Phosphatase inhibitor PPP1R11 modulates resistance of human T cells toward Treg-mediated suppression of cytokine expression

Regulatory T cells (Tregs) act as indispensable unit for maintaining peripheral immune tolerance mainly by regulating effector T cells. T cells resistant to suppression by Tregs pose therapeutic challenges in the treatment of autoimmune diseases, while augmenting susceptibility to suppression may be desirable for cancer therapy. To understand the cell intrinsic signals in T cells during suppression by Tregs, we have previously performed a global phosphoproteomic characterization. We revealed altered phosphorylation of protein phosphatase 1 regulatory subunit 11 (PPP1R11; Inhibitor‐3) in conventional T cells upon suppression by Tregs. Here, we show that silencing of PPP1R11 renders T cells resistant toward Treg‐mediated suppression of TCR‐induced cytokine expression. Furthermore, whole‐transcriptome sequencing revealed that PPP1R11 differentially regulates not only the expression of specific T cell stimulation‐induced cytokines but also other molecules and pathways in T cells. We further confirmed the target of PPP1R11, PP1, to augment TCR‐induced cytokine expression. In conclusion, we present PPP1R11 as a novel negative regulator of T cell activation‐induced cytokine expression. Targeting PPP1R11 may have therapeutic potential to regulate the T cell activation status including modulating the susceptibility of T cells toward Treg‐mediated suppression, specifically altering the stimulation‐induced T cell cytokine milieu.

Phosphoproteomics Reveals Regulatory T Cell-Mediated DEF6 Dephosphorylation That Affects Cytokine Expression in Human Conventional T Cells

Regulatory T cells (Tregs) control key events of immune tolerance, primarily by suppression of effector T cells. We previously revealed that Tregs rapidly suppress T cell receptor (TCR)-induced calcium store depletion in conventional CD4⁺CD25⁻ T cells (Tcons) independently of IP₃ levels, consequently inhibiting NFAT signaling and effector cytokine expression. Here, we study Treg suppression mechanisms through unbiased phosphoproteomics of primary human Tcons upon TCR stimulation and Treg-mediated suppression, respectively. Tregs induced a state of overall decreased phosphorylation as opposed to TCR stimulation. We discovered novel phosphosites (T595_S597) in the DEF6 (SLAT) protein that were phosphorylated upon TCR stimulation and conversely dephosphorylated upon coculture with Tregs. Mutation of these DEF6 phosphosites abrogated interaction of DEF6 with the IP₃ receptor and affected NFAT activation and cytokine transcription in primary Tcons. This novel mechanism and phosphoproteomics data resource may aid in modifying sensitivity of Tcons to Treg-mediated suppression in autoimmune disease or cancer.

In Vitro Differentiation of Human CD4+FOXP3+ Induced Regulatory T Cells (iTregs) from Naïve CD4+ T Cells Using a TGF-β-containing Protocol

Regulatory T cells (Tregs) are an integral part of peripheral tolerance, suppressing immune reactions against self-structures and thus preventing autoimmune diseases. Clinical approaches to adoptively transfer Tregs, or to deplete Tregs in cancer, are underway with promising first outcomes. Because the number of naturally occurring Tregs (nTregs) is very limited, studying certain Treg features using in vitro induced Tregs (iTregs) can be advantageous. To date, the best although not absolutely specific protein marker to delineate Tregs is the transcription factor FOXP3. Despite the importance of Tregs including non-redundant roles of peripherally induced Tregs, the protocols to generate iTregs are currently controversial, particularly for human cells. This protocol therefore describes the in vitro differentiation of human CD4+FOXP3+ iTregs from human naïve T cells using a range of Treg-inducing factors (TGF-β plus IL-2 only, or their combination with retinoic acid, rapamycin or butyrate) in parallel. It also describes the phenotyping of these cells by flow cytometry and qRT-PCR. These protocols result in reproducible expression of FOXP3 and other Treg signature genes and enable the study of general FOXP3-regulatory mechanisms as well as protocol-specific effects to delineate the impact of certain factors. iTregs can be utilized to study various phenotypic aspects as well as molecular mechanisms of Treg induction. Detailed molecular studies are facilitated by relatively large cell numbers that can be obtained. A limitation for the application of iTregs is the relative instability of FOXP3 expression in these cells compared to nTregs. iTregs generated by these protocols can also be used for functional assays such as studying their suppressive function, in which iTregs induced by TGF-β plus retinoic acid and rapamycin display superior suppressive activity. However, the suppressive capacity of iTregs can differ from nTregs and the use of appropriate controls is crucial.

Human macrophages induce CD4(+)Foxp3(+) regulatory T cells via binding and re-release of TGF-β

While pro-inflammatory immune responses are a requirement to combat microbes, uncontrolled self-directed inflammatory immune responses are the hallmark of autoimmune diseases. Restoration of immunological tolerance involves both suppression of ongoing tissue-destructive immune responses and re-education of the host immune system. Both functionally immunosuppressive macrophages (M2) and regulatory T cells (Tregs) are implicated in these processes. Their mutual interaction is synergistic in this context and adoptive transfer of each cell type has been functioning as immunotherapy in experimental models, being particularly effective when using M2 macrophages generated with an optimized interleukin-4 (IL-4)/interleukin-10 (IL-10)/transforming growth factor-β (TGF-β) combination. As a prerequisite for eventual translation of M2 therapy into clinical settings we herein studied the induction, stability and mechanism of generation of human induced Tregs (iTregs) by M2 macrophages generated with IL-4/IL-10/TGF-β. The supernatants of monocyte-derived human M2 macrophages robustly induced FOXP3 and other Treg signature molecules such as CTLA-4 and IKZF4 in human naïve CD4 T cells. M2-induced iTregs displayed enhanced FOXP3 stability and low expression of pro-inflammatory cytokines interferon-γ and IL-17, as well as functional immunosuppressive activity compared with control T cells. The FOXP3-inducing activity was dependent on TGF-β, which was both expressed and captured with re-release by M2 macrophages into the soluble supernatant fraction, in which the TGF-β was not confined to extracellular vesicles such as exosomes. We propose that adoptive transfer of human M2 macrophages may be exploited in the future to induce Tregs in situ by delivering TGF-β, which could be developed as a therapeutic strategy to target autoimmune and other inflammatory diseases.

Comparison of propofol versus thiopentone with midazolam or lidocaine to facilitate laryngeal mask insertion

PURPOSE

To assess the ease of insertion of laryngeal mask airway (LMA) comparing propofol with lidocaine or midazolam followed by thiopentone and compare the costs with each technique.

METHODS

One hundred and fifty ASA 1 or 2 patients equally divided into three groups scheduled for elective surgery were recruited into this prospective, single blind, randomized, parallel groups study. Anaesthetic induction was achieved with 1 microgram.kg-1 fentanyl i.v. followed by either 2.5 mg.kg-1 propofol (group P), or a sequence of 1.5 mg.kg-1 lidocaine and 5 mg.kg-1 thiopentone (group LT), or midazolam 0.1 mg.kg-1 and, three minutes later, 5 mg.kg-1 thiopentone (group MT). The LMA was inserted by the blinded anaesthetist who assessed and graded the conditions for LMA insertion and noted any adverse responses (i.e., inadequate jaw relaxation, gagging, coughing, limb or head movement, hiccough and laryngospasm). Conditions were considered "excellent" if there were no adverse responses, and "satisfactory" if such a response was mild and transient.

RESULTS

Excellent or satisfactory conditions were observed in 48 (96%) patients in the midazolam-thiopentone group, 46 (92%) in the propofol group, and 34 (68%) in the lidocaine-thiopentone group (P = 0.0001). The incidence of gagging (P = 0.042), limb movement (P = 0.031), and laryngospasm (P = 0.0001) was higher in the lidocaine-thiopentone group.

CONCLUSIONS

With the above doses, a fentanyl-midazolam-thiopentone combination which is about 35% less expensive than fentanyl-propofol, provides equally good conditions for the insertion of LMA.

Normal ventricular size and ventriculo-hemispheric ratio in infants upto 6 months of age by cranial ultrasonography

Fifty cases each of preterm (greater than 34 weeks), full term and one month to six months age (400 total) were subjected to cranial ultrasonography for determination of ventricular size and ventriculohemispheric ratio. Ventricular size steadily increased from 4.64 +/- 1.84 mm in preterm to 10.72 +/- 2.92 mm in six months old infant. Ventriculohemispheric ratio increased from 0.12 +/- 0.052 in preterm to 0.17 +/- 0.056 in three months of age. Then steady level was maintained at 0.17 +/- 0.064 upto six months of age.

Bilateral hydrothorax and hydromediastinum after a subclavian line insertion

A 28-year-old male patient developed bilateral hydrothorax due to extravasation of fluid into the mediastinum from a subclavian line. The injection of radio-opaque dye through the central venous cannula confirmed spillage into the mediastinum. There was no direct communication between the central venous cannula and the pleural cavities. The hydrothorax appeared to develop as a result of a shift of fluid from the mediastinum into the pleural cavities due to pressure differences in the two compartments. Bilateral chest tubes were inserted, the subclavian cannula was removed and the patient made a good recovery.