Mobilization of systemic CCL4 following HIV pre-exposure prophylaxis in young men in Africa.

HIV-1 pre-exposure prophylaxis (PrEP) relies on inhibition of HIV-1 replication steps. To understand how PrEP modulates the immunological environment, we derived the plasma proteomic profile of men receiving emtricitabine-tenofovir (FTC-TDF) or emtricitabine-tenofovir alafenamide (FTC-TAF) during the CHAPS trial in South Africa and Uganda (NCT03986970). The CHAPS trial randomized 144 participants to one control and 8 PrEP arms, differing by drug type, number of PrEP doses and timing from final PrEP dose to sampling. Blood was collected pre- and post-PrEP. The inflammatory profile of plasma samples was analyzed using Olink (N=92 proteins) and Luminex (N=33) and associated with plasma drug concentrations using mass spectrometry. The proteins whose levels changed most significantly from pre- to post-PrEP were CCL4, CCL3 and TNF-α; CCL4 was the key discriminator between pre- and post-PrEP samples. CCL4 and CCL3 levels were significantly increased in post-PrEP samples compared to control specimens. CCL4 was significantly correlated with FTC drug levels in plasma. Production of inflammatory chemokines CCL4 and CCL3 in response to short-term PrEP indicates the mobilization of ligands which potentially block virus attachment to CCR5 HIV-1 co-receptor. The significant correlation between CCL4 and FTC levels suggests that CCL4 increase is modulated as an inflammatory response to PrEP.

Differential regulatory effects of chemotherapeutic protocol on CCL3_CCL4_CCL5/CCR5 axes in acute myeloid leukemia patients with monocytic lineage.

AIMS: AML (Acute myeloid leukemia) is characterized as a heterogeneous cancer. Chemokines play fundamental roles in the onset, progression cellular, migration, survival and improvement of AML therapy outcomes. The CCR5 receptors together with their ligands have indirect effects on the progression of cancer. In the present study, we have decided to investigate the impact of chemotherapy on the expression of CCR5 and its related ligands (CCL5, CCL4 and CCL3). MAIN METHODS: In this study, peripheral blood and bone marrow specimens were collected prior and post the first stage of (7 + 3) chemotherapy from 25 AML-M4/M5 patients. The expression of CCR by Lymphocytes in peripheral blood was examined by flow cytometry and QRT-PCR. The serum levels of chemokines were measured by ELISA. KEY FINDINGS: There was not observed leukemic blast cells in peripheral blood smear at post first stage of chemotherapy. We found that the expression of CCR5 was attenuated in patients post the first stage of chemotherapy and the healthy control subjects. We have also observed that the serum levels of chemokines were elevated in AML patients prior to chemotherapy. Although in post-chemotherapy stage, only CCL3 was found to reach to the baseline level, CCL5 and CCL4 have not returned to the basal level and were significantly higher than healthy control subjects. SIGNIFICANCE: The current chemotherapy protocol was not able to completely inhibit CCL5 and CCL4. In conclusion, our findings in harmony with previous studies suggest that inhibition of chemokines along with chemotherapy in AML patients may aid therapy.

The complement receptor 3 (CD11b/CD18) agonist Leukadherin-1 suppresses human innate inflammatory signalling.

Complement receptor 3 (CR3, CD11b/CD18) is a multi-functional receptor expressed predominantly on myeloid and natural killer (NK) cells. The R77H variant of CD11b, encoded by the ITGAM rs1143679 polymorphism, is associated robustly with development of the autoimmune disease systemic lupus erythematosus (SLE) and impairs CR3 function, including its regulatory role on monocyte immune signalling. The role of CR3 in NK cell function is unknown. Leukadherin-1 is a specific small-molecule CR3 agonist that has shown therapeutic promise in animal models of vascular injury and inflammation. We show that Leukadherin-1 pretreatment reduces secretion of interferon (IFN)-γ, tumour necrosis factor (TNF) and macrophage inflammatory protein (MIP)-1ß by monokine-stimulated NK cells. It was associated with a reduction in phosphorylated signal transducer and activator of transcription (pSTAT)-5 following interleukin (IL)-12 + IL-15 stimulation (P < 0·02) and increased IL-10 secretion following IL-12 + IL-18 stimulation (P < 0·001). Leukadherin-1 pretreatment also reduces secretion of IL-1ß, IL-6 and TNF by Toll-like receptor (TLR)-2 and TLR-7/8-stimulated monocytes (P < 0·01 for all). The R77H variant did not affect NK cell response to Leukadherin-1 using ex-vivo cells from homozygous donors; nor did the variant influence CR3 expression by these cell types, in contrast to a recent report. These data extend our understanding of CR3 biology by demonstrating that activation potently modifies innate immune inflammatory signalling, including a previously undocumented role in NK cell function. We discuss the potential relevance of this to the pathogenesis of SLE. Leukadherin-1 appears to mediate its anti-inflammatory effect irrespective of the SLE-risk genotype of CR3, providing further evidence to support its evaluation of Leukadherin-1 as a potential therapeutic for autoimmune disease.

Activation of innate immunity accelerates sialoadenitis in a mouse model for Sjögren's syndrome-like disease.

OBJECTIVE: Sjögren's syndrome is a chronic autoimmune disorder characterized by progressive lymphocytic infiltration within the salivary and lacrimal glands. This study was undertaken to investigate the effects of innate immunity activation on sialoadenitis in a mouse strain genetically susceptible for development of SS-like disease. METHODS: Female New Zealand Black X New Zealand White F1 mice were repeatedly treated with toll-like 3 receptor agonist poly(I:C). Submandibular glands were investigated at different time points for sialoadenitis by immunohistochemistry and for gene expression of different chemokines by quantitative PCR. Submandibular gland-infiltrating cells were characterized by flow cytometry. RESULTS: Poly(I:C) treatment significantly upregulated the expression of multiple chemokines within the submandibular glands. The severity and incidence of sialoadenitis was considerably higher in poly(I:C)-treated mice. There was a preponderance of dendritic cells and NK cells in the initial inflammatory cell infiltrates, and these were followed by CD4+ T cells. CONCLUSIONS: Our data clearly demonstrate that systemic activation of innate immunity accelerates sialoadenitis in a mouse model for SS-like disease. These findings suggest that chronic activation of innate immunity can influence certain features of SS.

Differential response of the human renal proximal tubular epithelial cell line HK-2 to Shiga toxin types 1 and 2.

Shiga toxins (Stxs) are expressed by the enteric pathogens Shigella dysenteriae serotype 1 and certain serotypes of Escherichia coli. Stx-producing bacteria cause bloody diarrhea with the potential to progress to acute renal failure. Stxs are potent protein synthesis inhibitors and are the primary virulence factors responsible for renal damage that may follow diarrheal disease. We explored the use of the immortalized human proximal tubule epithelial cell line HK-2 as an in vitro model of Stx-induced renal damage. We showed that these cells express abundant membrane Gb(3) and are differentially susceptible to the cytotoxic action of Stxs, being more sensitive to Shiga toxin type 1 (Stx1) than to Stx2. At early time points (24 h), HK-2 cells were significantly more sensitive to Stxs than Vero cells; however, by 72 h, Vero cell monolayers were completely destroyed while some HK-2 cells survived toxin challenge, suggesting that a subpopulation of HK-2 cells are relatively toxin resistant. Fluorescently labeled Stx1 B subunits localized to both lysosomal and endoplasmic reticulum (ER) compartments in HK-2 cells, suggesting that differences in intracellular trafficking may play a role in susceptibility to Stx-mediated cytotoxicity. Although proinflammatory cytokines were not upregulated by toxin challenge, Stx2 selectively induced the expression of two chemokines, macrophage inflammatory protein-1α (MIP-1α) and MIP-1ß. Stx1 and Stx2 differentially activated components of the ER stress response in HK-2 cells. Finally, we demonstrated significant poly(ADP-ribose) polymerase (PARP) cleavage after exposure to Stx1 or Stx2. However, procaspase 3 cleavage was undetectable, suggesting that HK-2 cells may undergo apoptosis in response to Stxs in a caspase 3-independent manner.

Cysteinyl leukotrienes induce macrophage inflammatory protein-1 in human monocytes/macrophages.

BACKGROUND: Macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta are known for their chemotactic and proinflammatory effects on monocytes/macrophages which have a cysteinyl leukotriene 1 (CysLT(1)) receptor. METHODS: We examined MIP-1alpha and MIP-1beta production stimulated by CysLTs (LTC(4), LTD(4), and LTE(4)) in THP-1 cells, a human monocytic leukemia cell line, and peripheral blood mononuclear cells (PBMCs). Moreover, we examined the inhibitory effect of pranlukast, a CysLT(1) receptor antagonist, and inhibitors of three major mitogen-activated protein kinases (MAPK) on the induction of MIP-1alpha and MIP-1beta production by CysLTs. RESULTS: ELISA demonstrated that CysLTs induced MIP-1alpha and MIP-1beta production in THP-1 cells and PBMCs. PCR demonstrated that LTD(4) increased MIP-1alpha and MIP-1beta mRNA expressions in THP-1 cells. Pranlukast blocked MIP-1alpha and MIP-1beta production promoted by LTD(4) in THP-1 cells and PBMCs. Moreover, an inhibitor of extracellular signal-regulated kinase (ERK) attenuated the induction of MIP-1alpha and MIP-1beta production by LTD(4) in THP-1 cells whereas the inhibitors of c-Jun NH2-terminal kinase or p38 MAPK did not. CONCLUSION: CysLTs induce MIP-1alpha and MIP-1beta production mediated by ERK via binding to the CysLT(1) receptor in human monocytes/macrophages.

Inhibitory effect of a potent and selective cytosolic phospholipase A2alpha inhibitor RSC-3388 on skin inflammation in mice.

Cytosolic phospholipase A2alpha (cPLA2alpha) preferentially hydrolyzes membrane phospholipids containing arachidonic acid, resulting in the biosynthesis of eicosanoids such as prostaglandins and leukotrienes. To examine the contribution of cPLA2alpha to skin inflammation, we evaluated the effect of (E)-N-[(2S,4R)-4-[N-(biphenyl-2-ylmethyl)-N-2-methylpropylamino]-1-[2-(2,4-difluorobenzoyl)benzoyl]pyrrolidin- 2-yl]methyl-3-[4-(2,4-dioxothiazolidin-5-ylidenemethyl) phenyl]acrylamide (RSC-3388), a potent and selective cPLA2alpha inhibitor, on 2,4,6-trinitro-1-chlorobenzene (TNCB)-induced ear inflammation and mite antigen-induced dermatitis in mice. Topical application of RSC-3388 showed a significant inhibitory activity against TNCB-induced ear swelling and eicosanoid production in mice. Comprehensive expression analysis using Gene-Chip technology and subsequent experiments concerning mRNA and protein expression demonstrated that RSC-3388 clearly reduced the levels of interleukin-1beta, macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta in a TNCB-induced mouse model. In addition, RSC-3388 ointment significantly alleviated atopic dermatitis-like skin lesions induced by repeated application of mite antigen. Furthermore, increased expression of cPLA(2)alpha, assessed by anti-phospho-cPLA2alpha antibody, was observed in the skin lesions of mite-antigen-induced dermatitis. These results indicate that cPLA2alpha is involved in the development of skin inflammation in mice, and RSC-3388 is expected to be useful for the treatment of inflammatory skin disorders such as atopic dermatitis.