RHEB: a potential regulator of chondrocyte phenotype for cartilage tissue regeneration

As articular cartilage has a limited ability to self-repair, successful cartilage regeneration requires clinical-grade chondrocytes with innate characteristics. However, cartilage regeneration via chondrocyte transplantation is challenging, because chondrocytes lose their innate characteristics during in vitro expansion. Here, we investigated the mechanistic underpinning of the gene Ras homologue enriched in brain (RHEB) in the control of senescence and dedifferentiation through the modulation of oxidative stress in chondrocytes, a hallmark of osteoarthritis. Serial expansion of human chondrocytes led to senescence, dedifferentiation and oxidative stress. RHEB maintained the innate characteristics of chondrocytes by regulating senescence, dedifferentiation and oxidative stress, leading to the upregulation of COL2 expression via SOX9 and the downregulation of p27 expression via MCL1. RHEB also decreased the expression of COL10. RHEB knockdown mimics decreased the expression of SOX9, COL2 and MCL1, while abrogating the suppressive function of RHEB on p27 and COL10 in chondrocytes. RHEB-overexpressing chondrocytes successfully formed cartilage tissue in vitro as well as in vivo, with increased expression of GAG matrix and chondrogenic markers. RHEB induces a distinct gene expression signature that maintained the innate chondrogenic properties over a long period. Therefore, RHEB expression represents a potentially useful mechanism in terms of cartilage tissue regeneration from chondrocytes, by which chondrocyte phenotypic and molecular characteristics can be retained through the modulation of senescence, dedifferentiation and oxidative stress. Copyright © 2016 John Wiley & Sons, Ltd.

Regulation of senescence associated signaling mechanisms in chondrocytes for cartilage tissue regeneration

Adult articular chondrocytes undergo slow senescence and dedifferentiation during in vitro expansion, restricting successful cartilage regeneration. A complete understanding of the molecular signaling pathways involved in the senescence and dedifferentiation of chondrocytes is essential in order to better characterize chondrocytes for cartilage tissue engineering applications. During expansion, cell fate is determined by the change in expression of various genes in response to aspects of the microenvironment, including oxidative stress, mechanical stress, and unsuitable culture conditions. Rapid senescence or dedifferentiation not only results in the loss of the chondrocytic phenotype but also enhances production of inflammatory mediators and matrix-degrading enzymes. This review focuses on the two groups of genes that play direct and indirect roles in the induction of senescence and dedifferentiation. Numerous degenerative signaling pathways associated with these genes have been reported. Upregulation of the genes interleukin 1 beta (IL-1β), p53, p16, p21, and p38 mitogen-activated protein kinase (MAPK) is responsible for the direct induction of senescence, whereas downregulation of the genes transforming growth factor-beta (TGF-β), bone morphogenetic protein-2 (BMP-2), SRY (sex determining region Y)-box 9 (SOX9), and insulin-like growth factor-1 (IGF-1), indirectly induces senescence. In senescent and dedifferentiated chondrocytes, it was found that TGF-β, BMP-2, SOX9, and IGF-1 are downregulated, while the levels of IL-1β, p53, p16, p21, and p38 MAPK are upregulated followed by inhibition of the normal molecular functioning of the chondrocytes. This review helps to elucidate the underlying mechanism in degenerative cartilage disease, which may help to improve cartilage tissue regeneration techniques.

Endoscopically assisted extralevator abdominoperineal excision

AIM

Extralevator abdominoperineal excision (ELAPE) has been advocated to optimize clearance of lower third rectal cancers with an involved or threatened circumferential resection margin. ELAPE could reduce positive margins and specimen perforation compared with standard abdominoperineal excision. However, there can be difficulties with ELAPE, particularly in identifying the anterior plane in male patients. Usually, the dissection is performed in the prone position, which can be hazardous, particularly in obese patients in whom wound problems are commonly encountered. We describe an endoscopically assisted approach for ELAPE in the lithotomy position.

METHOD

Three male patients with a rectal tumour located at the anorectal junction underwent an endoscopically assisted ELAPE in the lithotomy position after preoperative radiotherapy.

RESULTS

All the procedures were performed successfully with operation times of 180, 390 and 420 mins. There were no instances of intra-operative perforation or other complications. One patient developed postoperative intestinal obstruction which resolved on conservative management. There were no wound complications. Histopathological examination demonstrated clear margins and intact mesorectal planes in each patient.

CONCLUSION

We report a good outcome in three patients after endoscopically assisted ELAPE. This approach allows the patient to be operated on in the lithotomy position giving excellent views of the anterior dissection.

Optimal dissection for transanal total mesorectal excision using modified CO2 insufflation and smoke extraction

AIM

The new approach of transanal total mesorectal excision is technically challenging and demands a stable field of dissection with optimal view of anatomical landmarks. We aimed to describe and demonstrate a modification of both the insufflation of carbon dioxide and smoke evacuation, in order to optimize dissection.

METHOD

The comparison of standard insufflation to an AirSeal platform demonstrates a clear difference. This is shown in the accompanying video-recordings.

RESULTS

A more stable pneumorectum and better smoke evacuation as well as more convenient and precise dissection were achieved with the AirSeal platform.

CONCLUSION

Using the technique outlined, the operating surgeon is able to perform the surgical dissection in a stable operating environment with increased visibility compared to the standard approach.

The interaction of genetic determinants in the outcome of HCV infection: evidence for discrete immunological pathways

Diversity within the innate and adaptive immune response to hepatitis C is important in determining spontaneous resolution (SR) and treatment response. The aim of this study was to analyze how these variables interact in combination; furthering our understanding of the mechanisms that drive successful immunological clearance. Multivariate analysis was performed on retrospectively collected data for 357 patients previously genotyped for interferon (IFN)-λ3/4, killer cell immunoglobulin (KIR), human leukocyte antigen (HLA) class I and II and tapasin. High resolution KIR genotyping was performed for individuals with chronic infection and haplotypes determined. Outcomes for SR, IFN response and cirrhosis were examined. Statistical analysis included univariate methods, χ(2) test for trend, multivariate logistic regression, synergy and principal component analysis (PCA). Although KIR2DL3:HLA-C1C1 (P = 0.027), IFN-λ3/4 rs12979860 CC (P = 0.027), tapasin G in individuals with aspartate at residue 114 of HLA-B (TapG:HLA-B(114D) ) (P = 0.007) and HLA-DRB1*04:01 (P = 0.014) were associated with SR with a strong additive influence (χ(2) test for trend P < 0.0001); favorable polymorphisms did not interact synergistically, nor did patients cluster by outcome. In the treatment cohort, IFN-λ3/4 rs12979860 CC was protective in hepatitis C virus (HCV) G1 infection and KIR2DL3:HLA-C1 in HCV G2/3. In common with SR, variables did not interact synergistically. Polymorphisms predictive of viral clearance did not predict disease progression. In summary, different individuals resolve HCV infection using discrete and non-interacting immunological pathways. These pathways are influenced by viral genotype. This work provides novel insights into the complexity of the interaction between host and viral factors in determining the outcome of HCV infection.

Consequences of traffic noise in residents of Karachi, Pakistan

Objective:

To find out effect of road traffic noise on human beings in busy places of Karachi, working at these places and to compare its results with the previously done studies on this subject.

Methods:

This prospective epidemiological study was designed to evaluate effects of Noise induced hearing Loss due to road traffic at different places (Gurumander, Tibet Centre, Marry Weather Tower) of Karachi. A sample of 125 cases were randomly selected who had noise exposure of 90 dB or above of their surroundings for more than 6 months. The study was conducted from October 1^st 2013 to January 1^st 2013.

Results:

The minimum age was 18 years while maximum age was 47 years. The age group found most affected was from 23 years to 27 years. The males were 84% and females 16%. Subjects exposed to noise for more than 12 hours per day were 36.8%. Varying degree of hearing loss was evaluated in subjects where 17.6% were normal, 33.6% had mild hearing loss, 45.6% had moderate and 3.2% had moderately severe hearing loss. Traffic noise was found to bother 55.2% of subjects.

Conclusion:

Analysis of data indicates an enormous increase in noise levels as compared to previous studies. This study establishes that there exists a concrete direct link between NIHL and duration of exposure to noise above permissible levels. Traffic authorities should initiate measures to reduce the noise levels in the city particularly at more noisy places.

Complications in surgery for Crohn's disease after preoperative antitumour necrosis factor therapy

BACKGROUND

The use of biological therapy (biologicals) is established in the treatment of Crohn's disease. This study aimed to determine whether preoperative treatment with biologicals is associated with an increased rate of complications following surgery for Crohn's disease with intestinal anastomosis.

METHODS

All patients receiving biologicals and undergoing abdominal surgery with anastomosis or strictureplasty were identified at six tertiary referral centres. Demographic data, and preoperative, operative and postoperative details were registered. Patients who were treated with biologicals within 2 months before surgery were compared with a control group who were not. Postoperative complications were classified according to anastomotic, infectious or other complications, and graded according to the Clavien-Dindo classification.

RESULTS

Some 111 patients treated with biologicals within 2 months before surgery were compared with 187 patients in the control group. The groups were well matched. There were no differences between the treatment and control groups in the rate of complications of any type (34·2 versus 28·9 per cent respectively; P = 0·402), anastomotic complications (7·2 versus 8·0 per cent; P = 0·976) and non-anastomotic infectious complications (16·2 versus 13·9 per cent; P = 0·586). In univariable regression analysis, biologicals were not associated with an increased risk of any complication (odds ratio (OR) 1·33, 95 per cent confidence interval 0·81 to 2·20), anastomotic complication (OR 0·89, 0·37 to 2·17) or infectious complication (OR 1·09, 0·62 to 1·91).

CONCLUSION

Treatment with biologicals within 2 months of surgery for Crohn's disease with intestinal anastomosis was not associated with an increased risk of complications.

Effect of dietary supplementation of prebiotics and probiotics on intestinal microarchitecture in broilers reared under cyclic heat stress

This study was designed to evaluate the effect of dietary supplementation of prebiotics, mannanoligosaccharides (MOS) and/or probiotics (LBP) on intraepithelial lymphocytes (IEL) count, goblet cells (GC) count and differentiation and intestinal micro-architecture in broilers reared under cyclic heat stress. Day-old broilers (n = 250) were randomly divided into five groups. Fifty birds were reared within the thermoneutral zone (TNZ). Remaining birds were subjected to cyclic heat stress from day 21 to 42 (35° C, 75% RH, 8 h/d). The birds were fed corn-soy-based basal diet or the same diet supplemented with 0.5% MOS (HS-MOS), or 0.1% LBP (HS-LBP), or their combination (HS-SYN). The birds were slaughtered on day 42. Tissue samples were collected from mid-duodenum, jejunum and ileum, and stained with haematoxylin and eosin or combined Alcian blue and PAS technique. All differences were considered significant at p < 0.05. The IEL count increased in all intestinal segments of the HS group compared with the TNZ group and decreased in all supplemented groups compared with the HS group. Compared with the TNZ, heat stress reduced villus height, crypt depth and surface area in duodenum and ileum, and increased crypt depth in ileum. Villus width decreased in duodenum and jejunum compared with the TNZ group. Supplementation of LBP, MOS and SYN reversed all these changes in duodenum, while only increased villus height and surface area in ileum. In jejunum, the villus height and surface area increased with HS-LBP, and crypt depth increased with HS-MOS. The number of GC containing acid mucins (duodenum and ileum) and mixed mucins (ileum) were increased in the HS compared with the TNZ. Supplementation of MOS, LBP and SYN maintained the enhanced activity of goblet cells. In conclusion, dietary supplementation of MOS and/or LBP may be helpful in alleviating some of the detrimental effects of heat stress on microstructure of the broiler gut.

Differences in structural and pain phenotypes in the sodium monoiodoacetate and meniscal transection models of osteoarthritis

OBJECTIVES

To characterize differences in joint pathology and pain behavior between two rat models of osteoarthritis (OA) in order to inform selection of animal models for interventional studies.

METHOD

Knee OA was induced in Sprague Dawley rats by either meniscal transection (MNX) or intra-articular injection of monosodium iodoacetate (MIA). Controls were subjected to sham surgery or saline-injection. In a separate experiment, a single intra-articular injection of triamcinolone acetonide was administered 14 days after MNX or MIA arthritis induction. Pain behavior and joint pathology were quantified.

RESULTS

Both models displayed synovial inflammation, chondropathy and osteophytosis. Chondropathy scores increased with time similarly in the two models. Inflammation and osteophyte scores were greater in MNX model compared to the MIA model. At day 49, the MNX model exhibited a greater number of channels crossing the osteochondral junction compared to all other groups. The MNX model exhibited greater weight bearing asymmetry compared to the MIA model, whereas the MIA model displayed more consistent hindpaw allodynia. Triamcinolone attenuated weight bearing asymmetry and distal allodynia to control levels in the MNX model, but distal allodynia was unaltered in the MIA model.

CONCLUSIONS

The comparison of the two models of OA in rats, using identical assessment tools has demonstrated that although both models display features of OA, there are differences between the models which may represent different aspects of human OA. Thus, model selection should be based on the pathological aspects of OA under investigation.

A critical appraisal of endorectal ultrasound and transanal endoscopic microsurgery and decision-making in early rectal cancer

AIM

Transanal endoscopic microsurgery (TEM) for early rectal cancer (ERC) gives results similar to major surgery in selected cases. Endorectal ultrasound (ERUS) is an important part of the preoperative selection process. This study reports its accuracy and impact for patients entered on the UK TEM database.

METHOD

The UK TEM database comprises prospectively collected data on 494 patients. This data set was used to determine the prevalence of ERUS in preoperative staging and its accuracy by comparing preoperative T-stage with definitive pathological staging following TEM.

RESULTS

ERUS was performed in 165 of 494 patients who underwent TEM for rectal cancer. It inaccurately staged rectal cancer in 44.8% of tumours: 32.7% were understaged and 12.1% were overstaged. There was no significant difference in the depth of TEM excision or R1 rate between the patients who underwent ERUS before TEM and those who did not (P = 0.73).

CONCLUSION

The data show that ERUS is employed in a minority of patients with rectal cancers undergoing TEM in the UK and its accuracy in this 'Real World' practice is disappointing.

Lymphatic vessels in osteoarthritic human knees

OBJECTIVES

The distribution and function of lymphatic vessels in normal and diseased human knees are understood incompletely. This study aimed to investigate whether lymphatic density is associated with clinical, histological or radiographic parameters in osteoarthritis (OA).

METHODS

Sections of synovium from 60 knees from patients with OA were compared with 60 post mortem control knees (from 37 individuals). Lymphatic vessels were identified using immunohistochemistry for podoplanin, and quantified as lymphatic vessel density (LVD) and lymphatic endothelial cell (LEC) fractional area. Effusion status was determined by clinical examination, radiographs were scored for OA changes, and inflammation grading used haematoxylin and eosin stained sections of synovium.

RESULTS

Lymphatic vessels were present in synovia from both disease groups, but were not identified in subchondral bone. Synovial lymphatic densities were independent of radiological severity and age. Synovia from patients with OA displayed lower LVD (z=-3.4, P=0.001) and lower LEC fractional areas (z=-4.5, P<0.0005) than non-arthritic controls. In patients with OA, low LVD was associated with clinically detectable effusion (z=-2.2, P=0.027), but not with histological evidence of synovitis. The negative associations between lymphatics and OA/effusion appeared to be independent of other measured confounders.

CONCLUSION

Lymphatic vessels are present in lower densities in OA synovia. Abnormalities of synovial fluid drainage may confound the value of effusion as a clinical sign of synovitis in OA.