Activated regulatory T-cells promote duodenal bacterial translocation into necrotic areas in severe acute pancreatitis

OBJECTIVE

In acute pancreatitis (AP), bacterial translocation and subsequent infection of pancreatic necrosis are the main risk factors for severe disease and late death. Understanding how immunological host defence mechanisms fail to protect the intestinal barrier is of great importance in reducing the mortality risk of the disease. Here, we studied the role of the T_reg/Th17 balance for maintaining the intestinal barrier function in a mouse model of severe AP.

DESIGN

AP was induced by partial duct ligation in C57Bl/6 or DEREG mice, in which regulatory T-cells (T_reg) were depleted by intraperitoneal injection of diphtheria toxin. By flow cytometry, functional suppression assays and transcriptional profiling we analysed T_reg activation and characterised T-cells of the lamina propria as well as intraepithelial lymphocytes (IELs) regarding their activation and differentiation. Microbiota composition was examined in intestinal samples as well as in murine and human pancreatic necrosis by 16S rRNA gene sequencing.

RESULTS

The prophylactic T_reg-depletion enhanced the proinflammatory response in an experimental mouse model of AP but stabilised the intestinal immunological barrier function of Th17 cells and CD8⁺/γδTCR⁺ IELs. T_reg depleted animals developed less bacterial translocation to the pancreas. Duodenal overgrowth of the facultative pathogenic taxa Escherichia/Shigella which associates with severe disease and infected necrosis was diminished in T_reg depleted animals.

CONCLUSION

T_regs play a crucial role in the counterbalance against systemic inflammatory response syndrome. In AP, T_reg-activation disturbs the duodenal barrier function and permits translocation of commensal bacteria into pancreatic necrosis. Targeting T_regs in AP may help to ameliorate the disease course.

Experimental and population-genetic evidence for inflammation control functions of long noncoding RNAs and a novel tRNA-like transcript arising from the human NEAT1-MALAT1 genomic region

Background

Uncontrolled inflammation is a key driver of atherosclerosis, myocardial infarction (MI), and multiple other diseases. Beyond proteins and microRNAs, long noncoding RNAs (lncRNAs) are implicated in inflammation control. We previously reported suppression of lncRNA NEAT1 in circulating immune cells of post-MI patients. In mice lacking lncRNAs NEAT1 or MALAT1 we observed major immune disturbances affecting monocyte-macrophage and T cell differentiation and rendering the immune system unstable and highly vulnerable to immune stress. Here, we report functions of a novel tRNA-type transcript arising from the NEAT1-MALAT1 gene cluster, and on genetic heterogeneity of this region in the human population.

Methods and results

While previously investigated mice were deficient in the entire NEAT1 or MALAT1 locus, we here aimed to selectively disrupted only the novel 59-nt tRNA-like transcript “menRNA” with hitherto unknown functions. Through CRISPR/Cas9 editing we developed 4 human THP-1 monocyte-macrophage cell line clones with deletions of different extension all of which prevented, however, normal transcript folding and formation of “menRNA”. Transcriptome mapping of all clones by RNA-sequencing identified dysregulation of innate immunity-related genes (IFI16, IFITM3, IRAK3, IRF2BP2, IRF3), chemokine and interleukin receptors (CCR10, IL11RA, IL12RB2, IL23A), cell surface receptors (CD37, CD40LG, CD72, FOCAD, ITGA6, MAEA, THY1), macrophage function-associated genes (ELANE, GRN, MIF, MMP25, MST1P2, PRTN3), tRNA-processing transcripts (GARS, QRSL1P3, QTRT1P1, THG1L, VARS), and small nucleolar RNAs (SNORA26.62.64, SNORD65.112). These data and functional assays indicate functions of NEAT1-derived “menRNA” distinct from those previously described for MALAT1-derived mascRNA.

As multiple data suggest inflammation control functions of the NEAT1-MALAT1 region, we investigated the extent of genetic variability of this region in humans. In cohorts from the SHIP study coordinated by the Institute for Community Medicine Greifswald, screening of this region for sequence variants and possible phenotype associations was conducted the results of which are given in Figure 1. Consistent with prior findings, a MALAT1 SNP with very low minor allele frequency (MAF=0.01) was associated (p=0.0062) with systemic low level inflammation (CRP >3.0 mg/L). Unexpected was the association (p<0.01) of eight SNPs (low MAF=0.09 for all) with BMI >35 kg/m2 and LDL >164 mg/dl.

Conclusions

First, selective disruption of menRNA formation in human monocyte-macrophages provides evidence that this novel type of noncoding RNA has immunoregulatory functions. Second, the phenotype associations of SNPs within the NEAT1-MALAT1 gene cluster warrant further in-depth investigation of the molecular basis of these associations, and of their allele frequencies in cardiovascular disease patient cohorts.

The first three and the last authors contributed equally to this work.

Figure 1

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): “Transcriptome analysis of circulating immune cells to improve the assessment of prognosis and the response to novel anti-inflammatory treatments after myocardial infarction”; DZHK Shared Expertise project B19-006_SE FKZ 81X2100257

The Cardiac Fibroblast in heart failure – an inflammatory cell

Introduction

Cardiac inflammation with subsequent remodeling of the extracellular matrix (ECM) with fibrosis formation is an important precursor of heart failure. In myocardial inflammation release of cytokines, such as TNF-α was previously linked to the development of fibrosis. However, their exact role in fibroblasts activation, leading to their transformation into myofibroblasts and ultimately fibrosis is unknown. Therefore, the purpose of this work was to study the secretome of isolated cardiac fibroblasts of heart failure patients in vitro.

Methods and results

Human cardiac fibroblasts were obtained from endomyocardial biopsies of patients with reduced ejection fraction. Secretome- and gene expression analysis was performed on TNF-α (10 ng/ml) and TGF-β (5 ng/ml) treated and untreated fibroblasts. The analysis of the secretome in cell culture supernatant of these fibroblasts was performed by nano-LC-ESI tandem mass spectrometry. Subsequently, RNA was isolated from fibroblasts and expression analysis was performed using affymetrix gene chips and verified for the stimulation experiments using TaqMan. The secretome and gene expression studies are constistent regarding the most frequent ECM components. The proteins involved in the construction of the ECM accounted for 56% of the total protein intensity. The fibronectin represented the largest proportion of ECM proteins (50%), with collagens accounting for 29% and MMPs and TIMPs for approximately 5% and a small proportion of cytokines. In the secretome as well as in the gene expression, Il-6 and Il-8 showed the highest proportion of cytokines and type I as well as type IV (each approx. 40%) of collagens. MMP2, MMP1 and TIMP1 accounted for the largest proportion of MMPs and TIMPs.

Stimulation with TGF-β and TNF-α led to changes in the composition of the cytokines and ECM proteins. After the stimulation with TNF-α, the proportion of cytokines increased from 3.1% to 6.6%, while the proportion of ECM proteins decreased slightly. Accordingly, after stimulation with TGF-β a well-known inductor of fibrosis, the proportion of collagens and other matrix proteins increased, while the proportion of cytokines decreased slightly.

Conclusion

In this study, we identified the most abundant proteins of the ECM and demonstrated their expansion caused by TGF-β stimulation of fibroblasts. Surprisingly, TNF-α led to an increase of cytokines secreted by the fibroblasts with a minimal reduction of ECM proteins. Here, the differentiated regulation of the fibroblast in the transformation of the ECM could be seen. TNF-α stimulation demonstrated to increase gene expression of the cytokines in fibroblasts, which in turn maintain inflammation with chemotactic effect. Hence, cardiac fibroblasts seem to be supporting cells for cardiac inflammation. There seemed to be no pro-fibrotic effect. In this work we could show the pro-inflammatory role of the cardiac fibroblast upon inflammatory stimulation.

Funding Acknowledgement

Type of funding source: None

Ocular fibroblast types differ in their mRNA profiles--implications for fibrosis prevention after aqueous shunt implantation

PURPOSE

For an aqueous shunt draining from the anterior chamber into the choroidal space, fibroblasts from the choroidea and/or the sclera are most likely responsible for a fibrotic response around the outflow region of such a shunt. The prevention of fibrosis should extend the operating life of the shunt. A detailed characterization of fibroblasts derived from choroidea and sclera should provide information about whether a fibrosis reaction can be inhibited by cell type-specific agents.

METHODS

We generated mRNA profiles of fibroblasts from the choroidea, sclera, and Tenon's space by gene array hybridization to provide a basis on which to search for potential pharmacological targets for fibrosis prevention. Hybridization data were analyzed by the Rosetta Resolver system and Limma to obtain mRNA profiles of the three fibroblast types.

RESULTS

The three fibroblast types investigated shared fibroblast-specific gene expression patterns concerning extracellular matrix proteins as collagens and fibronectin, but also showed distinct mRNA patterns.

CONCLUSIONS

Individual mRNA species overexpressed in one of the fibroblast types might serve as markers for the identification of the fibroblast type in histological analyses. Future in-depth analyses of the gene expression patterns might help identify pharmacological targets for fibrosis prevention.

Parametric hybrid scattering from light-induced ferroelectric and photorefractive structures

Processes of photo-induced light scattering are studied in single crystals of LiNbO(3):Fe to uncover the origin of a new part of the entire scattering pattern which can be observed on a viewing screen. The new scattering manifests itself as two arcs enclosing the directly transmitting pump beam. It is shown that this type of scattering is due to a parametric wave-mixing process of coherent optical noise and a pump beam on a combination of photorefractively recorded phase-gratings and photo-induced ferroelectric structures. Phase-matching conditions corresponding to the new scattering are introduced. All photo-induced scattering phenomena contributing to the total scattering pattern are discussed, compared and classified.

Isolation and characterization of Bacillus subtilis sigB operon mutations that suppress the loss of the negative regulator RsbX

sigmaB, a transcription factor that controls the Bacillus subtilis general stress response regulon, is activated by either a drop in intracellular ATP or exposure to environmental stress. RsbX, one of seven sigmaB regulators (Rsb proteins) whose genes are cotranscribed with sigmaB, is a negative regulator in the stress-dependent activation pathway. To better define the interactions that take place among the Rsb proteins, we analyzed sigB operon mutations which suppress the high-level sigmaB activity that normally accompanies the loss of RsbX. Each of these mutations was in one of three genes (rsbT, -U, and -V) which encode positive regulators of sigmaB, and they all defined amino acid changes which either compromised the activities of the mutant Rsbs or affected their ability to accumulate. sigmaB activity remained inducible by ethanol in several of the RsbX- suppressor strains. This finding supports the notion that RsbX is not needed as the target for sigmaB activation by at least some stresses. sigmaB activity in several RsbX- strains with suppressor mutations in rsbT or -U was high during growth and underwent a continued, rather than a transient, increase following stress. Thus, RsbX is likely responsible for maintaining low sigmaB activity during balanced growth and for reestablishing sigmaB activity at prestress levels following induction. Although RsbX likely participates in limiting the sigmaB induction response, a second mechanism for curtailing unrestricted sigmaB activation was suggested by the sigmaB induction profile in two suppressor strains with mutations in rsbV. sigmaB activity in these mutants was stress inducible but transient, even in the absence of RsbX.

Stress activation of Bacillus subtilis sigma B can occur in the absence of the sigma B negative regulator RsbX

Environmental stress activates sigma B, the general stress response sigma factor of Bacillus subtilis, by a pathway that is negatively controlled by the RsbX protein. To determine whether stress activation of sigma B occurs by a direct effect of stress on RsbX, we constructed B. subtilis strains which synthesized various amounts of RsbX or lacked RsbX entirely and subjected these strains to ethanol stress. Based on the induction of a sigma B-dependent promoter, stress activation of sigma B can occur in the absence of RsbX. Higher levels of RsbX failed to detectably influence stress induction, but reduced levels of RsbX resulted in greater and longer-lived sigma B activation. The data suggest that RsbX is not a direct participant in the sigma B stress induction process but rather serves as a device to limit the magnitude of the stress response.

The yeast two-hybrid system detects interactions between Bacillus subtilis sigmaB regulators

SigmaB, the general stress response sigma factor of Bacillus subtilis, is regulated by the products of seven genes (rsbR, S, T, U, V, W, and X) with which it is cotranscribed. Biochemical techniques previously revealed physical associations among RsbW, RsbV, and sigmaB but failed to detect interactions of RsbR, S, T, U, or X with each other or RsbV, RsbW, or sigmaB. Using the yeast two-hybrid system, we have now obtained evidence for such interactions. The yeast reporter system was activated when RsbS was paired with either RsbR or RsbT, RsbR was paired with RsbT, and RsbV was paired with either RsbU or RsbW. In addition, RsbW2 and RsbR2 dimer formation was detected. RsbX failed to show interactions with itself or any of the other sigB operon products.

Reactivation of the Bacillus subtilis anti-sigma B antagonist, RsbV, by stress- or starvation-induced phosphatase activities

sigma B is a secondary sigma factor that controls the general stress regulon in Bacillus subtilis. The regulon is activated when sigma B is released from a complex with an anti-sigma B protein (RsbW) and becomes free to associate with RNA polymerase. Two separate mechanisms cause sigma B release: an ATP-responsive mechanism that correlates with nutritional stress and an ATP-independent mechanism that responds to environmental insult (e.g., heat shock and ethanol treatment). ATP levels are thought to directly affect RsbW's binding preference. Low levels of ATP cause RsbW to release sigma B and bind to an alternative protein (RsbV), while high levels of ATP favor RsbW-sigma B complex formation and inactivation of RsbV by an RsbW-dependent phosphorylation. During growth, most of the RsbV is phosphorylated (RsbV-P) and inactive. Environmental stress induces the release of sigma B and the formation of the RsbW-RsbV complex, regardless of ATP levels. This pathway requires the products of additional genes encoded within the eight-gene operon (sigB) that includes the genes for sigma B, RsbW, and RsbV. By using isoelectric focusing techniques to distinguish RsbV from RsbV-P and chloramphenicol treatment or pulse-chase labeling to identify preexisting RsbV-P, we have now determined that stress induces the dephosphorylation of RsbV-P to reactivate RsbV. RsbV-P was also found to be dephosphorylated upon a drop in intracellular ATP levels. The stress-dependent and ATP-responsive dephosphorylations of RsbV-P differed in their requirements for the products of the first four genes (rsbR, -S, -T, and -U) of the sigB operon. Both dephosphorylation reactions required at least one of the genes included in a deletion that removed rsbR, -S, and -T; however, only an environmental insult required RsbU to reactivate RsbV.

Relative levels and fractionation properties of Bacillus subtilis σ(B) and its regulators during balanced growth and stress

sigma B is a secondary sigma factor that controls the general stress response in Bacillus subtilis. sigma B-dependent genes are activated when sigma B is released from an inhibitory complex with an anti-sigma B protein (RsbW) and becomes free to associate with RNA polymerase. Two separate pathways, responding either to a drop in intracellular ATP levels or to environmental stress (e.g., heat, ethanol, or salt), cause the release of sigma B from RsbW. rsbR, rsbS, rsbT, and rsbU are four genes now recognized as the upstream half of an operon that includes sigB (sigma B) and its principal regulators. Using reporter gene assays, we find that none of these four genes are essential for stationary-phase (i.e., ATP-dependent) activation of sigma B, but rsbU and one or more of the genes contained within an rsbR,S,T deletion are needed for stress induction of sigma B. In other experiments, Western blot (immunoblot) analyses showed that the levels of RsbR, RsbS, Rsb, and RsbU, unlike those of the sigB operon's four downstream gene products (RsbV, RsbW, RsbX and sigma B), are not elevated during sigma B activation. Gel filtration and immunoprecipitation studies did not reveal the formation of complexes between any of the four upstream sigB operon products and the products of the downstream half of the operon. Much of the detectable RsbR, RsbS, RsbT, and RsbU did, however, fractionate as a large-molecular-mass (approximately 600-kDa) aggregate which was excluded from our gel filtration matrix. The downstream sigB operon products were not present in this excluded material. The unaggregated RsbR, RsbS, and RsbU, which were retarded by the gel matrix, elated from the column earlier than expected from their molecular weights. The RsbR and RsbS fractionation profile was consistent with homodimers (60 and 30 kDa, respectively), while the RsbU appeared larger, suggesting a protein complex of approximately 90 to 100 kDa.

Separate mechanisms activate sigma B of Bacillus subtilis in response to environmental and metabolic stresses

sigma B is a secondary sigma factor that controls the general stress response of Bacillus subtilis. sigma B-dependent transcription is induced by the activation of sigma B itself, a process that involves release of sigma B from an inhibitory complex with its primary regulator, RsbW. sigma B becomes available to RNA polymerase when RsbW forms a complex with an additional regulatory protein (RsbV) and, because of this, fails to bind sigma B. Using Western blot (immunoblot) analyses, reporter gene fusion assays, and measurements of nucleotide pool sizes, we provide evidence for two independent processes that promote the binding of RsbW to RsbV. The first occurs during carbon limitation or entry into stationary phase. Activation of sigma B under these circumstances correlates with a drop in the intracellular levels of ATP and may be a direct consequence of ATP levels on RsbW's binding preference. The second activation process relies on the product of a third regulatory gene, rsbU. RsbU is dispensable for sigma B activation during carbon limitation or stationary phase but is needed for activation of sigma B in response to any of a number of different environmental insults (ethanol treatment, salt or acid shock, etc.). RsbU, or a process dependent on it, alters RsbW binding without regard for intracellular levels of ATP. In at least some instances, the effects of multiple inducing stimuli are additive. The data are consistent with RsbW being a regulator at which distinct signals from separate effectors can be integrated to modulate sigma B activity.

The Bacillus subtilis rsbU gene product is necessary for RsbX-dependent regulation of sigma B

sigma B is a secondary sigma factor of Bacillus subtilis. sigma B-dependent transcription is induced when B. subtilis enters the stationary phase of growth or is exposed to any of a number of different environmental stresses. Three genes (rsbV, rsbW, and rsbX), which are cotranscribed with the sigma B structural gene (sigB), encode regulators of sigma B-dependent gene expression. RsbW and RsbV have been shown to control sigma B activity, functioning as an inhibitory sigma B binding protein and its antagonist, respectively. Using the SPAC promoter (PSPAC) to control the expression of the sigB operon, a ctc::lacZ reporter system to monitor sigma B activity, and monoclonal antibodies to determine the levels of sigB operon products, we have now obtained evidence that RsbX is an indirect regulator of sigma B activity. Genetic data and in vivo measurements argue that RsbX negatively regulates an extension of the RsbV-RsbW pathway that requires the product of an additional regulatory gene (rsbU) which lies immediately upstream of the sigB operon. The results are consistent with RsbU, or a process dependent on RsbU, being able to facilitate the RsbV-dependent release of sigma B from RsbW but normally prevented from doing this by RsbX.