. This review summarizes the clinical and preclinical evidence supporting a role for the intestinal microbiome in mediating behavioral comorbidities through peripheral immune activation in patients with cancer who are receiving chemotherapy. In addition, evidence suggesting that targeted modification of the intestinal microbiome during cancer treatment could ameliorate associated behavioral comorbidities is reviewed.

Sex hormones promote immunoregulatory effects on multiple sclerosis. The current study evaluated estrogen effects on regulatory B cells and resident CNS microglia during experimental autoimmune encephalomyelitis (EAE). Herein, we demonstrate an estrogen-dependent induction of multiple regulatory B cell markers indicative of IL-10 dependent as well as IFN-γ dependent pathways. Moreover, although estrogen pretreatment of EAE mice inhibited the infiltration of pro-inflammatory cells into the CNS, it enhanced the frequency of regulatory B cells and M2 microglia. Our study suggests that estrogen has a broad effect on the development of regulatory B cells during EAE, which in turn could promote neuroprotection.

Background: Human coagulation factor (F) XI deficiency, a defect of the contact activation system, protects against venous thrombosis, stroke, and heart attack, whereas FXII, plasma prekallikrein, or kininogen deficiencies are asymptomatic. FXI deficiency, inhibition of FXI production, activated FXI (FXIa) inhibitors, and antibodies to FXI that interfere with FXI/FXII interactions reduce experimental thrombosis and inflammation. FXI inhibitors are antithrombotic in patients, and FXI and FXII deficiencies are atheroprotective in apolipoprotein E-deficient mice. Objectives: Investigate the effects of pharmacological targeting of FXI in experimental models of atherogenesis and established atherosclerosis. Methods and Results: Low-density lipoprotein receptor-knockout (Ldlr −/−) mice were administered high-fat diet (HFD) for 8 weeks; concomitantly, FXI was targeted with anti-FXI antibody (14E11) or FXI antisense oligonucleotide (ASO). 14E11 and FXI-ASO reduced atherosclerotic lesion area in proximal aortas when compared with controls, and 14E11 also reduced aortic sinus lesions. In an established disease model, in which therapy was given after atherosclerosis had developed, Ldlr −/− mice were fed HFD for 8 weeks and then administered 14E11 or FXI-ASO weekly until 16 weeks on HFD. In this established disease model, 14E11 and FXI-ASO reduced atherosclerotic lesion area in proximal aortas, but not in aortic sinus. In cultures of human endothelium, FXIa exposure disrupted VE-Cadherin expression and increased endothelial lipoprotein permeability. Strikingly, we found that 14E11 prevented the disruption of VE-Cadherin expression in aortic sinus lesions observed in the atherogenesis mouse model. Conclusion: Pharmacological targeting of FXI reduced atherogenesis in Ldlr −/− mice.

BackgroundDRα1-mouse(m)MOG-35-55, a novel construct developed in our laboratory as a simpler and potentially less immunogenic alternative to two-domain class II constructs, was shown previously to target the MIF/CD74 pathway and to reverse clinical and histological signs of experimental autoimmune encephalomyelitis (EAE) in DR*1501-Tg mice in a manner similar to the parent DR2β1-containing construct.MethodsIn order to determine whether DRα1-mMOG-35-55 could treat EAE in major histocompatibility complex (MHC)-mismatched mice and to evaluate the treatment effect on central nervous system (CNS) inflammation, C57BL/6 mice were treated with DRα1-mMOG-35-55. In addition, gene expression profile was analyzed in spinal cords of EAE DR*1501-Tg mice that were treated with DRα1-mMOG-35-55.ResultsWe here demonstrate that DRα1-mMOG-35-55 could effectively treat EAE in MHC-mismatched C57BL/6 mice by reducing CNS inflammation, potentially mediated in part through an increased frequency of M2 monocytes in the spinal cord. Microarray analysis of spinal cord tissue from DRα1-mMOG-35-55-treated vs. vehicle control mice with EAE revealed decreased expression of a large number of pro-inflammatory genes including CD74, NLRP3, and IL-1β and increased expression of genes involved in myelin repair (MBP) and neuroregeneration (HUWE1).ConclusionThese findings indicate that the DRα1-mMOG-35-55 construct retains therapeutic, anti-inflammatory, and neuroprotective activities during treatment of EAE across MHC disparate barriers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0342-4) contains supplementary material, which is available to authorized users.

D-dopachrome tautomerase (D-DT) shares amino acid sequence similarity, structural architecture and biological activity with the cytokine MIF. Recent studies show that the two protein homologues also bind to the same cell surface receptor, CD74, to activate the ERK1/2 pathway that ultimately leads to pro-inflammatory and pro-survival gene expression. We recently showed that RTL1000 and DRa1-MOG-35-55, two biological drugs with potent anti-inflammatory properties that treat experimental autoimmune encephalomyelitis (EAE) in mice, bind to the cell surface receptor CD74 with high affinity and compete with MIF for binding to the same regions of CD74. Computational modeling of MIF and RTL1000 binding interactions with CD74 predicted the presence of three CD74 binding regions for each MIF homotrimer. Through a similar approach we have now expanded our work to study the D-DT (MIF2) interaction with CD74 that is mainly defined by three elements scattered throughout the disordered regions of the interacting molecules. The model predicted: a) a hydrophobic cradle between CD74 and D-DT consisting of N-terminal tyrosine residues of three CD74 monomers arranged in a planar alignment interacts with aromatic amino acid residues located in the disordered D-DT C-terminus; b) a triad consisting of the E103 residue on one D-DT monomer in close contact with R179 and S181 on one chain of the CD74 trimer forms an intermolecular salt bridge; and c) amino acid residues on the C-terminus random coil of CD74 chain C form a long interacting area of ~500Å2 with a disordered region of D-DT chain B. These three binding elements were also present in MIF/CD74 binding interactions, with involvement of identical or highly similar amino acid residues in each MIF homotrimer that partner with the exact same residues in CD74. Topologically, however, the location of the three CD74 binding regions of the D-DT homotrimer differs substantially from that of the three MIF binding regions. This key difference in orientation appears to derive from a sequence insertion in D-DT that topologically limits binding to only one CD74 molecule per D-DT homotrimer, in contrast to predicted binding of up to three CD74 molecules per MIF homotrimer. These results have implications for the manner in which D-DT and MIF compete with each other for binding to the CD74 receptor and for the relative potency of DRa1-MOG-35-55 and RTL1000 for competitive inhibition of D-DT and MIF binding and activation through CD74.

Circulating platelets establish a variety of immunological programs and orchestrate inflammatory responses at the endothelium. Platelets express the innate immunity family of Toll-like receptors (TLRs). While TLR2/TLR1 ligands are known to activate platelets, the effects of TLR2/TLR6 ligands on platelet function remain unclear. Here, we aim to determine whether the TLR2/TLR6 agonists Pam2CSK4 and FSL-1 activate human platelets. In addition, human umbilical vein endothelial cells (HUVECs) and platelets were co-cultured to analyze the role of platelet TLR2/TLR6 on inflammation and adhesion to endothelial cells. Pam2CSK4, but not FSL-1, induced platelet granule secretion and integrin αIIbβ3 activation in a concentration-dependent manner. Moreover, Pam2CSK4 promoted platelet aggregation and increased platelet adhesion to collagen-coated surfaces. Mechanistic studies with blocking antibodies and pharmacologic inhibitors demonstrated that the TLR2/Nuclear factor-κB axis, Bruton’s-tyrosine kinase, and a secondary ADP feedback loop are involved in Pam2CSK4-induced platelet functional responses. Interestingly, Pam2CSK4 showed cooperation with immunoreceptor tyrosine-based activation motif (ITAM)-mediated signaling to enhance platelet activation. Finally, the presence of platelets increased inflammatory responses in HUVECs treated with Pam2CSK4, and platelets challenged with Pam2CSK4 showed increased adhesion to HUVECs under static and physiologically relevant flow conditions. Herein, we define a functional role for platelet TLR2-mediated signaling, which may represent a druggable target to dampen excessive platelet activation in thrombo-inflammatory diseases.