CD69 guides CD4+ T cells to the seat of memory

Hybrid Immunity against SARS-CoV-2 Variants: A Narrative Review of the Literature

The emergence of SARS-CoV-2 led to a global health crisis and the burden of the disease continues to persist. The rapid development and emergency authorization of various vaccines, including mRNA-based vaccines, played a pivotal role in mitigating severe illness and mortality. However, rapid viral mutations, leading to several variants of concern, challenged vaccine effectiveness, particularly concerning immune evasion. Research on immunity, both from natural infection and vaccination, revealed that while neutralizing antibodies provide protection against infection, their effect is short-lived. The primary defense against severe COVID-19 is derived from the cellular immune response. Hybrid immunity, developed from a combination of natural infection and vaccination, offers enhanced protection, with convalescent vaccinated individuals showing significantly higher levels of neutralizing antibodies. As SARS-CoV-2 continues to evolve, understanding the durability and breadth of hybrid immunity becomes crucial. This narrative review examines the latest data on humoral and cellular immunity from both natural infection and vaccination, discussing how hybrid immunity could inform and optimize future vaccination strategies in the ongoing battle against COVID-19 and in fear of a new pandemic.

Type I conventional dendritic cells facilitate immunotherapy in pancreatic cancer

Inflammation and tissue damage associated with pancreatitis can precede or occur concurrently with pancreatic ductal adenocarcinoma (PDAC). We demonstrate that in PDAC coupled with pancreatitis (ptPDAC), antigen-presenting type I conventional dendritic cells (cDC1s) are specifically activated. Immune checkpoint blockade therapy (iCBT) leads to cytotoxic CD8+ T cell activation and elimination of ptPDAC with restoration of life span even upon PDAC rechallenge. Using PDAC antigen-loaded cDC1s as a vaccine, immunotherapy-resistant PDAC was rendered sensitive to iCBT with elimination of tumors. cDC1 vaccination coupled with iCBT identified specific CDR3 sequences in the tumor-infiltrating CD8+ T cells with potential therapeutic importance. This study identifies a fundamental difference in the immune microenvironment in PDAC concurrent with, or without, pancreatitis and provides a rationale for combining cDC1 vaccination with iCBT as a potential treatment option.

Blood defense system - Proposal for a new concept of an immune system against blood borne pathogens comprising the liver, spleen and bone marrow

Blood-borne pathogen (BBP) infections can rapidly progress to life-threatening sepsis and must therefore be promptly eliminated by the host's immune system. Intravascular macrophages of the liver sinusoid, splenic marginal zone and red pulp and perisinusoidal macrophage protrusions in the bone marrow (BM) directly phagocytose BBPs in the blood as an innate immune response. The liver, spleen and BM thereby work together as the blood defence system (BDS) in response to BBPs by exerting their different immunological roles. The liver removes the vast majority of these invading organisms via innate immunity, but their complete elimination is not possible without the actions of antibodies. Splenic marginal zone B cells promptly produce IgM and IgG antibodies against BBPs. The splenic marginal zone transports antigenic information from the innate to the adaptive immune systems. The white pulp of the spleen functions as adaptive immune tissue and produces specific and high-affinity antibodies with an immune memory against BBPs. The BM works to maintain immune memory by supporting the survival of memory B cells, memory T cells and long-lived plasma cells (LLPCs), all of which have dedicated niches. Furthermore, BM perisinusoidal naïve follicular B cells promptly produce IgM antibodies against BBPs in the BM sinusoid and the IgG memory B cells residing in the BM rapidly transform to plasma cells which produce high-affinity IgG antibodies upon reinfection. This review describes the complete immune defence characteristics of the BDS against BBPs through the collaboration of the liver, spleen and BM with combined different immunological roles.

Antigen-presenting type-I conventional dendritic cells facilitate curative checkpoint blockade immunotherapy in pancreatic cancer

Inflammation and tissue damage associated with pancreatitis can precede or occur concurrently with pancreatic ductal adenocarcinoma (PDAC). We demonstrate that in PDAC coupled with pancreatitis (ptPDAC), antigen-presenting type-I conventional dendritic cells (cDC1s) are specifically activated. Immune checkpoint blockade therapy (iCBT) leads to cytotoxic CD8 + T cell activation and eradication of ptPDAC with restoration of lifespan even upon PDAC re-challenge. Such eradication of ptPDAC was reversed following specific depletion of dendritic cells. Employing PDAC antigen-loaded cDC1s as a vaccine, immunotherapy-resistant PDAC was rendered sensitive to iCBT with a curative outcome. Analysis of the T-cell receptor (TCR) sequences in the tumor infiltrating CD8 + T cells following cDC1 vaccination coupled with iCBT identified unique CDR3 sequences with potential therapeutic significance. Our findings identify a fundamental difference in the immune microenvironment and adaptive immune response in PDAC concurrent with, or without pancreatitis, and provides a rationale for combining cDC1 vaccination with iCBT as a potential treatment option.

Persistence of spike-specific immune responses in BNT162b2-vaccinated donors and generation of rapid ex-vivo T cells expansion protocol for adoptive immunotherapy: A pilot study

Introduction

The BNT162b2 mRNA-based vaccine has shown high efficacy in preventing COVID-19 infection but there are limited data on the types and persistence of the humoral and T cell responses to such a vaccine.

Methods

Here, we dissect the vaccine-induced humoral and cellular responses in a cohort of six healthy recipients of two doses of this vaccine.

Results and discussion

Overall, there was heterogeneity in the spike-specific humoral and cellular responses among vaccinated individuals. Interestingly, we demonstrated that anti-spike antibody levels detected by a novel simple automated assay (Jess) were strongly correlated (r=0.863, P<0.0001) with neutralizing activity; thus, providing a potential surrogate for neutralizing cell-based assays. The spike-specific T cell response was measured with a newly modified T-spot assay in which the high-homology peptide-sequences cross-reactive with other coronaviruses were removed. This response was induced in 4/6 participants after the first dose, and all six participants after the second dose, and remained detectable in 4/6 participants five months post-vaccination. We have also shown for the first time, that BNT162b2 vaccine enhanced T cell responses also against known human common viruses. In addition, we demonstrated the efficacy of a rapid ex-vivo T cell expansion protocol for spike-specific T cell expansion to be potentially used for adoptive-cell therapy in severe COVID-19, immunocompromised individuals, and other high-risk groups. There was a 9 to 13.7-fold increase in the number of expanded T cells with a significant increase of anti-spike specific response showing higher frequencies of both activation and cytotoxic markers. Interestingly, effector memory T cells were dominant in all four participants' CD8+ expanded memory T cells; CD4+ T cells were dominated by effector memory in 2/4 participants and by central memory in the remaining two participants. Moreover, we found that high frequencies of CD4+ terminally differentiated memory T cells were associated with a greater reduction of spike-specific activated CD4+ T cells. Finally, we showed that participants who had a CD4+ central memory T cell dominance expressed a high CD69 activation marker in the CD4+ activated T cells.

Adoptive therapy with amyloid-β specific regulatory T cells alleviates Alzheimer's disease

Rationale: Neuroinflammation is a primary feature of Alzheimer's disease (AD), for which an increasing number of drugs have been specifically developed. The present study aimed to define the therapeutic impact of a specific subpopulation of T cells that can suppress excessive inflammation in various immune and inflammatory disorders, namely, CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs). Methods: To generate Aβ antigen-specific Tregs (Aβ⁺ Tregs), Aβ 1-42 peptide was applied in vivo and subsequent in vitro splenocyte culture. After isolating Tregs by magnetic bead based purification method, Aβ⁺ Tregs were adoptively transferred into 3xTg-AD mice via tail vein injection. Therapeutic efficacy was confirmed with behavior test, Western blot, quantitative real-time PCR (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry staining (IHC). In vitro suppression assay was performed to evaluate the suppressive activity of Aβ⁺ Tregs using flow cytometry. Thy1.1⁺ Treg trafficking and distribution was analyzed to explore the infused Tregs migration into specific organs in an antigen-driven manner in AD mice. We further assessed cerebral glucose metabolism using ¹⁸F-FDG-PET, an imaging approach for AD biological definition. Subsequently, we evaluated the migration of Aβ⁺ Tregs toward Aβ activated microglia using live cell imaging, chemotaxis, antibody blocking and migration assay. Results: We showed that Aβ-stimulated Tregs inhibited microglial proinflammatory activity and modulated the microglial phenotype via bystander suppression. Single adoptive transfer of Aβ⁺ Tregs was enough to induce amelioration of cognitive impairments, Aβ accumulation, hyper-phosphorylation of tau, and neuroinflammation during AD pathology. Moreover, Aβ-specific Tregs effectively inhibited inflammation in primary microglia induced by Aβ exposure. It may indicate bystander suppression in which Aβ-specific Tregs promote immune tolerance by secreting cytokines to modulate immune responses during neurodegeneration. Conclusions: The administration of Aβ antigen-specific regulatory T cells may represent a new cellular therapeutic strategy for AD that acts by modulating the inflammatory status in AD.

Density of CD3+ and CD8+ cells in gingivo-buccal oral squamous cell carcinoma is associated with lymph node metastases and survival

The tumor immune microenvironment is emerging as a critical player in predicting cancer prognosis and response to therapies. However, the prognostic value of tumor-infiltrating immune cells in Gingivo-Buccal Oral Squamous Cell Carcinoma (GBOSCC) and their association with tumor size or lymph node metastases status require further elucidation. To study the relationship of tumor-infiltrating immune cells with tumor size (T stage) and lymph node metastases (N stages), we analyzed the density of tumor-infiltrating immune cells in archived, whole tumor resections from 94 patients. We characterized these sections by immune-histochemistry using 12 markers and enumerated tumor-infiltrating immune cells at the invasive margins (IM) and centers of tumors (CT). We observed that a higher density of CD3+ cells in the IM and CT was associated with smaller tumor size (T1-T2 stage). Fewer CD3+ cells was associated with larger tumor size (T3-T4 stage). High infiltration of CD3+and CD8+ cells in IM and CT as well as high CD4+ cell infiltrates in the IM was significantly associated with the absence of lymph node metastases. High infiltrates of CD3+ and CD8+ cells in CT was associated with significantly improved survival. Our results illustrate that the densities and spatial distribution of CD3+ and CD8+ cell infiltrates in primary GBOSCC tumors is predictive of disease progression and survival. Based on our findings, we recommend incorporating immune cell quantification in the TNM classification and routine histopathology reporting of GBOSCC. Immune cell quantification in CT and IM may help predict the efficacy of future therapies.

CD28 and CD57 define four populations with distinct phenotypic properties within human CD8+ T cells

After repeated antigen exposure, both memory and terminally differentiated cells can be generated within CD8⁺ T cells. Although, during their differentiation, activated CD8⁺ T cells may first lose CD28, and CD28^- cells may eventually express CD57 as a subsequent step, a population of CD28⁺ CD57⁺ (DP) CD8⁺ T cells can be identified in the peripheral blood. How this population is distinct from CD28^- CD57^- (DN) CD8⁺ T cells, and from the better characterized non-activated/early-activated CD28⁺ CD57^- and senescent-like CD28^- CD57⁺ CD8⁺ T cell subsets is currently unknown. Here, RNA expression of the four CD8⁺ T cell subsets isolated from human PBMCs was analyzed using microarrays. DN cells were more similar to "early" highly differentiated cells, with decreased TNF and IFN-γ production, impaired DNA damage response and apoptosis. Conversely, increased apoptosis and expression of cytokines, co-inhibitory, and chemokine receptors were found in DP cells. Higher levels of DP CD8⁺ T cells were observed 7 days after Hepatitis B vaccination, and decreased levels of DP cells were found in rheumatoid arthritis patients. More DP and DN CD8⁺ T cells were present in the bone marrow, in comparison with PBMCs. In summary, our results indicate that DP and DN cells are distinct CD8⁺ T cell subsets displaying defined properties.

Malawian children with uncomplicated and cerebral malaria have decreased activated Vγ9Vδ2 γδ T cells which increase in convalescence

Malaria is responsible for almost half a million deaths annually. The role of Vγ9Vδ2 γδ T cells in malaria is still unclear. Studies have reported an association between this cell subset and malaria symptoms and severity. Profiles of Vγ9Vδ2 γδ T cells in bigger cohorts with different levels of clinical severity have not been described. Proportion, numbers, and activation status of Vγ9Vδ2 γδ T cells were measured by flow cytometry in 59 healthy controls (HCs), 58 children with uncomplicated malaria (UM) and 67 with cerebral malaria (CM,) during acute malaria and in convalescence 28 days later. Vγ9Vδ2 γδ T cell were lower in children presenting with UM and CM than in HCs. Cell counts did not vary with malaria severity (CM median counts 40 x 10³ cells/μL, IQR [23–103]; UM median counts 30 x 10³ cells/μL [10–90], P = 0.224). Vγ9Vδ2 γδ T cell counts increased during convalescence for UM (70 [40–60] x 10³ cells/μL and CM (90 [60–140] x 10³ cells/μL), to levels similar to those in HCs (70 [50–140] x 10³ cells/μL), p = 0.70 and p = 0.40 respectively. Expression of the activation markers CD69 and HLA-DR on Vγ9Vδ2 γδ T cells was higher in malaria cases than in controls (HCs vs UM or CM, p < 0.0001) but was similar between UM and CM. HLA-DR expression remained elevated at 28 days, suggesting sustained activation of Vγ9Vδ2 γδ T cells during recovery. Vγ9Vδ2 γδ T cell proportions and cells counts were suppressed in acute disease and normalized in convalescence, a phenomenon previously hypothesized to be due to transient migration of the cells to secondary lymphoid tissue. The presence of highly activated Vγ9Vδ2 γδ T cells suggests that this T cell subset plays a specific role in response to malaria infection.

Antigen Priming with Enantiospecific Cationic Lipid Nanoparticles Induces Potent Antitumor CTL Responses through Novel Induction of a Type I IFN Response

Certain types of cationic lipids have shown promise in cancer immunotherapy, but their mechanism of action is poorly understood. In this study, we describe the properties of an immunotherapeutic consisting of the pure cationic lipid enantiomer R-1,2-dioleoyl-3-trimethyl-ammonium-propane (R-DOTAP) formulated with modified viral or self-peptide Ags. R-DOTAP formulations with peptide Ags stimulate strong cross-presentation and potent CD8 T cell responses associated with a high frequency of polyfunctional CD8 T cells. In a human papillomavirus tumor model system, a single s.c. injection of tumor-bearing mice with R-DOTAP plus human papillomavirus Ags induces complete regression of large tumors associated with an influx of Ag-specific CD8 T cells and a reduction of the ratio of regulatory/Ag-specific CD8 T cells. R-DOTAP also synergizes with an anti-PD1 checkpoint inhibitor, resulting in a significant inhibition of B16 melanoma tumor growth. We found that R-DOTAP stimulates type I IFN production by dendritic cells in vivo and in vitro. s.c. injection of R-DOTAP results in an IFN-dependent increase in draining lymph node size and a concomitant increase in CD69 expression. Using knockout mice, we show that type I IFN is required for the induction of CD8 T cell activity following administration of R-DOTAP plus Ag. This response requires Myd88 but not TRIF or STING. We also show that R-DOTAP stimulates both TLR7 and 9. Collectively, these studies reveal that R-DOTAP stimulates endosomal TLRs, resulting in a Myd88-dependent production of type I IFN. When administered with Ag, this results in potent Ag-specific CD8 T cell responses and antitumor activity.

Human Fetal TNF-α-Cytokine-Producing CD4+ Effector Memory T Cells Promote Intestinal Development and Mediate Inflammation Early in Life

Although the fetal immune system is considered tolerogenic, preterm infants can suffer from severe intestinal inflammation, including necrotizing enterocolitis (NEC). Here, we demonstrate that human fetal intestines predominantly contain tumor necrosis factor-α (TNF-α)⁺CD4⁺CD69⁺ T effector memory (Tem) cells. Single-cell RNA sequencing of fetal intestinal CD4⁺ T cells showed a T helper 1 phenotype and expression of genes mediating epithelial growth and cell cycling. Organoid co-cultures revealed a dose-dependent, TNF-α-mediated effect of fetal intestinal CD4⁺ T cells on intestinal stem cell (ISC) development, in which low T cell numbers supported epithelial development, whereas high numbers abrogated ISC proliferation. CD4⁺ Tem cell frequencies were higher in inflamed intestines from preterm infants with NEC than in healthy infant intestines and showed enhanced TNF signaling. These findings reveal a distinct population of TNF-α-producing CD4⁺ T cells that promote mucosal development in fetal intestines but can also mediate inflammation upon preterm birth.

Clearance of attenuated rabies virus from brain tissues is required for long-term protection against CNS challenge with a pathogenic variant

Rabies virus is a neurotropic lyssavirus which is 100% fatal in its pathogenic form when reaching unprotected CNS tissues. Death can be prevented by mechanisms delivering appropriate immune effectors across the blood-brain barrier which normally remains intact during pathogenic rabies virus infection. One therapeutic approach is to superinfect CNS tissues with attenuated rabies virus which induces blood-brain barrier permeability and immune cell entry. Current thinking is that peripheral rabies immunization is sufficient to protect against a challenge with pathogenic rabies virus. While this is undoubtedly the case if the virus is confined to the periphery, what happens if the virus reaches the CNS is less well-understood. In the current study, we find that peripheral immunization does not fully protect mice long-term against an intranasal challenge with pathogenic rabies virus. Protection is significantly better in mice that have cleared attenuated virus from the CNS and is associated with a more robust CNS recall response evidently due to the presence in CNS tissues of elevated numbers of lymphocytes phenotypically resembling long-term resident immune cells. Adoptive transfer of cells from rabies-immune mice fails to protect against CNS challenge with pathogenic rabies virus further supporting the concept that long-term resident immune cell populations must be established in brain tissues to protect against a subsequent CNS challenge with pathogenic rabies virus.

Improvement Efficacy of Influenza Nanovaccine in Combination with Hemokinin-1 Molecular Adjuvant

BACKGROUND

H9N2 avian influenza viruses have the potential to become the next human pandemic threat and next generation vaccine technologies are needed. Current studies introduce nanoparticles as a proper vaccine delivery vehicle for induction of protective immunity. In this study, the efficacy of chitosan nanoparticle-based H9N2 influenza vaccine with and without hemokinin-1 (HK-1) as a molecular adjuvant to induce protective immunity against the virus was examined.

METHODS

The H9N2 antigen was prepared in MDCK cells and inactivated with formalin. The inactivated antigen alone and in combination with HK-1 was encapsulated into chitosan nanoparticles. Groups of BALB/c mice received chitosan nanoparticle-based H9N2 antigen alone or in combination with HK-1 in a prime/boost platform via eye drop method. To evaluate the efficacy of the adjuvanted-nanovaccine candidate, systemic antibody responses were compared among the groups of animals.

RESULTS

Serological analysis indicated that mice receiving the HK-1/H9N2 nanoparticles formulation induced higher antibody titers that were sustained until the end of experiment. However, in the immunized mice, influenza specific antibody titers were comparable to that in the animals which were immunized either with inactivated antigen alone or the H9N2 nanoparticles without HK-1 adjuvant.

CONCLUSION

The data demonstrate the synergy between HK-1 as an adjuvant and chitosan nanoparticles as a delivery antigen/adjuvant carrier in the improvement of influenza immune responses.

Inactivated probiotic Bacillus coagulans GBI-30 induces complex immune activating, anti-inflammatory, and regenerative markers in vitro

Objective

The aim of this study was to document the immune activating and anti-inflammatory effects of inactivated probiotic Bacillus coagulans GBI-30, 6086 (Staimune™) cells on human immune cells in vitro.

Methods

In vitro cultures of human peripheral blood mononuclear cells (PBMC) from healthy blood donors were treated with inactivated B. coagulans GBI-30, 6086 cells for 24 hours. After incubation, the PBMC were stained with fluorochrome-labeled monoclonal antibodies for CD3, CD56, and CD69 to monitor cellular activation by flow cytometry. The culture supernatants were tested for cytokine profile using a 27-plex Luminex array, including pro- and anti-inflammatory cytokines, chemokines, and growth factors.

Results

Inactivated B. coagulans GBI-30, 6086 cells induced the CD69 early activation marker on CD3⁺ CD56⁻ T lymphocytes, CD3⁺ CD56⁺ NKT cells, CD3⁻CD56⁺ NK cells, and also some cells within the CD3⁻CD56⁻ non-T non-NK cell subset. Culture supernatants showed robust increases in the immune-activating cytokines IL-1β, IL-6, IL-17A, and TNF-α. IFN-γ levels were increased, along with three chemokines, MCP-1, MIP-1α, and MIP-1β. The two anti-inflammatory cytokines IL-1ra and IL-10 showed increases, as well as the G-CSF growth factor involved in repair and stem cell biology. In contrast, GM-CSF levels showed a mild decrease, showing a highly selective growth factor response.

Conclusion

The inactivated B. coagulans GBI-30, 6086 cells activated human immune cells and altered the production of both immune activating and anti-inflammatory cytokines and chemokines. Of special importance is the novel demonstration of a selective upregulation of the G-CSF growth factor involved in postinjury and postinflammation repair and regeneration. This suggests that important immunogenic cell wall components, such as lipoteichoic acid, are undamaged after the inactivation and retain the complex beneficial biological activities previously demonstrated for the cell walls from live B. coagulans GBI-30, 6086 (GanedenBC30) probiotic bacteria.

Sexual Dimorphic Responses in Lymphocytes of Healthy Individuals after Carica papaya Consumption

Sexual dimorphism in immune response is widely recognized, but few human studies have observed this distinction. Food with endo-immunomodulatory potential may reveal novel sex-biased in vivo interactions. Immunomodulatory effects of Carica papaya were compared between healthy male and female individuals. Volunteers were given fixed meals supplemented with papaya for 2 days. Changes in blood immune profiles and hormone levels were determined. In females, total natural killer (NK) cell percentages decreased (12.7 ± 4.4 vs 14.6 ± 5.8%, p = 0.018, n = 18) while B cells increased (15.2 ± 5.5 vs 14.5 ± 5.0, p = 0.037, n = 18) after papaya consumption. Increased 17β-estradiol (511.1 ± 579.7 vs 282.7 ± 165.0 pmol/l, p = 0.036, n = 9) observed in females may be crucial to this change. Differentiation markers (CD45RA, CD69, CD25) analyzed on lymphocytes showed naïve (CD45RA⁺) non-CD4⁺ lymphocytes were reduced in females (40.7 ± 8.1 vs 46.8 ± 5.4%, p = 0.012, n = 8) but not males. A general suppressive effect of papaya on CD69⁺ cells, and higher percentage of CD69⁺ populations in females and non-CD4 lymphocytes, may be relevant. CD107a⁺ NK cells were significantly increased in males (16.8 ± 7.0 vs 14.7 ± 4.8, p = 0.038, n = 9) but not females. Effect in females may be disrupted by the action of progesterone, which was significantly correlated with this population (R = 0.771, p = 0.025, n = 8) after papaya consumption. In males, total T helper cells were increased (33.4 ± 6.4 vs 32.4 ± 6.1%, p = 0.040, n = 15). Strong significant negative correlation between testosterone and CD25⁺CD4⁺ lymphocytes, may play a role in the lower total CD4⁺ T cells reported in males. Thus, dissimilar immune profiles were elicited in the sexes after papaya consumption and may have sex hormone influence.

Safety and immunogenicity of a novel recombinant adenovirus type-5 vector-based Ebola vaccine in healthy adults in China: preliminary report of a randomised, double-blind, placebo-controlled, phase 1 trial

BACKGROUND

Up to now, all tested Ebola virus vaccines have been based on the virus strain from the Zaire outbreak in 1976. We aimed to assess the safety and immunogenicity of a novel recombinant adenovirus type-5 vector-based Ebola vaccine expressing the glycoprotein of the 2014 epidemic strain.

METHODS

We did this randomised, double-blind, placebo-controlled, phase 1 clinical trial at one site in Taizhou County, Jiangsu Province, China. Healthy adults (aged 18-60 years) were sequentially enrolled and randomly assigned (2:1), by computer-generated block randomisation (block size of six), to receive placebo, low-dose adenovirus type-5 vector-based Ebola vaccine, or high-dose vaccine. Randomisation was pre-stratified by dose group. All participants, investigators, and laboratory staff were masked to treatment allocation. The primary safety endpoint was occurrence of solicited adverse reactions within 7 days of vaccination. The primary immunogenicity endpoints were glycoprotein-specific antibody titres and T-cell responses at day 28 after the vaccination. Analysis was by intention to treat. The study is registered with ClinicalTrials.gov, number NCT02326194.

FINDINGS

Between Dec 28, 2014, and Jan 9, 2015, 120 participants were enrolled and randomly assigned to receive placebo (n=40), low-dose vaccine (n=40), or high-dose vaccine. Participants were followed up for 28 days. Overall, 82 (68%) participants reported at least one solicited adverse reaction within 7 days of vaccination (n=19 in the placebo group vs n=27 in the low-dose group vs n=36 in the high-dose group; p=0·0002). The most common reaction was mild pain at the injection site, which was reported in eight (20%) participants in the placebo group, 14 (35%) participants in the low-dose group, and 29 (73%) participants in the high-dose vaccine group (p<0·0001). We recorded no statistical differences in other adverse reactions and laboratory tests across groups. Glycoprotein-specific antibody titres were significantly increased in participants in the low-dose and high-dose vaccine groups at both day 14 (geometric mean titre 421·4 [95% CI 249·7-711·3] and 820·5 [598·9-1124·0], respectively; p<0·0001) and day 28 (682·7 [424·3-1098·5] and 1305·7 [970·1-1757·2], respectively; p<0·0001). T-cell responses peaked at day 14 at a median of 465·0 spot-forming cells (IQR 180·0-1202·5) in participants in the low-dose group and 765·0 cells (400·0-1460·0) in those in the high-dose group. 21 (18%) participants had mild fever (n=9 in the placebo group, n=6 in the low-dose group, and n=6 in the high-dose group). No serious adverse events were recorded.

INTERPRETATION

Our findings show that the high-dose vaccine is safe and robustly immunogenic. One shot of the high-dose vaccine could mount glycoprotein-specific humoral and T-cell response against Ebola virus in 14 days.

FUNDING

China National Science and Technology, Beijing Institute of Biotechnology, and Tianjin CanSino Biotechnology.

Distinct p21 requirements for regulating normal and self-reactive T cells through IFN-γ production

Self/non-self discrimination characterizes immunity and allows responses against pathogens but not self-antigens. Understanding the principles that govern this process is essential for designing autoimmunity treatments. p21 is thought to attenuate autoreactivity by limiting T cell expansion. Here, we provide direct evidence for a p21 role in controlling autoimmune T cell autoreactivity without affecting normal T cell responses. We studied C57BL/6, C57BL/6/lpr and MRL/lpr mice overexpressing p21 in T cells, and showed reduced autoreactivity and lymphadenopathy in C57BL/6/lpr, and reduced mortality in MRL/lpr mice. p21 inhibited effector/memory CD4(+) CD8(+) and CD4(-)CD8(-) lpr T cell accumulation without altering defective lpr apoptosis. This was mediated by a previously non-described p21 function in limiting T cell overactivation and overproduction of IFN-γ, a key lupus cytokine. p21 did not affect normal T cell responses, revealing differential p21 requirements for autoreactive and normal T cell activity regulation. The underlying concept of these findings suggests potential treatments for lupus and autoimmune lymphoproliferative syndrome, without compromising normal immunity.

CD4 positive T helper cells contribute to retinal ganglion cell death in mouse model of ischemia reperfusion injury

Neuron degeneration is a common pathological process associated with many disease conditions in the central nervous system including retina. Although immune responses have been proposed as one potential element in triggering neural damage, the mechanism of action of specific immune components underlying the pathogenesis is unclear. In this study we focus on adaptive immune activities to evaluate CD4 positive helper cells in the retinal ganglion cell (RGC) degeneration in response to transient retinal ischemic/reperfusion (I/R) injury. Transient retinal ischemia was induced in four mouse strains with different immune backgrounds, including wild type mice from C57BL/6 and BABL/c strains, severe combined immunodeficient (SCID) mice lacking T and B lymphocytes, SCID mice with transferred wild type CD4+ T cells, and the STAT6 deficient mice without T helper 2 (TH2) cells. In SCID mice RGCs showed a strong resistance to cell death in response to I/R injury (89% ± 3% of the survival cells in contralateral eye) compared with C57BL/6 (p = 0.018) and BALB/C (p = 0.038) wild types. By transferring the mature CD4+ T cells from matched wild type into SCID mice, the resistance of RGCs to injury was significantly compromised (p < 0.05). Furthermore a significant resistance of RGCs to cell death (p < 0.05) accompanied with an overexpression of STAT1 and STAT3 was confirmed in STAT6 deficient mice in response to I/R injury compared with the wild type controls, indicating that TH2 cells maturation might be involved in RGC damage. Adaptive immunity carried by CD4 T cells plays an essential role in RGC degeneration.

Significant increase in cytotoxic T lymphocytes and natural killer cells by triphala: a clinical phase I study

Background. Searching for drugs or herbal formulations to improve the immunity of HIV/AIDS positive people is an important issue for researchers in this field. Triphala, a Thai herbal formulation, is reported to have immunomodulatory effects in mice. However, it has not yet been investigated for immunostimulatory and side effects in healthy human volunteers. Objective. To evaluate the immunostimulatory and side effects of Triphala in a clinical phase I study. Materials and Methods. All volunteers took Triphala, 3 capsules per day for 2 weeks. Complete physical examination, routine laboratory analysis, and immunological studies were performed before ingestion and after initial meeting for 4 consecutive weeks. Results. We found that Triphala demonstrated significant immunostimulatory effects on cytotoxic T cells (CD3⁻CD8⁺) and natural killer cells (CD16⁺CD56⁺). Both of them increased significantly when compared with those of the control samples. However, no significant change in cytokine secretion was detected. All volunteers were healthy and showed no adverse effects throughout the duration of the study. Conclusion. Triphala has significant immunostimulatory effects on cellular immune response, especially cytotoxic T cells and natural killer cells. Increases in the absolute number of these cells may provide a novel adjuvant therapy for HIV/AIDS positive people in terms of immunological improvement.