Molecular mechanism of distinct chemokine engagement and functional divergence of the human Duffy antigen receptor.

The Duffy antigen receptor is a seven-transmembrane (7TM) protein expressed primarily at the surface of red blood cells and displays strikingly promiscuous binding to multiple inflammatory and homeostatic chemokines. It serves as the basis of the Duffy blood group system in humans and also acts as the primary attachment site for malarial parasite Plasmodium vivax and pore-forming toxins secreted by Staphylococcus aureus. Here, we comprehensively profile transducer coupling of this receptor, discover potential non-canonical signaling pathways, and determine the cryoelectron microscopy (cryo-EM) structure in complex with the chemokine CCL7. The structure reveals a distinct binding mode of chemokines, as reflected by relatively superficial binding and a partially formed orthosteric binding pocket. We also observe a dramatic shortening of TM5 and 6 on the intracellular side, which precludes the formation of the docking site for canonical signal transducers, thereby providing a possible explanation for the distinct pharmacological and functional phenotype of this receptor.

Heterogeneity of Human CD4(+) T Cells Against Microbes.

CD4(+) T helper (Th) cells play a central role in the adaptive immune response by providing help to B cells and cytotoxic T cells and by releasing different types of cytokines in tissues to mediate protection against a wide range of pathogenic microorganisms. These functions are performed by different types of Th cells endowed with distinct migratory capacities and effector functions. Here we discuss how studies of the human T cell response to microbes have advanced our understanding of Th cell functional heterogeneity, in particular with the discovery of a distinct Th1 subset involved in the response to Mycobacteria and the characterization of two types of Th17 cells specific for extracellular bacteria or fungi. We also review new approaches to dissect at the clonal level the human CD4(+) T cell response induced by pathogens or vaccines that have revealed an unexpected degree of intraclonal diversification and propose a progressive and selective model of CD4(+) T cell differentiation.

Structural Basis for Allosteric Ligand Recognition in the Human CC Chemokine Receptor 7.

The CC chemokine receptor 7 (CCR7) balances immunity and tolerance by homeostatic trafficking of immune cells. In cancer, CCR7-mediated trafficking leads to lymph node metastasis, suggesting the receptor as a promising therapeutic target. Here, we present the crystal structure of human CCR7 fused to the protein Sialidase NanA by using data up to 2.1 Å resolution. The structure shows the ligand Cmp2105 bound to an intracellular allosteric binding pocket. A sulfonamide group, characteristic for various chemokine receptor ligands, binds to a patch of conserved residues in the Gi protein binding region between transmembrane helix 7 and helix 8. We demonstrate how structural data can be used in combination with a compound repository and automated thermal stability screening to identify and modulate allosteric chemokine receptor antagonists. We detect both novel (CS-1 and CS-2) and clinically relevant (CXCR1-CXCR2 phase-II antagonist Navarixin) CCR7 modulators with implications for multi-target strategies against cancer.

COVID-19 immune signatures reveal stable antiviral T cell function despite declining humoral responses.

Cellular and humoral immunity to SARS-CoV-2 is critical to control primary infection and correlates with severity of disease. The role of SARS-CoV-2-specific T cell immunity, its relationship to antibodies, and pre-existing immunity against endemic coronaviruses (huCoV), which has been hypothesized to be protective, were investigated in 82 healthy donors (HDs), 204 recovered (RCs), and 92 active COVID-19 patients (ACs). ACs had high amounts of anti-SARS-CoV-2 nucleocapsid and spike IgG but lymphopenia and overall reduced antiviral T cell responses due to the inflammatory milieu, expression of inhibitory molecules (PD-1, Tim-3) as well as effector caspase-3, -7, and -8 activity in T cells. SARS-CoV-2-specific T cell immunity conferred by polyfunctional, mainly interferon-γ-secreting CD4+ T cells remained stable throughout convalescence, whereas humoral responses declined. Immune responses toward huCoV in RCs with mild disease and strong cellular SARS-CoV-2 T cell reactivity imply a protective role of pre-existing immunity against huCoV.

Separating Actin-Dependent Chemokine Receptor Nanoclustering from Dimerization Indicates a Role for Clustering in CXCR4 Signaling and Function.

A current challenge in cell motility studies is to understand the molecular and physical mechanisms that govern chemokine receptor nanoscale organization at the cell membrane, and their influence on cell response. Using single-particle tracking and super-resolution microscopy, we found that the chemokine receptor CXCR4 forms basal nanoclusters in resting T cells, whose extent, dynamics, and signaling strength are modulated by the orchestrated action of the actin cytoskeleton, the co-receptor CD4, and its ligand CXCL12. We identified three CXCR4 structural residues that are crucial for nanoclustering and generated an oligomerization-defective mutant that dimerized but did not form nanoclusters in response to CXCL12, which severely impaired signaling. Overall, our data provide new insights to the field of chemokine biology by showing that receptor dimerization in the absence of nanoclustering is unable to fully support CXCL12-mediated responses, including signaling and cell function in vivo.

Altered CXCR4 dynamics at the cell membrane impairs directed cell migration in WHIM syndrome patients.

Chemokine receptor nanoscale organization at the cell membrane is orchestrated by the actin cytoskeleton and influences cell responses. Using single-particle tracking analysis we show that CXCR4R334X, a truncated mutant chemokine receptor linked to WHIM syndrome (warts, hypogammaglobulinemia, infections, myelokathexis), fails to nanoclusterize after CXCL12 stimulation, and alters the lateral mobility and spatial organization of CXCR4 when coexpressed. These findings correlate with multiple phalloidin-positive protrusions in cells expressing CXCR4R334X, and their inability to correctly sense chemokine gradients. The underlying mechanisms involve inappropriate actin cytoskeleton remodeling due to the inadequate ß-arrestin1 activation by CXCR4R334X, which disrupts the equilibrium between activated and deactivated cofilin. Overall, we provide insights into the molecular mechanisms governing CXCR4 nanoclustering, signaling and cell function, and highlight the essential scaffold role of ß-arrestin1 to support CXCL12-mediated actin reorganization and receptor clustering. These defects associated with CXCR4R334X expression might contribute to the severe immunological symptoms associated with WHIM syndrome.

α1B/D-adrenoceptors regulate chemokine receptor-mediated leukocyte migration via formation of heteromeric receptor complexes.

It is known that catecholamines regulate innate immune functions. The underlying mechanisms, however, are not well understood. Here we show that at least 20 members of the human chemokine receptor (CR) family heteromerize with one or more members of the α1-adrenergic receptor (AR) family in recombinant systems and that such heteromeric complexes are detectable in human monocytes and the monocytic leukemia cell line THP-1. Ligand binding to α1-ARs inhibited migration toward agonists of the CR heteromerization partners of α1B/D-ARs with high potency and 50 to 77% efficacy but did not affect migration induced by a noninteracting CR. Incomplete siRNA knockdown of α1B/D-ARs in THP-1 cells partially inhibited migration toward agonists of their CR heteromerization partners. Complete α1B-AR knockout via CRISPR-Cas9 gene editing in THP-1 cells (THP-1_ADRA1BKO) resulted in 82% reduction of α1D-AR expression and did not affect CR expression. Migration of THP-1_ADRA1BKO cells toward agonists of CR heteromerization partners of α1B/D-ARs was reduced by 82 to 95%. Our findings indicate that CR:α1B/D-AR heteromers are essential for normal function of CR heteromerization partners, provide a mechanism underlying neuroendocrine control of leukocyte trafficking, and offer opportunities to modulate leukocyte and/or cancer cell trafficking in disease processes.

Key roles of glial cells in the encephalopathy of prematurity.

Across the globe, approximately one in 10 babies are born preterm, that is, before 37 weeks of a typical 40 weeks of gestation. Up to 50% of preterm born infants develop brain injury, encephalopathy of prematurity (EoP), that substantially increases their risk for developing lifelong defects in motor skills and domains of learning, memory, emotional regulation, and cognition. We are still severely limited in our abilities to prevent or predict preterm birth. No longer just the "support cells," we now clearly understand that during development glia are key for building a healthy brain. Glial dysfunction is a hallmark of EoP, notably, microgliosis, astrogliosis, and oligodendrocyte injury. Our knowledge of glial biology during development is exponentially expanding but hasn't developed sufficiently for development of effective neuroregenerative therapies. This review summarizes the current state of knowledge for the roles of glia in infants with EoP and its animal models, and a description of known glial-cell interactions in the context of EoP, such as the roles for border-associated macrophages. The field of perinatal medicine is relatively small but has worked passionately to improve our understanding of the etiology of EoP coupled with detailed mechanistic studies of pre-clinical and human cohorts. A primary finding from this review is that expanding our collaborations with computational biologists, working together to understand the complexity of glial subtypes, glial maturation, and the impacts of EoP in the short and long term will be key to the design of therapies that improve outcomes.

The CXCL12/CXCR4/ACKR3 Axis in the Tumor Microenvironment: Signaling, Crosstalk, and Therapeutic Targeting.

Elevated expression of the chemokine receptors CXCR4 and ACKR3 and of their cognate ligand CXCL12 is detected in a wide range of tumors and the tumor microenvironment (TME). Yet, the molecular mechanisms by which the CXCL12/CXCR4/ACKR3 axis contributes to the pathogenesis are complex and not fully understood. To dissect the role of this axis in cancer, we discuss its ability to impinge on canonical and less conventional signaling networks in different cancer cell types; its bidirectional crosstalk, notably with receptor tyrosine kinase (RTK) and other factors present in the TME; and the infiltration of immune cells that supporttumor progression. We discuss current and emerging avenues that target the CXCL12/CXCR4/ACKR3 axis. Coordinately targeting both RTKs and CXCR4/ACKR3 and/or CXCL12 is an attractive approach to consider in multitargeted cancer therapies. In addition, inhibiting infiltrating immune cells or reactivating the immune system along with modulating the CXCL12/CXCR4/ACKR3 axis in the TME has therapeutic promise.

Imbalance of SARS-CoV-2-specific CCR6+ and CXCR3+ CD4+ T cells and IFN-γ + CD8+ T cells in patients with Long-COVID.

Long-COVID (LC) is characterised by persistent symptoms for at least 3 months after acute infection. A dysregulation of the immune system and a persistent hyperinflammatory state may cause LC. LC patients present differences in activation and exhaustion states of innate and adaptive compartments. Different T CD4+ cell subsets can be identified by differential expression of chemokine receptors (CCR). However, changes in T cells with expression of CCRs such as CCR6 and CXCR3 and their relationship with CD8+ T cells remains unexplored in LC. Here, we performed unsupervised analysis and found CCR6+ CD4+ subpopulations enriched in COVID-19 convalescent individuals upon activation with SARS-CoV-2 peptides. SARS-CoV-2 specific CCR6+ CD4+ are decreased in LC patients, whereas CXCR3+ CCR6- and CCR4+ CCR6- CD4+ T cells are increased. LC patients showed lower IFN-γ-secreting CD8+ T cells after stimulation with SARS-CoV-2 Spike protein. This work underscores the role of CCR6 in the pathophysiology of LC.

CCR4+ CD8+ T cells clonally expand to differentiated effectors in murine psoriasis and in human psoriatic arthritis.

Psoriasis is a chronic inflammatory skin disease with an autoimmune component and associated with joint inflammation in up to 30% of cases. To investigate autoreactive T cells, we developed an imiquimod-induced psoriasis-like inflammation model in K5-mOVA.tg C57BL/6 mice expressing ovalbumin (OVA) on the keratinocyte membrane, adoptively transferred with OT-I OVA-specific CD8+ T cells. We evaluated the expansion of OT-I CD8+ T cells and their localization in skin, blood, and spleen. scRNA-seq and TCR sequencing data from patients with psoriatic arthritis were also analyzed. In the imiquimod-treated K5-mOVA.tg mouse model, OT-I T cells were markedly expanded in the skin and blood at early time points. OT-I T cells in the skin showed mainly CXCR3+ effector memory phenotype, whereas in peripheral blood there was an expansion of CCR4+ CXCR3+ OT-I cells. At a later time point, expanded OVA-specific T-cell population was found in the spleen. In patients with psoriatic arthritis, scRNA-seq and TCR sequencing data showed clonal expansion of CCR4+ TCM cells in the circulation and further expansion in the synovial fluid. Importantly, there was a clonotype overlap between CCR4+ TCM in the peripheral blood and CD8+ T-cell effectors in the synovial fluid. This mechanism could play a role in the generation and spreading of autoreactive T cells to the synovioentheseal tissues in psoriasis patients at risk of developing psoriatic arthritis.

VNN2-expressing circulating monocytes exhibit unique functional characteristics and are decreased in patients with primary Sjögren's syndrome.

OBJECTIVE: This study aims to elucidate the significance of VNN2 expression in peripheral blood monocytes and its clinical relevance in primary Sjögren's syndrome (pSS). METHODS: We investigated VNN2 expression by analyzing single-cell RNA sequencing (scRNA-seq) data from peripheral blood mononuclear cells. Flow cytometry was used to detect and compare VNN2 expression in total monocytes, classical monocytes (cMo), intermediate monocytes (iMo) and non-classical monocytes (ncMo). Additionally, we examined the expression of HLA, ICAM1, CD62L, ITGAM, S100A8, S100A9, CCR2, CCR6, CX3CR1 and CXCR3 in VNN2+ and VNN2- cells. We analyzed the correlation between VNN2 expression and clinical indicators and assessed the clinical utility of VNN2+ monocytes in pSS diagnosis using receiver operating characteristic curves. RESULTS: We observed high VNN2 expression in monocytes, with significantly higher levels in CD14++ monocytes compared to ncMo. VNN2+ monocytes exhibited decreased expression of HLA and CD62L and increased expression of ICAM1, ITGAM, S100A8, S100A9, CCR2, CCR6, CX3CR1 and CXCR3 compared to VNN2- monocytes. Although scRNA-seq data showed that VNN2 mRNA was upregulated, cell surface expression of VNN2 was decreased in monocytes from pSS patients compared to healthy controls. The reduced levels of VNN2+ monocyte subpopulations in pSS patients were negatively correlated with anti-ribosome antibody levels and positively correlated with complement 4 levels. Detection of VNN2 expression in monocytes can aid in the auxiliary diagnosis of pSS. CONCLUSION: Monocytes expressing cell surface VNN2 are significantly reduced in pSS patients. This suggests a potential role for VNN2 in pSS development and its potential use as a diagnostic marker for pSS.

Differential alterations of CXCR3, CXCR5 and CX3CR1 in patients with immune thrombocytopenia.

As a versatile element for maintaining homeostasis, the chemokine system has been reported to be implicated in the pathogenesis of immune thrombocytopenia (ITP). However, research pertaining to chemokine receptors and related ligands in adult ITP is still limited. The states of several typical chemokine receptors and cognate ligands in the circulation were comparatively assessed through various methodologies. Multiple variable analyses of correlation matrixes were conducted to characterize the correlation signatures of various chemokine receptors or candidate ligands with platelet counts. Our data illustrated a significant decrease in relative CXCR3 expression and elevated plasma levels of CXCL4, 9-11, 13, and CCL3 chemokines in ITP patients with varied platelet counts. Flow cytometry assays revealed eminently diminished CXCR3 levels on T and B lymphocytes and increased CXCR5 on cytotoxic T cell (Tc) subsets in ITP patients with certain platelet counts. Meanwhile, circulating CX3CR1 levels were markedly higher on T cells with a concomitant increase in plasma CX3CL1 level in ITP patients, highlighting the importance of aberrant alterations of the CX3CR1-CX3CL1 axis in ITP pathogenesis. Spearman's correlation analyses revealed a strong positive association of peripheral CXCL4 mRNA level, and negative correlations of plasma CXCL4 concentration and certain chemokine receptors with platelet counts, which might serve as a potential biomarker of platelet destruction in ITP development. Overall, these results indicate that the differential expression patterns and distinct activation states of peripheral chemokine network, and the subsequent expansion of circulating CXCR5+ Tc cells and CX3CR1+ T cells, may be a hallmark during ITP progression, which ultimately contributes to thrombocytopenia in ITP patients.

Tissue-specific differentiation of CD8+ resident memory T cells.

CD8+ tissue-resident memory T (TRM) cells play crucial roles in defense against infections and cancer and have been implicated in autoimmune diseases such as psoriasis. In mice and humans, they exist in all nonlymphoid organs and share key characteristics across all tissues, including downregulation of tissue egress and lymph node homing pathways. However, recent studies demonstrate considerable heterogeneity across TRM cells lodged in different tissues - linked to the activity of tissue-specific molecules, including chemokines, cytokines, and transcription factors. Current work indicates that transforming growth factor (TGF)-ß plays a major role in generating TRM heterogeneity at phenotypic and functional levels. Here, we review common and unique features of TRM cells in different tissues and discuss putative strategies aimed at harnessing TRM cells for site-specific protection against infectious and malignant diseases.

Chronic Lymphocytic Leukemia: Disease Biology.

BACKGROUND: B-cell receptor (BCR) signaling is crucial for normal B-cell development and adaptive immunity. In chronic lymphocytic leukemia (CLL), the malignant B cells display many features of normal mature B lymphocytes, including the expression of functional B-cell receptors (BCRs). Cross talk between CLL cells and the microenvironment in secondary lymphatic organs results in BCR signaling and BCR-driven proliferation of the CLL cells. This critical pathomechanism can be targeted by blocking BCR-related kinases (BTK, PI3K, spleen tyrosine kinase) using small-molecule inhibitors. Among these targets, Bruton tyrosine kinase (BTK) inhibitors have the highest therapeutic efficacy; they effectively block leukemia cell proliferation and generally induce durable remissions in CLL patients, even in patients with high-risk disease. By disrupting tissue homing receptor (i.e., chemokine receptor and adhesion molecule) signaling, these kinase inhibitors also mobilize CLL cells from the lymphatic tissues into the peripheral blood (PB), causing a transient redistribution lymphocytosis, thereby depriving CLL cells from nurturing factors within the tissue niches. SUMMARY: The clinical success of the BTK inhibitors in CLL underscores the central importance of the BCR in CLL pathogenesis. Here, we review CLL pathogenesis with a focus on the role of the BCR and other microenvironment cues. KEY MESSAGES: (i) CLL cells rely on signals from their microenvironment for proliferation and survival. (ii) These signals are mediated by the BCR as well as chemokine and integrin receptors and their respective ligands. (iii) Targeting the CLL/microenvironment interaction with small-molecule inhibitors provides a highly effective treatment strategy, even in high-risk patients.

Scavenging of soluble and immobilized CCL21 by ACKR4 regulates peripheral dendritic cell emigration.

Leukocyte homing driven by the chemokine CCL21 is pivotal for adaptive immunity because it controls dendritic cell (DC) and T cell migration through CCR7. ACKR4 scavenges CCL21 and has been shown to play an essential role in DC trafficking at the steady state and during immune responses to tumors and cutaneous inflammation. However, the mechanism by which ACKR4 regulates peripheral DC migration is unknown, and the extent to which it regulates CCL21 in steady-state skin and lymph nodes (LNs) is contested. Specifically, our previous findings that CCL21 levels are increased in LNs of ACKR4-deficient mice [I. Comerford et al., Blood 116, 4130-4140 (2010)] were refuted [M. H. Ulvmar et al., Nat. Immunol. 15, 623-630 (2014)], and no differences in CCL21 levels in steady-state skin of ACKR4-deficient mice were reported despite compromised CCR7-dependent DC egress in these animals [S. A. Bryce et al., J. Immunol. 196, 3341-3353 (2016)]. Here, we resolve these issues and reveal that two forms of CCL21, full-length immobilized and cleaved soluble CCL21, exist in steady-state barrier tissues, and both are regulated by ACKR4. Without ACKR4, extracellular CCL21 gradients in barrier sites are saturated and nonfunctional, DCs cannot home directly to lymphatic vessels, and excess soluble CCL21 from peripheral tissues pollutes downstream LNs. The results identify the mechanism by which ACKR4 controls DC migration in barrier tissues and reveal a complex mode of CCL21 regulation in vivo, which enhances understanding of functional chemokine gradient formation.

Multiplex Detection of Fluorescent Chemokine Binding to CXC Chemokine Receptors by NanoBRET.

NanoLuc-mediated bioluminescence resonance energy transfer (NanoBRET) has gained popularity for its ability to homogenously measure ligand binding to G protein-coupled receptors (GPCRs), including the subfamily of chemokine receptors. These receptors, such as ACKR3, CXCR4, CXCR3, play a crucial role in the regulation of the immune system, are associated with inflammatory diseases and cancer, and are seen as promising drug targets. The aim of this study was to optimize NanoBRET-based ligand binding to NLuc-ACKR3 and NLuc-CXCR4 using different fluorescently labeled chemokine CXCL12 analogs and their use in a multiplex NanoBRET binding assay of two chemokine receptors at the same time. The four fluorescent CXCL12 analogs (CXCL12-AZD488, -AZD546, -AZD594, -AZD647) showed high-affinity saturable binding to both NLuc-ACKR3 and NLuc-CXCR4, with relatively low levels of non-specific binding. Additionally, the binding of all AZDye-labeled CXCL12s to Nluc receptors was inhibited by pharmacologically relevant unlabeled chemokines and small molecules. The NanoBRET binding assay for CXCL10-AZD488 binding to Nluc-CXCR3 was also successfully established and successfully employed for the simultaneous measurement of the binding of unlabeled small molecules to NLuc-CXCR3 and NLuc-CXCR4. In conclusion, multiplexing the NanoBRET-based competition binding assay is a promising tool for testing unlabeled (small) molecules against multiple GPCRs simultaneously.

CC Chemokine Family Members' Modulation as a Novel Approach for Treating Central Nervous System and Peripheral Nervous System Injury-A Review of Clinical and Experimental Findings.

Despite significant progress in modern medicine and pharmacology, damage to the nervous system with various etiologies still poses a challenge to doctors and scientists. Injuries lead to neuroimmunological changes in the central nervous system (CNS), which may result in both secondary damage and the development of tactile and thermal hypersensitivity. In our review, based on the analysis of many experimental and clinical studies, we indicate that the mechanisms occurring both at the level of the brain after direct damage and at the level of the spinal cord after peripheral nerve damage have a common immunological basis. This suggests that there are opportunities for similar pharmacological therapeutic interventions in the damage of various etiologies. Experimental data indicate that after CNS/PNS damage, the levels of 16 among the 28 CC-family chemokines, i.e., CCL1, CCL2, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9, CCL11, CCL12, CCL17, CCL19, CCL20, CCL21, and CCL22, increase in the brain and/or spinal cord and have strong proinflammatory and/or pronociceptive effects. According to the available literature data, further investigation is still needed for understanding the role of the remaining chemokines, especially six of them which were found in humans but not in mice/rats, i.e., CCL13, CCL14, CCL15, CCL16, CCL18, and CCL23. Over the past several years, the results of studies in which available pharmacological tools were used indicated that blocking individual receptors, e.g., CCR1 (J113863 and BX513), CCR2 (RS504393, CCX872, INCB3344, and AZ889), CCR3 (SB328437), CCR4 (C021 and AZD-2098), and CCR5 (maraviroc, AZD-5672, and TAK-220), has beneficial effects after damage to both the CNS and PNS. Recently, experimental data have proved that blockades exerted by double antagonists CCR1/3 (UCB 35625) and CCR2/5 (cenicriviroc) have very good anti-inflammatory and antinociceptive effects. In addition, both single (J113863, RS504393, SB328437, C021, and maraviroc) and dual (cenicriviroc) chemokine receptor antagonists enhanced the analgesic effect of opioid drugs. This review will display the evidence that a multidirectional strategy based on the modulation of neuronal-glial-immune interactions can significantly improve the health of patients after CNS and PNS damage by changing the activity of chemokines belonging to the CC family. Moreover, in the case of pain, the combined administration of such antagonists with opioid drugs could reduce therapeutic doses and minimize the risk of complications.

Dynamics of Cellular Regulation of Fractalkine/CX3CL1 and Its Receptor CX3CR1 in the Rat Trigeminal Subnucleus Caudalis after Unilateral Infraorbital Nerve Lesion-Extended Cellular Signaling of the CX3CL1/CX3CR1 Axis in the Development of Trigeminal Neuropathic Pain.

The cellular distribution and changes in CX3CL1/fractalkine and its receptor CX3CR1 protein levels in the trigeminal subnucleus caudalis (TSC) of rats with unilateral infraorbital nerve ligation (IONL) were investigated on postoperation days 1, 3, 7, and 14 (POD1, POD3, POD7, and POD14, respectively) and compared with those of sham-operated and naïve controls. Behavioral tests revealed a significant increase in tactile hypersensitivity bilaterally in the vibrissal pads of both sham- and IONL-operated animals from POD1 to POD7, with a trend towards normalization in sham controls at POD14. Image analysis revealed increased CX3CL1 immunofluorescence (IF) intensities bilaterally in the TSC neurons of both sham- and IONL-operated rats at all survival periods. Reactive astrocytes in the ipsilateral TSC also displayed CX3CL1-IF from POD3 to POD14. At POD1 and POD3, microglial cells showed high levels of CX3CR1-IF, which decreased by POD7 and POD14. Conversely, CX3CR1 was increased in TSC neurons and reactive astrocytes at POD7 and POD14, which coincided with high levels of CX3CL1-IF and ADAM17-IF. This indicates that CX3CL1/CX3CR1 may be involved in reciprocal signaling between TSC neurons and reactive astrocytes. The level of CatS-IF in microglial cells suggests that soluble CX3CL1 may be involved in neuron-microglial cell signaling at POD3 and POD7, while ADAM17 allows this release at all studied time points. These results indicate an extended CX3CL1/CX3CR1 signaling axis and its role in the crosstalk between TSC neurons and glial cells during the development of trigeminal neuropathic pain.

Chemokine clouding and liver cancer heterogeneity: Does it impact clinical outcomes?

Tumor heterogeneity is a predominant feature of hepatocellular carcinoma (HCC) that plays a crucial role in chemoresistance and limits the efficacy of available chemo/immunotherapy regimens. Thus, a better understanding regarding the molecular determinants of tumor heterogeneity will help in developing newer strategies for effective HCC management. Chemokines, a sub-family of cytokines are one of the key molecular determinants of tumor heterogeneity in HCC and are involved in cell survival, growth, migration, and angiogenesis. Herein, we provide a panoramic insight into the role of chemokines in HCC heterogeneity at genetic, epigenetic, metabolic, immune cell composition, and tumor microenvironment levels and its impact on clinical outcomes. Interestingly, our in-silico analysis data showed that expression of chemokine receptors impacts infiltration of various immune cell populations into the liver tumor and leads to heterogeneity. Thus, it is evident that aberrant chemokines clouding impacts HCC tumor heterogeneity and understanding this phenomenon in depth could be harnessed for the development of personalized medicine strategies in future.