We previously demonstrated that a synthetic retinoic acid receptor agonist, Am80, attenuated intracerebral hemorrhage (ICH)-induced neuropathological changes and neurological dysfunction. Because inflammatory events are among the prominent features of ICH pathology that are affected by Am80, this study investigated the potential involvement of proinflammatory cytokines/chemokines in the effect of Am80 on ICH. ICH induced by collagenase injection into mouse striatum caused prominent upregulation of mRNAs for interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, CXCL1, CXCL2, and CCL3. We found that dexamethasone (DEX) and Am80 differently modulated the increase in expression of these cytokines/chemokines; TNF-α expression was attenuated only by DEX, whereas CXCL2 expression was attenuated only by Am80. Expression of IL-1β and IL-6 was inhibited both by DEX and Am80. Neurological assessments revealed that Am80, but not DEX, significantly alleviated motor dysfunction of mice after ICH. From these results, we suspected that CXCL2 might be critically involved in determining the extent of motor dysfunction. Indeed, magnetic resonance imaging-based classification of ICH in individual mice revealed that invasion of hematoma into the internal capsule, which has been shown to cause severe neurological disabilities, was associated with higher levels of CXCL2 expression than ICH without internal capsule invasion. Moreover, a CXCR1/2 antagonist reparixin ameliorated neurological deficits after ICH. Overall, suppression of CXCL2 expression may contribute to the beneficial effect of Am80 as a therapeutic agent for ICH, and interruption of CXCL2 signaling may provide a promising target for ICH therapy.
Infiltration of neutrophils has been suggested to play an important role in the pathogenesis of intracerebral hemorrhage (ICH) for which effective therapeutic interventions remain unavailable. In the present study we focused on leukotriene B (LTB) as a potent chemotactic factor for neutrophils in order to address its contribution to the pathologic events associated with ICH. ICH with hematoma expansion into the internal capsule that resulted in severe sensorimotor dysfunction was induced by injection of collagenase in mouse striatum. We found that LTB as well as mRNAs of 5-lipoxygenase (5-LOX) and 5-LOX-activating protein were increased in the brain after ICH. Daily treatment with a 5-LOX inhibitor zileuton (3 or 10 mg/kg, i.v.) prevented ICH-induced increase in LTB, attenuated neutrophil infiltration into the hematoma, and ameliorated sensorimotor dysfunction. In addition, mice deficient in LTB receptor BLT exhibited a lower number of infiltrating neutrophils in the hematoma and lower levels of sensorimotor dysfunction after ICH than did wild-type mice. Similarly, daily treatment of mice with BLT antagonist ONO-4057 (30 or 100 mg/kg, by mouth) from 3 hours after induction of ICH inhibited neutrophil infiltration and ameliorated sensorimotor dysfunction. ONO-4057 also attenuated inflammatory responses of microglia/macrophages in the perihematoma region and axon injury in the internal capsule. These results identify LTB as a critical factor that plays a major role in the pathogenic events in ICH, and BLT is proposed as a promising target for ICH therapy.
Intracerebral hemorrhage (ICH) is associated with diverse sets of neurological symptoms and prognosis, depending on the site of bleeding. Relative rate of hemorrhage occurring in the cerebral cortex (lobar hemorrhage) has been increasing, but there is no report on effective pharmacotherapeutic approaches for cortical hemorrhage either in preclinical or clinical studies. The present study aimed to establish an experimental model of cortical hemorrhage in mice for evaluation of effects of therapeutic drug candidates. Type VII collagenase at 0.015 U, injected into the parietal cortex, induced hemorrhage expanding into the whole layer of the posterior parts of the sensorimotor cortex in male C57BL/6 mice. Mice with ICH under these conditions exhibited significant motor deficits as revealed by beam-walking test. Daily administration of nicotine (1 and 2 mg/kg), with the first injection given at 3 hr after induction of ICH, improved motor performance of mice in a dose-dependent manner, although nicotine did not alter the volume of hematoma. Immunohistochemical examinations revealed that the number of neurons was drastically decreased within the hematoma region. Nicotine at 2 mg/kg partially but significantly increased the number of remaining neurons within the hematoma at 3 days after induction of ICH. ICH also resulted in inflammatory activation of microglia/macrophages in the perihematoma region, and nicotine (1 and 2 mg/kg) significantly attenuated the increase of microglia. These results suggest that nicotine can provide a therapeutic effect on cortical hemorrhage, possibly via its neuroprotective and anti-inflammatory actions. © 2017 Wiley Periodicals, Inc.
Objectives T peripheral helper (Tph) cells have major roles in pathological processes in systemic lupus erythematosus (SLE). We sought to clarify the mechanisms of Tph cell differentiation and their relevance to clinical features in patients with SLE. Method Phenotypes and functions of Tph cell–related markers in human CD4+ T cells purified from volunteers or patients were analyzed using flow cytometry and quantitative PCR. Renal biopsy specimens from patients with lupus nephritis (LN) were probed by multicolor immunofluorescence staining. Results Among multiple cytokines, transforming growth factor (TGF)-β3 characteristically induced programmed cell death protein 1 (PD-1) hi musculoaponeurotic fibrosarcoma (MAF)+, interleukin (IL)-21+IL-10+ Tph-like cells with a marked upregulation of related genes including PDCD-1, MAF, SOX4, and CXCL13. The induction of Tph-like cells by TGF-β3 was suppressed by the neutralization of TGF-β type II receptor (TGF-βR2). TGF-β3-induced Tph-like cells efficiently promoted the differentiation of class-switch memory B cells into plasmocytes, resulting in enhanced antibody production. The proportion of Tph cells in the peripheral blood was significantly increased in patients with SLE than in healthy volunteers in concordance with disease activity and severity of organ manifestations such as LN. TGF-β3 was strongly expressed on macrophages, which was associated with the accumulation of CD4+ C-X-C chemokine receptor (CXCR5)-PD-1+ Tph cells, in the renal tissue of patients with active LN. Conclusion The induction of Tph-like cells by TGF-β3 mainly produced from tissue macrophages plays a pivotal role in the pathological processes of active LN by enhancing B cell differentiation in patients with SLE.
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