Memory Immune Responses Research Articles

CD40 agonist engineered immunosomes modulated tumor microenvironment and showed pro-immunogenic response, reduced toxicity, and tumor free survival in mice bearing glioblastoma

CD40 agonist antibodies (αCD40) have shown promising anti-tumor response in both preclinical and early clinical studies. However, its systemic administration is associated with immune- and hepato-toxicities which hampers its clinical usage. In addition, αCD40 showed low tumor retention and induced PD-L1 expression which makes tumor microenvironment (TME) immunosuppressive. To overcome these issues, in this study, we have developed a multifunctional Immunosome where αCD40 is conjugated on the surface and RRX-001, a small molecule immunomodulator was encapsulated inside it. Immunosomes showed higher tumor accumulation till 96 h of administration and displayed sustained release of αCD40 in vivo. Immunosomes significantly delayed tumor growth and showed tumor free survival in mice bearing GL-261 glioblastoma by increasing the population of CD45+CD8+ T cells, CD45+CD20+ B cells, CD45+CD11c+ DCs and F4/80+CD86+ cells in TME. Immunosome significantly reduced the population of T-regulatory cells, M2 macrophage, and MDSCs and lowered the PD-L1 expression. Moreover, Immunosomes significantly enhanced the levels of Th1 cytokines (IFN-γ, IL-6, IL-2) over Th2 cytokines (IL-4 and IL-10) which supported anti-tumor response. Most interestingly, Immunosomes averted the in vivo toxicities associated with free αCD40 by lowering the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), IL-6, IL-1α and reduced the degree of liver damage. In addition, Immunosomes treated long-term surviving mice showed tumor specific immune memory response which prevented tumor growth upon rechallenge. Our results suggested that this novel formulation can be further explored in clinics to improve in vivo anti-tumor efficacy of αCD40 with long-lasting tumor specific immunity while reducing the associated toxicities.

Safety and efficacy of C. muridarum vaccines adjuvanted with CpG-1826 and four concentrations of Montanide-ISA-720-VG

It is recommended that the adjuvant Montanide ISA 720 VG be used at a concentration of 70% v/v. At this concentration, Montanide causes at the site of immunization a local granuloma that can last for several weeks. To determine the safety and protective efficacy of a Chlamydia muridarum MOMP vaccine, formulated with CpG-1826 and four different concentrations of Montanide (70%, 50%, 30% and 10%), BALB/c (H-2d) female mice were immunized twice intramuscularly. Local reactogenicity was significant for vaccines formulated with 70% or 50% Montanide but not for those inoculated with 30% or 10% Montanide. Robust humoral and cell mediated memory immune responses were elicited by the 70%, 50% and 30% Montanide formulations. Mice were challenged intranasally with 104 C. muridarum inclusion forming units (IFU). Based on changes in body weight, lungs’s weight and number of IFU recovered, mice vaccinated with the 70%, 50% and 30% Montanide formulations were significantly protected, but not mice receiving 10% Montanide. To conclude, we recommend the 30% Montanide concentration to be tested in humans and animal models to determine its safety and efficacy, in comparison to the 70% Montanide concentration currently used. The 30% Montanide formulation could significantly facilitate licensing of this adjuvant for human use.

Temporal Trends in SARS-CoV-2 Antibody Levels Among COVID-19 Patients in Kerala During the First Wave and Pre-vaccination Period.

The SARS-CoV-2 virus interacts with host cells through the S1 domain of its spike protein. This study measures the IgG immune response to this domain in COVID-19 patients from Kerala, India, and explores its association with various health factors. A cohort of 258 COVID-19 patients was analyzed for IgG antibodies targeting the S1 spike protein domain. The temporal pattern of the IgG response and its correlation with hospitalization needs, intensive care, and pre-existing conditions such as diabetes, hypertension, and coronary artery disease were assessed. A significant IgG response (76.4%) was detected, indicating robust immune activation post-infection. The IgG levels peaked between two tofour and four to eight weeks post-infection, with a notable increase at 12 weeks, hinting at possible secondary exposure or an immune memory response. No correlation was found between IgG levels and the presence of diabetes mellitus, hypertension, or coronary artery disease. However, higher IgG responses correlated with the severity of the infection, as seen in patients requiring hospitalization or intensive care. The IgG response to the S1 spike protein domain serves as a potential marker of immune activation in COVID-19. It reflects the body's defense mechanism against the virus and may predict disease severity and outcomes. The findings suggest that IgG levels could be indicative of the viral load, inflammatory response, and possibly the likelihood of protection against reinfection.

Long-term relapse-free survival enabled by integrating targeted antibacteria in antitumor treatment

The role of tumor-resident intracellular microbiota (TRIM) in carcinogenesis has sparked enormous interest. Nevertheless, the impact of TRIM-targeted antibacteria on tumor inhibition and immune regulation in the tumor microenvironment (TME) remains unexplored. Herein, we report long-term relapse-free survival by coordinating antibacteria with antitumor treatment, addressing the aggravated immunosuppression and tumor overgrowth induced by TRIM using breast and prostate cancer models. Combining Ag+ release with a Fenton-like reaction and photothermal conversion, simultaneous bacteria killing and multimodal antitumor therapy are enabled by a single agent. Free of immune-stimulating drugs, the agent restores antitumor immune surveillance and activates immunological responses. Secondary inoculation and distal tumor analysis confirm lasting immunological memory and systemic immune responses. A relapse-free survival of >700 days is achieved. This work unravels the crucial role of TRIM-targeted antibacteria in tumor inhibition and unlocks an unconventional route for immune regulation in TME and a complete cure for cancer.

Improved ELISPOT protocol for monitoring Th1/Th17 T-cell response following T.gondii infection.

In the monitoring of human Toxoplasma gondii infection, it is crucial to confirm the development of a specific Th1/Th17 immune response memory. The use of a simple, specific, and sensitive assay to follow the T-cell activation is thus required. Current protocols are not always specific as stimulation with peptides is Human Leukocyte Antigen (HLA)-dependent, while stimulation with total-lysis antigens tends to stimulate seronegative donors resulting to false positives. Here, an improved ELISPOT protocol is reported, using peripheral blood mononuclear cells (PBMC) of T.gondii-infected donors, incubated with the inactivated parasite. The results showed that, contrary to standard protocols, a pre-incubation step at high cell density in presence of the inactivated parasite allowed a specific Th1/Th17 response with the secretion of IFN-γ, IL-2, IL-12 and IL-17 cytokines. This protocol allows to evaluate precisely the immune response after a T.gondii infection.

Atypical chemokine receptors in the immune system.

Leukocyte migration is a fundamental component of innate and adaptive immune responses as it governs the recruitment and localization of these motile cells, which is crucial for immune cell priming, effector functions, memory responses and immune regulation. This complex cellular trafficking system is controlled to a large extent via highly regulated production of secreted chemokines and the restricted expression of their membrane-tethered G-protein-coupled receptors. The activity of chemokines and their receptors is also regulated by a subfamily of molecules known as atypical chemokine receptors (ACKRs), which are chemokine receptor-like molecules that do not couple to the classical signalling pathways that promote cell migration in response to chemokine ligation. There has been a great deal of progress in understanding the biology of these receptors and their functions in the immune system in the past decade. Here, we describe the contribution of the various ACKRs to innate and adaptive immune responses, focussing specifically on recent progress. This includes recent findings that have defined the role for ACKRs in sculpting extracellular chemokine gradients, findings that broaden the spectrum of chemokine ligands recognized by these receptors, candidate new additions to ACKR family, and our increasing understanding of the role of these receptors in shaping the migration of innate and adaptive immune cells.

A Bioactive Injectable Hydrogel Regulates Tumor Metastasis and Wound Healing for Melanoma via NIR-Light Triggered Hyperthermia.

Surgical resection remains the mainstream treatment for malignant melanoma. However, challenges in wound healing and residual tumor metastasis pose significant hurdles, resulting in high recurrence rates in patients. Herein, a bioactive injectable hydrogel (BG-Mngel) formed by crosslinking sodium alginate (SA) with manganese-doped bioactive glass (BG-Mn) is developed as a versatile platform for anti-tumor immunotherapy and postoperative wound healing for melanoma. The incorporation of Mn2+ within bioactive glass (BG) can activate the cGAS-STING immune pathway to elicit robust immune response for cancer immunotherapy. Furthermore, doping Mn2+ in BG endows system with excellent photothermal properties, hence facilitating STING activation and reversing the tumor immune-suppressive microenvironment. BG exhibits favorable angiogenic capacity and tissue regenerative potential, and Mn2+ promotes cell migration in vitro. When combining BG-Mngel with anti-PD-1 antibody (α-PD-1) for the treatment of malignant melanoma, it shows enhanced anti-tumor immune response and long-term immune memory response. Remarkably, BG-Mngel can upregulate the expression of genes related to blood vessel formation and promote skin tissue regeneration when treating full-thickness wounds. Overall, BG-MnGel serves as an effective adjuvant therapy to regulate tumor metastasis and wound healing for malignant melanoma.

Next-generation probiotic Bacteroides. dorei: Improving the efficacy of COVID-19 vaccinations

Bacteroides. dorei (B. dorei) is regarded as the “next-generation probiotics”, and it has been demonstrated to fight influenza infection and alter the composition of gut microbiota. The role of the gut microbiota in the immune response to antiviral vaccination has been fully established in animal experiments and clinical studies. However, whether oral B. dorei can affect the immune response to COVID-19 vaccines remains unknown. This study reported that B. dorei enhanced SARS-CoV-2 vaccine efficacy as indicated by elevation in immunoglobulin G antibody and neutralizing antibody titers, mucosal immune response and Th1 immune response, and memory immune responses. Moreover, B. dorei alone could induce maturation of dendritic cells to promote Th1 response, which was crucial for antiviral immunity. These results suggest that B. dorei may potentially be used as an immunoadjuvant or immunopotentiator to enhance immune function, especially in individuals with impaired immune function.

Peak transgene expression after intramuscular immunization of mice with adenovirus 26-based vector vaccines correlates with transgene-specific adaptive immune responses.

Non-replicating adenovirus-based vectors have been broadly used for the development of prophylactic vaccines in humans and are licensed for COVID-19 and Ebola virus disease prevention. Adenovirus-based vectored vaccines encode for one or more disease specific transgenes with the aim to induce protective immunity against the target disease. The magnitude and duration of transgene expression of adenovirus 5- based vectors (human type C) in the host are key factors influencing antigen presentation and adaptive immune responses. Here we characterize the magnitude, duration, and organ biodistribution of transgene expression after single intramuscular administration of adenovirus 26-based vector vaccines in mice and evaluate the differences with adenovirus 5-based vector vaccine to understand if this is universally applicable across serotypes. We demonstrate a correlation between peak transgene expression early after adenovirus 26-based vaccination and transgene-specific cellular and humoral immune responses for a model antigen and SARS-CoV-2 spike protein, independent of innate immune activation. Notably, the memory immune response was similar in mice immunized with adenovirus 26-based vaccine and adenovirus 5-based vaccine, despite the latter inducing a higher peak of transgene expression early after immunization and a longer duration of transgene expression. Together these results provide further insights into the mode of action of adenovirus 26-based vector vaccines.

Programmable Bacteria‐Based Biohybrids as Living Biotherapeutics for Enhanced Cancer Sonodynamic‐Immunotherapy

AbstractSynthetic biology is propelling medicine into a new era through its capacity to genetically program living cells. One of the particular interests is engineering bacteria as a live and targeted therapeutic delivery system. Herein, the bacterial biohybrid (E. coli‐pE@PCN) is developed by genetically engineering Escherichia coli BL21 to overexpress catalase (E. coli‐pE) and electrostatically adsorbing nano‐sonosensitizers (PCN NPs) for enhanced and targeted sonodynamic therapy (SDT). Leveraging the ability to colonize and penetrate deep in tumors, engineered bacteria can not only sustainably express catalase to relieve tumor hypoxia, but also facilitate the enriched and expanded distribution of the carried sonosensitizer at the tumor site, so as to trigger effective SDT. More interestingly, it is found that E. coli‐pE@PCN‐based SDT can successfully inhibit the growth of subcutaneous and orthotopic colorectal tumors by inducing potent antitumor immune responses due to the released tumor‐associated antigens and native immunogenicity of bacterial pathogen‐associated molecular patterns. Furthermore, E. coli‐pE@PCN‐based SDT can not only prime a strong immune memory response to prevent tumor recurrence but also elicit a potent abscopal effect to inhibit tumor metastasis. Therefore, the programmable bacteria‐based biohybrids developed here pave an avenue to prepare next‐generation sonodynamic‐immunotherapeutics to eliminate cancer and prevent its relapse and metastasis.

Immune Responses in Discharged COVID-19 Patients With and Without Long COVID Symptoms.

The immune mechanisms of long coronavirus disease 2019 (COVID) are not yet fully understood. We aimed to investigate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific memory immune responses in discharged COVID-19 patients with and without long COVID symptoms. In this cross-sectional study, we included 1041 hospitalized COVID-19 patients with the original virus strain in Wuhan (China) 12 months after initial infection. We simultaneously conducted a questionnaire survey and collected peripheral blood samples from the participants. Based on the presence or absence of long COVID symptoms during the follow-up period, we divided the patients into 2 groups: a long COVID group comprising 480 individuals and a convalescent group comprising 561 individuals. Both groups underwent virus-specific immunological analyses, including enzyme-linked immunosorbent assay, interferon-γ-enzyme-linked immune absorbent spot, and intracellular cytokine staining. At 12 months after infection, 98.5% (1026/1041) of the patients were found to be seropositive and 93.3% (70/75) had detectable SARS-CoV-2-specific memory T cells. The long COVID group had significantly higher levels of receptor binding domain (RBD)-immunoglobulin G (IgG) levels, presented as OD450 values, than the convalescent controls (0.40 ± 0.22 vs 0.37 ± 0.20; P = .022). The magnitude of SARS-CoV-2-specific T-cell responses did not differ significantly between groups, nor did the secretion function of the memory T cells. We did not observe a significant correlation between SARS-CoV-2-IgG and magnitude of memory T cells. This study revealed that long COVID patients had significantly higher levels of RBD-IgG antibodies when compared with convalescent controls. Nevertheless, we did not observe coordinated SARS-CoV-2-specific cellular immunity. As there may be multiple potential causes of long COVID, it is imperative to avoid adopting a "one-size-fits-all" approach to future treatment modalities.

Ad26.ZEBOV, MVA-BN-Filo Ebola virus disease vaccine regimen plus Ad26.ZEBOV booster at 1 year versus 2 years in health-care and front-line workers in the Democratic Republic of the Congo: secondary and exploratory outcomes of an open-label, randomised, phase 2 trial

Health-care providers and front-line workers are at risk of contracting Ebola virus disease during an Ebola virus outbreak and consequently of becoming drivers of the disease. We aimed to assess the long-term immunogenicity of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen and the safety of and immune memory response to an Ad26.ZEBOV booster vaccination at 1 year or 2 years after the first dose in this at-risk population. This open-label, single-centre, randomised, phase 2 trial was conducted at one study site within a hospital in Boende, Democratic Republic of the Congo. Adult health-care providers and front-line workers, excluding those with a known history of Ebola virus disease, were vaccinated with a two-dose heterologous regimen administered at a 56-day interval via a 0·5 mL intramuscular injection in the deltoid muscle, comprising Ad26.ZEBOV as the first dose and MVA-BN-Filo as the second dose. After the initial vaccination on day 1, participants were randomly assigned (1:1) via randomisation envelopes, opened in a sequential order, to receive an Ad26.ZEBOV booster vaccination at 1 year (group 1) or 2 years (group 2) after the first dose. We present the secondary and exploratory objectives of the trial-results of the primary objective have been published elsewhere. We measured immunogenicity at six timepoints per group as geometric mean concentrations (GMCs) of Ebola virus glycoprotein-specific IgG binding antibodies, using the Filovirus Animal Non-Clinical Group ELISA. We assessed serious adverse events occurring up to 6 months after the last dose and local and systemic solicited and unsolicited adverse events reported for 7 days after the booster vaccination. Antibody responses were analysed per protocol, serious adverse events per full analysis set (FAS), and adverse events for all boosted FAS participants. This trial is registered as completed on ClinicalTrials.gov (NCT04186000). Between Dec 18, 2019, and Feb 8, 2020, 699 health-care providers and front-line workers were enrolled and 698 were randomly assigned (350 to group 1 and 348 to group 2 [FAS]); 534 (77%) participants were male and 164 (23%) were female. 319 in group 1 and 317 in group 2 received the booster. 29 (8%) in group 1 and 26 (7%) in group 2 did not complete the study, mostly due to loss to follow-up or moving out of the study area. In both groups, injection-site pain or tenderness (87 [27%] of 319 group 1 participants vs 90 [28%] of 317 group 2 participants) and headache (91 [29%] vs 93 [29%]) were the most common solicited adverse events related to the investigational product. One participant (in group 2) had a related serious adverse event after booster vaccination (fever of ≥40·0°C). Before booster vaccination, Ebola virus glycoprotein-specific IgG binding antibody GMCs were 279·9 ELISA units (EU) per mL (95% CI 250·6-312·7) in 314 group 1 participants (1 year after first dose) and 274·6 EU/mL (242·1-311·5) in 310 group 2 participants (2 years after first dose). These values were 5·2 times higher in group 1 and 4·9 times higher in group 2 than before vaccination on day 1. 7 days after booster vaccination, these values increased to 10 781·6 EU/mL (9354·4-12 426·4) for group 1 and 10 746·9 EU/mL (9208·7-12 542·0) for group 2, which were approximately 39 times higher than before booster vaccination in both groups. 1 year after booster vaccination in 299 group 1 participants, a GMC that was 7·6-times higher than before booster vaccination was still observed (2133·1 EU/mL [1827·7-2489·7]). Overall, the vaccine regimen and booster dose were well tolerated. A similar and robust humoral immune response was observed for participants boosted 1 year and 2 years after the first dose, supporting the use of the regimen and flexibility of booster dose administration for prophylactic vaccination in at-risk populations. Innovative Medicines Initiative 2 Joint Undertaking and Coalition for Epidemic Preparedness Innovations.

Abstract 2652: NDI-101150 is a potent and highly selective HPK1 inhibitor that both synergizes with and differentiates from anti-PD1 immune checkpoint blockade

Abstract Introduction HPK1 is a member of the MAP4K family of protein serine/threonine kinases that negatively regulates activation signals in multiple immune cells and is an attractive therapeutic target for many cancers. Using structure-based drug design, we developed a highly selective HPK1 inhibitor, NDI-101150, with nanomolar potency and physiochemical properties suitable for once daily oral administration. Methods & Results HPK1 inhibition with NDI-101150 has a differentiated pharmacology profile when compared directly to PD1 blockade. NDI-101150 was able to overcome the immunosuppressive effects of prostaglandin E2, adenosine, and TGF-β on human T cell activation. HPK1 inhibition also directly limited the suppressive capacity of T regulatory cells. In contrast, anti-PD1 treatment was not able to overcome the immunosuppressive activity associated with any of these mechanisms. In vivo, HPK1 inhibition significantly enhanced the production of antigen-specific antibodies in response to immunization with both T-dependent and T-independent antigens, while anti-PD1 treatment had minimal to no effects on antibody production. In the EMT-6 syngeneic model, 7/10 mice receiving NDI-101150 exhibited complete tumor regressions, compared to only 1/10 from an anti-PD1 cohort. Furthermore, NDI-101150 established a robust and durable immune memory response as 100% of treated mice showed complete rejection of tumor growth upon subsequent re-challenge. HPK1 inhibition with NDI-101150 also shows robust synergy with PD1 blockade in vitro and in vivo. Both NDI-101150 and anti-PD1 were able to reinvigorate exhausted human T cells, restoring cytokine production and proliferative effects in mixed lymphocyte reactions. Further, in combination HPK1 inhibition and PD1 blockade synergized to enhance the activity of exhausted human T cells to an extent exceeding that observed with naïve human T cells in similar experiments. In vivo, while NDI-101150 or anti-PD1 treatments alone induced tumor growth inhibition in the murine CT-26 syngeneic tumor model, NDI-101150 and anti-PD1 in combination mediated complete tumor regressions in several mice. Furthermore, NDI-101150 seemed to induce a durable immune memory response as evidenced by the combination-treated animals showing complete rejection of tumor growth upon subsequent re-challenge, without any further dosing of NDI-101150. Conclusions Pharmacological inhibition of HPK1 with NDI-101150 represents a powerful system-wide immunomodulatory approach with the potential to enhance anti-tumor immunity in patients failing to respond to currently approved immune checkpoint therapies or in combination with immune checkpoint blockade therapies. NDI-101150 is currently being tested in a Phase 1/2 trial (NCT05128487) in patients with advanced solid tumors. Citation Format: David Ciccone, Fu-Shan Kuo, Scott Daigle, Neelu Kaila, Gene Yau, Mark Carlson, Denise Levasseur, Bhaskar Srivastava, Frank G. Basile, Christine Loh. NDI-101150 is a potent and highly selective HPK1 inhibitor that both synergizes with and differentiates from anti-PD1 immune checkpoint blockade [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 2652.

Abstract 5081: Immune sensitization of melanoma to checkpoint inhibitor therapy using acoustically active nanoparticles

Abstract Advanced melanoma remains the most fatal form of skin cancer with novel therapeutic approaches required to treat inoperable metastatic lesions. While immunotherapies have shown promise in improving long-term melanoma survival, its treatment efficacy is limited, with only 50% of patients responding. Focused ultrasound (FUS) offers as a non-invasive strategy for targeted tumor ablation, thereby strengthening immunotherapy efficacy by release of tumor associated materials. However, control over tumor material release through FUS, without causing excessive thermal damage to surrounding healthy tissue remains challenging. To address this challenge, our group has previously developed acoustically active nanoparticles (AANPs) responsive to low intensity ultrasound for mechanical tumor ablation by generating strong and durable acoustic cavitation in the tumor tissue. Building upon previous success with AANPs, our current work focuses on sensitizing melanoma tumors to checkpoint inhibitor therapy by releasing tumor antigens into circulation using AANPs and FUS. Our findings revealed sensitization of an immunologically cold B16-F10 metastatic melanoma tumors following treatment, which resulted in a notable 12-day stall in tumor growth. When combined with immune checkpoint inhibitors α-PD-L1 and α-CTLA-4, this approach showed a complete response in B16-F10 bearing mice with impressive memory immune response upon a tumor rechallenge. Herein, these novel AANPs represent a promising advancement to enable accurate immune surveillance by boosting the release of tumor antigens and offers new strategies for improved immunotherapy of melanoma and other solid tumors. Citation Format: Michael Ian Henderson, Li Xiang, Samuel Drennan, Xin Yi, Jared Fischer, Adem Yildirim. Immune sensitization of melanoma to checkpoint inhibitor therapy using acoustically active nanoparticles [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 5081.

CD4 T Cell-Derived IL-21 Is Critical for Sustaining Plasmodium Infection-Induced Germinal Center Responses and Promoting the Selection of Memory B Cells with Recall Potential.

Development of Plasmodium-specific humoral immunity is critically dependent on CD4 Th cell responses and germinal center (GC) reactions during blood-stage Plasmodium infection. IL-21, a cytokine primarily produced by CD4 T cells, is an essential regulator of affinity maturation, isotype class-switching, B cell differentiation, and maintenance of GC reactions in response to many infection and immunization models. In models of experimental malaria, mice deficient in IL-21 or its receptor IL-21R fail to develop memory B cell populations and are not protected against secondary infection. However, whether sustained IL-21 signaling in ongoing GCs is required for maintaining GC magnitude, organization, and output is unclear. In this study, we report that CD4+ Th cells maintain IL-21 expression after resolution of primary Plasmodium yoelii infection. We generated an inducible knockout mouse model that enabled cell type-specific and timed deletion of IL-21 in peripheral, mature CD4 T cells. We found that persistence of IL-21 signaling in active GCs had no impact on the magnitude of GC reactions or their capacity to produce memory B cell populations. However, the memory B cells generated in the absence of IL-21 exhibited reduced recall function upon challenge. Our data support that IL-21 prevents premature cellular dissolution within the GC and promotes stringency of selective pressures during B cell fate determination required to produce high-quality Plasmodium-specific memory B cells. These data are additionally consistent with a temporal requirement for IL-21 in fine-tuning humoral immune memory responses during experimental malaria.

Evaluation of different types of adjuvants in a malaria transmission-blocking vaccine

Adjuvants are critical components for vaccines, which enhance the strength and longevity of the antibody response and influence the types of immune response. Limited research has been conducted on the immunogenicity and protective efficacy of various adjuvants in malaria transmission-blocking vaccines (TBVs). In this study, we formulated a promising TBV candidate antigen, the P. berghei ookinete surface antigen PSOP25, with different types of adjuvants, including the TLR4 agonist monophosphoryl lipid A (MPLA), the TLR9 agonist cytosine phosphoguanosine oligodeoxynucleotides (CpG ODN 1826) (CpG), a saponin adjuvant QS-21, aluminum hydroxide (Alum), and two combination adjuvants MPLA + QS-21 and QS-21 + CpG. We demonstrated that adjuvanted vaccines results in elevated elicited antibody levels, increased proliferation of plasma cells, and efficient formation of germinal centers (GCs), leading to enhanced long-term protective immune responses. Furthermore, CpG group exhibited the most potent inhibition of ookinete formation and transmission-blocking activity. We found that the rPSOP25 with CpG adjuvant was more effective than MPLA, QS-21, MPLA + QS-21, QS-21 + CpG adjuvants in dendritic cells (DCs) activation and differentiation. Additionally, the CpG adjuvant elicited more rubust immune memory response than Alum adjuvant. CpG and QS-21 adjuvants could activate the Th1 response and promote the secretion of IFN-γ and TNF-α. PSOP25 induced a higher number of Tfh cells in splenocytes when combined with MPLA, CpG, and QS-21 + CpG; and there was no increase in these cell populations when PSOP25 was administered with Alum. In conclusion, CpG may confer enhanced efficacy for the rPSOP25 vaccine, as evidenced by the ability of the elicited antisera to induce protective immune responses and improved transmission-blocking activity.

Effect of Corticosteroids on Long-Term Humoral and Memory T-Cell Responses in Follow-Up Visit of Hospitalized Patients With COVID-19

Corticosteroids have beneficial effects in improving outcomes in hospitalized patients with severe COVID-19 by suppressing excessive immune responses. However, the effect of corticosteroids on the humoral and T-cell responses of survivors of COVID-19 1 year after infection remains uncertain, as it relates to the extent of immediate, antigen-specific defense provided by protective memory. What is the effect of corticosteroids on long-term humoral and T-cell immune responses? In this retrospective cohort study conducted at a single center, we analyzed data from a cohort who had survived COVID-19 to compare the 1-year seropositivity and titer changes in neutralizing antibodies (NAbs) and SARS-CoV-2-specific antibodies. Additionally, we evaluated the magnitude and rate of SARS-CoV-2-specific T-cell response in individuals who received corticosteroids during hospitalization and those who did not. Our findings indicated that corticosteroids do not statistically influence the kinetics or seropositive rate of NAbs against the Wuhan strain of SARS-CoV-2 from 6months to 1 year. However, subgroup analysis revealed a numerical increase of NAbs titers, from 20.0 to 28.2, in categories where long-term (> 15days) and high-dose (> 560mg) corticosteroids were administered. Similarly, corticosteroids showed no significant effect on nucleoprotein and receptor-binding domain IgG at 1 year, except for spike protein IgG (β, 0.08; 95%CI, 0.04-0.12), which demonstrated a delayed decline of titers. Regarding T-cell immunity, corticosteroids did not affect the rate or magnitude of T-cell responses significantly. However, functional assessment of memory Tcells revealed higher interferon-γ responses in CD4 (β, 0.61; 95%CI, 0.10-1.12) and CD8 (β, 0.63; 95%CI, 0.11-1.15) memory Tcells in the corticosteroids group at 1 year. Based on our findings, short-term and low-dose corticosteroid therapy during hospitalization does not appear to have a significant effect on long-term humoral kinetics or the magnitude and rate of memory T-cell responses to SARS-CoV-2 antigens. However, the potential harmful effects of long-term and high-dose corticosteroid use on memory immune responses require further investigation.

Humoral and cellular immune responses to COVID-19 mRNA vaccines in immunosuppressed liver transplant recipients

BackgroundLiver transplant recipients (LTRs) are at a high risk of severe COVID-19 owing to immunosuppression and comorbidities. LTRs are less responsive to mRNA vaccines than healthy donors (HDs) or other immunosuppressed patients. However, the disruption mechanism in humoral and cellular immune memory responses is unclear.MethodsWe longitudinally collected peripheral blood mononuclear cells and plasma samples from HDs (n = 44) and LTRs (n = 54) who received BNT162b2 or mRNA-1273 vaccines. We measured the levels of anti-receptor-binding domain (RBD) antibodies and spike-specific CD4+ and CD8+ T-cell responses.ResultsHere, we show that the induction of anti-RBD IgG was weaker in LTRs than in HDs. The use of multiple immunosuppressive drugs is associated with lower antibody titers than only calcineurin inhibitor, and limits the induction of CD4+ T-cell responses. However, spike-specific CD4+ T-cell and antibody responses improved with a third vaccination. Furthermore, mRNA vaccine-induced spike-specific CD8+ T cells are quantitatively, but not qualitatively, limited to LTRs. Both CD4+ and CD8+ T cells react to omicron sublineages, regardless of the presence in HDs or LTRs. However, there is no boosting effect of spike-specific memory CD8+ T-cell responses after a third vaccination in HDs or LTRs.ConclusionsThe third mRNA vaccination improves both humoral responses and spike-specific CD4+ T-cell responses in LTRs but provides no booster effect for spike-specific memory CD8+ T-cell responses. A third mRNA vaccination could be helpful in LTRs to prevent severe COVID-19, although further investigation is required to elicit CD8+ T-cell responses in LTRs and HDs.

Activating CD8+ T Cells by Pt(IV) Prodrug-Based Nanomedicine and aPD-L1 Antibody for Enhanced Cancer Immunotherapy.

Recent years have witnessed substantial progress in cancer immunotherapy, specifically T cell-based therapies. However, the application of T cell therapies has been primarily limited to hematologic malignancies, with limited success in the treatment of solid tumors. The main challenge in treating solid tumor is immune escape, which is characterized by reduced antigenicity, diminished immunogenicity, and the development of suppressive tumor immune microenvironments. To address these obstacles and restore T cell-mediated anti-tumor responses, a novel nanoparticle formulation known as PRA@Oxa-c16 is developed. This innovative approach combines retinoic acid and Pt(IV) to specifically target and overcome immune escape. Notably, the therapeutic efficacy of PRA@Oxa-c16 primarily relies on its ability to induce anti-tumor T cell responses, in contrast to the cytotoxicity associated with conventional chemotherapeutic agents. When combined with an immune checkpoint blockade, anti-programmed death-ligand 1 antibody, PRA@Oxa-c16 effectively eliminates solid tumors and induces immune memory responses, which prevent tumor metastasis and recurrence. This promising approach holds great potential for enhancing the treatment of solid tumors with T cell-based immunotherapy.

STING activator 2'3'-cGAMP enhanced HSV-1-based oncolytic viral therapy.

Oncolytic viruses (OVs) can selectively replicate in tumor cells and remodel the microenvironment of immunologically cold tumors, making them a promising strategy to evoke antitumor immunity. Similarly, agonists of the stimulator of interferon genes (STING)-interferon (IFN) pathway, the main cellular antiviral system, provide antitumor benefits by inducing the activation of dendritic cells (DC). Considering how the activation of the STING-IFN pathway could potentially inhibit OV replication, the use of STING agonists alongside OV therapy remains largely unexplored. Here, we explored the antitumor efficacy of combining an HSV-1-based OV, C-REV, with a membrane-impermeable STING agonist, 2'3'-GAMP. Our results demonstrated that tumor cells harbor a largely defective STING-IFN pathway, thereby preventing significant antiviral IFN induction regardless of the permeability of the STING agonist. In vivo, the combination therapy induced more proliferative KLRG1-high PD1-low CD8+ T-cells and activated CD103+ DC in the tumor site and increased tumor-specific CD44+ CD8+ T-cells in the lymph node. Overall, the combination therapy of C-REV with 2'3'-cGAMP elicited antitumor immune memory responses and significantly enhanced systemic antitumor immunity in both treated and non-treated distal tumors.