Soluble Ligand Research Articles

Experimental validation of computerised models of clustering of platelet glycoprotein receptors that signal via tandem SH2 domain proteins.

The clustering of platelet glycoprotein receptors with cytosolic YxxL and YxxM motifs, including GPVI, CLEC-2 and PEAR1, triggers activation via phosphorylation of the conserved tyrosine residues and recruitment of the tandem SH2 (Src homology 2) domain effector proteins, Syk and PI 3-kinase. We have modelled the clustering of these receptors with monovalent, divalent and tetravalent soluble ligands and with transmembrane ligands based on the law of mass action using ordinary differential equations and agent-based modelling. The models were experimentally evaluated in platelets and transfected cell lines using monovalent and multivalent ligands, including novel nanobody-based divalent and tetravalent ligands, by fluorescence correlation spectroscopy. Ligand valency, receptor number, receptor dimerisation, receptor phosphorylation and a cytosolic tandem SH2 domain protein act in synergy to drive receptor clustering. Threshold concentrations of a CLEC-2-blocking antibody and Syk inhibitor act in synergy to block platelet aggregation. This offers a strategy for countering the effect of avidity of multivalent ligands and in limiting off-target effects.

Novel amino analogs of the trimethoxyphenyl ring in potent colchicine site ligands improve solubility by the masked polar group incorporation (MPGI) strategy

The low aqueous solubility of colchicine site antimitotic agents, of which the trimethoxyphenyl (A ring) is a heavy contributor, is a serious drawback in their clinical development. We have designed new A ring analogs with chameleonic masked polar amino groups able to increase aqueous solubility and also behave as non-polar through intramolecular hydrogen bonds when bound to tubulin. We have incorporated these new A rings in several scaffolds (sulfonamides, combretastatins, phenstatins, isocombretastatins), synthesized, and assayed 43 representatives. The amino analogs show improved aqueous solubility and some of them (8, 60Z, and 67) nanomolar anti-proliferative potencies against human cancer cell lines, with the most favorable substituent being a 3-methylamino group. The antiproliferative effect relates to tubulin inhibition as shown by in vitro tubulin polymerization inhibition, immunofluorescence microscopy, and cell cycle and apoptosis analysis by flow cytometry. The compounds arrest the cell cycle of treated cells in G2/M and later develop an apoptotic response. Docking studies suggested binding at the colchicine site of tubulin with good agreement with the DFT models of the new structural variations made. The 3-methylamino-4,5‑dimethoxyphenyl moiety is an example of the masked polar group incorporation (MPGI) strategy for soluble ligands binding to hydrophobic sites and a good trimethoxyphenyl ring replacement for the development of new colchicine site ligands.

016 PC111, a novel, First In Class, human anti-FasL antibody for the treatment of Pemphigus: a translational study

Pemphigus is a rare and debilitating autoimmune blistering disease due to keratinocyte cell-cell detachment (acantholysis). Treatments focus on immune suppression but are often associated with severe side effects, slow onset of action and frequent clinical relapses; therefore, innovative and non-immunosuppressive therapies are needed to provide rapid, safer and long-lasting responses. Patients’ autoantibodies (PVIgG) are fundamental for initiating the pathologic mechanisms of pemphigus. We have recently demonstrated that soluble Fas Ligand (sFasL), that is massively up-regulated and released from keratinocytes upon PVIgG binding, is essential for blister formation.

Pembrowm: Results of a Multi-Centre Phase II Trial Investigating the Safety and Efficacy of Rituximab and Pembrolizumab in Relapsed/Refractory Waldenström's Macroglobulinaemia

Background Waldenström's macroglobulinemia (WM) is a rare low grade B-cell NHL, with generally excellent outcomes underpinned by treatment with Rituximab combination therapies and covalent BTK inhibitors (cBTKi). However, these options are not curative and there are very little data to guide treatment options or a clear understanding of prognosis of relapsed/refractory (R/R) WM post cBTKi. PD-1 inhibition has been shown to be highly effective in classical Hodgkin lymphoma, and soluble PD-1 ligands have been implicated in T-cell regulatory function in the WM microenvironment. There is therefore a clear rationale to investigate the efficacy of PD-1 blockade in WM. Aim To determine the safety, tolerability and efficacy of pembrolizumab in combination with rituximab for the treatment of relapsed/refractory WM following prior cBTKi exposure. Methods PembroWM is a phase II, non-randomised, single arm, open label NCRI UK-wide study (NCT03630042) enrolling patients (pts) with R/R WM who had received 1 or more prior lines of treatment, who were not refractory to rituximab based therapy (progressing on or relapsing within 6 months of a rituximab containing regimen). Eligible pts accross 6 sites received rituximab 375mg/m2 weekly for 4 weeks, then 3 monthly (total of 8 doses) and pembrolizumab 200mg IV on a 3-weekly cycle, for a maximum of 18 cycles. The primary end point was the percentage of pts achieving an overall response rate (ORR) of greater than 25% reduction in serum IgM at 24 weeks post treatment. Secondary end points included safety and tolerability, response rates (CR/VGPR) , progression free survival (PFS) and overall survival (OS) at 1 year. Disease response was assessed with serum paraprotein/immunofixation, BM and CT imaging at 24 weeks and 1 year using the International Working Group for WM response criteria. The trial required recruitment of 42 patients with a 55% response rate to meet the primary end point. The trial closed early due to low recruitment rate with a total of 17 patients with a revised response requirement of 9 patients to meet primary end point. Results 17 patients were registered with median age of 70 years (range 43-84), 83% were male, 94% had a PS of 0-1, and the median number of lines of previous treatment was 3 (range 1-6). The majority of patients had a cBTKi as their last treatment prior to enrollment (only 2 patients were BTK naïve). 8 patients were positive for the MYD88 L265P mutation, and 4 patients had mutations in BTKC481. Median IgM levels were 40 g/L (range 2.5-72g/L) with 53% of patients exhibiting WM cells in bone marrow and extra nodal disease in 6%. Median follow up is 15.1 months (0.5 - 24.9). ORR at 24 weeks post treatment was 47.1% (60% CI 34.5-60%) with 6% attaining VGPR, 18% PR, 18% MR and in 6% response was unavailable but there was evidence of MR at week 12. 47% were non-responders; 35% progressed, 12% had stable disease and one patient withdrew during cycle 1 so was non-evaluable. ORR at 52 weeks post treatment was 36.4% (95% CI 10.9-69.2%) with 9% obtaining a VGPR, 27% PR and nil achieving CR. Median PFS was 12.6 months (95% CI 3-n/a) and median OS was not reached. 5 patients completed 18 cycles of treatment. 6 progressed, 3 withdrew due to AE, 2 withdrew consent and one withdrew to an unrelated clinician decision. The AE leading to withdrawal were immune thrombocytopenia (one), and infection in the other two (including one COVID-19 infection) The majority of adverse events were grade 1-2 with the commonest events involving anaemia (29%), fever (29%), infusion related reactions (35%) and raised creatinine (29%)., There were only 2 grade 3 infections. 1 patient experienced an embolic stroke and 1 patient died from respiratory failure; both events were considered unrelated to treatment. Conclusions PEMBROWM is the first study to investigate checkpoint inhibition in WM, and demonstrates the safety and tolerability of the combination of pembrolizumab and rituximab, with encouraging efficacy in a heavily pre-treated population. The recruitment challenges highlighted the combination of reduction in research activity during the COVID-19 pandemic, the difficulties of recruiting to an investigator-led study in a rare indication and the timing of availability/effectiveness of cBTKi in WM in the United Kingdom. A randomised study would be required to evaluate the additional benefit that PD-1 blockade is adding to rituximab monotherapy in a highly relapsed/refractory patient population. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Selected Factors of Vascular Changes: The Potential Pathological Processes Underlying Primary Headaches in Children.

The prevalence, social consequences and complicated pathogenesis make headaches in children a significant clinical issue. Studies in adults suggest that primary headaches could be the first sign of atherosclerosis and platelet aggregation. To analyze the blood levels of selected biomarkers of vascular changes potentially associated with a higher risk of atherosclerosis in children with primary headaches. The medical family history, brain-derived neurotrophic factor (BDNF), soluble CD40 ligands (sCD40L), endothelial plasminogen activator inhibitor (PAI I), vascular endothelial growth factor (VEGF) and intima-media thickness (IMT) measurements were performed in the 83 children (52 with primary headaches, 31 controls). Selected factors were compared with basic laboratory parameters that are potentially related to atherosclerosis: C-reactive protein (CRP) and lipid concentration. There were no significant differences in biomarkers of vascular changes in the study group and controls in general. In the study group, boys had a higher BDNF level than girls (p = 0.046). Normal-weight migraine patients had significantly higher PAI-I levels than controls (p = 0.034). A positive correlation between PAI-1 and triglycerides (TG) was observed. IMT did not differ between children with primary headaches and controls; however, IMT showed a positive correlation with BMI z-score and TG. Children with headaches had, more often, a positive family history of cardiovascular disease (p = 0.049). There were no clear clinical changes indicative of atherosclerosis in the study population. However, some trends are visible. Primary headaches are more often related to a family history of cardiovascular diseases. IMT is associated with TG levels and BMI z-score. The measured biomarkers of vascular changes show mutual relations.

Evaluation of Natural killer activated receptor NKG2D, Inhibitory receptor KIR2DL1 and soluble ligand MICA in Iraqi patients of Acute myeloid leukemia

Background: AML is a leukemic disease that related to the rapidly myeloid proliferation progenitor cells are transformed and leadingto stop proliferation and self-renewing. AML have many abilities to evading immune system one of them down expression of NK cellsactivating receptors NKG2D which is elaborate in in cooperation innate and adaptive immunities, and occupations as a “principalswitch” in influential the stimulation of natural killer (NK) cells. NKG2D can binds to a various ligand molecule, which are onlyexpressed at small concentration in usual cells but can be increase by a cellular tension response. And the realizing soluble NKG2Dligands MICA which is express by tumor cells and by binding with NKG2D lead to activated NK cells.Patients and methods: This study consists of 30 new diagnosed patients with AML and 24 out of 30 patients follow up at 14 days aftertreatment, 20 healthy looking persons match age and sex as control group. NKG2D detection by Flowcytometry and soluble MICAdetection by ELISA.Results: The NK cells activation receptor down expression in patients of AML as well as increase releasing of soluble ligand MICA.Conclusion: The NKG2D in patients with AML down expression which may due to increase soluble ligand MICA which lead to maskNKG2D receptors. There was relationship between down expression of NKG2D besides releasing soluble ligand MICA.

Ephrin Micropatterns Exogenously Modulate Cell Organization in Organoid‐Derived Intestinal Epithelial Monolayers

AbstractEph‐ephrin signaling acts as spatial cue to define the tissue boundaries, the axonal growth, or the organization of compartmentalized tissues in vertebrates. By the regulation of tension, adhesion, and repulsion, intermingling of cells expressing the membrane‐tethered ligand and cells expressing the membrane‐tethered receptor is prevented. Despite being surface‐bound, most of the studies addressing Eph‐ephrin interactions use soluble ligands, which lack the spatial component needed to study tissue patterning. Here, it is shown that spatial patterns of ephrin ligands can modulate the organization of the different compartments in organoid‐derived intestinal epithelial monolayers. A modified version of the microcontact printing technique is used to create spatial cues of ephrin ligand on basement membrane surrogates. It is shown that both ligand concentration and cellular density can impact the strength of the repulsive effect triggered by Eph‐ephrin signaling. Finally, it is demonstrated that by using micropatterned ephrin spatial cues one can modify the orientation of intestinal crypts and align them in the direction set by the pattern. The approach presented here is believed to be an excellent tool to study exogenous signal with relevant spatial distribution in vivo.

Serum soluble Fas ligand is a severity and mortality prognostic marker for COVID-19 patients.

Finding cytokine storm initiator factors associated with uncontrolled inflammatory immune response is necessary in COVID-19 patients. The aim was the identification of Fas/Fas Ligand (FasL) role in lung involvement and mortality of COVID-19 patients. In this case-control study, mild (outpatient), moderate (hospitalized), and severe (ICU) COVID-19 patients and healthy subjects were investigated. RNA isolated from PBMCs for cDNA synthesis and expression of mFas/mFasL mRNA was evaluated by RT-PCR. Serum sFas/sFasL protein by ELISA and severity of lung involvement by CT-scan were evaluated. Also, we docked Fas and FasL via Bioinformatics software (in silico) to predict the best-fit Fas/FasL complex and performed molecular dynamics simulation (MDS) in hyponatremia and fever (COVID-19 patients), and healthy conditions. mFasL expression was increased in moderate and severe COVID-19 patients compared to the control group. Moreover, mFas expression showed an inverse correlation with myalgia symptom in COVID-19 patients. Elevation of sFasL protein in serum was associated with reduced lung injury and mortality. Bioinformatics analysis confirmed that blood profile alterations of COVID-19 patients, such as fever and hyponatremia could affect Fas/FasL complex interactions. Our translational findings showed that decreased sFasL is associated with lung involvement; severity and mortality in COVID-19 patients. We think that sFasL is a mediator of neutrophilia and lymphopenia in COVID-19. However, additional investigation is suggested. This is the first report describing that the serum sFasL protein is a severity and mortality prognostic marker for the clinical management of COVID-19 patients.

Impact of CTLA-4 checkpoint antibodies on ligand binding and Transendocytosis.

Anti-CTLA-4 antibodies have pioneered the field of tumour immunotherapy. However, despite impressive clinical response data, the mechanism by which anti-CTLA-4 antibodies work is still controversial. Two major checkpoint antibodies (ipilimumab and tremelimumab) have been trialled clinically. Both have high affinity binding to CTLA-4 and occupy the ligand binding site, however recently it has been suggested that in some settings such antibodies may not block ligand-CTLA-4 interactions. Here we evaluated blocking capabilities of these antibodies in a variety of settings using both soluble and cell bound target proteins. We found that when ligands (CD80 or CD86) were expressed on cells, soluble CTLA-4-Ig bound in line with affinity expectations and that this interaction was effectively disrupted by both ipilimumab and tremelimumab antibodies. Similarly, cellular CTLA-4 binding to soluble ligands was comparably prevented. We further tested the ability of these antibodies to block transendocytosis, whereby CTLA-4 captures ligands from target cells during a cognate cell-cell interaction. Once again ipilimumab and tremelimumab were similar in preventing removal of ligand by transendocytosis. Furthermore, even once transendocytosis was ongoing and cell contact was fully established, the addition of these antibodies could prevent further ligand transfer. Together these data indicate that the above checkpoint inhibitors performed in-line with predictions based on affinity and binding site data and are capable of blocking CTLA-4-ligand interactions in a wide range of settings tested.

Evaluation of an association between RANKL and OPG with bone disease in people with cystic fibrosis

BackgroundAs people with Cystic Fibrosis (CF) live longer, extra-pulmonary complications such as CF-related bone disease (CFBD) are becoming increasingly important. The etiology of CFBD is poorly understood but is likely multifactorial. Bones undergo continuous remodeling via pathways including RANK (receptor activator of NF-κB)/sRANKL (soluble ligand)/OPG (osteoprotegerin). We sought to examine the association between sRANKL (stimulant of osteoclastogenesis) and OPG levels (inhibitor of osteoclast formation) and CFBD to investigate their potential utility as biomarkers of bone turnover in people with CF. MethodsWe evaluated sRANKL and OPG in plasma from people with CF and healthy controls (HC) and compared levels in those with CF to bone mineral density results. We used univariable and multivariable analysis to account for factors that may impact sRANKL and OPG. ResultsWe found a higher median [IQR] sRANKL 10,896pg/mL [5,781–24,243] CF; 2,406pg.mL [659.50–5,042] HC; p= 0.0009), lower OPG 56.68pg/mL [36.28–124.70] CF; 583.20pg/mL [421.30–675.10] HC; p < 0.0001), and higher RANKL/OPG in people with CF no BD than in HC (p < 0.0001). Furthermore, we found a higher RANKL/OPG ratio 407.50pg/mL [214.40–602.60] CFBD; 177.70pg/mL [131.50–239.70] CF no BD; p = 0.007) in people with CFBD versus CF without bone disease. This difference persisted after adjusting for variables thought to impact bone health. ConclusionsThe current screening recommendations of imaging for CFBD may miss important markers of bone turnover such as the RANKL/OPG ratio. These findings support the investigation of therapies that modulate the RANK/RANKL/OPG pathway as potential therapeutic targets for bone disease in CF.

Low quantity and quality of anti-spike humoral response is linked to CD4 T-cell apoptosis in COVID-19 patients

In addition to an inflammatory reaction, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-infected patients present lymphopenia, which we recently reported as being related to abnormal programmed cell death. As an efficient humoral response requires CD4 T-cell help, we hypothesized that the propensity of CD4 T cells to die may impact the quantity and quality of the humoral response in acutely infected individuals. In addition to specific immunoglobulins (Ig)A, IgM, and IgG against SARS-CoV-2 nucleocapsid (N), membrane (M), and spike (S1) proteins, we assessed the quality of IgG response by measuring the avidity index. Because the S protein represents the main target for neutralization and antibody-dependent cellular cytotoxicity responses, we also analyzed anti-S-specific IgG using S-transfected cells (S-Flow). Our results demonstrated that most COVID-19 patients have a predominant IgA anti-N humoral response during the early phase of infection. This specific humoral response preceded the anti-S1 in time and magnitude. The avidity index of anti-S1 IgG was low in acutely infected individuals compared to convalescent patients. We showed that the percentage of apoptotic CD4 T cells is inversely correlated with the levels of specific IgG antibodies. These lower levels were also correlated positively with plasma levels of CXCL10, a marker of disease severity, and soluble Fas ligand that contributes to T-cell death. Finally, we found lower S-Flow responses in patients with higher CD4 T-cell apoptosis. Altogether, these results demonstrate that individuals with high levels of CD4 T-cell apoptosis and CXCL10 have a poor ability to build an efficient anti-S response. Consequently, preventing CD4 T-cell death might be a strategy for improving humoral response during the acute phase, thereby reducing COVID-19 pathogenicity.

Fibroblasts in intestinal homeostasis, damage, and repair.

The mammalian intestine is a self-renewing tissue that ensures nutrient absorption while acting as a barrier against environmental insults. This is achieved by mature intestinal epithelial cells, the renewing capacity of intestinal stem cells at the base of the crypts, the development of immune tolerance, and the regulatory functions of stromal cells. Upon intestinal injury or inflammation, this tightly regulated mucosal homeostasis is disrupted and is followed by a series of events that lead to tissue repair and the restoration of organ function. It is now well established that fibroblasts play significant roles both in the maintenance of epithelial and immune homeostasis in the intestine and the response to tissue damage mainly through the secretion of a variety of soluble mediators and ligands and the remodeling of the extracellular matrix. In addition, recent advances in single-cell transcriptomics have revealed an unexpected heterogeneity of fibroblasts that comprise distinct cell subsets in normal and inflammatory conditions, indicative of diverse functions. However, there is still little consensus on the number, terminology, and functional properties of these subsets. Moreover, it is still unclear how individual fibroblast subsets can regulate intestinal repair processes and what is their impact on the pathogenesis of inflammatory bowel disease. In this mini-review, we aim to provide a concise overview of recent advances in the field, that we believe will help clarify current concepts on fibroblast heterogeneity and functions and advance our understanding of the contribution of fibroblasts in intestinal damage and repair.

Pan-cancer distribution of cleaved cell-surface amphiregulin, the target of the GMF-1A3 antibody drug conjugate.

Amphiregulin is a transmembrane protein which, when cleaved by the TACE/ADAM17 protease, releases a soluble epidermal growth factor receptor ligand domain that promotes proliferation of normal and malignant cells. We previously described a rabbit monoclonal antibody, GMF-1A3, that selectively recognizes the cell-associated cleaved amphiregulin epitope. Antibody-drug conjugates had anti-tumor activity against human breast cancer xenografts. Several tumor types express amphiregulin, but evidence for a functional requirement for amphiregulin in these malignancies is limited. By directly evaluating amphiregulin cleavage with immunohistochemistry, GMF-1A3 provides a more direct measure of amphiregulin activity. Using 370 specimens from 10 tumor types (as well as normal controls), we demonstrate that cleaved amphiregulin is widely expressed in solid tumors and is especially common (> 50% of cases) in breast, prostate, liver and lung cancer. As a potential companion diagnostic for this antibody-drug conjugate, this assay allows identification of tumors with high levels of the cleaved amphiregulin target.

ROR2-Vangl2 complexes direct ovarian cancer cell motility in response to Wnt5a (265)

<b>Objectives:</b> In both developmental and cancer contexts, collective migration has shown to be at least partially dependent upon asymmetric localization of core protein complexes within leader and follower cells. A critical function of non-canonical Wnt signaling in vertebrates is to regulate planar cell polarity (PCP), the polarity axis that organizes the plane of a tissue. Cells at the invasive front of cellular aggregates exhibit elevated expression of genes associated with motility pathways, including Wnt/PCP signaling. Using microfluidic devices, we have previously shown the soluble non-canonical Wnt ligand, <i>WNT5A</i>, influencing the directional motion of ovarian cancer cells via the ROR2 receptor. We sought to determine whether asymmetrical localization of ROR2 could guide <i>WNT5A-</i>directed motility. <b>Methods:</b> A DNA sequence encoding a fusion protein of ROR2 with a C-terminal Emerald (Em) fluorescent protein tag was introduced into ES2 ovarian cancer cells. Aggregated spheroids of ES2 ROR2-Em cells were plated onto a fibronectin-coated surface, and time-lapse fluorescent images were obtained of the radial migration in the presence or absence of <i>WNT5A</i>. Based on the direction of motion, cells were divided into leading or trailing half for analysis of the localization of ROR2 protein. Data were presented as mean +/- SEM. For co-immunoprecipitation experiments, ES2 cells expressing a Myctagged ROR2 DNA construct were utilized, with Myc epitope used for pulldown. <b>Results:</b> In the absence of <i>WNT5A</i>, ROR2 was uniformly distributed among the leading and lagging edge of the migrating cells (46.9% +/-2.452 ROR2 localized on the leading edge). In the presence of <i>WNT5A</i>, ROR2 was preferentially located to the leading edge of migrating cells (64.6% +/- 3.908 ROR2 localized on the leading edge). <i>VANGL2</i>, a core component in planar cell polarity, formed Wnt-induced receptor complexes with ROR2 in developing limb buds and other tumor types. <i>VANGL2</i> had been shown to reside at the protrusive edge of leader cells. To address whether <i>VANGL2</i>-ROR2 complexes contributed to the leading-edge localization of ROR2 in ovarian cancer cells, co-IP experiments were performed. Complex formation of ROR2-<i>VANGL2</i> was present in ovarian cancer cells at baseline (<i>VANGL2</i>:ROR2 IP ratio 1), yet was increased in the presence of <i>WNT5A</i> (<i>VANGL2</i>:ROR2 IP ratio 1.5). <b>Conclusions:</b> We have previously shown that <i>WNT5A</i> promotes the motility of ovarian cancer cells by influencing both directionality of motion as well as the degree of displacement in a ROR2 dependent manner. Asymmetric localization of Wnt/PCP core component complexes within leader and follower cells is crucial for cell motility, an intrinsic metastatic property. Our studies suggest that under the influence of <i>WNT5A</i>, ROR2 localizes to the leading edge of migrating cells. Additionally, ROR2 complexes with <i>VANGL2</i> in ovarian cancer cells, and this complex is enhanced in the presence of <i>WNT5A</i>. As <i>WNT5A</i> is produced at high levels by peritoneal mesothelial cells and omental adipose tissue in the microenvironment of ovarian cancer metastasis, disruption of the ROR2-<i>VANGL2</i> complex represents an attractive target for disrupting metastatic colonization of ovarian tumors.

Algorithm for predicting sepsis in newborns with respiratory pathology and perinatal lesions of the central nervous system on mechanical ventilation

BACKGROUND: Predicting sepsis in ventilated neonates remains a challenge in neonatology.&#x0D; AIM: To increase the efficiency of predicting sepsis diagnosis in newborns by developing a decision rule for its development based on decision trees.&#x0D; MATERIALS AND METHODS: This clinical study retrospectively reviewed 200 full-term newborns with respiratory pathology that are admitted to the intensive care unit and are on mechanical ventilation without clinical signs of bacterial infection.&#x0D; Upon admission to the department on days 1, 35, and 20, an enzyme-linked immunosorbent assay determined the plasma concentration of interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor-, granulocyte colony-stimulating factor, soluble Fas ligand, fibroblast growth factors, and nitric oxide (NO), and immunophenotyping method determined CD3+CD19, CD3CD19+, CD3+CD4+, CD3+CD8+, CD69+, CD71+, CD95+, HLADR+, CD34+, CD14+, CD3CD56+; lymphocytes expressing AnnexinV-FITC+PI, and AnnexinV-FITC+PI+. The possibility of diagnosing sepsis upon intensive care unit admission was assessed by statistical cluster analysis of the total studied immunological criteria. The method of decision trees in the statistical environment R formed a diagnostic rule for predicting sepsis.&#x0D; RESULTS: Visualization of the cluster analysis results of admitted patients did not exclude the presence of two clusters among them (with and without sepsis, which explain the 60.81% of the point variability).&#x0D; Sepsis prediction rule are as follows: disease progression occurs if on day 1 CD95 is 16.8% and NO is 9.6 mkmol/l or CD95 is 16.8%, CD34 is 0.2%, CD69 is 4.12% or CD95 is 16.8%, CD34 is 0.2%, CD69 is 4.12%, and lymphocytes expressing AnnexinV-FITC+PI is 12.3%. The diagnostic accuracy was 96.00%; sensitivity was 97.00%; specificity was 94.90%; the false-positive proportion of diagnoses was 5.10%; the false-negative proportion of diagnoses was 2.94%; the positive result accuracy was 95.19%; and the negative result was 96.88%. The disease was complicated by bacterial sepsis development on 45 days of observation in 45 newborns.&#x0D; CONCLUSIONS: Significant importance in sepsis development belongs to the prevalence of altered immunocompetent cells over proliferation and endogenous synthesis of nitric oxide. The cumulative determination of CD95+, CD69+, AnnexinV-FITC+PI, CD34+, and plasma nitric oxide concentration helped diagnose sepsis development at the preclinical stage. The obtained results indirectly confirm the relevance of studies on sepsis prevention and treatment by drug correction of apoptosis and inhaled NO.

Immune surveillance in glioblastoma: Role of the NKG2D system and novel cell-based therapeutic approaches.

Glioblastoma, formerly known as glioblastoma multiforme (GBM), is the most frequent and most aggressive brain tumour in adults. The brain is an immunopriviledged organ, and the blood-brain barrier shields the brain from immune surveillance. In this review, we discuss the composition of the immunosuppressive tumour micromilieu and potential immune escape mechanisms in GBM. In this respect, we focus on the role of the NKG2D receptor/ligand system. NKG2D ligands are frequently expressed on GBM tumour cells and can activate NKG2D-expressing killer cells including NK cells and γδ T cells. Soluble NKG2D ligands, however, contribute to tumour escape from immunological attack. We also discuss the current immunotherapeutic strategies to improve the survival of GBM patients. Such approaches include the modulation of the NKG2D receptor/ligand system, the application of checkpoint inhibitors, the adoptive transfer of ex vivo expanded and/or modified immune cells or the application of antibodies and antibody constructs to target cytotoxic effector cells in vivo. In view of the multitude of pursued strategies, there is hope for improved overall survival of GBM patients in the future.

Assessment of Soluble Natural Killer Group 2d Ligand (MHC Class I A and UL16 Binding Protein 1) in Iraqi Patients with Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is “a heterogeneous disease,” defined by a wide range of genetic alterations and molecular mutations that have an effect on clinical outcomes and could be used to develop new drugs. In AML, the immune system is tricked and actively suppressed by leukemia itself and by mechanisms that leukemia picked up through further mutations under suppression of selection. Myeloblasts in Acute myeloid leukemia can evasion the naturak killer cell killing by many ways, one of the these way, the myelocblast cells shed NKG2D soluble ligand (MIC A/B and or ULPB 1-6) in blood and bound to NKG2D activation receptor which lead to inhibit activation of NK cells. The Aim of Study: The aim of this study assessment of Soluble ligand (MICA and ULPB-1) in patients with AML. Patients and Methods: Thirty patients newly diagnosed as AML were enrolled in this study, 24 patients out of 30 were follow up after 14 days of tratment. after 30 days of treatment we get result of therapy. twenty healthy looking persons were considered as control subjects. We used ELISA technique to detection the level of soluble legand (MICA and ULPB-1). Results: The study showed that in order level of sMICA, there were significant differences in AML patients at diagnosis and after 14 days of treatment in comparison to control subjects while there were no significant differences in the level of sULPB1 between AML patients at diagnosis and after 14 days of treatment in comparison to control subjects. Conclusion: This study showed that there was an elevated level of sMICA in AML patients at diagnosis and 14 days to treatment while there was no elevated level of sULPB1 in comparison to the control group.

Plasma Phage Load is Positively Related to the Immune Checkpoints in Patients Living with Human Immunodeficiency Virus.

Microbial Translocation (MT) and altered gut microbiota are involved in immune activation and inflammation, whereas immune checkpoint proteins play an important role in maintaining immune self-tolerance and preventing excessive immune activation. This study aims to investigate the relationship between plasma phage load and immune homeostasis in people living with HIV(PLWH). We recruited 15 antiretroviral therapy (ART)-naive patients, 23 ART-treated (AT) patients, and 34 Healthy Participants (HP) to explore the relationship between the plasma phage load and immune checkpoint proteins. The Deoxyribonucleic Acid (DNA) load of the lambda (λ) phage was detected using fluorescence quantitative Polymerase Chain Reaction (PCR). The Immune Checkpoints (ICPs) were detected using multiplex immunoassay. Our study demonstrated that the plasma phage load was increased in people living with HIV (PLWH) (P<0.05), but not in the ART-naive and AT groups (P>0.05). Plasma ICPs, including cluster of differentiation 27 (CD27), soluble glucocorticoid-induced Tumor Necrosis Factor (TNF) receptor (sGITR), soluble cluster of differentiation 80 (sCD80), sCD86, soluble glucocorticoidinduced TNF receptor-related ligand (sGITRL), soluble induced T-cell Costimulatory (sICOS), sCD40, soluble toll-like receptor 2 (sTLR2), and sCD28, were markedly decreased among the ARTnaive group (P<0.05) but not in the AT and HP groups (P>0.05). The plasma phage load was positively correlated with ICP and C-reactive protein (CRP) levels in PLWH (P<0.05). Our study indicated that the plasma phage load in PLWH was positively related to the expression of ICPs and inflammation, which may be used as a promising marker for the immune level of PLWH.

P480: NKG2D-MEDIATED ANTI-TUMOR IMMUNITY CONTRIBUTES TO THE FAVORABLE PROGNOSIS IN APL

Background: Acute myeloid leukemia (AML) is an aggressive hematological malignancy with a poor prognosis. Acute promyelocytic leukemia (APL) is a unique subtype of AML, with PML-RARA fusion caused by t(15;17)(q22;q12) translocation, and is now considered a highly curable disease. Exploring the difference between APL and non-APL AML, may shed new insight on the treatment of AML. NKG2D is an activating receptor on NK cells that recognizes ligands on the surface of tumor cells and plays a crucial role in tumor cell killing. Prior studies have demonstrated that one mechanism of AML immune evasion is downregulation of NKG2D ligands (NKG2DL) or secretion of receptor-blocking soluble ligands. Whereas, reports on NKG2DL expression in APL are still lacking. In this study, we investigate the differences of NKG2DL expression on APL and non-APL cells. Aims: Exploring the difference between APL and non-APL AML, may shed new insight on the treatment of AML. Methods: Bone marrow samples were derived from de novo APL and non-APL AML patients, diagnosed according to French-American-British (FAB) criteria in The First Affiliated Hospital of Xi’an Jiao Tong University. Flow cytometry was performed with the anti-NKG2DL mAbs (MIC-A/B-PE, ULBP-1-APC, ULBP-2/5/6-PerCP). Leukemic blasts were identified using the CD45/SSC gating procedure. Non-APL AML patients were divided into high or low group based on the median expression levels of NKG2DL for survival analysis. Results: Totally 46 patients comprising of 23 APL and 23 non-APL AML were enrolled in this study. There was no significant difference in the baseline characteristics between the two groups. All non‐APL AML cells had low or no NKG2DL surface expression, while most APL cells expressed high NKG2DL levels. In particular, just two APL patients was negative for the NKG2DL but positive for CD34. The median percentage of NKG2DL among non-APL AML cells and APL cells were 1.2% vs 20.3% in MIC-A/B (P<0.01), 1.1% vs 54.8% in ULBP-1 (P=0.017), and 3.8% vs 36.35% in ULBP-2/5/6 (P<0.01). (Fig.1) 23 non-APL AML patients were enrolled for study inclusion; one patient dropped out due to cerebral infarction. The median follow-up time was 17.2 weeks. The high ULBP-2/5/6 group showed a superior overall survival rate compared to the low ULBP-2/5/6 group (P < 0.01), but there was no significant difference between high and low MIC-A/B groups (P = 0.31) or between the high and low ULBP-1 groups (P = 0.52). Image:Summary/Conclusion: NKG2DL was decreased significantly on the surface of non-APL AML cells compared with APL cells. These results may indicate that NKG2D-mediated anti-tumor immunity contributes to the favorable prognosis in APL, while immune escape is an underlying mechanism for unfavorable prognosis in non-APL AML. NKG2DL may be used as a potential biomarker to predict prognosis of patients with non-APL AML, and upregulation of its expression could improve the clinical efficacy. Further studies with larger sample size and longer follow-up are required to confirm our conclusion.

Abstract 2078: CLN-049 is a bispecific T cell engaging IgG-like antibody targeting FLT3 on AML cells

Abstract Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults, with few options for curative treatment. In lymphoid malignancies, the introduction of chimeric antigen receptor T (CAR-T) cells and bispecific antibodies (bsAbs) has achieved remarkable success. However, such immunotherapeutic strategies are not yet established for AML, likely due to a dearth of appropriate targets. The fms like tyrosine kinase 3 (FLT3)/CD135 surface receptor is expressed on AML cells in the large majority of AML patients and constitutes a highly selective target antigen for immunotherapy, as expression on healthy tissues is limited to low levels on dendritic cells, monocytes and hematopoietic progenitor cells. We report here on the development of CLN-049, a bispecific humanized antibody that binds to FLT3 on leukemic cells and the CD3 epsilon subunit of the T cell receptor complex on T cells. CLN-049 recognizes the membrane proximal domain of FLT3 and has a silenced Fc gamma 1 domain, with anti-CD3 single chain variable fragments (scFv) fused to the C-termini of the heavy chains. While FLT3 kinase inhibitors are limited to treatment of patients with specific intracellular FLT3 mutations, CLN-049 recognizes the extracellular domain of FLT3 and would therefore be more broadly applicable in AML therapy. CLN-049 showed low-nanomolar binding to both FLT3-expressing and CD3-expressing cells. The antibody induced target-dependent activation of CD4+ and CD8+ T cells as well as corresponding cytokine production by T cells only when co-cultured with FLT3+ AML cells. Human AML cell lines expressing a broad range of surface levels of FLT3 were efficiently lysed upon treatment with sub-nanomolar concentrations of CLN-049 when co-cultured with heterologous PBMCs, regardless of the expression level or mutational status of FLT3. Intriguingly, FLT3-expressing hematopoietic progenitor cells and dendritic cells were not found to be sensitive to CLN-049 killing. The in vitro lysis of leukemic cells by CLN-049 was not affected by supraphysiological levels of soluble FLT3 or FLT3 ligand. In mouse xenograft studies, CLN-049 was highly active against the MOLM-13 human AML model. In these studies, CLN-049 demonstrated significant dose-dependent activity as measured by survival as well as reduction of AML cells in the blood. In summary, CLN-049 is a promising FLT3-targeted T cell engaging antibody construct expected to have robust anti-tumor activity in the clinic against AML. CLN-049 is currently in a phase 1 clinical trial for the treatment of patients with relapsed/refractory AML. Citation Format: Kristan Meetze, Naveen K. Mehta, Martin Pfluegler, Bochong Li, Patrick A. Baeuerle, Jennifer S. Michaelson, Gundram Jung, Helmut Salih. CLN-049 is a bispecific T cell engaging IgG-like antibody targeting FLT3 on AML cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2078.