ICAM-1 a ligand for LFA-1-dependent adhesion of B, T and myeloid cells

Intercellular adhesion molecule-1 (ICAM-1): From molecular functions to clinical applications in cancer investigation

Intercellular adhesion molecule-1 (ICAM-1) is a versatile molecule that plays a critical role in various physiological and pathological processes, particularly in tumor development where its impact is bidirectional. On the one hand, it augments the immune response by promoting immune cell migration, infiltration, and the formation of immunological synapses, thus facilitating potent antitumor effects. Simultaneously, it contributes to tumor immune evasion and influences metastasis by mediating transendothelial migration (TEM), epithelial-to-mesenchymal transition (EMT), and epigenetic modification of tumor cells. Despite its significant potential, the full clinical utility of ICAM-1 has yet to be fully realized. In this review, we thoroughly examine recent advancements in understanding the role of ICAM-1 in tumor development, its relevance in predicting therapeutic efficacy and prognosis, as well as the progress in clinical translational research on anti-ICAM-1-based therapies, encompassing including monoclonal antibodies, immunotherapy, antibody-drug conjugate (ADC), and conventional treatments. By shedding light on these innovative strategies, we aim to underscore ICAM-1's significance as a valuable and multifaceted target for cancer treatment, igniting enthusiasm for further research and facilitating translation into clinical applications.

Deletion of Talin1 in Myeloid Cells Facilitates Atherosclerosis in Mice

BACKGROUND

Integrin-regulated monocyte recruitment and cellular responses of monocyte-derived macrophages are critical for the pathogenesis of atherosclerosis. In the canonical model, talin1 controls ligand binding to integrins, a prerequisite for integrins to mediate leukocyte recruitment and induce immune responses. However, the role of talin1 in the development of atherosclerosis has not been studied. Our study investigated how talin1 in myeloid cells regulates the progression of atherosclerosis.

METHODS

On an Apoe-/- background, myeloid talin1-deficient mice and the control mice were fed with a high-fat diet for 8 or 12 weeks to induce atherosclerosis. The atherosclerosis development in the aorta and monocyte recruitment into atherosclerotic lesions were analyzed.

RESULTS

Myeloid talin1 deletion facilitated the formation of atherosclerotic lesions and macrophage deposition in lesions. Talin1 deletion abolished integrin β2-mediated adhesion of monocytes but did not impair integrin α4β1-dependent cell adhesion in a flow adhesion assay. Strikingly, talin1 deletion did not prevent Mn2+- or chemokine-induced activation of integrin α4β1 to the high-affinity state for ligands. In an in vivo competitive homing assay, monocyte infiltration into inflamed tissues was prohibited by antibodies to integrin α4β1 but was not affected by talin1 deletion or antibodies to integrin β2. Furthermore, quantitative polymerase chain reaction and ELISA (enzyme-linked immunosorbent assay) analysis showed that macrophages produced cytokines to promote inflammation and the proliferation of smooth muscle cells. Ligand binding to integrin β3 inhibited cytokine generation in macrophages, although talin1 deletion abolished the negative effects of integrin β3.

CONCLUSIONS

Integrin α4β1 controls monocyte recruitment during atherosclerosis. Talin1 is dispensable for integrin α4β1 activation to the high-affinity state and integrin α4β1-mediated monocyte recruitment. Yet, talin1 is required for integrin β3 to inhibit the production of inflammatory cytokines in macrophages. Thus, intact monocyte recruitment and elevated inflammatory responses cause enhanced atherosclerosis in talin1-deficient mice. Our study provides novel insights into the roles of myeloid talin1 and integrins in the progression of atherosclerosis.

Unveiling the crucial role of intercellular adhesion molecule-1 in secondary diabetic complications

Diabetes mellitus is associated with secondary complications such as diabetic retinopathy (DR), nephropathy (DN), and cardiomyopathy (DCM), all of which significantly impact patient health. Intercellular adhesion molecule-1 (ICAM-1) has been implicated in inflammatory responses and endothelial dysfunction, both crucial in the pathogenesis of these complications. The goal of this review is to investigate at potential therapy methods that target ICAM-1 pathways and to better understand the multifaceted role of ICAM-1 in secondary diabetic problems. A meticulous analysis of scholarly literature published globally was conducted to examine ICAM-1involvement in inflammatory processes, endothelial dysfunction, and oxidative stress related to diabetes and its complications. Elevated ICAM-1 levels are strongly associated with augmented leukocyte adhesion, compromised microvascular function, and heightened oxidative stress in diabetes. These pathways contribute significantly to DR, DN, and DCM pathogenesis, highlighting ICAM-1 as a key player in their progression. Understanding ICAM-1 role in secondary diabetic complications offers insights into novel therapeutic strategies. Targeting ICAM-1 pathways may mitigate inflammation, improve endothelial function, and ultimately attenuate diabetic complications, thereby enhancing patient health outcomes. Continued research in this area is crucial for developing effective targeted therapies.

Accelerated onset of diabetes in non-obese diabetic mice fed a refined high-fat diet

AIM

Type 1 diabetes results from autoimmune events influenced by environmental variables, including changes in diet. This study investigated how feeding refined versus unrefined (aka 'chow') diets affects the onset and progression of hyperglycaemia in non-obese diabetic (NOD) mice.

METHODS

Female NOD mice were fed either unrefined diets or matched refined low- and high-fat diets. The onset of hyperglycaemia, glucose tolerance, food intake, energy expenditure, circulating insulin, liver gene expression and microbiome changes were measured for each dietary group.

RESULTS

NOD mice consuming unrefined (chow) diets developed hyperglycaemia at similar frequencies. By contrast, mice consuming the defined high-fat diet had an accelerated onset of hyperglycaemia compared to the matched low-fat diet. There was no change in food intake, energy expenditure, or physical activity within each respective dietary group. Microbiome changes were driven by diet type, with chow diets clustering similarly, while refined low- and high-fat bacterial diversity also grouped closely. In the defined dietary cohort, liver gene expression changes in high-fat-fed mice were consistent with a greater frequency of hyperglycaemia and impaired glucose tolerance.

CONCLUSION

Glucose intolerance is associated with an enhanced frequency of hyperglycaemia in female NOD mice fed a defined high-fat diet. Using an appropriate matched control diet is an essential experimental variable when studying changes in microbiome composition and diet as a modifier of disease risk.

Identification of marker genes for spinal cord injury

Introduction

Spinal cord injury (SCI) is a profoundly disabling and devastating neurological condition, significantly impacting patients' quality of life. It imposes unbearable psychological and economic pressure on both patients and their families, as well as placing a heavy burden on society.

Methods

In this study, we integrated datasets GSE5296 and GSE47681 as training groups, analyzed gene variances between sham group and SCI group mice, and conducted Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis based on the differentially expressed genes. Subsequently, we performed Weighted Gene Correlation Network Analysis (WGCNA) and Lasso regression analyses.

Results

We identified four characteristic disease genes: Icam1, Ch25h, Plaur and Tm4sf1. We examined the relationship between SCI and immune cells, and validated the expression of the identified disease-related genes in SCI rats using PCR and immunohistochemistry experiments.

Discussion

In conclusion, we have identified and verified four genes related to SCI: Icam1, Ch25h, Plaur and Tm4sf1, which could offer insights for SCI treatment.

Integrins in Health and Disease-Suitable Targets for Treatment?

Integrin receptors are heterodimeric surface receptors that play multiple roles regarding cell-cell communication, signaling, and migration. The four members of the β2 integrin subfamily are composed of an alternative α (CD11a-d) subunit, which determines the specific receptor properties, and a constant β (CD18) subunit. This review aims to present insight into the multiple immunological roles of integrin receptors, with a focus on β2 integrins that are specifically expressed by leukocytes. The pathophysiological role of β2 integrins is confirmed by the drastic phenotype of patients suffering from leukocyte adhesion deficiencies, most often resulting in severe recurrent infections and, at the same time, a predisposition for autoimmune diseases. So far, studies on the role of β2 integrins in vivo employed mice with a constitutive knockout of all β2 integrins or either family member, respectively, which complicated the differentiation between the direct and indirect effects of β2 integrin deficiency for distinct cell types. The recent generation and characterization of transgenic mice with a cell-type-specific knockdown of β2 integrins by our group has enabled the dissection of cell-specific roles of β2 integrins. Further, integrin receptors have been recognized as target receptors for the treatment of inflammatory diseases as well as tumor therapy. However, whereas both agonistic and antagonistic agents yielded beneficial effects in animal models, the success of clinical trials was limited in most cases and was associated with unwanted side effects. This unfavorable outcome is most probably related to the systemic effects of the used compounds on all leukocytes, thereby emphasizing the need to develop formulations that target distinct types of leukocytes to modulate β2 integrin activity for therapeutic applications.

ICAM-1 mediated cell-cell adhesion exerts dual roles on human B cell differentiation and IgG production

Intercellular adhesion molecule 1 (ICAM-1) plays prominent roles in mediating cell-cell adhesion which also facilitates B cell activation and differentiation with the help from CD4+ T cells. Here, we have reported a unique phenomenon that increased ICAM-1 on purified human CD4+ T cells upon anti-CD3/CD28 stimulation enhanced CD4+ T-B cell adhesion whereas induced less B cell differentiation and IgG production. This was largely due to increased PD-1 expression on CD19hi B cells after coculturing with hyperactivated CD4+ T cells. Consequently, ICAM-1 blockade during CD4+ T cell-B cell coculture promoted IgG production with the activation of ERK1/2 and Blimp-1/IRF4 upregulation. Consistently, CD4+ T cells from moderate-to-severe SLE patients with high ICAM-1 expression mediated less IgG production after T-B coculture. Therefore, ICAM-1-mediated human CD4+ T-B cell adhesion provides dual roles on B cell differentiation and IgG production partially depending on expression levels of PD-1 on B cells, supporting cell adhesion and subsequent PD-1 induction as an alternative intrinsic checkpoint for B cell differentiation.

Islet beta-cells and intercellular adhesion molecule-1 (ICAM-1): Integrating immune responses that influence autoimmunity and graft rejection

Type 1 diabetes (T1D) develops due to autoimmune targeting of the pancreatic islet β-cells. Clinical symptoms arise from reduced insulin in circulation. The molecular events and interactions between discrete immune cell populations, infiltration of such leukocytes into pancreatic and islet tissue, and selective targeting of the islet β-cells during autoimmunity and graft rejection are not entirely understood. One protein central to antigen presentation, priming of immune cells, trafficking of leukocytes, and vital for leukocyte effector function is the intercellular adhesion molecule-1 (ICAM-1). The gene encoding ICAM-1 is transcriptionally regulated and rapidly responsive (i.e., within hours) to pro-inflammatory cytokines. ICAM-1 is a transmembrane protein that can be glycosylated; its presence on the cell surface provides co-stimulatory functions for immune cell activation and stabilization of cell-cell contacts. ICAM-1 interacts with the β2-integrins, CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1), which are present on discrete immune cell populations. A whole-body ICAM-1 deletion protects NOD mice from diabetes onset, strongly implicating this protein in autoimmune responses. Since several different cell types express ICAM-1, its biology is fundamentally essential for various physiological and pathological outcomes. Herein, we review the role of ICAM-1 during both autoimmunity and islet graft rejection to understand the mechanism(s) leading to islet β-cell death and dysfunction that results in insufficient circulating quantities of insulin to control glucose homeostasis.

LFA-1/ICAM-1 Adhesion Pathway Mediates the Homeostatic Migration of Lymphocytes from Peripheral Tissues into Lymph Nodes through Lymphatic Vessels

Lymphocyte function-associated antigen-1 (LFA-1) and its endothelial ligand intercellular adhesion molecule-1 (ICAM-1) are important for the migration of lymphocytes from blood vessels into lymph nodes. However, it is largely unknown whether these molecules mediate the homeostatic migration of lymphocytes from peripheral tissues into lymph nodes through lymphatic vessels. In this study, we find that, in naive mice, ICAM-1 is expressed on the sinus endothelia of lymph nodes, but not on the lymphatic vessels of peripheral tissues. In in vivo lymphocyte migration assays, memory CD4+ T cells migrated to lymph nodes from peripheral tissues much more efficiently than from blood vessels, as compared to naive CD4+ T cells. Moreover, ICAM-1 deficiency in host mice significantly inhibited the migration of adoptively transferred wild-type donor lymphocytes from peripheral tissues, but not from blood vessels, into lymph nodes. The migration of LFA-1-deficient donor lymphocytes from peripheral tissues into the lymph nodes of wild-type host mice was also significantly reduced as compared to wild-type donor lymphocytes. Furthermore, the number of memory T cells in lymph nodes was significantly reduced in the absence of ICAM-1 or LFA-1. Thus, our study extends the functions of the LFA-1/ICAM-1 adhesion pathway, indicating its novel role in controlling the homeostatic migration of lymphocytes from peripheral tissues into lymph nodes and maintaining memory T cellularity in lymph nodes.

Nanoengineering facilitating the target mission: targeted extracellular vesicles delivery systems design

Precision medicine has put forward the proposition of "precision targeting" for modern drug delivery systems. Inspired by techniques from biology, pharmaceutical sciences, and nanoengineering, numerous targeted drug delivery systems have been developed in recent decades. But the large-scale applications of these systems are limited due to unsatisfactory targeting efficiency, cytotoxicity, easy removability, and instability. As such, the natural endogenous cargo delivery vehicle-extracellular vesicles (EVs)-have sparked significant interest for its unique inherent targeting properties, biocompatibility, transmembrane ability, and circulatory stability. The membranes of EVs are enriched for receptors or ligands that interact with target cells, which endows them with inherent targeting mission. However, most of the natural therapeutic EVs face the fate of being cleared by macrophages, resulting in off-target. Therefore, the specificity of natural EVs delivery systems urgently needs to be further improved. In this review, we comprehensively summarize the inherent homing mechanisms of EVs and the effects of the donor cell source and administration route on targeting specificity. We then go over nanoengineering techniques that modify EVs for improving specific targeting, such as source cell alteration and modification of EVs surface. We also highlight the auxiliary strategies to enhance specificity by changing the external environment, such as magnetic and photothermal. Furthermore, contemporary issues such as the lack of a gold standard for assessing targeting efficiency are discussed. This review will provide new insights into the development of precision medicine delivery systems.

Interferon-γ induces immunosuppression in salivary adenoid cystic carcinoma by regulating programmed death ligand 1 secretion

Interferon-γ (IFN-γ), a key effector molecule in anti-tumor immune response, has been well documented to correlate with the intratumoral infiltration of immune cells. Of interest, however, a high level of IFN-γ has been reported in salivary adenoid cystic carcinoma (SACC), which is actually a type of immunologically cold cancer with few infiltrated immune cells. Investigating the functional significance of IFN-γ in SACC would help to explain such a paradoxical phenomenon. In the present study, we revealed that, compared to oral squamous cell carcinoma cells (a type of immunologically hot cancer), SACC cells were less sensitive to the growth-inhibition effect of IFN-γ. Moreover, the migration and invasion abilities of SACC cells were obviously enhanced upon IFN-γ treatment. In addition, our results revealed that exposure to IFN-γ significantly up-regulated the level of programmed death ligand 1 (PD-L1) on SACC cell-derived small extracellular vesicles (sEVs), which subsequently induced the apoptosis of CD8⁺ T cells through antagonizing PD-1. Importantly, it was also found that SACC patients with higher levels of plasma IFN-γ also had higher levels of circulating sEVs that carried PD-L1 on their surface. Our study unveils a mechanism that IFN-γ induces immunosuppression in SACC via sEV PD-L1, which would account for the scarce immune cell infiltration and insensitivity to immunotherapy.

Proteolytic modulation of tumor microenvironment signals during cancer progression

Under normal conditions, the cellular microenvironment is optimized for the proper functioning of the tissues and organs. Cells recognize and communicate with the surrounding cells and extracellular matrix to maintain homeostasis. When cancer arises, the cellular microenvironment is modified to optimize its malignant growth, evading the host immune system and finding ways to invade and metastasize to other organs. One means is a proteolytic modification of the microenvironment and the signaling molecules. It is now well accepted that cancer progression relies on not only the performance of cancer cells but also the surrounding microenvironment. This mini-review discusses the current understanding of the proteolytic modification of the microenvironment signals during cancer progression.

ICAM-1 Abundance Is Increased in Pancreatic Islets of Hyperglycemic Female NOD Mice and Is Rapidly Upregulated by NF-κB in Pancreatic β-Cells

Type 1 diabetes (T1D) is classified as an autoimmune disease where pancreatic β-cells are specifically targeted by cells of the immune system. The molecular mechanisms underlying this process are not completely understood. Herein, we identified that the Icam1 gene and ICAM-1 protein were selectively elevated in female NOD mice relative to male mice, fitting with the sexual dimorphism of diabetes onset in this key mouse model of T1D. In addition, ICAM-1 abundance was greater in hyperglycemic female NOD mice than in age-matched normoglycemic female NOD mice. Moreover, we discovered that the Icam1 gene was rapidly upregulated in response to IL-1β in mouse, rat, and human islets and in 832/13 rat insulinoma cells. This early temporal genetic regulation requires key components of the NF-κB pathway and was associated with rapid recruitment of the p65 transcriptional subunit of NF-κB to corresponding κB elements within the Icam1 gene promoter. In addition, RNA polymerase II recruitment to the Icam1 gene promoter in response to IL-1β was consistent with p65 occupancy at κB elements, histone chemical modifications, and increased mRNA abundance. Thus, we conclude that β-cells undergo rapid genetic reprogramming by IL-1β to enhance expression of the Icam1 gene and that elevations in ICAM-1 are associated with hyperglycemia in NOD mice. These findings are highly relevant to, and highlight the importance of, pancreatic β-cell communication with the immune system. Collectively, these observations reveal a portion of the complex molecular events associated with onset and progression of T1D.

RNA sequence analysis reveals ITGAL/CD11A as a stromal regulator of murine low-grade glioma growth

BACKGROUND

Emerging insights from numerous laboratories have revealed important roles for nonneoplastic cells in the development and progression of brain tumors. One of these nonneoplastic cellular constituents, glioma-associated microglia (GAM), represents a unique population of brain monocytes within the tumor microenvironment that have been reported to both promote and inhibit glioma proliferation. To elucidate the role of GAM in the setting of low-grade glioma (LGG), we leveraged RNA sequencing meta-analysis, genetically engineered mouse strains, and human biospecimens.

METHODS

Publicly available disease-associated microglia (DAM) RNA-seq datasets were used, followed by immunohistochemistry and RNAScope validation. CD11a-deficient mouse microglia were used for in vitro functional studies, while LGG growth in mice was assessed using anti-CD11a neutralizing antibody treatment of Neurofibromatosis type 1 (Nf1) optic glioma mice in vivo.

RESULTS

We identified Itgal/CD11a enrichment in GAM relative to other DAM populations, which was confirmed in several independently generated murine models of Nf1 optic glioma. Moreover, ITGAL/CD11A expression was similarly increased in human LGG (pilocytic astrocytoma) specimens from several different datasets, specifically in microglia from these tumors. Using CD11a-knockout mice, CD11a expression was shown to be critical for murine microglia CX3CL1 receptor (Cx3cr1) expression and CX3CL1-directed motility, as well as glioma mitogen (Ccl5) production. Consistent with an instructive role for CD11a+ microglia in stromal control of LGG growth, antibody-mediated CD11a inhibition reduced mouse Nf1 LGG growth in vivo.

CONCLUSIONS

Collectively, these findings establish ITGAL/CD11A as a critical microglia regulator of LGG biology relevant to future stroma-targeted brain tumor treatment strategies.

Gene regulation of intracellular adhesion molecule-1 (ICAM-1): A molecule with multiple functions

Intracellular adhesion molecule 1 (ICAM-1) is one of the most extensively studied inducible cell adhesion molecules which is responsible for several immune functions like T cell activation, extravasation, inflammation, etc. The molecule is constitutively expressed over the cell surface and is regulated up / down in response to inflammatory mediators like cellular stress, proinflammatory cytokines, viral infection. These stimuli modulate the expression of ICAM-1 primarily through regulating the ICAM-1 gene transcription. On account of the presence of various binding sites for NF-κB, AP-1, SP-1, and many other transcription factors, the architecture of the ICAM-1 promoter become complex. Transcription factors in union with other transcription factors, coactivators, and suppressors promote their assembly in a stereospecific manner on ICAM-1 promoter which mediates ICAM-1 regulation in response to different stimuli. Along with transcriptional regulation, epigenetic modifications also play a pivotal role in controlling ICAM-1 expression on different cell types. In this review, we summarize the regulation of ICAM-1 expression both at the transcriptional as well as post-transcriptional level with an emphasis on transcription factors and signaling pathways involved.

Distinctive Properties of Endothelial Cells from Tumor and Normal Tissue in Human Breast Cancer

Tumor microenvironments shape aggressiveness and are largely maintained by the conditions of angiogenesis formation. Thus, endothelial cells’ (ECs) biological reactions are crucial to understand and control the design of efficient therapies. In this work, we used models of ECs to represent a breast cancer tumor site as well as the same, healthy tissue. Cells characterization was performed at the transcriptome and protein expression levels, and the cells functional biological responses (angiogenesis and permeability) were assessed. We showed that the expression of proteins specific to ECs (ACE+, VWF+), their differentiation (CD31+, CD 133+, CD105+, CD34-), their adhesion properties (ICAM-1+, VCAM-1+, CD62-L+), and their barrier formation (ZO-1+) were all downregulated in tumor-derived ECs. NGS-based differential transcriptome analysis confirmed CD31-lowered expression and pointed to the increase of Ephrin-B2 and SNCAIP, indicative of dedifferentiation. Functional assays confirmed these differences; angiogenesis was impaired while permeability increased in tumor-derived ECs, as further validated by the distinctly enhanced VEGF production in response to hypoxia, reflecting the tumor conditions. This work showed that endothelial cells differed highly significantly, both phenotypically and functionally, in the tumor site as compared to the normal corresponding tissue, thus influencing the tumor microenvironment.

Shear forces induce ICAM-1 nanoclustering on endothelial cells that impact on T-cell migration

The leukocyte-specific β₂-integrin LFA-1 and its ligand ICAM-1, expressed on endothelial cells (ECs), are involved in the arrest, adhesion, and transendothelial migration of leukocytes. Although the role of mechanical forces on LFA-1 activation is well established, the impact of forces on its major ligand ICAM-1 has received less attention. Using a parallel-plate flow chamber combined with confocal and super-resolution microscopy, we show that prolonged shear flow induces global translocation of ICAM-1 on ECs upstream of flow direction. Interestingly, shear forces caused actin rearrangements and promoted actin-dependent ICAM-1 nanoclustering before LFA-1 engagement. T cells adhered to mechanically prestimulated ECs or nanoclustered ICAM-1 substrates developed a promigratory phenotype, migrated faster, and exhibited shorter-lived interactions with ECs than when adhered to non mechanically stimulated ECs or to monomeric ICAM-1 substrates. Together, our results indicate that shear forces increase ICAM-1/LFA-1 bonds because of ICAM-1 nanoclustering, strengthening adhesion and allowing cells to exert higher traction forces required for faster migration. Our data also underscore the importance of mechanical forces regulating the nanoscale organization of membrane receptors and their contribution to cell adhesion regulation.

Structural assessment of SARS-CoV2 accessory protein ORF7a predicts LFA-1 and Mac-1 binding potential

ORF7a is an accessory protein common to SARS-CoV1 and the recently discovered SARS-CoV2, which is causing the COVID-19 pandemic. The ORF7a protein has a structural homology with ICAM-1 which binds to the T lymphocyte integrin receptor LFA-1. As COVID-19 has a strong immune component as part of the disease, we sought to determine whether SARS-CoV2 would have a similar structural interaction with LFA-1. Using molecular docking simulations, we found that SARS-CoV2 ORF7a has the key structural determinants required to bind LFA-1 but also the related leukocyte integrin Mac-1, which is also known to be expressed by macrophages. Our study shows that SARS-CoV2 ORF7a protein has a conserved Ig immunoglobulin-like fold containing an integrin binding site that provides a mechanistic hypothesis for SARS-CoV2's interaction with the human immune system. This suggests that experimental investigation of ORF7a-mediated effects on immune cells such as T lymphocytes and macrophages (leukocytes) could help understand the disease further and develop effective treatments.

The adhesion molecule ICAM-1 in diffuse large B-cell lymphoma post-rituximab era: relationship with prognostic importance and rituximab resistance

Intercellular adhesion molecule-1 (ICAM-1) is a cell-surface receptor contributing to lymphocyte homing, adhesion and activation. The prognostic significance of the protein is unknown in diffuse large B-cell lymphoma (DLBCL) in post-rituximab era. We detected expression of ICAM-1 immunohistochemically in 102 DLBCL tissue samples. Overexpression of ICAM-1 was found in 28 (27.5%) cases. In patients with low ICAM-1 expression levels, the addition of rituximab to CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) chemotherapy resulted in an improved overall response rate, progression-free survival (PFS) and overall survival (OS) (P=0.019, 0.01, 0.02). In pre-clinical models, we found that chronic exposure of cell lines to rituximab led to downregulation of ICAM-1 and acquirement of a rituximab resistant phenotype. In vitro exposure of rituximab resulted in rapid aggregation of B-cells regardless of the ICAM-1 expression levels. MTT assay showed knockdown of ICAM-1 could cause rituximab resistance. Neutralization of ICAM-1 did not affect rituximab activity in vitro and in vivo. Our data illustrated that in post-rituximab era, R-CHOP significantly improved the ORR, PFS and OS in ICAM-1 negative subset patients. Downregulation of ICAM-1 may contribute to rituximab resistance, and that rituximab, by promoting cell-cell aggregation, may sensitize cells to the cytotoxic effects of chemotherapy agents.

Distinct Roles of LFA-1 and ICAM-1 on ILC2s Control Lung Infiltration, Effector Functions, and Development of Airway Hyperreactivity

Asthma is a heterogeneous airway inflammatory disease characterized by increased airway hyperreactivity (AHR) to specific and unspecific stimuli. Group 2 innate lymphoid cells (ILC2)s are type-2 cytokine secreting cells capable of inducing eosinophilic lung inflammation and AHR independent of adaptive immunity. Remarkably, reports show that ILC2s are increased in the blood of human asthmatics as compared to healthy donors. Nevertheless, whether ILC2 expression of adhesion molecules regulates ILC2 trafficking remains unknown. Our results show that IL-33-activated ILC2s not only express LFA-1 but also strikingly LFA-1 ligand ICAM-1. Both LFA-1^-/- and ICAM-1^-/- mice developed attenuated AHR in response to IL-33 intranasal challenge, associated with a lower airway inflammation and less lung ILC2 accumulation compared to controls. Our mixed bone marrow chimera studies however revealed that ILC2 expression of LFA-1 - but not ICAM-1 - was required for their accumulation in the inflamed lungs. Importantly, we found that LFA-1 remarkably controlled ILC2 homing to the lungs, suggesting that LFA-1 is involved in ILC2 trafficking to the lungs. Our exploratory transcriptomic analysis further revealed that ICAM-1 deficiency on ILC2s significantly affects their effector functions. While it downregulated pro-inflammatory cytokines such as Il5, Il9, Il13, and Csf2, it however notably also upregulated cytokines including Il10 both at the transcriptomic and protein levels. These findings provide novel avenues for future investigations, as modulation of LFA-1 and/or ICAM-1 represents an unappreciated regulatory mechanism for ILC2 trafficking and cytokine production respectively, potentially serving as therapeutic target for ILC2-dependent diseases such as allergic asthma.

Integrin-Ligand Interactions in Inflammation, Cancer, and Metabolic Disease: Insights Into the Multifaceted Roles of an Emerging Ligand Irisin

Integrins are transmembrane proteins that mediate cellular adhesion and migration to neighboring cells or the extracellular matrix, which is essential for cells to undertake diverse physiological and pathological pathways. For integrin activation and ligand binding, bidirectional signaling across the cell membrane is needed. Integrins aberrantly activated under pathologic conditions facilitate cellular infiltration into tissues, thereby causing inflammatory or tumorigenic progressions. Thus, integrins have emerged to the forefront as promising targets for developing therapeutics to treat autoimmune and cancer diseases. In contrast, it remains a fact that integrin-ligand interactions are beneficial for improving the health status of different tissues. Among these ligands, irisin, a myokine produced mainly by skeletal muscles in an exercise-dependent manner, has been shown to bind to integrin αVβ5, alleviating symptoms under unfavorable conditions. These findings may provide insights into some of the underlying mechanisms by which exercise improves quality of life. This review will discuss the current understanding of integrin-ligand interactions in both health and disease. Likewise, we not only explain how diverse ligands play different roles in mediating cellular functions under both conditions via their interactions with integrins, but also specifically highlight the potential roles of the emerging ligand irisin in inflammation, cancer, and metabolic disease.

Modes of Communication between T Cells and Relevance for Immune Responses

T cells are essential mediators of the adaptive immune system, which constantly patrol the body in search for invading pathogens. During an infection, T cells that recognise the pathogen are recruited, expand and differentiate into subtypes tailored to the infection. In addition, they differentiate into subsets required for short and long-term control of the pathogen, i.e., effector or memory. T cells have a remarkable degree of plasticity and heterogeneity in their response, however, their overall response to a given infection is consistent and robust. Much research has focused on how individual T cells are activated and programmed. However, in order to achieve a critical level of population-wide reproducibility and robustness, neighbouring cells and surrounding tissues have to provide or amplify relevant signals to tune the overall response accordingly. The characteristics of the immune response-stochastic on the individual cell level, robust on the global level-necessitate coordinated responses on a system-wide level, which facilitates the control of pathogens, while maintaining self-tolerance. This global coordination can only be achieved by constant cellular communication between responding cells, and faults in this intercellular crosstalk can potentially lead to immunopathology or autoimmunity. In this review, we will discuss how T cells mount a global, collective response, by describing the modes of T cell-T cell (T-T) communication they use and highlighting their physiological relevance in programming and controlling the T cell response.

Manufacturing and preclinical validation of CAR T cells targeting ICAM-1 for advanced thyroid cancer therapy

While the majority of thyroid cancer patients are easily treatable, those with anaplastic or poorly differentiated recurrent thyroid carcinomas have a very poor prognosis with a median survival of less than a year. Previously, we have shown a significant correlation between ICAM-1 overexpression and malignancy in thyroid cancer, and have pioneered the use of ICAM-1 targeted CAR T cells as a novel treatment modality. For clinical translation of this novel modality, we designed CAR T cells possessing micromolar rather than nanomolar affinity to ICAM-1 to avoid cytotoxicity in normal cells with basal levels of ICAM-1 expression. Herein, we report the automated process of CAR T cell manufacturing with CliniMACS Prodigy (Miltenyi Biotec) using cryopreserved peripheral blood leukocytes from apheresis collections. Using Prodigy, thawed leukopak cells were enriched for CD4⁺ and CD8⁺ T cells, subjected to double transduction using lentiviral vector, and expanded in culture for a total of 10 days with a final yield of 2–4 × 10⁹ cells. The resulting CAR T cells were formulated for cryopreservation to be used directly for infusion into patients after thawing with no further processing. We examined cross-reactivity of CAR T cells toward both human and murine ICAM-1 and ICAM-1 expression in human and mouse tissues to demonstrate that both efficacy and on-target, off-tumor toxicity can be studied in our preclinical model. Selective anti-tumor activity in the absence of toxicity provides proof-of-concept that micromolar affinity tuned CAR T cells can be used to target tumors expressing high levels of antigen while avoiding normal tissues expressing basal levels of the same antigen. These studies support the initiation of a phase I study to evaluate the safety and potential efficacy of micromolar affinity tuned CAR T cells against newly diagnosed anaplastic and refractory or recurrent thyroid cancers.

PLANT: A Method for Detecting Changes of Slope in Noisy Trajectories

Time traces obtained from a variety of biophysical experiments contain valuable information on underlying processes occurring at the molecular level. Accurate quantification of these data can help explain the details of the complex dynamics of biological systems. Here, we describe PLANT (Piecewise Linear Approximation of Noisy Trajectories), a segmentation algorithm that allows the reconstruction of time-trace data with constant noise as consecutive straight lines, from which changes of slopes and their respective durations can be extracted. We present a general description of the algorithm and perform extensive simulations to characterize its strengths and limitations, providing a rationale for the performance of the algorithm in the different conditions tested. We further apply the algorithm to experimental data obtained from tracking the centroid position of lymphocytes migrating under the effect of a laminar flow and from single myosin molecules interacting with actin in a dual-trap force-clamp configuration.

Unraveling the Mechanobiology of the Immune System

Cells respond and actively adapt to environmental cues in the form of mechanical stimuli. This extends to immune cells and their critical role in the maintenance of tissue homeostasis. Multiple recent studies have begun illuminating underlying mechanisms of mechanosensation in modulating immune cell phenotypes. Since the extracellular microenvironment is critical to modify cellular physiology that ultimately determines the functionality of the cell, understanding the interactions between immune cells and their microenvironment is necessary. This review focuses on mechanoregulation of immune responses mediated by macrophages, dendritic cells, and T cells, in the context of modern mechanobiology.

Membrane-bound ICAM-1 contributes to the onset of proinvasive tumor stroma by controlling acto-myosin contractility in carcinoma-associated fibroblasts

Acto-myosin contractility in carcinoma-associated fibroblasts leads to assembly of the tumor extracellular matrix. The pro-inflammatory cytokine LIF governs fibroblast activation in cancer by regulating the myosin light chain 2 activity. So far, however, how LIF mediates cytoskeleton contractility remains unknown. Using phenotypic screening assays based on knock-down of LIF-dependent genes in fibroblasts, we identified the glycoprotein ICAM-1 as a crucial regulator of stroma fibroblast proinvasive matrix remodeling. We demonstrate that the membrane-bound ICAM-1 isoform is necessary and sufficient to promote inflammation-dependent extracellular matrix contraction, which favors cancer cell invasion. Indeed, ICAM-1 mediates generation of acto-myosin contractility downstream of the Src kinases in stromal fibroblasts. Moreover, acto-myosin contractility regulates ICAM-1 expression by establishing a positive feedback signaling. Thus, targeting stromal ICAM-1 might constitute a possible therapeutic mean to counteract tumor cell invasion and dissemination.

Immunosuppressive Factors: Role in Cancer Development and Progression

The concept of the immunological surveillance against neoplastic cells was initially proposed by Erlich in 1909 and later elaborated by Burnet. This hypothesis states that the normal function of the immune system, in particular the cell-mediated immunity, is to recognize and destroy the transformed and proliferating tumor cells. The role of cell-mediated immunity during the first steps of tumorigenesis remains controversial. However, there is certain evidence about its importance in the progression and dissemination of cancer. The frequent immunosuppressed condition of cancer patients at tumor relapse or recurrence of secondary tumors is a clinical sign supporting this hypothesis, and many studies have demonstrated a defective immune response in patients diagnosed with advanced cancer. Several mechanisms of escape from the immune surveillance have been described, including the immunoselection of tumor antigen-negative variants, the downregulation of MHC class I expression, suppressive T cells, and the elaboration of immunosuppressive cytokines and other factors. Because of the technical difficulty of isolating the very small amounts from culture supernatants or body fluids, only a few of these substances have been characterized and studied with respect to their biological activity: transforming growth factor-β (TGF-β), the protein p15E, interleukin 10 (IL-10), prostaglandin E2 (PGE2), mucins, suppressive E-receptor (SER), immunosuppressive acidic protein (IAP), and adhesion molecules. The possibility of monitoring cancer patients by testing biochemical factors related to cancer growth led to a proposal to measure a number of these factors as tumor markers. Some of them, e.g mucins, enjoy the consensus of the oncologic community, as for some indications they can help the clinician in the management of cancer patients. Except for the class of mucins, the other above-mentioned immunosuppressive factors have not found any clinical application in the laboratory routine because the information deriving from their measurement, although of speculative and scientific interest, has limited clinical value at present. Nevertheless, even if they have no impact on patient management, these substances do have a potential role to play in the study of cancer patients, and should be taken into account when developing new therapeutic strategies.

Inflammation and Cancer: In Medio Stat Nano

Cancer treatment still remains a challenge due to the several limitations of currently used chemotherapeutics, such as their poor pharmacokinetics, unfavorable chemical properties, as well as inability to discriminate between healthy and diseased tissue. Nanotechnology offered potent tools to overcome these limitations. Drug encapsulation within a delivery system permitted i) to protect the payload from enzymatic degradation/ inactivation in the blood stream, ii) to improve the physicochemical properties of poorly water-soluble drugs, like paclitaxel, and iii) to selectively deliver chemotherapeutics to the cancer lesions, thus reducing the off-target toxicity, and promoting the intracellular internalization. To accomplish this purpose, several strategies have been developed, based on biological and physical changes happening locally and systemically as a consequence of tumorigenesis. Here, we will discuss the role of inflammation in the different steps of tumor development and the strategies based on the use of nanoparticles that exploit the inflammatory pathways in order to selectively target the tumor-associated microenvironment for therapeutic and diagnostic purposes.

A Functional Analysis on the Interspecies Interaction between Mouse LFA-1 and Human Intercellular Adhesion Molecule-1 at the Cell Level

The interaction between intercellular adhesion molecules (ICAM) and the integrin leukocyte function-associated antigen-1 (LFA-1) is crucial for the regulation of several physiological and pathophysiological processes like cell-mediated elimination of tumor or virus infected cells, cancer metastasis, or inflammatory and autoimmune processes. Using purified proteins it was reported a species restriction for the interaction of ICAM-1 and LFA-1, being mouse ICAM-1 able to interact with human LFA-1 but not human ICAM-1 with mouse LFA-1. However, in vivo results employing tumor cells transfected with human ICAM-1 suggest that functionally mouse LFA-1 can recognize human ICAM-1. In order to clarify the interspecies cross-reactivity of the ICAM-1/LFA-1 interaction, we have performed functional studies analyzing the ability of human soluble ICAM-1 and human/mouse LFA-1 derived peptides to inhibit cell aggregation and adhesion as well as cell-mediated cytotoxicity in both mouse and human systems. In parallel, the affinity of the interaction between mouse LFA-1-derived peptides and human ICAM-1 was determined by calorimetry assays. According to the results obtained, it seems that human ICAM-1 is able to interact with mouse LFA-1 on intact cells, which should be taking into account when using humanized mice and xenograft models for the study of immune-related processes.

Role of liver ICAM-1 in metastasis

Intercellular adhesion molecule (ICAM)-1, is a transmembrane glycoprotein of the immunoglobulin (Ig)-like superfamily, consisting of five extracellular Ig-like domains, a transmembrane domain and a short cytoplasmic tail. ICAM-1 is expressed in various cell types, including endothelial cells and leukocytes, and is involved in several physiological processes. Furthermore, it has additionally been reported to be expressed in various cancer cells, including melanoma, colorectal cancer and lymphoma. The majority of studies to date have focused on the expression of the ICAM-1 on the surface of tumor cells, without research into ICAM-1 expression at sites of metastasis. Cancer cells frequently metastasize to the liver, due to its unique physiology and specialized liver sinusoid capillary network. Liver sinusoidal endothelial cells constitutively express ICAM-1, which is upregulated under inflammatory conditions. Furthermore, liver ICAM-1 may be important during the development of liver metastasis. Therefore, it is necessary to improve the understanding of the mechanisms mediated by this adhesion molecule in order to develop host-directed anticancer therapies.

Iodine-131 therapy alters the immune/inflammatory responses in the thyroids of patients with Graves' disease

The aim of the present study was to evaluate the serum levels of interleukin-6 (IL-6), CXC chemokine ligand-10 (CXCL-10) and intercellular adhesion molecule-l (ICAM-1) in patients with Graves' disease (GD) following iodine-131 (¹³¹I) therapy. A total of 30 patients with GD participated in the present study. Serum cytokine levels were measured with ELISA, and correlation analyses were performed. Serum levels of IL-6, CXCL-10 and ICAM-1 were significantly higher in patients with GD prior to treatment than those in the control subjects (P<0.01). Following ¹³¹I therapy, the serum levels of IL-6 and CXCL-10 in patients with GD were markedly increased within the first week, gradually decreased to the pretreatment level in the subsequent six months and decreased further at 18 months post-treatment. However, the serum levels of IL-6 and CXCL-10 in patients with GD at 18 months following ¹³¹I therapy remained significantly higher than in control subjects (P<0.01). Conversely, serum ICAM-1 levels in patients with GD were gradually increased in the 12 months following ¹³¹I therapy and reached a relatively stable level thereafter. Furthermore, the Pearson's correlation analysis indicated that the serum levels of IL-6, CXCL-10 and ICAM-1 were not associated with free triiodothyronine, the free thyroxine index, and thyroid-stimulating hormone in these patients. ¹³¹I therapy was able to alter the immune/inflammatory responses in the thyroids of patients with GD. However, these cytokines (IL-6, CXCL-10, and ICAM-1) are not associated with thyroid function; therefore, they cannot be used as prognostic markers for the ¹³¹I therapy of GD.

Indole-3-carbinol is a potent inhibitor of ischemia-reperfusion-induced inflammation

BACKGROUND

Ischemia-reperfusion (I/R) induces tissue inflammation, which is characterized by an increased leukocyte-endothelial cell interaction and leukocyte transmigration. These processes are mediated by the activation of the nuclear factor (NF)κB signaling pathway, resulting in an elevated expression of specific adhesion molecules. The phytochemical indole-3-carbinol (I3C) has been shown to exert anti-inflammatory effects by interfering with NFκB signal transduction. The aim of the present study was to investigate whether I3C is capable of counteracting the pathogenesis of I/R injury.

MATERIALS AND METHODS

We investigated the inhibitory effect of I3C on endothelial surface protein expression during hypoxia and reoxygenation by flow cytometry. Moreover, the subcellular localization of NFκB was analyzed by immunofluorescence and Western blot. Adhesion protein levels on leukocytes after tumor necrosis factor-α stimulation were determined using flow cytometry. Finally, leukocyte-endothelial cell interaction and leukocyte transmigration during I/R was investigated in dorsal skinfold chambers of BALB/c mice by means of repetitive intravital fluorescence microscopy and immunohistochemistry.

RESULTS

I3C suppressed the expression of E-selectin and intercellular adhesion molecule-1 on human dermal microvascular endothelial cells by reducing the transcriptional activity of NFκB. Furthermore, surface protein levels of macrophage-1 antigen as well as activated lymphocyte function-associated antigen-1 were markedly reduced on I3C-treated leukocytes. In vivo, I3C treatment decreased the numbers of adherent and transmigrated leukocytes. This was associated with a reduced macromolecular leakage when compared with vehicle-treated controls.

CONCLUSIONS

These novel results indicate that I3C reduces the expression of endothelial and leukocytic adhesion proteins, resulting in attenuated leukocyte-endothelial cell interactions during I/R. Accordingly, dietary supplements containing I3C may be beneficial for the treatment of I/R-induced inflammation.

Actin polymerization-dependent activation of Cas-L promotes immunological synapse stability

The immunological synapse formed between a T-cell and an antigen-presenting cell is important for cell-cell communication during T-cell-mediated immune responses. Immunological synapse formation begins with stimulation of the T-cell receptor (TCR). TCR microclusters are assembled and transported to the center of the immunological synapse in an actin polymerization-dependent process. However, the physical link between TCR and actin remains elusive. Here we show that lymphocyte-specific Crk-associated substrate (Cas-L), a member of a force sensing protein family, is required for transport of TCR microclusters and for establishing synapse stability. We found that Cas-L is phosphorylated at TCR microclusters in an actin polymerization-dependent fashion. Furthermore, Cas-L participates in a positive feedback loop leading to amplification of Ca2+ signaling, inside-out integrin activation, and actomyosin contraction. We propose a new role for Cas-L in T-cell activation as a mechanical transducer linking TCR microclusters to the underlying actin network and coordinating multiple actin-dependent structures in the immunological synapse. Our studies highlight the importance of mechanotransduction processes in T-cell-mediated immune responses.

Leukocyte arrest: Biomechanics and molecular mechanisms of β2 integrin activation

Integrins are a group of heterodimeric transmembrane receptors that play essential roles in cell-cell and cell-matrix interaction. Integrins are important in many physiological processes and diseases. Integrins acquire affinity to their ligand by undergoing molecular conformational changes called activation. Here we review the molecular biomechanics during conformational changes of integrins, integrin functions in leukocyte biorheology (adhesive functions during rolling and arrest) and molecules involved in integrin activation.

Identification of Stage-Specific Surface Markers in Early B Cell Development Provides Novel Tools for Identification of Progenitor Populations

Whereas the characterization of B lymphoid progenitors has been facilitated by the identification of lineage- and stage-specific surface markers, the continued identification of differentially expressed proteins increases our capacity to explore normal and malignant B cell development. To identify novel surface markers with stage-specific expression patterns, we explored the reactivity of CD19(+) B cell progenitor cells to Abs targeted to 176 surface proteins. Markers with stage-specific expression were identified using a transgenic reporter gene system subdividing the B cell progenitors into four surface IgM(-) stages. This approach affirmed the utility of known stage-specific markers, as well as identifying additional proteins that selectively marked defined stages of B cell development. Among the stage-specific markers were the cell adhesion proteins CD49E, CD11A, and CD54 that are highly expressed selectively on the most immature progenitors. This work identifies a set of novel stage-specific surface markers that can be used as a complement to the classical staining protocols to explore B lymphocyte development.

Roles of Proteoglycans and Glycosaminoglycans in Wound Healing and Fibrosis

A wound is a type of injury that damages living tissues. In this review, we will be referring mainly to healing responses in the organs including skin and the lungs. Fibrosis is a process of dysregulated extracellular matrix (ECM) production that leads to a dense and functionally abnormal connective tissue compartment (dermis). In tissues such as the skin, the repair of the dermis after wounding requires not only the fibroblasts that produce the ECM molecules, but also the overlying epithelial layer (keratinocytes), the endothelial cells, and smooth muscle cells of the blood vessel and white blood cells such as neutrophils and macrophages, which together orchestrate the cytokine-mediated signaling and paracrine interactions that are required to regulate the proper extent and timing of the repair process. This review will focus on the importance of extracellular molecules in the microenvironment, primarily the proteoglycans and glycosaminoglycan hyaluronan, and their roles in wound healing. First, we will briefly summarize the physiological, cellular, and biochemical elements of wound healing, including the importance of cytokine cross-talk between cell types. Second, we will discuss the role of proteoglycans and hyaluronan in regulating these processes. Finally, approaches that utilize these concepts as potential therapies for fibrosis are discussed.

2,3,4',5-tetrahydroxystilbene-2-O-β-D-glucoside suppresses expression of adhesion molecules in aortic wall of dietary atherosclerotic rats and promonocytic U937 cells

We sought to investigate whether TSG suppressed the ICAM-1/VCAM-1 expression in dietary atherosclerotic rats and in Ox-LDL-induced U937 cells. For this purpose, 60 male Sprague-Dawley rats were randomly-and-equally divided into six groups. Atherosclerosis was induced by feeding rats a hyperlipidemic diet. TSG (120, 60 or 30 mg/kg/day) was administered by oral gavage. Simvastatin (2 mg/kg/day) was administered as positive control whereas physiological saline (0.9% NaCl) served as untreated control. After 12 weeks, rats were euthanized by ethyl carbonate (1,200 mg/kg) and aortic wall samples were collected. Besides, U937 cells were stimulated for 48 h by Ox-LDL (80 μg/mL) with and without TSG (120, 60, 30 μg/L) or simvastatin (100 μg/L). ICAM-1/VCAM-1 mRNA expression was determined by RT-PCR and protein expression was detected by immunohistochemistry and/or western blotting. The data show that ICAM-1/VCAM-1 mRNA/protein expression was significantly enhanced in atherosclerotic aortas compared with normal diet group. Ox-LDL-induced ICAM-1/VCAM-1 mRNA/protein expression in U937 cells. Importantly, TSG significantly inhibited ICAM-1/VCAM-1 expression in atherosclerotic aortas in a dose-dependent manner. TSG-pretreatment also inhibited ICAM-1/VCAM-1 expression in Ox-LDL-induced U937 cells. Therefore, we concluded that TSG suppressed the expression of adhesion (ICAM-1/VCAM-1) molecules both in vivo (in aortic wall of dietary atherosclerotic rats) and in vitro (U937 cells).

Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells

LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.

Integrin α4β1 is necessary for CD4+ T cell-mediated protection against genital Chlamydia trachomatis infection

Chlamydia trachomatis infection is the most common sexually transmitted bacterial infection in the United States and a significant health burden worldwide. Protection from Chlamydia infection in the genital mucosa is dependent on IFN-γ derived from CD4(+) Th1 cells. These CD4(+) T cells must home successfully to the genital tract to exert their effector function and decrease C. trachomatis burden. Although adhesion receptors expressed by CD4(+) T cells in the genital tract have been characterized, the integrin receptor required for Chlamydia-specific CD4(+) T cell-mediated protection has not been explored. In this study, we demonstrate that C. trachomatis infection of the upper genital tract results in recruitment of Chlamydia-specific CD4(+) T cells robustly expressing the integrin α4β1. Interfering with α4β1, but not α4β7, function resulted in defective CD4(+) T cell trafficking to the uterus and high bacterial load. We conclude that integrin α4β1 is necessary for CD4(+) T cell-mediated protection against C. trachomatis infection in the genital mucosa. By identifying homing molecules required for successful CD4(+) T cell trafficking to C. trachomatis-infected tissues, we will be better equipped to design vaccines that elicit sterilizing, long-lasting immunity without inducing immune pathologies in the upper genital tract.

Memory CD4 T cells in influenza

Influenza A virus is a significant cause of morbidity and mortality worldwide, particularly among young children and the elderly. Current vaccines induce neutralizing antibody responses directed toward highly variable viral surface proteins, resulting in limited heterosubtypic protection to new viral serotypes. By contrast, memory CD4 T cells recognize conserved viral proteins and are cross-reactive to multiple influenza strains. In humans, virus-specific memory CD4 T cells were found to be the protective correlate in human influenza challenge studies, suggesting their key role in protective immunity. In mouse models, memory CD4 T cells can mediate protective responses to secondary influenza infection independent of B cells or CD8 T cells, and can influence innate immune responses. Importantly, a newly defined, tissue-resident CD4 memory population has been demonstrated to be retained in lung tissue and promote optimal protective responses to an influenza infection. Here, we review the current state of results regarding the generation of memory CD4 T cells following primary influenza infection, mechanisms for their enhanced efficacy in protection from secondary challenge including their phenotype, localization, and function in the context of both mouse models and human infection. We also discuss the generation of memory CD4 T cells in response to influenza vaccines and its future implications for vaccinology.

Inhibition of proliferation and invasiveness of ovarian cancer C13* cells by a poly(ADP-ribose) polymerase inhibitor and the role of nuclear factor-κB

Objective

To investigate the effect of the poly(ADP-ribose) polymerase-1 (PARP-1) inhibitor PJ34 on the proliferation and invasiveness of ovarian cancer C13* cells and the role of nuclear factor-κB (NF-κB).

Methods

Proliferation of C13* cells was measured using a 3 -(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide assay after incubation with PJ34 at different concentrations and for different treatment durations. In addition, expression of PARP-1 and the NF-κB p65 subunit after treatment with PJ34 was measured using Western blot and immunocytochemistry. The effect of PJ34 on cell invasiveness was examined using a transwell invasion assay.

Results

PJ34 inhibited proliferation of C13* cells in a time- and dose-dependent manner. PJ34 treatment was also associated with a dose-dependent decrease in PARP-1 and NF-κB p65 expression and attenuated invasiveness of C13* cells. PARP-1 expression was positively correlated with NF-κB p65 expression.

Conclusion

The PARP-1 inhibitor PJ34 can markedly inhibit the proliferation and invasiveness of C13* cells, possibly due to PARP-1-mediated attenuation of NF-κB activity.

Exogenous microparticles of iron oxide bind to activated endothelial cells but, unlike monocytes, do not trigger an endothelial response

Targeting particles to sites of inflammation is of considerable interest for applications relating to molecular imaging and drug delivery. We and others have described micron-sized particles of iron oxide (MPIO) that can be directed using specific ligands (e.g. antibodies, peptides and oligosaccharides) to bind to mediators of vascular inflammation in vivo. Since leukocyte binding to these molecules can induce changes in the target cell, an outstanding question has been whether the binding of imaging particles to these mediators induces biologically significant changes in the endothelial cells, potentially initiating or propagating inflammation. Here, we address these questions by looking for changes in endothelial cells following binding of contrast agent. Specifically, we have quantified calcium flux, rearrangement of the actin cytoskeleton, production of reactive oxygen species (ROS), apoptosis and potential secondary changes, such as changes in gene and protein expression follow binding events to primary endothelial cells in vitro. Although leukocytes induced changes to endothelial cell function, we did not see any significant changes to endothelial calcium flux, cytoskeletal organisation, production of ROS or induction of apoptosis in response to antibody-MPIO binding. Furthermore, there were no changes to gene expression monitored via real-time RT-PCR or presentation of protein on the cell surface measured using flow cytometry. Our experiments demonstrate that whilst antibody-targeted microparticles mimic the binding capability of leukocytes to inflamed endothelium, they do not trigger the same cellular responses and do not appear to initiate or compound inflammation. These properties are desirable for targeted therapeutic and diagnostic agents.

Endothelial heterogeneity and adhesion molecules N-glycosylation: implications in leukocyte trafficking in inflammation

Inflammation is a major contributing element to a host of diseases with the interaction between leukocytes and the endothelium being key in this process. Much is understood about the nature of the adhesion molecule proteins expressed on any given leukocyte and endothelial cell that modulates adhesive interactions. Although it is appreciated that these proteins are heavily glycosylated, relatively little is known about the roles of these posttranslational modifications and whether they are regulated, and if so how during inflammation. Herein, we suggest that a paucity in this understanding is one major reason for the lack of successful therapies to date for modulating leukocyte-endothelial interactions in human inflammatory disease and discuss developing paradigms of (i) how endothelial adhesion molecule glycosylation (with a focus on N-glycosylation) maybe a critical element in understanding endothelial heterogeneity between different vascular beds and species, (ii) how adhesion molecule N-glycosylation may be under distinct, and as yet, unknown modes of regulation during inflammatory stress to affect the inflammatory response in a vascular bed- and disease-specific manner (analogous to a "zip code" for inflammation) and finally (iii) to underscore the concept that a fuller appreciation of the role of adhesion molecule glycoforms is needed to provide foundations for disease and tissue-specific targeting of inflammation.

Free circulating ICAM-1 in serum and cerebrospinal fluid of HIV-1 infected patients correlate with TNF-alpha and blood-brain barrier damage

The mechanism for the initiation of blood-brain barrier damage and intrathecal inflammation in patients infected with the human immunodeficiency virus (HIV) is poorly understood. We have recently reported that tumour necrosis factor-alpha (TNF-alpha) mediates active neural inflammation and blood-brain barrier damage in HIV-1 infection. Stimulation of endothelial cells by TNF-alpha induces the expression of intercellular adhesion molecule-1 (ICAM-1), which is an important early marker of immune activation and response. We report herein for the first time the detection of high levels of free circulating ICAM-1 in serum and cerebrospinal fluid of patients with HIV-1 infection. Free circulating ICAM-1 in these patients correlated with TNF-alpha concentrations and with the degree of blood-brain barrier damage and were detected predominantly in patients with neurologic involvement. These findings have important implications for the understanding and investigation of the intrathecal inflammatory response in HIV-1 infection.

Carboxyl terminus of heat shock protein 70-interacting protein inhibits angiotensin II-induced cardiac remodeling

BACKGROUND

The carboxyl terminus of heat shock protein 70-interacting protein (CHIP), an E3 ligase/chaperone, was found to protect cardiomyocytes against apoptosis induced by ischemic injury; however, the functional role of CHIP in remodeling induced by angiotensin II (Ang II) remains unclear.

METHODS

We generated CHIP-overexpressed transgenic (TG) mice infused with Ang II (1,500 ng/kg/min) or saline for days or small interfering RNA (siRNA) knockdown of neonatal rat cardiomyocytes. Heart sections were stained with hematoxylin and eosin, Masson trichrome, TdT-mediated dUTP nick-end labeling (TUNEL) staining, and immunohistochemistry, and the levels of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPK) were measured by western blot analysis.

RESULTS

Seven days after Ang II infusion, cardiac-specific overexpression of CHIP significantly enhanced cardiac contractile performance in mice and attenuated cardiac apoptosis, fibrosis, and inflammation: the number of TUNEL-positive cells, fibrotic areas, macrophage infiltration, and the expression of interleukin-1β (IL-1β), IL-6, monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) in heart tissues were decreased as compared with wild-type (WT) mice (all P < 0.05). In contrast, CHIP siRNA knockdown markedly increased Ang II-induced apoptosis and the expression of proinflammatory cytokines, as compared with siRNA control. The mechanisms underlying these beneficial actions were associated with CHIP-mediated inhibition of NF-κB and MAPK (p38 and JNK) pathways.

CONCLUSIONS

CHIP plays an important role in regulating Ang II-triggered hypertensive cardiac apoptosis, inflammation, and fibrosis.

TNF-α increases bone marrow mesenchymal stem cell migration to ischemic tissues

The objective of this study was to analyze the influence of TNF-α on rat mesenchymal stem cells (MSCs) and to assess feasibility of MSC transplantation to repair ischemic injury. In this study, adhesion molecules and cell specific surface markers on MSCs were measured after exposure to different concentrations of TNF-α. MSCs stimulated with varying concentrations of TNF-α were cultured with aortic endothelial cells, and the adhesion rate was measured. MSCs were then stimulated with an optimum concentration of TNF-α as determined in vitro, and injected intravenously into rats with ischemic hind limb injury. The number of MSCs in muscle samples from the ischemic area was counted. The results showed that (1) TNF-α induced a concentration-dependent increase in VCAM-1 expression in MSCs, whereas the expression of L-selectin, ICAM-1 and VLA-4 did not change significantly. Expression of MSC-specific antigens was unchanged. (2) MSCs pretreated with 10 ng/ml TNF-α showed significantly increased adhesion to endothelial cells in vitro, and accumulated to a greater extent in the areas of ischemic damage in rat hind limbs. We were able to conclude that TNF-α has no effect on expression of MSC-specific markers, but can increase the expression of VCAM-1 on rat MSCs. Suitable concentrations of TNF-α can promote MSC adhesion to endothelial cells and migration to damaged tissue.

Protein kinase R is a novel mediator of CD40 signaling and plays a critical role in modulating immunoglobulin expression during respiratory syncytial virus infection

Effective immunoglobulin responses play a vital role in protection against most pathogens. However, the molecular mediators and mechanisms responsible for signaling and selective expression of immunoglobulin types remain to be elucidated. Previous studies in our laboratory have demonstrated that protein kinase R (PKR) plays a crucial role in IgE responses to double-stranded RNA (dsRNA) in vitro. In this study, we show that PKR plays a critical role in IgG expression both in vivo and in vitro. PKR(-/-) mice show significantly altered serum IgG levels during respiratory syncytial virus (RSV) infection. IgG2a expression is particularly sensitive to a lack of PKR and is below the detection level in mock- or RSV-infected PKR(-/-) mice. Interestingly, we show that upon activation by anti-CD40 and gamma interferon (IFN-γ), B cells from PKR(-/-) mice show diminished major histocompatibility complex class II (MHC II), CD80, and CD86 levels on the cell surface compared to wild-type (WT) mice. Our data also show that PKR is necessary for optimal expression of adhesion molecules, such as CD11a and ICAM-1, that are necessary for homotypic aggregation of B cells. Furthermore, in this report we demonstrate for the first time that upon CD40 ligation, PKR is rapidly phosphorylated and activated, indicating that PKR is an early and novel downstream mediator of CD40 signaling pathways.