Loss Of CD4 Research Articles

Central Memory CD4 T Cells from Persons with HIV Accumulate DNA Content Defects During Proliferative Response.

Central memory (TCM) cells are a subpopulation of CD4 T cells that sustain overall CD4 T cell counts in HIV infection. The mechanisms underlying their eventual demise, which leads to loss of CD4 T cell counts, are not known. To understand their proneness to death despite their increased movement to proliferation, we examined cell division together with possible cell accumulation in different phases of the cell cycle. Purified circulating TCM cells from untreated people living with HIV (PLWH) (n = 9) and healthy controls (n = 10) were stimulated in vitro using anti-CD3/CD28 agonistic antibodies plus IL-2 and cultured for 4 days. Cell viability, DNA content, proliferation, and cyclin A and cyclin B expression were measured. We found that PLWH TCM cells more frequently had a DNA content lower than G0/G1, compared with controls (p = .043). These cells accumulated with each division. The proportion of cells with sub-G0/G1 DNA content that were cycling (expressing cyclin A) was greater in the PLWH group (p = .003). The percentage of TCM cells expressing cyclin A+ among those in G0/G1 and was also greater in the PLWH group (p = .043), suggesting arrest before G2/M. While TCM cells from PLWH can proliferate, during this process some of them accumulate defects in DNA content that are incompatible with viability, suggesting that they could be intrinsically prone to cell cycle-dependent death. This provides a possible mechanism underlying the increased TCM cell turnover in HIV infection.

Allogeneic CD5-specific CAR-T therapy for relapsed/refractory T-ALL: a phase 1 trial.

Refractory or relapsed T cell acute lymphoblastic leukemia (r/r T-ALL) patients have poor prognoses, due to the lack of effective salvage therapies. Recently, CD7-targeting chimeric antigen receptor (CAR)-T therapies show efficacy in patients with r/r T-ALL, but relapse with CD7 loss is common. This study evaluates a CD5-gene-edited CAR-T cell therapy targeting CD5 in 19 r/r T-ALL patients, most of whom had previously failed CD7 CAR-T interventions. CAR-T products were derived from previous transplant donors (Cohort A) or newly matched donors (Cohort B). Primary endpoints were dose-limiting toxicity at 21 days and adverse events within 30 days. Secondary endpoints were responses, pharmacokinetics and severe adverse events after 30 days. A total of 16 received infusions, 10 at target dose of 1 × 106 kg-1. All encountered grade 3-4 cytopenias and one had a grade 3 infection within 30 days. All patients (100%) achieved complete remission or complete remission with incomplete blood count recovery by day 30. At a median follow-up of 14.3 months, four received transplantation; three were in remission and one died of infection. Of 12 untransplanted patients, 2 were in remission, 3 relapsed, 5 died of infection and 2 of thrombotic microangiopathy. CAR-T cells persisted and cleared CD5+ T cells. CD5- T cells, mostly CD5-gene-edited, increased but remained below normal levels. These results suggest this CD5-specific CAR-T intervention has a high remission rate for T-ALL patients. Evidence also suggests the risk of late-onset severe infection may be mitigated with consolidative transplantation. This study provides insights that could help to optimize this promising intervention. ClinicalTrials.gov registration: NCT05032599 .

Long-term Tolerance to Islet Transplantation via Targeted Reduction of beta cell-specific T cells.

Activated beta-cell reactive CD4 + and CD8 + T effector cells undergo a profound DNA-damage response which is targetable by small molecule inhibitors of the p53 and cell cycle pathways that lead to apoptosis. The use of a combination of MDM2 and WEE1 inhibitors, which termed "p53 potentiation with checkpoint abrogation" (PPCA), conferred significant therapeutic efficacy in treating mouse models of new onset T1D. Specific targeting of these T effector cells by PPCA results in a loss of inflammatory T cell subsets, notably proliferation CD4 + Th0 and Th1 subsets and CD8 + T effector memory cells, as determined by single cell RNA-seq studies with the preservation of T regulatory cells. When autologous islet grafts are given to established diabetic NOD mice, a single course of PPCA results in long-term islet graft acceptance, restoration of normoglycemia and loss of beta cell specific CD4 + and CD8 + T cells. PPCA shows promise as a potential means of estimating islet graft tolerance in T1D recipients of islet graft transplantation.

The histone methyltransferase Mixed-lineage-leukemia-1 drives T cell phenotype via Notch signaling in diabetic tissue repair.

Immune cell-mediated inflammation is important in normal tissue regeneration but can be pathologic in diabetic wounds. Limited literature exists on the role of CD4+ T cells in normal or diabetic wound repair; however, the imbalance of CD4+ Th17/Tregs has been found to promote inflammation in other diabetic tissues. Here, using human tissue and murine transgenic models, we identified that the histone methyltransferase Mixed-lineage-leukemia-1 (MLL1) directly regulates the Th17 transcription factor RORγ via an H3K4me3 mechanism and increases expression of Notch receptors and downstream Notch signaling. Furthermore, we found that Notch receptor signaling regulates CD4+ Th cell differentiation and is critical for normal wound repair, and loss of upstream Notch pathway mediators or receptors in CD4+ T cells resulted in the loss of CD4+ Th cell differentiation in wounds. In diabetes, MLL1 and Notch-receptor signaling was upregulated in wound CD4+ Th cells, driving CD4+ T cells toward the Th17 cell phenotype. Treatment of diabetic wound CD4+ T cells with a small molecule inhibitor of MLL1 (MI-2) yielded a significant reduction in CD4+ Th17 cells and IL-17A. This is the first study to our knowledge to identify the MLL1-mediated mechanisms responsible for regulating the Th17/Treg balance in normal and diabetic wounds and to define the complex role of Notch signaling in CD4+ T cells in wounds, where increased or decreased Notch signaling both result in pathologic wound repair. Therapeutic targeting of MLL1 in diabetic CD4+ Th cells may decrease pathologic inflammation through regulation of CD4+ T cell differentiation.

Tumor CD20 Loss and Poor Outcome in Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)

Tumor CD20 Loss and Poor Outcome in Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)

ABCL-119 Tumor CD20 Loss and Poor Outcome in Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)

ABCL-119 Tumor CD20 Loss and Poor Outcome in Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)

Metabolism of immune cells in septic shock in children

In septic shock the hyperimmune response and immunosuppression can occur at the same time, being defined as mixed antagonist response syndrome. Under standard conditions, mitochondria supports cellular energy metabolism through the citric cycle and the phosphorylation chain. Both NK and T cells produce an immediate effector response to inflammatory signals using the rapid production of energy in aerobic glycolysis (glucose-lactate]. When the inflammatory signal is eliminated, they return to metabolism in the Krebs cycle. Septic shock in the children was accompanied by immunoparalysis (TNFα <200pg/ml), lower monocyte human antigen (HLA-DR), loss of peripheral non-naive CD4 T cells and low mitochondrial respiration. Children with septic shock had a in hospital mortality rate of 10.8-33.5%, high risk of hospitali­zation in the next 28 days and in the following months with predominantly respiratory infections. The treatment of mitochondrial dysfunction, insufficiently structured, is based on antioxidant medication, but the results await confirmation.

CD19 expression in diffuse large B-cell lymphoma (DLBCL) patient biopsies after treatment with tafasitamab.

e19050 Background: Tafasitamab (tafa) is a CD19-targeting immunotherapy that induces enhanced antibody dependent cellular cytotoxicity and phagocytosis. Tafa received accelerated FDA approval in 2020 for treating relapsed or refractory DLBCL in combination with lenalidomide in patients ineligible for autologous stem cell transplant, based on results from L-MIND, a multicenter, open-label, single-arm, phase 2 trial. FirmMIND (NCT05429268) is an ongoing identical study, further evaluating efficacy and safety of tafa in this setting. Several other CD19 targeting agents are available; however, CD19 antigen loss following treatment with chimeric antigen receptor T-cell therapy targeting CD19 (CART19) has raised concerns over CD19-targeted therapy sequencing. Loss of CD19 has not been observed to date in tafa clinical trials or practice. Methods: To evaluate CD19 expression at screening and after disease progression in firmMIND, we developed an immunohistochemistry (IHC) assay using a mAb that binds to an intracellular epitope of CD19 clone LE-CD19. To validate that CD19 expression is detectable after tafa treatment, we treated cultured SU-DHL-4 or Jurkat cells with tafa at a saturating concentration for 24 hours. After washing out unbound tafa, cells were harvested at specific timepoints. Resulting cell line blocks were assessed for CD19 expression by IHC. We also monitored CD19 trafficking in response to fluorescently labeled tafa by confocal microscopy. Results: By IHC, CD19 expression was comparable between treatment conditions, suggesting the assay can effectively measure CD19 expression in lymphoma biopsy samples post-tafa. Confocal microscopy showed a fraction of tafa-bound CD19 internalized and colocalized with a CD19 intracellular pool labeled with anti-CD19 mAb clone EPR5906; this mAb also detected CD19 that remained localized on the cell surface. The data demonstrated that CD19 persists on tumor cells after tafa treatment at levels that could be bound by other CD19-targeting therapies. As of the January 25, 2024 data cutoff, we received 6 end-of-treatment (EOT) samples from patients in firmMIND. Biopsies were collected 14-26 days after the last tafa dose; 5 of 6 samples were biopsies from lymph nodes or liver and showed ≥80% of tumor cells staining CD19+ on membranes with 3+ intensity by IHC, except 1 that was collected only 6 days after last dose and showed 50% positivity. The sixth biopsy (extranodal subcutaneous lesion) showed no CD19 expression at baseline or EOT. Conclusions: Patient biopsy analysis and preclinical data suggest that following tafa treatment, CD19 antigen is preserved on the surface of tumor cells after short and transient internalization and could be targeted by other CD19 agents, such as CART therapy. This conclusion is supported by sequential treatment with tafa followed by CART in vivo (Sakemura, 2024). Analyses are ongoing to confirm these findings.

PMB-CT01 (BAFFR-CAR T cell) therapy to examine preliminary safety and clinical responses in patients with B-cell malignancies who are ineligible for or failed CD19-directed therapy, including CD19-negative disease.

6534 Background: CD19-targeted therapies have shown remarkable efficacy in patients with B-cell malignancies. However, relapse with CD19 loss as a mechanism of tumor escape is common and represents a serious challenge. Patients who are ineligible for or have failed prior CD19-directed therapy have limited salvage options and a very poor prognosis. The B-cell activating factor receptor (BAFF-R) is functionally expressed in B-cell acute lymphoblastic leukemia (B-ALL) and non-Hodgkin lymphomas (NHL), including in patients with CD19-negative relapse (Qin et al., Sci Transl Med. 2019). As a critical regulator of B-cell function and survival, BAFF-R may be less prone to downregulation by tumors as a mechanism of antigen escape. Methods: We are conducting two phase 1 clinical trials of BAFFR-CAR T cells in patients with relapsed/refractory (r/r) B-ALL (NCT04690595) and NHL (NCT05370430). Primary endpoints are dose limiting toxicities (DLTs) and all other toxicities. Secondary endpoints include response rate, minimal residual disease (MRD) negative rate, PFS and OS. Response is evaluated using European LeukemiaNet criteria for B-ALL and Lugano 2014 for NHL. Results: As of Feb. 1st, 2024, 1 B-ALL and 3 NHL patients have completed treatment and post-treatment evaluations. Each received 50M BAFFR CAR T cells (starting dose level in both trials). The B-ALL patient had CD19/CD20/CD22-negative disease, and had received prior blinatumomab. NHL patients #1 and #2 both had CD19-expressing mantle cell lymphoma (MCL) and had received prior CD19 CAR T cells. Patient #2 had also received a CD3/CD20 bispecific antibody. NHL patient #3 had CD19/CD20-negative T cell/histiocyte-rich large B-cell lymphoma (THRBCL) and had not received prior CD19 CAR T cells. There were no DLTs, all patients had Gr. 1 cytokine release syndrome, and 2/3 NHL patients had Gr. 1 immune effector cell-associated neurotoxicity syndrome. Robust CAR T cell expansion was seen in all patients with a peak on days 12-14 post-infusion. The B-ALL and the 2 MCL patients reached MRD-negative complete response (CR) at 1 month post-treatment. The THRBCL patient had partial response (PR) at 1 month that converted to CR at 3 months. The B-ALL patient successfully transitioned to allogeneic HCT while in CR at 3 months post-infusion. Responses are ongoing in all NHL patients at 14, 10, and 8 months for patients #1, #2 and #3, respectively. Additional patients have been enrolled at the next dose level (200M CAR T cells). Results for these patients will be presented at the meeting. Conclusions: With a 100% CR rate at 3 months in the first 4 patients and durable responses at dose level 1, BAFFR-CAR T cells are a promising therapeutic option for patients with r/r B-cell malignancies who are ineligible or failed prior CD19-targeted therapy, including with CD19 antigen loss. Clinical trial information: NCT04690595 , NCT05370430 .

Relapse after glofitamab, a novel unmet medical need with high rates of CD20 loss.

The prognosis of r/r DLBCL has changed substantially over the past decade due to the introduction of T-cell-activating therapies. Besides generating a new curative perspective for a proportion of r/r DLBCL, chimeric antigen receptor T-cell therapy and bispecific antibodies are generating new unmet needs. The report by Grigg and colleagues now shows that glofitamab-refractory, CD20-negative patients represent a new unmet medical need requiring therapeutic targets other than CD20 and novel therapies to reduce the risk of CD20 loss. Commentary on: Grigg etal. Relapse after glofitamab has a poor prognosis, and rates of CD20 loss are high. Br J Haematol 2024;205:122-126.

Fluorescence tracking demonstrates T cell recirculation is transiently impaired by radiation therapy to the tumor

T cells recirculate through tissues and lymphatic organs to scan for their cognate antigen. Radiation therapy provides site-specific cytotoxicity to kill cancer cells but also has the potential to eliminate the tumor-specific T cells in field. To dynamically study the effect of radiation on CD8 T cell recirculation, we used the Kaede mouse model to photoconvert tumor-infiltrating cells and monitor their movement out of the field of radiation. We demonstrate that radiation results in loss of CD8 T cell recirculation from the tumor to the lymph node and to distant sites. Using scRNASeq, we see decreased proliferating CD8 T cells in the tumor following radiation therapy resulting in a proportional enrichment in exhausted phenotypes. By contrast, 5 days following radiation increased recirculation of T cells from the tumor to the tumor draining lymph node corresponds with increased immunosurveillance of the treated tumor. These data demonstrate that tumor radiation therapy transiently impairs systemic T cell recirculation from the treatment site to the draining lymph node and distant untreated tumors. This may inform timing therapies to improve systemic T cell-mediated tumor immunity.

The Gut and the Translocated Microbiomes in HIV Infection: Current Concepts and Future Avenues.

It is widely acknowledged that HIV infection results in disruption of the gut's mucosal integrity partly due a profound loss of gastrointestinal CD4+ T cells that are targets of the virus. In addition, systemic inflammation and immune activation that drive disease pathogenesis are reduced but not normalized by antiretroviral therapy (ART). It has long been postulated that through the process of microbial translocation, the gut microbiome acts as a key driver of systemic inflammation and immune recovery in HIV infection. As such, many studies have aimed at characterizing the gut microbiota in order to unravel its influence in people with HIV and have reported an association between various bacterial taxa and inflammation. This review assesses both contra-dictory and consistent findings among several studies in order to clarify the overall mechanisms by which the gut microbiota in adults may influence immune recovery in HIV infection. Independently of the gut microbiome, observations made from analysis of microbial products in the blood provide direct insight into how the translocated microbiome may drive immune recovery. To help better understand strengths and limitations of the findings reported, this review also highlights the numerous factors that can influence microbiome studies, be they experimental methodologies, and host-intrinsic or host-extrinsic factors. Altogether, a fuller understanding of the interplay between the gut microbiome and immunity in HIV infection may contribute to preventive and therapeutic approaches.

RIPK1 protects naive and regulatory T cells from TNFR1-induced apoptosis

The T cell population size is stringently controlled before, during, and after immune responses, as improper cell death regulation can result in autoimmunity and immunodeficiency. RIPK1 is an important regulator of peripheral T cell survival and homeostasis. However, whether different peripheral T cell subsets show a differential requirement for RIPK1 and which programmed cell death pathway they engage in vivo remains unclear. In this study, we demonstrate that conditional ablation of Ripk1 in conventional T cells (Ripk1ΔCD4) causes peripheral T cell lymphopenia, as witnessed by a profound loss of naive CD4+, naive CD8+, and FoxP3+ regulatory T cells. Interestingly, peripheral naive CD8+ T cells in Ripk1ΔCD4 mice appear to undergo a selective pressure to retain RIPK1 expression following activation. Mixed bone marrow chimeras revealed a competitive survival disadvantage for naive, effector, and memory T cells lacking RIPK1. Additionally, tamoxifen-induced deletion of RIPK1 in CD4-expressing cells in adult life confirmed the importance of RIPK1 in post-thymic survival of CD4+ T cells. Ripk1K45A mice showed no change in peripheral T cell subsets, demonstrating that the T cell lymphopenia was due to the scaffold function of RIPK1 rather than to its kinase activity. Enhanced numbers of Ripk1ΔCD4 naive T cells expressed the proliferation marker Ki-67+ despite the peripheral lymphopenia and single-cell RNA sequencing revealed T cell-specific transcriptomic alterations that were reverted by additional caspase-8 deficiency. Furthermore, Ripk1ΔCD4Casp8 ΔCD4 and Ripk1ΔCD4Tnfr1−/− double-knockout mice rescued the peripheral T cell lymphopenia, revealing that RIPK1-deficient naive CD4+ and CD8+ cells and FoxP3+ regulatory T cells specifically die from TNF- and caspase-8-mediated apoptosis in vivo. Altogether, our findings emphasize the essential role of RIPK1 as a scaffold in maintaining the peripheral T cell compartment and preventing TNFR1-induced apoptosis.

Relapse after glofitamab has a poor prognosis and rates of CD20 loss are high.

We reviewed cases with aggressive B-cell non-Hodgkin lymphoma who relapsed or progressed following glofitamab. The prognosis was poor, with low rates of response to subsequent salvage therapies, and a median overall survival of 4.1 months from the time of progression. There were high rates of CD20 loss (59%) at the time of relapse. In a field where CD20 × CD3 bispecific antibodies are entering routine clinical use, our experience highlights a potential means of resistance. It illustrates both the need to further characterise mechanisms of CD20 loss, and to pursue clinical trials of novel non-CD20-directed treatments in this cohort.

The Role of Pericytes in Lipopolysaccharide-Induced Murine Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a heterogeneous clinical syndrome that is most commonly triggered by infection-related inflammation. Lung pericytes can respond to infection and act as immune and proangiogenic cells; moreover, these cells can differentiate into myofibroblasts in nonresolving ARDS and contribute to the development of pulmonary fibrosis. Here, we aimed to characterize the role of lung cells, which present characteristics of pericytes, such as peri-endothelial location and expression of a panel of specific markers. A murine model of lipopolysaccharide (LPS)-induced resolving ARDS was used to study their role in ARDS. The development of ARDS was confirmed after LPS instillation, which was resolved 14 days after onset. Immunofluorescence and flow cytometry showed early expansion of neural-glial antigen 2+ β-type platelet-derived growth factor receptor+ pericytes in murine lungs with loss of CD31+ β-type platelet-derived growth factor receptor+ endothelial cells. These changes were accompanied by specific changes in lung structure and loss of vascular integrity. On day 14 after ARDS onset, the composition of pericytes and endothelial cells returned to baseline values. LPS-induced ARDS activated NOTCH signaling in lung pericytes, the inhibition of which during LPS stimulation reduced the expression of its downstream target genes, pericyte markers, and angiogenic factors. Together, these data indicate that lung pericytes in response to inflammatory injury activate NOTCH signaling that supports their maintenance and in turn can contribute to recovery of the microvascular endothelium.

Plasmablastic Lymphoma and Plasmablastic Myeloma: А Diagnostic Dilemma (Literature Review)

Plasmablastic lymphoma and plasmablastic myeloma are similar in morphology. Tumor substrate in both is characterized by large cells with blastic morphology, central or somewhat eccentric nuclei, large central nucleolus or some distinct nucleoli, and abundant eosinophilic cytoplasm. The common characteristic of both B-cell tumors is the expression of plasma cell differentiation markers (CD38, CD138, MUM-1/IRF-4, interferon regulatory factor 4, PRDM-1, PR domain zinc finger protein 1, and/or XBP-1, X-box-1 binding protein) with a frequent loss of CD20. These rare nosological entities with similar morphological and immunohistochemical features present a challenge for differential and reliable diagnosis. The present review deals with clinical signs, diagnostically significant immunohistochemical markers, and molecular genetic characteristics which are essential for differential diagnosis of plasmablastic lymphoma and plasmablastic myeloma.

Abstract 4019: Development of mRNA chimeric antigen receptor T cells targeting MET in aggressive B-cell lymphomas

Abstract Multiple versions of CAR T cells targeting the cell surface protein CD19 are approved by the FDA to treat refractory B-cell malignancies. However, durable remissions range from 60% in B-cell leukemias to 40% in B-cell lymphomas. Major reasons for resistance to CD19-CAR treatment relate to heterogeneous or loss of CD19 expression. In addition, CD19-CAR leads to B-cell depletion which increases the risk for infection. These limiting factors necessitate research into alternative targets for CAR therapy against B-cell lymphomas.Using a large data set from clinical trials, we found that approximately 30-70% of diffuse large B-cell lymphomas (DLBCL) express MET. We hypothesize that these MET-positive B-cell lymphomas can potentially be targeted with chimeric antigen receptor (CAR) T-cells against MET receptor. We constructed a second-generation anti-MET-CAR by fusing the scFv fragment of an anti-MET monoclonal antibody with the human CD28 hinge/transmembrane/cytoplasmic domain and CD3ζ cytoplasmic domain. Stable MET-CAR Jurkat cells showed increased CD69 expression upon stimulation by MET-positive lymphoma cell lines such as Karpas-422 and OCI-LY3. Using primary human T cells, we further demonstrated that the mRNA MET-CAR T-cells mediated cytotoxicity against DLBCL cell lines. Of note, while CD19-CAR T-cells showed only low level of cytotoxicity against the CD19-/MET+ OCI-LY3 cell line, MET-CAR T cell was able to mediate substantial tumor cell lysis.In summary, the preliminary data demonstrate that MET-CAR is capable of mediating cytotoxicity against MET-positive DLBCL. Some cell lines such as OCI-LY3 are negative for CD19 but positive for MET expression, and MET-CAR is capable of mediating cell lysis while CD19-CAR is ineffective. These results suggest that some large B-cell lymphomas negative for CD19, either intrinsic or secondary to loss of CD19 as a result of resistance mechanism, may show MET expression and will likely benefit from MET-targeted immunotherapy. Citation Format: Po-Han Chen, Rianna Raghunandan, Markus Muschen, Samuel G. Katz. Development of mRNA chimeric antigen receptor T cells targeting MET in aggressive B-cell lymphomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4019.

High lymphocyte signature genes expression in parathyroid endocrine cells and its downregulation linked to tumorigenesis

To date, because of the difficulty in obtaining normal parathyroid gland samples in human or in animal models, our understanding of this last-discovered organ remains limited. In the present study, we performed a single-cell transcriptome analysis of six normal parathyroid and eight parathyroid adenoma samples using 10×Genomics platform. We have provided a detailed expression atlas of parathyroid endocrine cells. Interestingly, we found an exceptional high expression levels of CD4 and CD226 in parathyroid endocrine cells, which were even higher than those in lymphocytes. This unusual expression of lymphocyte markers in parathyroid endocrine cells was associated with the depletion of CD4 T cells in normal parathyroid glands. Moreover, CD4 and CD226 expression in endocrine cells was significantly decreased in parathyroid adenomas, which was associated with a significant increase in Treg counts. Finally, along the developmental trajectory, we discovered the loss of POMC, ART5, and CES1 expression as the earliest signature of parathyroid hyperplasia. We propose that the loss of CD4 and CD226 expression in parathyroid endocrine cells, coupled with an elevated number of Treg cells, could be linked to the pathogenesis of parathyroid adenoma. Our data also offer valuable information for understanding the noncanonical function of CD4 molecule. This work was supported by the National Key R&D Program of China (2022YFA0806100), National Natural Science Foundation of China (82130025, 82270922, 31970636, 32211530422), Shandong Provincial Natural Science Foundation of China (ZR2020ZD14), Innovation Team of Jinan (2021GXRC048) and the Outstanding University Driven by Talents Program and Academic Promotion Program of Shandong First Medical University (2019LJ007).

Distinct genetic clusters in HIV-1 CRF01_AE-infected patients induced variable degrees of CD4+ T-cell loss.

Retroviruses swiftly adapt, employing error-prone enzymes for genetic and phenotypic evolution, optimizing survival strategies, and enhancing virulence levels. HIV-1 CRF01_AE has persistently undergone adaptive selection, and cluster 1 and 2 infections display lower counts and fast loss of CD4+ T cells than other HIV-1 sub-types and CRF01_AE clusters. Its mechanisms are associated with increased CXCR4 tropism due to an envelope structure change favoring a tropism shift from CCR5 to CXCR4, thereby shaping viral phenotype features and impacting pathogenicity. This underscores the significance of consistently monitoring HIV-1 genetic evolution and phenotypic transfer to see whether selection bias across risk groups alters the delicate balance of transmissible versus toxic trade-offs, since virulent strains such as CRF01_AE clusters 1 and 2 could seriously compromise the efficacy of antiviral treatment. Only through such early warning and diagnostic services can precise antiviral treatments be administered to those infected with more virulent HIV-1 strains.

Immunotherapy-resistant acute lymphoblastic leukemia cells exhibit reduced CD19 and CD22 expression and BTK pathway dependency.

While therapies targeting CD19 by antibodies, chimeric antigen receptor T cells (CAR-T), and T cell engagers have improved the response rates in B cell malignancies, the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19 immunotoxin. Single-cell RNA-Seq (scRNA-Seq) showed an increase in transcriptionally distinct CD19lo populations among resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19lo-resistant cells. An assay for transposase-accessible chromatin with sequencing (ATAC-Seq) showed decreased chromatin accessibility at promoters of both CD19 and CD22 in the resistant cell populations. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with B cell acute lymphoblastic leukemia (B-ALL) that relapsed after CD19 CAR-T-targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19lo resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both Bruton's tyrosine kinase (BTK) and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.