Anti-Pneumococcal Vaccine-Induced Cellular Immune Responses in Post-Traumatic Splenectomized Individuals

Single-cell RNA sequencing indicates AP-1 as a potential therapeutic target for autoimmune uveitis

Autoimmune uveitis (AU) is a sight-threatening eye disease, marked by a complex pathogenesis and limited treatment options. Herein, we conducted single-cell RNA sequencing (scRNA-seq) on the spleen and cervical draining lymph nodes (CDLNs) of both normal and experimental autoimmune uveitis (EAU) mice and found common alterations in celluar composition and transcriptional regulation occurred throughout the EAU process. Moreover, we identified activator protein-1 (AP-1) as a pivotal disease-related molecule in the pathogenesis of EAU. Inhibiting AP-1 alleviated symptoms of EAU and reduced the retina infiltration of T helper 17 cells (Th17) and Th1 cells. Additionally, following treatment with the AP-1 inhibitor, both the spleen and CDLNs showed decreased Th17 and Th1 cell proportions. Meanwhile, in vitro studies revealed that treatment with AP-1 inhibitor reduced the level of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-23 (IL-23), two pivotal molecules implicated in the Th17 cell pathogenicity, during EAU. The adoptive transfer experiment also showed that inhibiting AP-1 in CD4+ T cells suppressed their ability to elicit EAU. Altogether, our study demonstrates that AP-1 might involved in EAU pathogenesis by supporting Th17 cell pathogenicity via the GM-CSF/IL-23 feedback loop. Thus, AP-1 inhibition might be a novel treatment strategy for uveitis.

Streptococcus pneumoniae epidemiology, pathogenesis and control

Infections caused by Streptococcus pneumoniae (also known as pneumococci) pose a threat to human health. Pneumococcal infections are the most common cause of milder respiratory tract infections, such as otitis and sinusitis, and of more severe diseases, including pneumonia (with or without septicaemia) and meningitis. The introduction of pneumococcal conjugate vaccines in the childhood vaccination programme in many countries has led to a notable decrease of severe invasive pneumococcal disease in vaccinated children. However, infections caused by non-vaccine types have concurrently increased, causing invasive pneumococcal disease in unvaccinated populations (such as older adults), which has hampered the effect of these vaccines. Moreover, emerging antibiotic resistance is threatening effective therapy. Thus, new approaches are needed for the treatment and prevention of pneumococcal infections, and recent advances in the field may pave the way for new strategies. Recently, several important findings have been gained regarding pneumococcal epidemiology, genomics and the effect of the introduction of pneumococcal conjugate vaccines and of the COVID-19 pandemic. Moreover, elucidative pathogenesis studies have shown that the interactions between pneumococcal virulence factors and host receptors may be exploited for new therapies, and new vaccine candidates have been suggested. In this Review, we summarize some recent findings from clinical disease to basic pathogenesis studies that may be of importance for future control strategies.

Evaluation of Th1/Th2/Th17 Balance in Pulmonary Cystic Echinococcosis Patients

PURPOSE

Cystic echinococcosis (CE) is a neglected tropical disease prevalent worldwide, particularly in rural areas. Previous studies evaluated immune responses in patients with hepatic CE, however none had assessed Th1, Th2 and Th17 levels simultaneously in pulmonary CE patients. This study aimed to fill this gap in literature by using flow cytometry analysis.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples collected from healthy control (HC) volunteers and patients with active pulmonary CE cysts. The PBMCs were analysed to evaluate Th1, Th2, and Th17 cell levels within the CD3 + CD4 + T-cell population, using antibodies against interferon (IFN)-γ, interleukin (IL)-4, and IL-17, respectively.

RESULTS

Our analysis revealed elevated Th2 levels in CE patients, while Th1 and Th17 cell counts showed no significant difference between HC volunteers and patients with pulmonary CE.

CONCLUSION

The results indicate an imbalanced Th1/Th2/Th17 cell regulation in the pathogenesis of pulmonary CE. Future studies are recommended to compare immune responses between pulmonary and hepatic CE to confirm these findings and evaluate any potential difference in the immunopathology associated with the two clinical forms of CE.

The compensatory role of T cells from lymph nodes in mice with splenectomy

The spleen is a vital organ for the immune system, while splenectomy may be necessary for various reasons. However, there is limited research on the impact of splenectomy on T cell function in peripheral lymph nodes as a compensatory mechanism in preventing infections. This study aimed to investigate the characteristics and function of CD8+ and CD4+ T cells in different peripheral lymph nodes during viral infection using a well-established splenectomy model. The results revealed that splenectomy caused an increase in CD8+GP33+ T cells in the mesenteric lymph nodes (MLN). Moreover, we demonstrated that splenectomy resulted in an increase of effector KLRG1+ T cells in the MLN. Additionally, the number of CD4+ cytotoxic T cells (CD4 CTLs) was also elevated in the peripheral lymph nodes of mice with splenectomy. Surprisingly, aged mice exhibited a stronger compensatory ability than adult mice, as evidenced by an increase in effector CD8+ T cells in all peripheral lymph nodes. These findings provide compelling evidence that T cells in MLN play a crucial role in protecting individuals with splenectomy against viral infections. The study offers new insights into understanding the changes in the immune system of individuals with splenectomy and highlights the potential compensatory mechanisms involved by T cells in peripheral lymph nodes.

Efficacy, immunogenicity, and evidence for best-timing of pneumococcal vaccination in splenectomized adults: a systematic review

INTRODUCTION

: Streptococcus pneumoniae is the most frequent cause of overwhelming post-splenectomy infections. Pneumococcal vaccination is generally recommended for splenectomized individuals. However, most of our knowledge comes from a few observational studies or small randomized clinical trials. We conducted this systematic review to assess the evidence of efficacy, antibody response, and the best timing for pneumococcal vaccination in splenectomized individuals.

AREAS COVERED

: The systematic review was conducted according to the PRISMA guidelines. We screened 489 articles, included 21 articles, and assessed the risk of bias using Cochrane RoB 2 and ROBINS-I. We summarized the findings narratively due to the heterogeneity of the studies.

EXPERT OPINION

Splenectomized individuals seem to have adequate antibody responses to pneumococcal vaccines. No differences in antibody responses were observed compared to healthy controls, except in one study. The studies were heterogeneous, and the majority had moderate to high degree of bias. There is a lack of clinical evidence for efficacy and best timing of pneumococcal vaccination in splenectomized individuals. Randomized clinical trials addressing these issues are needed.

Establishment of an ELISpot Assay to Detect Cellular Immunity against S. pneumoniae in Vaccinated Kidney Transplant Recipients

In organ transplant recipients, the rate of invasive pneumococcal diseases is 25 times greater than in the general population. Vaccination against S. pneumoniae is recommended in this cohort because it reduces the incidence of this severe form of pneumococcal infection. Previous studies indicate that transplant recipients can produce specific antibodies after pneumococcal vaccination. However, it remains unclear if vaccination also induces specific cellular immunity. In the current study on 38 kidney transplant recipients, we established an interferon-γ ELISpot assay that can detect serotype-specific cellular responses against S. pneumoniae. The results indicate that sequential vaccination with the conjugated vaccine Prevenar 13 and the polysaccharide vaccine Pneumovax 23 led to an increase of serotype-specific cellular immunity. We observed the strongest responses against the serotypes 9N and 14, which are both components of Pneumovax 23. Cellular responses against S. pneumoniae correlated positively with specific IgG antibodies (r = 0.32, p = 0.12). In conclusion, this is the first report indicating that kidney transplant recipients can mount specific cellular responses after pneumococcal vaccination. The ELISpot we established will allow for further investigations. These could help to define, for example, factors influencing specific cellular immunity in immunocompromised cohorts or the duration of cellular immunity after vaccination.

Perioperative Immunization for Splenectomy and the Surgeon's Responsibility: A Review

Importance

Patients who have had splenectomy have a lifelong risk of overwhelming postsplenectomy infection (OPSI), a condition associated with high mortality rates. Surgeons must be aware of the rationale of vaccination in the case of splenectomy, to provide appropriate immunization in the perioperative time.

Observations

English-language articles published from January 1, 1990, to December 31, 2019, were retrieved from MEDLINE/PubMed, Cochrane Library, and ClinicalTrials.gov databases. Randomized clinical trials as well as systematic reviews and observational studies were considered. Asplenia yields an impairment of both innate and adaptive immunity, thus increasing the risk of severe encapsulated bacterial infections. Current epidemiology of OPSI ranges from 0.1% to 8.5% but is hard to ascertain because of ongoing shifts in patients' baseline conditions and vaccine penetration. Despite the lack of randomized clinical trials, immunization appears to be effective in reducing OPSI incidence. Unfortunately, vaccination coverage is still suboptimal, with a great variability in vaccination rates being reported across institutions and time frames. Notably, current guidelines do not advocate any particular health care qualification responsible for vaccine prescription or administration. Given the dearth of high-level basic science or clinical evidence, the optimal vaccination timing and the need for booster doses are not yet well established. Although almost all guidelines indicate to not administer vaccines within 14 days before and after surgery, most data suggest that immunization might be effective even in the immediate perioperative time, thus placing the surgeon in a primary position for vaccine delivery. Furthermore, revaccination schedules are the target of ongoing debates, since a vaccine-driven hyporesponsiveness has been postulated.

Conclusions and Relevance

In patients who have undergone splenectomy, OPSI might be effectively prevented by proper immunization. Surgeons have the primary responsibility for achieving adequate, initial immunization in the setting of both planned and urgent splenectomy.

Microphysiologic Human Tissue Constructs Reproduce Autologous Age-Specific BCG and HBV Primary Immunization in vitro

Current vaccine development disregards human immune ontogeny, relying on animal models to select vaccine candidates targeting human infants, who are at greatest risk of infection worldwide, and receive the largest number of vaccines. To help accelerate and de-risk development of early-life effective immunization, we engineered a human age-specific microphysiologic vascular-interstitial interphase, suitable for pre-clinical modeling of distinct age-targeted immunity in vitro. Our Tissue Constructs (TCs) enable autonomous extravasation of monocytes that undergo rapid self-directed differentiation into migratory Dendritic Cells (DCs) in response to adjuvants and licensed vaccines such as Bacille Calmette-Guérin (BCG) or Hepatitis B virus Vaccine (HBV). TCs contain a confluent human endothelium grown atop a tri-dimensional human extracellular matrix substrate, employ human age-specific monocytes and autologous non heat-treated plasma, and avoid the use of xenogenic materials and exogenous cytokines. Vaccine-pulsed TCs autonomously generated DCs that induced single-antigen recall responses from autologous naïve and memory CD4+ T lymphocytes, matching study participant immune-status, including BCG responses paralleling donor PPD status, BCG-induced adenosine deaminase (ADA) activity paralleling infant cohorts in vivo, and multi-dose HBV antigen-specific responses as demonstrated by lymphoproliferation and TCR sequencing. Overall, our microphysiologic culture method reproduced age- and antigen-specific recall responses to BCG and HBV immunization, closely resembling those observed after a birth immunization of human cohorts in vivo, offering for the first time a new approach to early pre-clinical selection of effective age-targeted vaccine candidates.

Advances and highlights in primary immunodeficiencies in 2017

This manuscript reviews selected topics in primary immunodeficiency diseases (PIDDs) published in 2017. These include (1) the role of follicular T cells in the differentiation of B cells and development of optimal antibody responses; (2) impaired nuclear factor κB subunit 1 signaling in the pathogenesis of common variable immunodeficiency, revealing an association between impaired B-cell maturation and development of inflammatory conditions; (3) autoimmune and inflammatory manifestations in patients with PIDDs in T- and B-cell deficiencies, as well as in neutrophil disorders; (4) newly described gene defects causing PIDDs, including exostosin-like 3 (EXTL3), TNF-α-induced protein 3 (TNFAIP3 [A20]), actin-related protein 2/3 complex-subunit 1B (ARPC1B), v-Rel avian reticuloendotheliosis viral oncogene homolog A (RELA), hypoxia upregulated 1 (HYOU1), BTB domain and CNC homolog 2 (BACH2), CD70, and CD55; (5) use of rapamycin and the phosphoinositide 3-kinase inhibitor leniolisib to reduce autoimmunity and regulate B-cell function in the activated phosphoinositide 3-kinase δ syndrome; (6) improved outcomes in hematopoietic stem cell transplantation for severe combined immunodeficiency (SCID) in the last decade, with an overall 2-year survival of 90% in part caused by early diagnosis through implementation of universal newborn screening; (7) demonstration of the efficacy of lentiviral vector-mediated gene therapy for patients with adenosine deaminase-deficient SCID; (8) the promise of gene editing for PIDDs using CRISPR/Cas9 and zinc finger nuclease technology for SCID and chronic granulomatous disease; and (9) the efficacy of thymus transplantation in Europe, although associated with an unexpected high incidence of autoimmunity. The remarkable progress in the understanding and management of PIDDs reflects the current interest in this area and continues to improve the care of immunodeficient patients.

The effect of splenectomy on the levels of PCV-13-induced memory B- and T cells

AIM

Splenectomised patients are associated with lifelong risk of fatal overwhelming post-splenectomy infection (OPSI), which is mostly caused by Streptococcus pneumoniae. Today OPSI cases can still be reported even in patients with appropriate vaccination. In our study, the levels of vaccine-specific memory B- and T cells were compared between control and splenectomised patients to enlighten the underlying reason.

MATERIALS AND METHODS

Five healthy and 14 post-traumatic splenectomised individuals were vaccinated with 13-valent pneumococcal conjugate vaccine (PCV-13) followed by 23-valent pneumococcal polysaccharide vaccine (PPV-23). The levels of memory B- and T cells were compared by ELISPOT analysis.

RESULTS

Splenectomised patients generated reduced levels of memory IgG B cells in response to PCV-13 vaccination, while the memory IFN-γ T-cell levels were undetectable in asplenic patients. This was despite the detection of vaccine-induced memory T-cell levels in control patients, which were analysed simultaneously following the same experimental protocol.

CONCLUSION

Our results suggest that spleen is important, but not essential, for survival and/or generation of memory IgG B cells. In contrast, it seems to be indispensable for PCV-13-specific memory T_H 1-cell levels. Studies enhancing the levels of vaccine-induced memory cells and further enlightening the immune responses in asplenic individuals are required to develop more effective vaccination strategies against OPSI.