International consensus definition of low anterior resection syndrome

AIM

Low anterior resection syndrome (LARS) is pragmatically defined as disordered bowel function after rectal resection leading to a detriment in quality of life. This broad characterization does not allow for precise estimates of prevalence. The LARS score was designed as a simple tool for clinical evaluation of LARS. Although the LARS score has good clinical utility, it may not capture all important aspects that patients may experience. The aim of this collaboration was to develop an international consensus definition of LARS that encompasses all aspects of the condition and is informed by all stakeholders.

METHOD

This international patient-provider initiative used an online Delphi survey, regional patient consultation meetings, and an international consensus meeting. Three expert groups participated: patients, surgeons and other health professionals from five regions (Australasia, Denmark, Spain, Great Britain and Ireland, and North America) and in three languages (English, Spanish, and Danish). The primary outcome measured was the priorities for the definition of LARS.

RESULTS

Three hundred twenty-five participants (156 patients) registered. The response rates for successive rounds of the Delphi survey were 86%, 96% and 99%. Eighteen priorities emerged from the Delphi survey. Patient consultation and consensus meetings refined these priorities to eight symptoms and eight consequences that capture essential aspects of the syndrome. Sampling bias may have been present, in particular, in the patient panel because social media was used extensively in recruitment. There was also dominance of the surgical panel at the final consensus meeting despite attempts to mitigate this.

CONCLUSION

This is the first definition of LARS developed with direct input from a large international patient panel. The involvement of patients in all phases has ensured that the definition presented encompasses the vital aspects of the patient experience of LARS. The novel separation of symptoms and consequences may enable greater sensitivity to detect changes in LARS over time and with intervention.

Multi-faceted inhibition of dendritic cell function by CD4+Foxp3+ regulatory T cells

CTLA-4 is required for CD4⁺Foxp3⁺ regulatory T (Treg) cell function, but its mode of action remains incompletely defined. Herein we generated Ctla-4^ex2fl/flFoxp3-Cre mice with Treg cells exclusively expressing a naturally occurring, ligand-independent isoform of CTLA-4 (liCTLA-4) that cannot interact with the costimulatory molecules CD80 and CD86. The mice did not exhibit any signs of effector T cell activation early in life, however, at 6 months of age they exhibited excessive T cell activation and inflammation in lungs. In contrast, mice with Treg cells completely lacking CTLA-4 developed lymphoproliferative disease characterized by multi-organ inflammation early in life. In vitro, Treg cells exclusively expressing liCTLA-4 inhibited CD80 and CD86 expression on dendritic cells (DC). Conversely, Treg cells required the extra-cellular part of CTLA-4 to up-regulate expression of the co-inhibitory molecule PD-L2 on DCs. Transcriptomic analysis of suppressed DCs revealed that Treg cells induced a specific immunosuppressive program in DCs.

Regulatory T cells control epitope spreading in autoimmune arthritis independent of cytotoxic T-lymphocyte antigen-4

CD4⁺  Foxp3⁺ regulatory T (Treg) cells can control both cellular and humoral immune responses; however, when and how Treg cells play a predominant role in regulating autoimmune disease remains elusive. To deplete Treg cells in vivo at given time-points, we used a mouse strain, susceptible to glucose-6-phosphate isomerase peptide-induced arthritis (GIA), in which the deletion of Treg cells can be controlled by diphtheria toxin treatment. By depleting Treg cells in the GIA mouse model, we found that a temporary lack of Treg cells at both priming and onset exaggerated disease development. Ablation of Treg cells led to the expansion of antigen-specific CD4⁺ T cells including granulocyte-macrophage colony-stimulating factor, interferon-γ and interleukin-17-producing T cells, and promoted both T-cell and B-cell epitope spreading, which perpetuated arthritis. Interestingly, specific depletion of cytotoxic T-lymphocyte antigen-4 (CTLA-4) on Treg cells only, was sufficient to protect mice from GIA, due to the expansion of CTLA-4^- Treg cells expressing alternative suppressive molecules. Collectively, our findings suggest that Treg cells, independently of CTLA-4, act as the key driving force in controlling autoimmune arthritis development.

Risk in the "Red Zone": Outcomes for Children Admitted to Ebola Holding Units in Sierra Leone Without Ebola Virus Disease

We collected data on 1054 children admitted to Ebola Holding Units in Sierra Leone and describe outcomes of 697/1054 children testing negative for Ebola virus disease (EVD) and accompanying caregivers. Case-fatality was 9%; 3/630 (0.5%) children discharged testing negative were readmitted EVD-positive. Nosocomial EVD transmission risk may be lower than feared.

CTLA-4 expressed by FOXP3+ regulatory T cells prevents inflammatory tissue attack and not T-cell priming in arthritis

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) -mediated regulation of already tolerized autoreactive T cells is critical for understanding autoimmune responses. Although defects in CTLA-4 contribute to abnormal FOXP3⁺ regulatory T (Treg) cell function in rheumatoid arthritis, its role in autoreactive T cells remains elusive. We studied immunity towards the dominant collagen type II (CII) T-cell epitope in collagen-induced arthritis both in the heterologous setting and in the autologous setting where CII is mutated at position E266D in mouse cartilage. CTLA-4 regulated all stages of arthritis, including the chronic phase, and affected the priming of autologous but not heterologous CII-reactive T cells. CTLA-4 expression by both conventional T (Tconv) cells and Treg cells was required but while Tconv cell expression was needed to control the priming of naive autoreactive T cells, CTLA-4 on Treg cells prevented the inflammatory tissue attack. This identifies a cell-type-specific time window when CTLA-4-mediated tolerance is most powerful, which has important implications for clinical therapy with immune modulatory drugs.

Tregs restrain dendritic cell autophagy to ameliorate autoimmunity

Design of efficacious Treg-based therapies and establishment of clinical tolerance in autoimmune diseases have proven to be challenging. The clinical implementation of Treg immunotherapy has been hampered by various impediments related to the stability and isolation procedures of Tregs as well as the specific in vivo targets of Treg modalities. Herein, we have demonstrated that Foxp3+ Tregs potently suppress autoimmune responses in vivo through inhibition of the autophagic machinery in DCs in a cytotoxic T-lymphocyte-associated protein 4-dependent (CTLA4-dependent) manner. Autophagy-deficient DCs exhibited reduced immunogenic potential and failed to prime autoantigen-specific CD4+ T cells to mediate autoimmunity. Mechanistically, CTLA4 binding promoted activation of the PI3K/Akt/mTOR axis and FoxO1 nuclear exclusion in DCs, leading to decreased transcription of the autophagy component microtubule-associated protein 1 light chain 3β (Lc3b). Human DCs treated with CTLA4-Ig, a fusion protein composed of the Fc region of IgG1 and the extracellular domain of CTLA4 (also known as abatacept, marketed as Orencia), demonstrated reduced levels of autophagosome formation, while DCs from CTLA4-Ig-treated rheumatoid arthritis patients displayed diminished LC3B transcripts. Collectively, our data identify the canonical autophagy pathway in DCs as a molecular target of Foxp3+ Treg-mediated suppression that leads to amelioration of autoimmune responses. These findings may pave the way for the development of therapeutic protocols that exploit Tregs for the treatment of autoimmunity as well as diseases in which disturbed tolerance is a common denominator.

Gene Therapy Induces Antigen-Specific Tolerance in Experimental Collagen-Induced Arthritis

Here, we investigate induction of immunological tolerance by lentiviral based gene therapy in a mouse model of rheumatoid arthritis, collagen II-induced arthritis (CIA). Targeting the expression of the collagen type II (CII) to antigen presenting cells (APCs) induced antigen-specific tolerance, where only 5% of the mice developed arthritis as compared with 95% of the control mice. In the CII-tolerized mice, the proportion of Tregs as well as mRNA expression of SOCS1 (suppressors of cytokine signaling 1) increased at day 3 after CII immunization. Transfer of B cells or non-B cell APC, as well as T cells, from tolerized to naïve mice all mediated a certain degree of tolerance. Thus, sustainable tolerance is established very early during the course of arthritis and is mediated by both B and non-B cells as APCs. This novel approach for inducing tolerance to disease specific antigens can be used for studying tolerance mechanisms, not only in CIA but also in other autoimmune diseases.

Germ-free mice deficient of reactive oxygen species have increased arthritis susceptibility

The NADPH oxidase 2 (NOX2) complex is responsible for the production of ROS in phagocytic cells. Genetic defects in NOX2 lead to opportunistic infections and inflammatory manifestations such as granulomas in humans, also known as chronic granulomatous disease (CGD). This condition is mirrored in mice with defective ROS production and interestingly both species are predisposed to autoimmune diseases. An unresolved question is whether the hyper-inflammation and tendency to develop autoimmunity are secondary to the increased infections, or whether these are parallel phenomena. We generated germ-free ROS deficient Ncf1 mutant mice that when reared in specific pathogen-free condition, are highly susceptible to collagen-induced arthritis compared with wild-type mice. Strikingly, arthritis incidence and severity was almost identical in germ-free and specific pathogen-free ROS-deficient mice. In addition, partial reduction of the microbial flora by antibiotics treatment did not alter the disease course. Taken together, this shows that ROS has a clear immune regulatory function that is decoupled from its function in host defence.

Reactive oxygen species deficiency induces autoimmunity with type 1 interferon signature

AIMS

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by mutations in the phagocyte reactive oxygen species (ROS)-producing NOX2 enzyme complex and characterized by recurrent infections associated with hyperinflammatory and autoimmune manifestations. A translational, comparative analysis of CGD patients and the corresponding ROS-deficient Ncf1(m1J) mutated mouse model was performed to reveal the molecular pathways operating in NOX2 complex deficient inflammation.

RESULTS

A prominent type I interferon (IFN) response signature that was accompanied by elevated autoantibody levels was identified in both mice and humans lacking functional NOX2 complex. To further underline the systemic lupus erythematosus (SLE)-related autoimmune process, we show that naïve Ncf1(m1J) mutated mice, similar to SLE patients, suffer from inflammatory kidney disease with IgG and C3 deposits in the glomeruli. Expression analysis of germ-free Ncf1(m1J) mutated mice reproduced the type I IFN signature, enabling us to conclude that the upregulated signaling pathway is of endogenous origin.

INNOVATION

Our findings link the previously unexplained connection between ROS deficiency and increased susceptibility to autoimmunity by the discovery that activation of IFN signaling is a major pathway downstream of a deficient NOX2 complex in both mice and humans.

CONCLUSION

We conclude that the lack of phagocyte-derived oxidative burst is associated with spontaneous autoimmunity and linked with type I IFN signature in both mice and humans.

Hydrogen peroxide as an immunological transmitter regulating autoreactive T cells

SIGNIFICANCE

An unexpected finding, revealed by positional cloning of genetic polymorphisms controlling models for rheumatoid arthritis, exposed a new function of Ncf1 and NADPH oxidase (NOX) 2 controlled oxidative burst.

RECENT ADVANCES

A decreased capacity to produce ROS due to a natural polymorphism was found to be the major factor leading to more severe arthritis and increased T cell-dependent autoimmunity.

CRITICAL ISSUES

In the vein of this finding, we here review a possible new role of ROS in regulating inflammatory cell and autoreactive T cell activity. It is postulated that peroxide is an immunologic transmitter secreted by antigen-presenting cells that downregulate the responses by autoreactive T cells.

FUTURE DIRECTIONS

This may operate at different levels of T cell selection and activation: during negative selection in the thymus, priming of T cells in draining lymph nodes, and while interacting with macrophages in peripheral target tissues.

Awareness of periconceptional folic acid supplementation among Nepalese women of childbearing age: a cross-sectional study

OBJECTIVE

Maternal folate deficiency is associated with neural tube defects (NTDs), the most common congenital birth defect at Maternity Hospital, Kathmandu, Nepal. NTDs can be prevented with periconceptional folic acid supplementation (FAS). This study was performed to assess the awareness of FAS among women of reproductive age in Kathmandu.

METHODS

A semi-structured questionnaire was administered to 400 randomly selected patients aged 15 to 45 years visiting Kathmandu Model Hospital from May to July 2011, seeking any awareness of FAS, knowledge of its impact on fetal development and knowledge of the appropriate time of supplementation.

RESULTS

Forty percent (95% CI 35.1-45.0) of women had heard about FAS, 16.3% (95% CI 12.8-20.2) knew that folate affects fetal health and 5.0% (95% CI 3.1-7.6) knew that it should be taken pre-pregnancy. Level of education was strongly associated with awareness (multivariate Odds Ratio for lowest vs. highest level of education: 0.29, 95% CI 0.15-0.56).

CONCLUSIONS

Knowledge of FAS is very low among women of childbearing age in Kathmandu. Inclusion of FAS information in health awareness programs is recommended.

Cell-autonomous and -non-autonomous roles of CTLA-4 in immune regulation

It is controversial how cytotoxic T lymphocyte antigen (CTLA)-4, a co-inhibitory molecule, contributes to immunological tolerance and negative control of immune responses. Its role as an inducer of cell-intrinsic negative signals to activated effector T cells is well documented. However, there is accumulating evidence that CTLA-4 is essential for the function of naturally occurring Foxp3(+) regulatory T (Treg) cells, which constitutively express the molecule. CTLA-4 deficiency in Foxp3(+) Treg cells indeed impairs their in vivo and in vitro suppressive function. Further, Treg cells can modulate the function of CD80- and CD86-expressing antigen-presenting cells via CTLA-4. Here we discuss how CTLA-4 expression by one T cell can influence the activation of another in a cell non-autonomous fashion and thus control immune responses.

Dynamics of peripheral tolerance and immune regulation mediated by Treg

Peripheral self-tolerance and immune homeostasis are maintained, at least in part, by the balance between Treg and effector T cells. Naturally, arising CD25(+)CD4(+) Treg, which express the transcription factor Foxp3, suppress the activation and proliferation of other lymphocytes in multiple ways. A CTLA-4-dependent suppressive mechanism is shared by every Foxp3(+) Treg at any location and its disruption breaches self-tolerance and immune homeostasis, suggesting that it is a core mechanism of suppression. Depending on the environment, Foxp3(+) Treg also differentiate to exhibit additional suppressive mechanisms, including the secretion of immunosuppressive cytokines. Naïve T cells acquire Foxp3 expression and suppressive activity under certain in vivo and in vitro conditions, whereas some Foxp3(+) T cells may lose Foxp3 and suppressive activity following proliferation in an IL-2-deficient environment. Moreover, activated effector T cells frequently secrete suppressive cytokines, such as IL-10, in a negative feedback fashion. These findings, when taken together, indicate that peripheral immune tolerance and homeostasis are dynamically maintained by functional differentiation within the Foxp3(+) population, occasional conversion between Treg and non-Treg cells, and the interactions among them. These dynamics provide ample opportunities for immune intervention for the benefit of the host.

Regulatory T cells: how do they suppress immune responses?

Regulatory T cells (Tregs), either natural or induced, suppress a variety of physiological and pathological immune responses. One of the key issues for understanding Treg function is to determine how they suppress other lymphocytes at the molecular level in vivo and in vitro. Here we propose that there may be a key suppressive mechanism that is shared by every forkhead box p3 (Foxp3)(+) Treg in vivo and in vitro in mice and humans. When this central mechanism is abrogated, it causes a breach in self-tolerance and immune homeostasis. Other suppressive mechanisms may synergistically operate with this common mechanism depending on the environment and the type of an immune response. Further, Treg-mediated suppression is a multi-step process and impairment or augmentation of each step can alter the ultimate effectiveness of Treg-mediated suppression. These findings will help to design effective ways for controlling immune responses by targeting Treg suppressive functions.

Functional delineation and differentiation dynamics of human CD4+ T cells expressing the FoxP3 transcription factor

FoxP3 is a key transcription factor for the development and function of natural CD4(+) regulatory T cells (Treg cells). Here we show that human FoxP3(+)CD4(+) T cells were composed of three phenotypically and functionally distinct subpopulations: CD45RA(+)FoxP3(lo) resting Treg cells (rTreg cells) and CD45RA(-)FoxP3(hi) activated Treg cells (aTreg cells), both of which were suppressive in vitro, and cytokine-secreting CD45RA(-)FoxP3(lo) nonsuppressive T cells. The proportion of the three subpopulations differed between cord blood, aged individuals, and patients with immunological diseases. Terminally differentiated aTreg cells rapidly died whereas rTreg cells proliferated and converted into aTreg cells in vitro and in vivo. This was shown by the transfer of rTreg cells into NOD-scid-common gamma-chain-deficient mice and by TCR sequence-based T cell clonotype tracing in peripheral blood in a normal individual. Taken together, the dissection of FoxP3(+) cells into subsets enables one to analyze Treg cell differentiation dynamics and interactions in normal and disease states, and to control immune responses through manipulating particular FoxP3(+) subpopulations.

65Zn turnover in short-term alloxan diabetic rats

65Zn was injected subcutaneously in eleven rats with alloxan diabetes of five days duration and in nine control rats. Fifty hours after the injection of 65Zn the animals were killed with an overdose of ether. In the alloxan diabetic rats signs of an altered zinc metabolism were found with an increased excretion of zinc in urine and possibly also faeces and an elevated zinc concentration in the liver compared to controls. The results also indicate an altered distribution of serum zinc in alloxan treated rats. Future studies will be necessary to demonstrate whether changes in zinc metabolism are secondary to the onset of diabetes or a primary effect of alloxan treatment.

CTLA-4 control over Foxp3+ regulatory T cell function

Naturally occurring Foxp3+CD4+ regulatory T cells (Tregs) are essential for maintaining immunological self-tolerance and immune homeostasis. Here, we show that a specific deficiency of cytotoxic T lymphocyte antigen 4 (CTLA-4) in Tregs results in spontaneous development of systemic lymphoproliferation, fatal T cell-mediated autoimmune disease, and hyperproduction of immunoglobulin E in mice, and it also produces potent tumor immunity. Treg-specific CTLA-4 deficiency impairs in vivo and in vitro suppressive function of Tregs-in particular, Treg-mediated down-regulation of CD80 and CD86 expression on dendritic cells. Thus, natural Tregs may critically require CTLA-4 to suppress immune responses by affecting the potency of antigen-presenting cells to activate other T cells.