Hematopoietic Prostaglandin D2 Synthase Controls Tfh/Th2 Communication and Limits Tfh Antitumor Effects

T follicular helper (Tfh) cells are a subset of CD4+ T cells essential in immunity and have a role in helping B cells produce antibodies against pathogens. However, their role during cancer progression remains unknown. The mechanism of action of Tfh cells remains elusive because contradictory data have been reported on their protumor or antitumor responses in human and murine tumors. Like Tfh cells, Th2 cells are also involved in humoral immunity and are regularly associated with tumor progression and poor prognosis, mainly through their secretion of IL4. Here, we showed that Tfh cells expressed hematopoietic prostaglandin D2 (PGD2) synthase in a pSTAT1/pSTAT3-dependent manner. Tfh cells produced PGD2, which led to recruitment of Th2 cells via the PGD2 receptor chemoattractant receptor homologous molecule expressed on Th type 2 cells (CRTH2) and increased their effector functions. This cross-talk between Tfh and Th2 cells promoted IL4-dependent tumor growth. Correlation between Th2 cells, Tfh cells, and hematopoietic PGD2 synthase was observed in different human cancers and associated with outcome. This study provides evidence that Tfh/Th2 cross-talk through PGD2 limits the antitumor effects of Tfh cells and, therefore, could serve as a therapeutic target.

Follicular helper-T cells restore CD8+-dependent antitumor immunity and anti-PD-L1/PD-1 efficacy

Background

T follicular helper cells (Tfh) are essential to shape B cell response during germinal center formation. Tfh accumulation has been reported in various human cancers, with positive or negative prognostic roles. However, the mechanisms explaining the accumulation of Tfh and their role in cancer remain obscure.

Methods

In vitro differentiated and mouse cell sorted Tfh phenotype was evaluated by flow cytometry and quantitative PCR (qPCR). Antitumor effect of Tfh was evaluated by adoptive transfer in different tumor-bearing mice models. The involvement of immune cells, cytokines and chemokines was evaluated, using depleting antibodies. Chemokines and cytokines expression and production were evaluated by qPCR and ELISA. In human, the impact of immune cells and chemokines on survival was evaluated by analyzing transcriptomic data from public databases and from our own patient cohorts.

Results

In this study, we show that Tfh exert an antitumor immune effect in a CD8⁺-dependent manner. Tfh produce interleukin-21, which sustains proliferation, viability, cytokine production and cytotoxic functions of exhausted T cells. The presence of Tfh is required for efficacy of antiprogrammed cell death ligand-1 therapy. Tfh accumulate in the tumor bed and draining lymph nodes in different mouse cancer models. This recruitment is due to the capacity of transforming growth factor β to drive Chemokine (C-X-C motif) Ligand 13 expression, a chemoattractant of Tfh, by intratumor CD8⁺ T cells. Accumulation of Tfh and exhausted CD8⁺ T cells predicts cancer outcome in various cancer types. In patients treated with anti-programmed cell death-1 mAb, accumulation of Tfh and CD8⁺ at the tumor site is associated with outcome.

Conclusion

This study provides evidence that CD8⁺/Tfh crosstalk is important in shaping antitumor immune response generated by immunotherapy.

The Tumor Microenvironment Impairs Th1 IFNγ Secretion through Alternative Splicing Modifications of Irf1 Pre-mRNA

It is clearly established that the immune system can affect cancer response to therapy. However, the influence of the tumor microenvironment (TME) on immune cells is not completely understood. In this respect, alternative splicing is increasingly described to affect the immune system. Here, we showed that the TME, via a TGFβ-dependent mechanism, increased alternative splicing events and induced the expression of an alternative isoform of the IRF1 transcription factor (IRF1Δ7) in Th1 cells. We found that the SFPQ splicing factor (splicing factor, proline- and glutamine-rich) was responsible for the IRF1Δ7 production. We also showed, in both mice and humans, that the IRF1 alternative isoform altered the full-length IRF1 transcriptional activity on the Il12rb1 promoter, resulting in decreased IFNγ secretion in Th1 cells. Thus, the IRF1Δ7 isoform was increased in the TME, and inhibiting IRF1Δ7 expression could potentiate Th1 antitumor responses.

Survivin-3B potentiates immune escape in cancer but also inhibits the toxicity of cancer chemotherapy

Dysregulation in patterns of alternative RNA splicing in cancer cells is emerging as a significant factor in cancer pathophysiology. In this study, we investigated the little known alternative splice isoform survivin-3B (S-3B) that is overexpressed in a tumor-specific manner. Ectopic overexpression of S-3B drove tumorigenesis by facilitating immune escape in a manner associated with resistance to immune cell toxicity. This resistance was mediated by interaction of S-3B with procaspase-8, inhibiting death-inducing signaling complex formation in response to Fas/Fas ligand interaction. We found that S-3B overexpression also mediated resistance to cancer chemotherapy, in this case through interactions with procaspase-6. S-3B binding to procaspase-6 inhibited its activation despite mitochondrial depolarization and caspase-3 activation. When combined with chemotherapy, S-3B targeting in vivo elicited a nearly eradication of tumors. Mechanistic investigations identified a previously unrecognized 7-amino acid region as responsible for the procancerous properties of survivin proteins. Taken together, our results defined S-3B as an important functional actor in tumor formation and treatment resistance.

Compact, highly efficient ytterbium doped bismuthate glass waveguide laser

Laser slope efficiencies close to the quantum defect limit and in excess of 78% have been obtained from an ultrafast laser inscribed buried channel waveguide fabricated in a ytterbium-doped bismuthate glass. The simultaneous achievement of low propagation losses and preservation of the fluorescence properties of ytterbium ions is the basis of the outstanding laser performance.

[Acute meningitidis, acute phase proteins and procalcitonin]

The prognosis of bacterial meningitis is critically dependent on a rapid causal diagnosis and implementation of an accurate treatment. However, clinical and biological parameters available within the few hours that follow the patient's admission are not reliable enough, except when bacteria are to be found in cerebrospinal fluid under the microscope. Therefore, the initial treatment of acute meningitis is still most of time presumptive so that the definitive diagnosis, however difficult, is often established when the therapeutic management has already been initiated. The use of biological markers, especially lymphokines and acute-phase proteins, has been proposed to facilitate the accuracy of the initial diagnosis. Today, C-reactive protein (CRP) is the most widely used inflammatory marker in emergency departments with aim to discriminate bacterial from viral infections. In 1998, Gerdes et al. published a meta-analysis from 35 studies questioning the usefulness of CRP in discriminating bacterial meningitis from viral meningitis. They outlined that the majority of authors proposed to use this inflammation marker as an additional tool for discriminating bacterial meningitis from viral meningitis, without having evaluated its independent contribution relative to other parameters such as white blood cell count, cerebrospinal fluid (CSF) white cell count, protein or glucose. Procalcitonin (PCT) is an acute-phase protein with faster kinetics than CRP, its concentration in serum rising within the few hours that follow the inception of a bacterial infection. Two French studies published in 1997 and 1998 have shown that, using a cut-off range of 0.5 through 2 ng/mL, the sensitivity and specificity of PCT were 100% in discriminating bacterial meningitis from viral meningitis. Some of the seven studies published since seemed to demonstrate the usefulness of PCT in diagnosing meningitis. Finally, PCT was used effectively to shorten unnecessary antibiotic treatment for children seen in an hospital in Paris (France) during summer 2000.

Prevalence of apolipoprotein E phenotypes in ischemic cerebrovascular disease. A case-control study

BACKGROUND AND PURPOSE

Apolipoprotein E polymorphism may influence the early development of coronary artery disease. We investigated the putative role of apolipoprotein E phenotypes in cerebral infarction.

METHODS

The apolipoprotein E phenotypes of 69 patients (mean +/- SD age, 72 +/- 11 years) who had suffered completed stroke or a transient ischemic attack and 68 sex- and age-matched control subjects free of cerebrovascular disease were determined by isoelectric focusing. The relative frequency of the apolipoprotein E phenotypes in the general population was estimated in 498 healthy blood donors (mean age, 37 years).

RESULTS

The prevalences of hypertension, diabetes mellitus, obesity, and intermittent claudication were significantly higher in patients than in control subjects. Serum lipid and apolipoprotein B concentrations and the composition of very low density lipoproteins were not significantly different between patients and control subjects. Apolipoprotein A-I and E levels were significantly lower in patients. Cholesterol levels were higher in male patients than in male control subjects (5.10 +/- 1.46 versus 4.41 +/- 0.80 mmol/L; p = 0.036), and the ratio of apolipoprotein A-I to B was lower (0.77 +/- 0.29 versus 1.03 +/- 0.37; p < 0.001). The E3/E3 phenotype was more frequent in control subjects (85%) than in patients (72.5%; p < 0.05) and healthy blood donors (64%; p < 0.02). The E3/E2 phenotype was more frequent in patients (10.1%) than in control subjects (1.4%; p < 0.05). A stepwise logistic regression showed that the presence of stroke was significantly related to high blood pressure (p < 0.0001), low apo E levels (p < 0.008), obesity (p < 0.041), the apo E phenotype (p < 0.05), and diabetes mellitus (p < 0.05).

CONCLUSIONS

The E3/E3 phenotype may protect against early vascular morbidity, and the epsilon 2 gene may be a risk factor for cerebrovascular morbidity, possibly related to diabetes, hypertension, and/or obesity.