Regulation of lentivirus neurovirulence by lipopolysaccharide conditioning: suppression of CXCL10 in the brain by IL-10

Akkermansia muciniphila and Its Pili-Like Protein Amuc_1100 Modulate Macrophage Polarization in Experimental Periodontitis

Periodontitis is a chronic inflammatory disease triggered by dysbiosis of the oral microbiome. Porphyromonas gingivalis is strongly implicated in periodontal inflammation, gingival tissue destruction, and alveolar bone loss through sustained exacerbation of the host response. Recently, the use of other bacterial species, such as Akkermansia muciniphila, has been suggested to counteract inflammation elicited by P. gingivalis In this study, the effects of A. muciniphila and its pili-like protein Amuc_1100 on macrophage polarization during P. gingivalis infection were evaluated in a murine model of experimental periodontitis. Mice were gavaged with P. gingivalis alone or in combination with A. muciniphila or Amuc_1100 for 6 weeks. Morphometric analysis demonstrated that the addition of A. muciniphila or Amuc_1100 significantly reduced P. gingivalis-induced alveolar bone loss. This decreased bone loss was associated with a proresolutive phenotype (M2) of macrophages isolated from submandibular lymph nodes as observed by flow cytometry. Furthermore, the expression of interleukin 10 (IL-10) at the RNA and protein levels was significantly increased in the gingival tissues of the mice and in macrophages exposed to A. muciniphila or Amuc_1100, confirming their anti-inflammatory properties. This study demonstrates the putative therapeutic interest of the administration of A. muciniphila or Amuc_1100 in the management of periodontitis through their anti-inflammatory properties.

Tumor inhibition or tumor promotion? The duplicity of CXCR3 in cancer

Tumor tissue includes cancer cells and normal stromal cells such as vascular endothelial cells, connective tissue cells (cancer associated fibroblast, mesenchymal stem cell), and immune cells (tumor-infiltrating lymphocytes or TIL, dendritic cells, eosinophils, basophils, mast cells, tumor-associated macrophages or TAM, myeloid-derived suppressor cells or MDSC). Anti-tumor activity is mainly mediated by infiltration of NK cells, Th1 and CD8⁺ T cells, and correlates with expression of NK cell and T cell attracting chemokines. Nevertheless, cancer cells hijack tissue homeostasis through secretion of cytokines and chemokines that mediate not only the induction of an inflamed status that supports cancer cell survival and growth, but also the recruitment and/or activation of immune suppressive cells. CXCL9, CXCL10, and CXCL11 are known for their tumor-inhibiting properties, but their overexpression in several hematologic and solid tumors correlates with disease severity, suggesting a role in tumor promotion. The dichotomous nature of CXCR3 ligands activity mainly depends on several molecular mechanisms induced by cancer cells themselves able to divert immune responses and to alter the whole local environment. A deep understanding of the nature of such phenomenon may provide a rationale to build up a CXCR3/ligand axis targeting strategy. In this review, we will discuss the role of CXCR3 in cancer progression and in regulation of anti-tumor immune response and immunotherapy.

Assessment of the Microbiome Role in Skin Protection Against UV Irradiation Via Network Analysis

Introduction: Diverse microbiotas which have some contributions to gene expression reside in human skin. To identify the protective role of the skin microbiome against UV exposure, proteinprotein interaction (PPI) network analysis is used to assessment gene expression alteration. Methods: A microarray dataset, GEO accession number GSE117359, was considered in this respect. Differential expressed genes (DEGs) in the germ-free (GF) and specific pathogen-free (SPF) groups are analyzed by GEO2R. The top significant DEGs were assigned for network analysis via Cytoscape 3.7.2 and its applications. Results: A total of 28 genes were identified as significant DEGs and the centrality analysis of the network indicated that only one of the seven hub-bottlenecks was from queried genes. The gene ontology analysis of Il6, Cxcl2, Cxcl1, TNF, Il10, Cxcl10, and Mmp9 showed that the crucial genes were highly enriched in the immune system. Conclusion: The skin microbiome plays a significant role in the protection of skin against UV irradiation and the role of TNF and IL6 is prominent in this regard.

HIV-induced neuroinflammation: impact of PAR1 and PAR2 processing by Furin

HIV-associated neurocognitive disorders (HAND) is a syndrome defined by neurocognitive deficits that are driven by viral neurotoxins, cytokines, free radicals, and proteases expressed in the brain. This neurological disease has also been linked to activation of Protease-Activated Receptors 1 and 2 (PAR1,2). These receptors are highly expressed in the central nervous system and are upregulated in HAND. Secretory basic-amino-acid-specific Proprotein Convertases (PCs), which cleave precursor proteins at basic residues, are also induced in HAND. They are vital for many biological processes including HIV-1 entry into cells. The cytoprotective role of Furin, PC5, and PACE4 has been linked to the presence of a potential PC-cleavage site R₄₁XXXXR₄₆↓ in PAR1. Furthermore, Furin binds PAR1 and both are trapped in the trans-Golgi-network (TGN) as inactive proteins, likely due to the intermediary trafficking role of phospho-Furin acidic cluster sorting protein 1 (PACS1). Nothing is known about PAR2 and its possible recognition by PCs at its putative R₃₁XXXXR₃₆↓ processing site. The present study implicates PACS1 in the retrograde trafficking of PAR1 to the TGN and demonstrates that the cytosolic extreme C-terminal tail of PAR1 contains an acidic phosphorylatable PACS1-sensitive domain. We further show the requirement of Asn₄₇ in PAR1 for its Furin-dependent TGN localization. Our data revealed that Furin is the only convertase that efficiently cleaves PAR2 at Arg₃₆↓. N-glycosylation of PAR2 at Asn₃₀ reduces the efficacy, but enhances selectivity of the Furin cleavage. Finally, in co-cultures comprised of human neuroblastoma SK-N-SH cells (stably expressing PAR1/2 and/or Furin) and HIV-1-infected primary macrophages, we demonstrate that the expression of Furin enhances neuronal cell viability in the context of PAR1- or PAR2-induced neuronal cytotoxicity. The present study provides insights into early stages of HIV-1 induced neuronal injury and the protective role of Furin in neurons co-expressing PAR1 and/or PAR2, as observed in HAND.

Neurologic disease in feline immunodeficiency virus infection: disease mechanisms and therapeutic interventions for NeuroAIDS

Feline immunodeficiency virus (FIV) is a lentivirus that causes immunosuppression through virus-mediated CD4+ T cell depletion in feline species. FIV infection is complicated by virus-induced disease in the nervous system. FIV enters the brain soon after primary infection and is detected as FIV-encoded RNA, DNA, and proteins in microglia, macrophages, and astrocytes. FIV infection activates neuroinflammatory pathways including cytokines, chemokines, proteases, and ROS with accompanying neuronal injury and loss. Neurobehavioral deficits during FIV infection are manifested as impaired motor and cognitive functions. Several treatment strategies have emerged from studies of FIV neuropathogenesis including the therapeutic benefits of antiretroviral therapies, other protease inhibitors, anti-inflammatory, and neurotrophic compounds. Recently, insulin's antiviral, anti-inflammatory, and neuroprotective effects were investigated in models of lentivirus brain infection. Insulin suppressed HIV-1 replication in human microglia as well as FIV replication of lymphocytes. Insulin treatment diminished cytokine and chemokine activation in HIV-infected microglia while also protecting neurons from HIV-1 Vpr protein-mediated neurotoxicity. Intranasal (IN) insulin delivery for 6 weeks suppressed FIV expression in the brains of treated cats. IN insulin also reduced neuroinflammation and protected neurons in the hippocampus, striatum, and neocortex of FIV-infected animals. These morphological and molecular effects of IN insulin were confirmed by neurobehavioral studies that showed IN insulin-treated FIV-infected animals displayed improved motor and cognitive performance compared to sham-treated FIV-infected animals. Thus, FIV infection of the nervous system provides a valuable comparative in vivo model for discovering and evaluating disease mechanisms as well as developing therapeutic strategies for NeuroAIDS in humans.

CSF biomarkers of monocyte activation and chemotaxis correlate with magnetic resonance spectroscopy metabolites during chronic HIV disease

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) persist despite combination antiretroviral therapy (cART), supporting the need to better understand HIV neuropathogenesis. Magnetic resonance spectroscopy (MRS) of the brain has demonstrated abnormalities in HIV-infected individuals despite cART. We examined the associations between MRS metabolites and selected cerebrospinal fluid (CSF) biomarkers reflecting monocyte/macrophage activation and chemotaxis. A multicenter cross-sectional study involving five sites in the USA was conducted. The following CSF biomarkers were measured: soluble CD14 (sCD14), monocyte chemotactic protein-1 (MCP-1), interferon inducible protein 10 (IP-10), and stromal cell-derived growth factor 1 alpha (SDF-1α). The following MRS metabolites were measured from basal ganglia (BG), frontal white matter (FWM), and frontal gray matter (FGM): N-acetylaspartate (NAA), myo-inositol (MI), choline (Cho), and creatine (Cr). CSF biomarkers were compared to absolute MRS metabolites as well as metabolite/Cr ratios using linear regression. Eighty-three HIV-infected individuals were included, 78 % on cART and 37 % with HAND. The most robust positive correlations were between MCP-1 and Cho in BG (R (2) 0.179, p < 0.001) as well as MCP-1 and MI in FWM (R (2) 0.137, p = 0.002). Higher Cr levels in FWM were associated with MCP-1 (R (2) 0. 075, p = 0.01) and IP-10 (R (2) 0.106, p = 0.003). Comparing biomarkers to MRS metabolite/Cr ratios impacted some relationships, e.g., higher sCD14 levels were associated with lower Cho/Cr ratios in FGM (R (2) 0.224, p < 0.001), although higher MCP-1 levels remained associated with Cho/Cr in BG. These findings provide evidence that monocyte activation and chemotaxis continue to contribute to HIV-associated brain abnormalities in cART-treated individuals.

FIV in cats--a useful model of HIV in people?

The feline immunodeficiency virus (FIV) shares genomic organization, receptor usage, lymphocyte tropism, and induction of immunodeficiency and increased susceptibility to cancer with the human immunodeficiency virus (HIV). Global distribution, marked heterogeneity and variable host adaptation are also properties of both viruses. These features render the FIV-cat model suitable to explore many aspects of lentivirus-host interaction and adaptation, and to explore treatment and prevention of infection. Examples of fundamental discoveries that have emerged from study in the FIV-cat model concern two-receptor entrance strategies that target memory T-lymphocytes, host factors that restrict retroviral infection, viral strategies for replication in non-dividing cells, and identification of correlates of immunity to the virus. This article provides a brief overview of strengths and limitations of the FIV-cat model for comparative biology and medicine.

Adult human glia, pericytes and meningeal fibroblasts respond similarly to IFNy but not to TGFβ1 or M-CSF

The chemokine Interferon gamma-induced protein 10 (IP-10) and human leukocyte antigen (HLA) are widely used indicators of glial activation and neuroinflammation and are up-regulated in many brain disorders. These inflammatory mediators have been widely studied in rodent models of brain disorders, but less work has been undertaken using human brain cells. In this study we investigate the regulation of HLA and IP-10, as well as other cytokines and chemokines, in microglia, astrocytes, pericytes, and meningeal fibroblasts derived from biopsy and autopsy adult human brain, using immunocytochemistry and a Cytometric Bead Array. Interferonγ (IFNγ) increased microglial HLA expression, but contrary to data in rodents, the anti-inflammatory cytokine transforming growth factor β1 (TGFβ1) did not inhibit this increase in HLA, nor did TGFβ1 affect basal microglial HLA expression or IFNγ-induced astrocytic HLA expression. In contrast, IFNγ-induced and basal microglial HLA expression, but not IFNγ-induced astrocytic HLA expression, were strongly inhibited by macrophage colony stimulating factor (M-CSF). IFNγ also strongly induced HLA expression in pericytes and meningeal fibroblasts, which do not basally express HLA, and this induction was completely blocked by TGFβ1, but not affected by M-CSF. In contrast, TGFβ1 did not block the IFNγ-induced increase in IP-10 in pericytes and meningeal fibroblasts. These results show that IFNγ, TGFβ1 and M-CSF have species- and cell type-specific effects on human brain cells that may have implications for their roles in adult human brain inflammation.

Differential type 1 interferon-regulated gene expression in the brain during AIDS: interactions with viral diversity and neurovirulence

The lentiviruses, human and feline immunodeficiency viruses (HIV-1 and FIV, respectively), infect the brain and cause neurovirulence, evident as neuronal injury, inflammation, and neurobehavioral abnormalities with diminished survival. Herein, different lentivirus infections in conjunction with neural cell viability were investigated, concentrating on type 1 interferon-regulated pathways. Transcriptomic network analyses showed a preponderance of genes involved in type 1 interferon signaling, which was verified by increased expression of the type 1 interferon-associated genes, Mx1 and CD317, in brains from HIV-infected persons (P<0.05). Leukocytes infected with different strains of FIV or HIV-1 showed differential Mx1 and CD317 expression (P<0.05). In vivo studies of animals infected with the FIV strains, FIV(ch) or FIV(ncsu), revealed that FIV(ch)-infected animals displayed deficits in memory and motor speed compared with the FIV(ncsu)- and mock-infected groups (P<0.05). TNF-α, IL-1β, and CD40 expression was increased in the brains of FIV(ch)-infected animals; conversely, Mx1 and CD317 transcript levels were increased in the brains of FIV(ncsu)-infected animals, principally in microglia (P<0.05). Gliosis and neuronal loss were evident among FIV(ch)-infected animals compared with mock- and FIV(ncsu)-infected animals (P<0.05). Lentiviral infections induce type 1 interferon-regulated gene expression in microglia in a viral diversity-dependent manner, representing a mechanism by which immune responses might be exploited to limit neurovirulence.

Programming of neurotoxic cofactor CXCL-10 in HIV-1-associated dementia: abrogation of CXCL-10-induced neuro-glial toxicity in vitro by PKC activator

Background

More than 50% of patients undergoing lifelong suppressive antiviral treatment for HIV-1 infection develop minor HIV-1-associated neurocognitive disorders. Neurological complications during HIV-1 infection are the result of direct neuronal damage by proinflammatory products released from HIV-1-infected or -uninfected activated lymphocytes, monocytes, macrophages, microglia and astrocytes. The specific pro-inflammatory products and their roles in neurotoxicity are far from clear. We investigated proinflammatory cytokines and chemokines in the cerebrospinal fluid (CSF) of HIV-demented (HIV-D) and HIV-nondemented (HIV-ND) patients and studied their affect on neuroglial toxicity.

Methods and results

Bioplex array showed elevated levels of signatory chemokines or cytokines (IL-6, IFN-γ, CXCL10, MCP-1 and PDGF) in the CSF of HIV-D patients (n = 7) but not in that of HIV-ND patients (n = 7). Among the signatory cytokines and chemokines, CXCL10 was distinctly upregulated in-vitro in HIV-1 (NLENG1)-activated human fetal astrocytes, HIV-1 (Ba-L)-infected macrophages, and HIV-1 (NLENG1)-infected lymphocytes. Virus-infected macrophages also had increased levels of TNF-α. Consistently, human fetal astrocytes treated with HIV-1 and TNF-α induced the signatory molecules. CXCL10 in combination with HIV-1 synergistically enhanced neuronal toxicity and showed chemotactic activity (~ 40 fold) for activated peripheral blood mononuclear cells (PBMC), suggesting the intersection of signaling events imparted by HIV-1 and CXCL10 after binding to their respective surface receptors, CXCR4 and CXCR3, on neurons. Blocking CXCR3 and its downstream MAP kinase (MAPK) signaling pathway suppressed combined CXCL10 and HIV-1-induced neurotoxicity. Bryostatin, a PKC modulator and suppressor of CXCR4, conferred neuroprotection against combined insult with HIV-1 and CXCL10. Bryostatin also suppressed HIV-1 and CXCL10-induced PBMC chemotaxis. Although, therapeutic targeting of chemokines in brain may have adverse consequences on the host, current findings and earlier evidence suggest that CXCL10 could strongly impede neuroinflammation.

Conclusion

We have demonstrated induction of CXCL10 and other chemokines/cytokines during HIV-1 infection in the brain, as well as synergism of CXCL10 with HIV-1 in neuronal toxicity, which was dampened by bryostatin.

Age- and disease-dependent HERV-W envelope allelic variation in brain: association with neuroimmune gene expression

Background

The glycoprotein, Syncytin-1, is encoded by a human endogenous retrovirus (HERV)-W env gene and is capable of inducing neuroinflammation. The specific allele(s) responsible for Syncytin-1 expression in the brain is uncertain. Herein, HERV-W env diversity together with Syncytin-1 abundance and host immune gene profiles were examined in the nervous system using a multiplatform approach.

Results

HERV-W env sequences were encoded by multiple chromosomal encoding loci in primary human neurons compared with less chromosomal diversity in astrocytes and microglia (p<0.05). HERV-W env RNA sequences cloned from brains of patients with systemic or neurologic diseases were principally derived from chromosomal locus 7q21.2. Within the same specimens, HERV-W env transcript levels were correlated with the expression of multiple proinflammatory genes (p<0.05). Deep sequencing of brain transcriptomes disclosed the env transcripts to be the most abundant HERV-W transcripts, showing greater expression in fetal compared with healthy adult brain specimens. Syncytin-1's expression in healthy brain specimens was derived from multiple encoding loci and linked to distinct immune and developmental gene profiles.

Conclusions

Syncytin-1 expression in the brain during disease was associated with neuroinflammation and was principally encoded by a full length provirus. The present studies also highlighted the diversity in HERV gene expression within the brain and reinforce the potential contributions of HERV expression to neuroinflammatory diseases.

Inflammation and epithelial cell injury in AIDS enteropathy: involvement of endoplasmic reticulum stress

Immunosuppressive lentivirus infections, including human, simian, and feline immunodeficiency viruses (HIV, SIV, and FIV, respectively), cause the acquired immunodeficiency syndrome (AIDS), frequently associated with AIDS enteropathy. Herein, we investigated the extent to which lentivirus infections affected mucosal integrity and intestinal permeability in conjunction with immune responses and activation of endoplasmic reticulum (ER) stress pathways. Duodenal biopsies from individuals with HIV/AIDS exhibited induction of IL-1β, CD3ε, HLA-DRA, spliced XBP-1(Xbp-1s), and CHOP expression compared to uninfected persons (P<0.05). Gut epithelial cells exposed to HIV-1 Vpr demonstrated elevated TNF-α, IL-1β, spliced Xbp-1s, and CHOP expression (P<0.05) together with calcium activation and disruption of epithelial cell monolayer permeability. In addition to reduced blood CD4(+) T lymphocyte levels, viral loads in the gut and plasma were high in FIV-infected animals (P<0.05). FIV-infected animals also exhibited a failure to gain weight and increased lactulose/mannitol ratios compared with uninfected animals (P<0.05). Proinflammatory and ER stress gene expression were activated in the ileum of FIV-infected animals (P<0.05), accompanied by intestinal epithelial damage with loss of epithelial cells and leukocyte infiltration of the lamina propria. Lentivirus infections cause gut inflammation and ensuing damage to intestinal epithelial cells, likely through induction of ER stress pathways, resulting in disruption of gut functional integrity.

Identification of the ovine mannose receptor and its possible role in Visna/Maedi virus infection

This study aims to characterize the mannose receptor (MR) gene in sheep and its role in ovine visna/maedi virus (VMV) infection. The deduced amino acid sequence of ovine MR was compatible with a transmembrane protein having a cysteine-rich ricin-type amino-terminal region, a fibronectin type II repeat, eight tandem C-type lectin carbohydrate-recognition domains (CRD), a transmembrane region, and a cytoplasmic carboxy-terminal tail. The ovine and bovine MR sequences were closer to each other compared to human or swine MR. Concanavalin A (ConA) inhibited VMV productive infection, which was restored by mannan totally in ovine skin fibroblasts (OSF) and partially in blood monocyte-derived macrophages (BMDM), suggesting the involvement of mannosylated residues of the VMV ENV protein in the process. ConA impaired also syncytium formation in OSF transfected with an ENV-encoding pN3-plasmid. MR transcripts were found in two common SRLV targets, BMDM and synovial membrane (GSM) cells, but not in OSF. Viral infection of BMDM and especially GSM cells was inhibited by mannan, strongly suggesting that in these cells the MR is an important route of infection involving VMV Env mannosylated residues. Thus, at least three patterns of viral entry into SRLV-target cells can be proposed, involving mainly MR in GSM cells (target in SRLV-induced arthritis), MR in addition to an alternative route in BMDM (target in SRLV infections), and an alternative route excluding MR in OSF (target in cell culture). Different routes of SRLV infection may thus coexist related to the involvement of MR differential expression.