Methyl gallate nanomicelles impairs neutrophil accumulated in zymosan-induced arthritis

Arthritis is a chronic disease that affects, approximately, 1 % of the total global population. It is characterized by chronic inflammation, accompanied in most of the cases of motor disability and sever pain. The main therapies available have high risk of failure and advanced treatments are scarce and highly cost. In this scenario, search for effective, safe and low-cost treatments is quite desirable. Methyl gallate (MG) is a plant-derived phenolic compound described to present remarkable anti-inflammatory effect in experimental models of arthritis. Thus, in this study we formulated nanomicelles of MG using Pluronic (F-127) as matrix and evaluated in vivo the pharmacokinetic, biodistribution and its effect in the mice model of zymosan-induced arthritis. The nanomicelles were formed with a size 126 nm. The biodistribution showed a ubiquitous tissue deposition with a renal excretion. The pharmacokinetics showed elimination half-life of 1.72 h and a clearance of 0.006 L/h. The oral pretreatment with nanomicelles containing MG (3.5 or 7 mg/kg) demonstrated a reduction in total leukocytes, neutrophils, and mononuclear cells from the inflammation site. The data supports the use of methyl gallate nanomicelles as an alternative drug for arthritis. DATA AVAILABILITY: All the data of this study are transparent.

IL-4 Receptor α Chain Protects the Kidney Against Tubule-Interstitial Injury Induced by Albumin Overload

Increasing evidence has highlighted the role of tubule-interstitial injury (TII) as a vital step in the pathogenesis of acute kidney injury (AKI). Incomplete repair of TII during AKI could lead to the development of chronic kidney disease. Changes in albumin endocytosis in proximal tubule epithelial cells (PTECs) is linked to the development of TII. In this context, interleukin (IL)-4 has been shown to be an important factor in modulating recovery of TII. We have studied the possible role of IL-4 in TII induced by albumin overload. A subclinical AKI model characterized by albumin overload in the proximal tubule was used, without changing glomerular function. Four groups were generated: (1) CONT, wild-type mice treated with saline; (2) BSA, wild-type mice treated with 10 g/kg/day bovine serum albumin (BSA); (3) KO, IL4Rα^–/– mice treated with saline; and (4) KO + BSA, IL4Rα^–/– mice treated with BSA. As reported previously, mice in the BSA group developed TII without changes in glomerular function. The following parameters were increased in the KO + BSA group compared with the BSA group: (1) tubular injury score; (2) urinary γ-glutamyltransferase; (3) CD4⁺ T cells, dendritic cells, macrophages, and neutrophils are associated with increases in renal IL-6, IL-17, and transforming growth factor β. A decrease in M2-subtype macrophages associated with a decrease in collagen deposition was observed. Using LLC-PK1 cells, a model of PTECs, we observed that (1) these cells express IL-4 receptor α chain associated with activation of the JAK3/STAT6 pathway; (2) IL-4 alone did not change albumin endocytosis but did reverse the inhibitory effect of higher albumin concentration. This effect was abolished by JAK3 inhibitor. A further increase in urinary protein and creatinine levels was observed in the KO + BSA group compared with the BSA group, but not compared with the CONT group. These observations indicate that IL-4 has a protective role in the development of TII induced by albumin overload that is correlated with modulation of the pro-inflammatory response. We propose that megalin-mediated albumin endocytosis in PTECs could work as a sensor, transducer, and target during the genesis of TII.

LPS Induces mTORC1 and mTORC2 Activation During Monocyte Adhesion

Monocyte adhesion is a crucial step in transmigration and can be induced by lipopolysaccharide (LPS). Here, we studied the role of mammalian target of rapamycin (mTOR) complexes, mTORC1 and mTORC2, and PKC in this process. We used THP-1 cells, a human monocytic cell line, to investigate monocyte adhesion under static and flow conditions. We observed that 1.0 μg/mL LPS increased PI3K/mTORC2 pathway and PKC activity after 1 h of incubation. WYE-354 10⁻⁶ M (mTORC2/mTORC1 inhibitor) and 10⁻⁶ M wortmannin avoided monocyte adhesion in culture plates. In addition, WYE also blocked LPS-induced CD11a expression. Interestingly, rapamycin and WYE-354 blocked both LPS-induced monocyte adhesion in a cell monolayer and actin cytoskeleton rearrangement, confirming mTORC1 involvement in this process. Once activated, PKC activates mTORC1/S6K pathway in a similar effect observed to LPS. Activation of the mTORC1/S6K pathway was attenuated by 10⁻⁶ M U0126, an MEK/ERK inhibitor, and 10⁻⁶ M calphostin C, a PKC inhibitor, indicating that the MEK/ERK/TSC2 axis acts as a mediator. In agreement, 80 nM PMA (a PKC activator) mimicked the effect of LPS on the activation of the MEK/ERK/TSC2/mTORC1/S6K pathway, monocyte adhesion to ECV cells and actin cytoskeleton rearrangement. Our findings show that LPS induces activation of mTOR complexes. This signaling pathway led to integrin expression and cytoskeleton rearrangement resulting in monocyte adhesion. These results describe a new molecular mechanism involved in monocyte adhesion in immune-based diseases.

Gedunin Binds to Myeloid Differentiation Protein 2 and Impairs Lipopolysaccharide-Induced Toll-Like Receptor 4 Signaling in Macrophages

Recognition of bacterial lipopolysaccharide (LPS) by innate immune system is mediated by the cluster of differentiation 14/Toll-like receptor 4/myeloid differentiation protein 2 (MD-2) complex. In this study, we investigated the modulatory effect of gedunin, a limonoid from species of the Meliaceae family described as a heat shock protein Hsp90 inhibitor, on LPS-induced response in immortalized murine macrophages. The pretreatment of wild-type (WT) macrophages with gedunin (0.01-100 µM, noncytotoxic concentrations) inhibited LPS (50 ng/ml)-induced calcium influx, tumor necrosis factor-α, and nitric oxide production in a concentration-dependent manner. The selective effect of gedunin on MyD88-adapter-like/myeloid differentiation primary response 88- and TRIF-related adaptor molecule/TIR domain-containing adapter-inducing interferon-β-dependent signaling pathways was further investigated. The pretreatment of WT, TIR domain-containing adapter-inducing interferon-β knockout, and MyD88 adapter-like knockout macrophages with gedunin (10 µM) significantly inhibited LPS (50 ng/ml)-induced tumor necrosis factor-α and interleukin-6 production, at 6 hours and 24 hours, suggesting that gedunin modulates a common event between both signaling pathways. Furthermore, gedunin (10 µM) inhibited LPS-induced prostaglandin E2 production, cyclooxygenase-2 expression, and nuclear factor κB translocation into the nucleus of WT macrophages, demonstrating a wide-range effect of this chemical compound. In addition to the ability to inhibit LPS-induced proinflammatory mediators, gedunin also triggered anti-inflammatory factors interleukin-10, heme oxygenase-1, and Hsp70 in macrophages stimulated or not with LPS. In silico modeling studies revealed that gedunin efficiently docked into the MD-2 LPS binding site, a phenomenon further confirmed by surface plasmon resonance. Our results reveal that, in addition to Hsp90 modulation, gedunin acts as a competitive inhibitor of LPS, blocking the formation of the Toll-like receptor 4/MD-2/LPS complex.

Murine IL-17+ Vγ4 T lymphocytes accumulate in the lungs and play a protective role during severe sepsis

Background

Lung inflammation is a major consequence of the systemic inflammatory response caused by severe sepsis. Increased migration of γδ T lymphocytes into the lungs has been previously demonstrated during experimental sepsis; however, the involvement of the γδ T cell subtype Vγ4 has not been previously described.

Methods

Severe sepsis was induced by cecal ligation and puncture (CLP; 9 punctures, 21G needle) in male C57BL/6 mice. γδ and Vγ4 T lymphocyte depletion was performed by 3A10 and UC3-10A6 mAb i.p. administration, respectively. Lung infiltrating T lymphocytes, IL-17 production and mortality rate were evaluated.

Results

Severe sepsis induced by CLP in C57BL/6 mice led to an intense lung inflammatory response, marked by the accumulation of γδ T lymphocytes (comprising the Vγ4 subtype). γδ T lymphocytes present in the lungs of CLP mice were likely to be originated from peripheral lymphoid organs and migrated towards CCL2, CCL3 and CCL5, which were highly produced in response to CLP-induced sepsis. Increased expression of CD25 by Vγ4 T lymphocytes was observed in spleen earlier than that by αβ T cells, suggesting the early activation of Vγ4 T cells. The Vγ4 T lymphocyte subset predominated among the IL-17⁺ cell populations present in the lungs of CLP mice (unlike Vγ1 and αβ T lymphocytes) and was strongly biased toward IL-17 rather than toward IFN-γ production. Accordingly, the in vivo administration of anti-Vγ4 mAb abrogated CLP-induced IL-17 production in mouse lungs. Furthermore, anti-Vγ4 mAb treatment accelerated mortality rate in severe septic mice, demonstrating that Vγ4 T lymphocyte play a beneficial role in host defense.

Conclusions

Overall, our findings provide evidence that early-activated Vγ4 T lymphocytes are the main responsible cells for IL-17 production in inflamed lungs during the course of sepsis and delay mortality of septic mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0098-8) contains supplementary material, which is available to authorized users.

Study of the antimalarial properties of hydroxyethylamine derivatives using green fluorescent protein transformed Plasmodium berghei

A rapid decrease in parasitaemia remains the major goal for new antimalarial drugs and thus, in vivo models must provide precise results concerning parasitaemia modulation. Hydroxyethylamine comprise an important group of alkanolamine compounds that exhibit pharmacological properties as proteases inhibitors that has already been proposed as a new class of antimalarial drugs. Herein, it was tested the antimalarial property of new nine different hydroxyethylamine derivatives using the green fluorescent protein (GFP)-expressing Plasmodium berghei strain. By comparing flow cytometry and microscopic analysis to evaluate parasitaemia recrudescence, it was observed that flow cytometry was a more sensitive methodology. The nine hydroxyethylamine derivatives were obtained by inserting one of the following radical in the para position: H, 4Cl, 4-Br, 4-F, 4-CH3, 4-OCH3, 4-NO2, 4-NH2 and 3-Br. The antimalarial test showed that the compound that received the methyl group (4-CH3) inhibited 70% of parasite growth. Our results suggest that GFP-transfected P. berghei is a useful tool to study the recrudescence of novel antimalarial drugs through parasitaemia examination by flow cytometry. Furthermore, it was demonstrated that the insertion of a methyl group at the para position of the sulfonamide ring appears to be critical for the antimalarial activity of this class of compounds.

Angiotensin II is a new component involved in splenic T lymphocyte responses during Plasmodium berghei ANKA infection

The contribution of T cells in severe malaria pathogenesis has been described. Here, we provide evidence for the potential role of angiotensin II (Ang II) in modulating splenic T cell responses in a rodent model of cerebral malaria. T cell activation induced by infection, determined by 3 to 4-fold enhancement in CD69 expression, was reduced to control levels when mice were treated with 20 mg/kg losartan (IC₅₀ = 0.966 mg/kg/d), an AT₁ receptor antagonist, or captopril (IC₅₀ = 1.940 mg/kg/d), an inhibitor of angiotensin-converting enzyme (ACE). Moreover, the production of interferon-γ and interleukin-17 by CD4+ T cells diminished 67% and 70%, respectively, by both treatments. Losartan reduced perforin expression in CD8+ T cells by 33% while captopril completely blocked it. The upregulation in chemokine receptor expression (CCR2 and CCR5) observed during infection was abolished and CD11a expression was partially reduced when mice were treated with drugs. T cells activated by Plasmodium berghei ANKA antigens showed 6-fold enhance in AT₁ levels in comparison with naive cells. The upregulation of AT₁ expression was reduced by losartan (80%) but not by captopril. Our results suggest that the AT₁/Ang II axis has a role in the establishment of an efficient T cell response in the spleen and therefore could participate in a misbalanced parasite-induced T cell immune response during P. berghei ANKA infection.

Early and late acute lung injury and their association with distal organ damage in murine malaria

Severe malaria is characterised by cerebral oedema, acute lung injury (ALI) and multiple organ dysfunctions, however, the mechanisms of lung and distal organ damage need to be better clarified. Ninety-six C57BL/6 mice were injected intraperitoneally with 5×10(6)Plasmodium berghei ANKA-infected erythrocytes or saline. At day 1, Plasmodium berghei infected mice presented greater number of areas with alveolar collapse, neutrophil infiltration and interstitial oedema associated with lung mechanics impairment, which was more severe at day 1 than day 5. Lung tumour necrosis factor-α and chemokine (C-X-C motif) ligand 1 levels were higher at day 5 compared to day 1. Lung damage occurred in parallel with distal organ injury at day 1; nevertheless, lung inflammation and the presence of malarial pigment in distal organs were more evident at day 5. In conclusion, ALI develops prior to the onset of cerebral malaria symptoms. Later during the course of infection, the established systemic inflammatory response increases distal organ damage.

Leukotriene B4 mediates gammadelta T lymphocyte migration in response to diverse stimuli

Herein, we investigated the involvement of the 5-LO-derived lipid mediator LTB(4) in gammadelta T cell migration. When injected into the i.pl. space of C57BL/6 mice, LTB(4) triggered gammadelta T lymphocyte mobilization in vivo, a phenomenon also observed in in vitro chemotaxis assays. The i.pl. injection of Escherichia coli endotoxin (LPS) triggered increased levels of LTB(4) in pleural cavities. The in vivo inhibition of LTB(4) biosynthesis by the 5-LO inhibitor zileuton or the FLAP inhibitor MK886 attenuated LPS-induced gammadelta T cell accumulation into pleural cavities. Accordingly, 5-LO KO mice failed to recruit gammadelta T cells into the inflammatory site after i.pl. LPS. Antagonists of the high-affinity LTB(4) receptor BLT1, CP105,696, and LY292476 also attenuated LPS-induced gammadelta T cell accumulation in pleural cavities as well as in vitro chemotaxis toward pleural washes obtained from LPS-simulated mice. LTB(4)/BLT1 also accounted for gammadelta T cell migration induced by i.pl. administration of Mycobacterium bovis BCG or antigen in sensitized mice. BLT1 was expressed on naïve, resident as well as LPS-recruited gammadelta T cells. Isolated gammadelta T cells were found to undergo F-actin cytoskeleton reorganization when incubated with LTB(4) in vitro, confirming that gammadelta T lymphocytes can respond directly to LTB(4). In addition to its direct effect on gammadelta T cells, LTB(4) triggered their accumulation indirectly, via modulation of CCL2 production in mouse pleural cavities. These data show that gammadelta T cell migration into the pleural cavity of mice during diverse inflammatory responses is dependent on LTB(4)/BLT1.