Therapeutic harnessing of adaptive immunity via checkpoint inhibition has transformed the treatment of many cancers. Despite unprecedented long-term responses, most patients do not respond to these ...therapies. Immunotherapy non-responders often harbor high levels of circulating myeloid-derived suppressor cells (MDSCs)—an immunosuppressive innate cell population. Through genetic and pharmacological approaches, we uncovered a pathway governing MDSC abundance in multiple cancer types. Therapeutic liver-X nuclear receptor (LXR) agonism reduced MDSC abundance in murine models and in patients treated in a first-in-human dose escalation phase 1 trial. MDSC depletion was associated with activation of cytotoxic T lymphocyte (CTL) responses in mice and patients. The LXR transcriptional target ApoE mediated these effects in mice, where LXR/ApoE activation therapy elicited robust anti-tumor responses and also enhanced T cell activation during various immune-based therapies. We implicate the LXR/ApoE axis in the regulation of innate immune suppression and as a target for enhancing the efficacy of cancer immunotherapy in patients.
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•LXR agonism reduces immunosuppressive MDSC levels in mice and cancer patients•LXR transcriptional target ApoE impairs MDSC survival•LXR-induced MDSC depletion enhances activation of cytotoxic T lymphocytes (CTLs)•CTL activation occurs in mice and patients, enhancing tumor immunotherapy in mice
Therapeutic agonism of the LXR/ApoE axis promotes anti-tumor immunity by targeting immunosuppressive innate immune cells.
The envelope glycoprotein (Env) trimer ((gp120/gp41)
) mediates human immunodeficiency virus (HIV-1) entry into cells. The "closed," antibody-resistant Env trimer is driven to more open conformations ...by binding the host receptor, CD4. Broadly neutralizing antibodies that recognize conserved elements of the closed Env are potentially protective, but are elicited inefficiently. HIV-1 has evolved multiple mechanisms to evade readily elicited antibodies against more open Env conformations. Small-molecule CD4-mimetic compounds (CD4mc) bind the HIV-1 gp120 Env and promote conformational changes similar to those induced by CD4, exposing conserved Env elements to antibodies. Here, we show that a CD4mc synergizes with antibodies elicited by monomeric HIV-1 gp120 to protect monkeys from multiple high-dose intrarectal challenges with a heterologous simian-human immunodeficiency virus (SHIV). The protective immune response persists for at least six months after vaccination. CD4mc should increase the protective efficacy of any HIV-1 Env vaccine that elicits antibodies against CD4-induced conformations of Env.
The HIV Env glycoprotein is the surface glycoprotein responsible for viral entry into CD4
immune cells. During infection, Env also serves as a primary target for antibody responses, which are robust ...but unable to control virus replication. Immune evasion by HIV-1 Env appears to employ complex mechanisms to regulate what antigenic states are presented to the immune system. Immunodominant features appear to be distinct from epitopes that interfere with Env functions in mediating infection. Further, cell-cell transmission studies indicate that vulnerable conformational states are additionally hidden from recognition on infected cells, even though the presence of Env at the cell surface is required for viral infection through the virological synapse. Cell-cell infection studies support that Env on infected cells is presented in distinct conformations from that on virus particles. Here we review data regarding the regulation of conformational states of Env and assess how regulated sorting of Env within the infected cell may underlie mechanisms to distinguish Env on the surface of virus particles versus Env on the surface of infected cells. These mechanisms may allow infected cells to avoid opsonization, providing cell-to-cell infection by HIV with a selective advantage during evolution within an infected individual. Understanding how distinct Env conformations are presented on cells versus viruses may be essential to designing effective vaccine approaches and therapeutic strategies to clear infected cell reservoirs.
The Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway has been well-characterized as a crucial signal transduction cascade that regulates vital biological responses ...including development, immunity and oncogenesis. Additionally to its canonical pathway that uses the phosphorylated form of the STAT transcription factor, recently the non-canonical pathway involving heterochromatin formation by unphosphorylated STAT was recently uncovered. Considering the significant role of the JAK/STAT pathway, we used the simple Drosophila system in which the non-canonical pathway was initially characterized, to compare putative canonical versus non-canonical transcriptional targets across the genome. We analyzed microarray expression patterns of wildtype, Jak gain- and loss-of-function mutants, as well as the Stat loss-of-function mutant during embryogenesis, since the contribution of the canonical signal transduction pathway has been well-characterized in these contexts. Previous studies have also demonstrated that Jak gain-of-function and Stat mutants counter heterochromatin silencing to de-repress target genes by the non-canonical pathway.
Compared to canonical target genomic loci, non-canonical targets were significantly more associated with sites enriched with heterochromatin-related factors (p = 0.004). Furthermore, putative canonical and non-canonical transcriptional targets identified displayed some differences in biological pathways they regulate, as determined by Gene Ontology (GO) enrichment analyses. Canonical targets were enriched mainly with genes relevant to development and immunity, as expected, whereas the non-canonical target gene set mainly showed enrichment of genes for various metabolic responses and stress response, highlighting the possibility that some differences may exist between the two loci.
Canonical and non-canonical JAK/STAT genes may regulate distinct and overlapping sets of genes and may perform specific overall functions in physiology. Further studies at different developmental stages, or using distinct tissues may identify additional targets and provide insight into which gene targets are unique to the canonical or non-canonical pathway.
Human immunodeficiency virus type 1 (HIV-1) entry into cells is mediated by the viral envelope glycoproteins (Env), a trimer of three gp120 exterior glycoproteins, and three gp41 transmembrane ...glycoproteins. The metastable Env is triggered to undergo entry-related conformational changes when gp120 binds sequentially to the receptors, CD4 and CCR5, on the target cell. Small-molecule CD4-mimetic compounds (CD4mc) bind gp120 and act as competitive inhibitors of gp120-CD4 engagement. Some CD4mc have been shown to trigger Env prematurely, initially activating Env function, followed by rapid and irreversible inactivation. Here, we study CD4mc with a wide range of anti-HIV-1 potencies and demonstrate that all tested CD4mc are capable of activating as well as inactivating Env function. Biphasic dose-response curves indicated that the occupancy of the protomers in the Env trimer governs viral activation versus inactivation. One CD4mc bound per Env trimer activated HIV-1 infection. Envs with two CD4mc bound were activated for infection of CD4-negative, CCR5-positive cells, but the infection of CD4-positive, CCR5-positive cells was inhibited. Virus was inactivated when all three Env protomers were occupied by the CD4mc, and gp120 shedding from the Env trimer was increased in the presence of some CD4mc. Env reactivity and the on rates of CD4mc binding to the Env trimer were found to be important determinants of the potency of activation and entry inhibition. Cross-sensitization of Env protomers that do not bind the CD4mc to neutralization by an anti-V3 antibody was not evident. These insights into the mechanism of antiviral activity of CD4mc should assist efforts to optimize their potency and utility.
The trimeric envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) mediate virus entry into host cells. Binding to the host cell receptors, CD4 and CCR5, triggers changes in the conformation of the HIV-1 envelope glycoprotein trimer important for virus entry. Small-molecule CD4-mimetic compounds inhibit HIV-1 infection by multiple mechanisms: (i) direct blockade of the interaction between the gp120 exterior envelope glycoprotein and CD4; (ii) premature triggering of conformational changes in the envelope glycoproteins, leading to irreversible inactivation; and (iii) exposure of cryptic epitopes to antibodies, allowing virus neutralization. The consequences of the binding of the CD4-mimetic compound to the HIV-1 envelope glycoproteins depends upon how many of the three subunits of the trimer are bound and upon the propensity of the envelope glycoproteins to undergo conformational changes. Understanding the mechanistic factors that influence the activity of CD4-mimetic compounds can help to improve their potency and coverage of diverse HIV-1 strains.
Human immunodeficiency virus type 1 (HIV-1) causes a chronic, incurable infection leading to immune activation and chronic inflammation in people with HIV-1 (PWH), even with virologic suppression on ...antiretroviral therapy (ART). The role of lymphoid structures as reservoirs for viral latency and immune activation has been implicated in chronic inflammation mechanisms. Still, the specific transcriptomic changes induced by HIV-1 infection in different cell types within lymphoid tissue remain unexplored.
In this study, we utilized human tonsil explants from healthy human donors and infected them with HIV-1
. We performed single-cell RNA sequencing (scRNA-seq) to analyze the cell types represented in the tissue and to investigate the impact of infection on gene expression profiles and inflammatory signaling pathways.
Our analysis revealed that infected CD4
T cells exhibited upregulation of genes associated with oxidative phosphorylation. Furthermore, macrophages exposed to the virus but uninfected showed increased expression of genes associated with the NLRP3 inflammasome pathway.
These findings provide valuable insights into the specific transcriptomic changes induced by HIV-1 infection in different cell types within lymphoid tissue. The activation of oxidative phosphorylation in infected CD4
T cells and the proinflammatory response in macrophages may contribute to the chronic inflammation observed in PWH despite ART. Understanding these mechanisms is crucial for developing targeted therapeutic strategies to eradicate HIV-1 infection in PWH.
Oxycodone is one a commonly used medication for pain, and is also a widely abused prescription opioid, like other short-acting MOPr agonists. Neurochemical and structural adaptations in brain ...following chronic MOPr-agonist administration are thought to underlie pathogenesis and persistence of opiate addiction. Many axon guidance molecules, such as integrins, semaphorins, and ephrins may contribute to oxycodone-induced neuroadaptations through alterations in axon-target connections and synaptogenesis, that may be implicated in the behaviors associated with opiate addiction. However, little is known about this important area. The aim of this study is to investigate alterations in expression of selected integrin, semaphorin, ephrins, netrin, and slit genes in the nucleus accumbens (NAc) and caudate putamen (CPu) of mice following extended 14-day oxycodone self-administration (SA), using RNAseq.
Total RNA from the NAc and CPu were isolated from adult male C57BL/6J mice within 1 h after the last session of oxycodone in a 14-day self-administration paradigm (4h/day, 0.25 mg/kg/infusion, FR1) or from yoked saline controls. Gene expressions were examined using RNA sequencing (RNA-Seq) technology. RNA-Seq libraries were prepared using Illumina's TruSeq® Stranded Total RNA LT kit. The reads were aligned to the mouse reference genome (version mm10) using STAR. DESeq2 was applied to the counts of protein coding genes to estimate the fold change between the treatment groups. False Discovery Rate (FDR)
< 0.1 were used to select genes that have a significant expression change. For selection of a subset of genes related to axon guidance pathway, REACTOME was used.
Among 38 known genes of the integrin, semaphorin, and ephrin gene families, RNA-seq data revealed up-regulation of six genes in the NAc: heterodimer receptor, integrins
, and
, and its ligand semaphorin
, two semaphorin receptors, plexins
and
. There was down-regulation of eight genes in this region: two integrin genes
and
, semaphorins
, semaphorin receptor neuropilin
, and ephrin receptor
. In the CPu, there were five differentially expressed axon guidance genes: up-regulation of three integrin genes,
, and down-regulation of
and ephrin
were thus observed. No significant alterations in expression of Netrin-1 or Slit were observed.
We provide evidence for alterations in the expression of selective axon guidance genes in adult mouse brain following chronic self-administration of oxycodone. Further examination of oxycodone-induced changes in the expression of these specific axon guidance molecules and integrin genes in relation to behavior may provide new insights into development of addiction to oxycodone.
Animals with mutations in the leptin receptor (ObR) exhibit an obese phenotype that is indistinguishable from that of leptin deficient ob/ob mice. ObR is expressed in many tissues, including brain, ...and the relative importance of leptin's effects on central versus peripheral sites has not been resolved. To address this, we generated mice with neuron-specific (ObR(SynI)KO) and hepatocyte-specific (ObR(Alb)KO) disruption of ObR. Among the ObR(SynI)KO mice, the extent of obesity was negatively correlated with the level of ObR in hypothalamus and those animals with the lowest levels of ObR exhibited an obese phenotype. The obese mice with low levels of hypothalamic ObR also show elevated plasma levels of leptin, glucose, insulin, and corticosterone. The hypothalamic levels of agouti-related protein and neuropeptide Y RNA are increased in these mice. These data indicate that leptin has direct effects on neurons and that a significant proportion, or perhaps the majority, of its weight-reducing effects are the result of its actions on brain. To explore possible direct effects of leptin on a peripheral tissue, we also characterized ObR(Alb)KO mice. These mice weigh the same as controls and have no alterations in body composition. Moreover, while db/db mice and ObR(SynI)KO mice have enlarged fatty livers, ObR(Alb)KO mice do not. In summary, these data suggest that the brain is a direct target for the weight-reducing and neuroendocrine effects of leptin and that the liver abnormalities of db/db mice are secondary to defective leptin signaling in the brain.
► Gestational PFOS exposure altered gene expressions in the fetal rat lung. ► PFOS exposure induced the expressions of PPARα target genes. ► PFOS also upregulated myogenin target genes.
...Perfluorooctane sulfonate (PFOS) is a persistent environmental contaminant found in the tissues of humans and wildlife. It has been reported that gestational exposure to PFOS causes neonatal death of rats. However, the mechanism is still unclear. In this study, we investigated the effects of gestational PFOS exposure on the gene expression profiling of fetal rat lung at pseudoglandular stage. Adult Sprague Dawley dams were dosed orally from gestational day 12–18 with 0 (control), 5mg/kg/day or 20mg/kg/day PFOS. Animals were euthanized on day 18.5, fetal lung samples were collected for histochemical staining and RNA profiling analysis. PFOS did not cause apparent microscopic changes of fetal lungs. Gene expression profiling revealed that PFOS dose-dependently up-regulated the expression of 21 (5mg/kg) and 43 (20mg/kg) genes. These genes include five PPARα target genes (Acot1, Hmgcs2, Fabp4, Fabp1 and Myh7), and 4 of them are involved in lipid metabolism. The other genes were primarily included in the categories of cytoskeletal structure (Tpm1, Tnnt2, Actn3, Myoz2, Tmod1, and Mfap5), extracellular matrix (Ckm, Lum, Tnnc1, Art3, Dcn, Col17a1, Aspn, Ctsk, Itm2a, Spock2 and Orm1), transporting (Cox8h, Cox6a2 and Scnn1a) and secreted proteins (Scgb3a1, Nppb and Spp1). Our study demonstrates that in utero PFOS exposure resulted in the alteration of a set of genes which are involved in significant cytoskeletal, extracellular matrix remodeling, lipid metabolism and secreted proteins in the fetal rat lung.
We report the development of a pseudorabies virus that can be used for retrograde tracing from selected neurons. This virus encodes a green fluorescent protein marker and replicates only in neurons ...that express the Cre recombinase and in neurons in synaptic contact with the originally infected cells. The virus was injected into the arcuate nucleus of mice that express Cre only in those neurons that express neuropeptide Y or the leptin receptor. Sectioning of the brains revealed that these neurons receive inputs from neurons in other regions of the hypothalamus, as well as the amygdala, cortex, and other brain regions. These data suggest that higher cortical centers modulate leptin signaling in the hypothalamus. This method of neural tracing may prove useful in studies of other complex neural circuits.
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