Mucus and Mucins: The Underappreciated Host Defence System

The mucosal surfaces that form the boundary between the external environment and the underlying tissue are protected by a mucus barrier. Mucin glycoproteins, both secreted and cell surface mucins, are the major components of the barrier. They can exclude pathogens and toxins while hosting the commensal bacteria. In this review, we highlight the dynamic function of the mucins and mucus during infection, how this mucosal barrier is regulated, and how pathogens have evolved mechanisms to evade this defence system.

IgM and IgA augmented autoantibody signatures improve early-stage detection of colorectal cancer prior to nodal and distant spread

Objectives

Tumor‐associated autoantibodies (AAbs) in individuals with cancer can precede clinical diagnosis by several months to years. The objective of this study was to determine whether the primary immune response in form of IgM and gut mucosa‐associated IgA can aid IgG AAbs in the detection of early‐stage colorectal cancer (CRC).

Methods

We developed a novel protein array comprising 492 antigens seropositive in CRC. The array was used to profile IgG, IgM and IgA antibody signatures in 99 CRC patients and 99 sex‐ and age‐matched non‐cancer controls. A receiver operating curve (ROC), Kaplan–Meier survival analysis and univariate and multivariate Cox regression analyses were conducted.

Results

We identified a panel of 16 multi‐isotype AAbs with a cumulative sensitivity of 91% and specificity of 74% (AUC 0.90, 95% CI: 0.850–0.940) across all CRC stages. IgM and IgG isotypes were conversely associated with disease stage with IgM contributing significantly to improved stage I and II sensitivity of 96% at 78% specificity (AUC 0.928, 95% CI: 0.884–0.973). A single identified IgA AAb reached an overall sensitivity of 5% at 99% specificity (AUC 0.520, 95% CI: 0.440–0.601) balanced across all CRC stages. Kaplan–Meier analysis revealed that se33‐1 (ZNF638) IgG AAbs were associated with reduced 5‐year overall survival (log‐rank test, P = 0.012), whereas cumulative IgM isotype signatures were associated with improved 5‐year overall survival (log‐rank test, P = 0.024).

Conclusion

IgM AAbs are associated with early‐stage colorectal cancer. Combining IgG, IgM and IgA AAbs is a novel strategy to improve early diagnosis of cancers.

[Dose-response relationship between maternal hemoglobin concentration and preterm birth, in pregnant women]

Objective: To investigate the dose-response relationship between hemoglobin concentration and preterm birth, during pregnancy. Methods: With Zhuang ethnicity, a total of 12 780 pregnant women and their infants that admitted to Wuming、Pingguo、Jingxi、Debao、Longan and Tiandong hospitals, were recruited, in Guangxi Zhuang Autonomous Region, from January 2015 to December 2017. Non-conditional logistic regression method was used to analyze the effect of anemia on preterm birth during pregnancy. Dose-response relationship between hemoglobin concentration and preterm birth was explored, using the restrictive cubic spline model. Results: After excluding 2 053 pregnant women with hypertension or aged 35 years and over, results from the non-conditional logistic regression analysis showed that the risk of preterm birth in the anemia group was 1.29 times (OR=1.29, 95%CI: 1.04-1.59, P=0.019) of the non-anemia group in the first trimester. Data from the restricted cubic sample showed that there appeared nonlinear "L" dose-response relationship between hemoglobin concentration and preterm birth in the first trimester and "U" shape in the third trimester (non-linearity test P<0.001). Conclusion: There appeared nonlinear dose-response relationship between the hemoglobin concentration and preterm birth, both in the first and third trimesters.

MUC13 protects colorectal cancer cells from death by activating the NF-κB pathway and is a potential therapeutic target

MUC13 is a transmembrane mucin glycoprotein that is over produced by many cancers, although its functions are not fully understood. Nuclear factor-κB (NF-κB) is a key transcription factor promoting cancer cell survival, but therapeutically targeting this pathway has proved difficult because NF-κB has pleiotropic functions. Here, we report that MUC13 prevents colorectal cancer cell death by promoting two distinct pathways of NF-kB activation, consequently upregulating BCL-X_L. MUC13 promoted tumor necrosis factor (TNF)-induced NF-κB activation by interacting with TNFR1 and the E3 ligase, cIAP1, to increase ubiquitination of RIPK1. MUC13 also promoted genotoxin-induced NF-κB activation by increasing phosphorylation of ATM and SUMOylation of NF-κB essential modulator. Moreover, elevated expression of cytoplasmic MUC13 and NF-κB correlated with colorectal cancer progression and metastases. Our demonstration that MUC13 enhances NF-κB signaling in response to both TNF and DNA-damaging agents provides a new molecular target for specific inhibition of NF-κB activation. As proof of principle, silencing MUC13 sensitized colorectal cancer cells to killing by cytotoxic drugs and inflammatory signals and abolished chemotherapy-induced enrichment of CD133⁺ CD44⁺ cancer stem cells, slowed xenograft growth in mice, and synergized with 5-fluourouracil to induce tumor regression. Therefore, these data indicate that combining chemotherapy and MUC13 antagonism could improve the treatment of metastatic cancers.

Expressions of survivin, P16(INK4a), COX-2, and Ki-67 in cervical cancer progression reveal the potential clinical application

PURPOSE OF INVESTIGATION

To explore the significance of survivin, P16(INK4a), COX-2, and Ki-67 expressions for prediction of cervical cancer progression.

MATERIALS AND METHODS

A retrospective study was performed in 129 cases including 24 squamous carcinoma of the cervix (SCC), 70 cervical intraepithelial neoplasias (CIN), 15 cervical condyloma acuminatum (CCA), ten chronic cervicitis (CC), and ten normal cervix (NC). Protein expressions were evaluated using immunohistochemistry.

RESULTS

Survivin, P16(INK4a); COX-2, and Ki-67 were highly expressed in SCC and CIN compared with others. Their expression rates were gradually increased in CIN I, CIN II, CIN III, and SCC groups, showing 72.00%, 88.00%, 90.00%, and 95.83% for P16(INK4a), 68.00%, 84.00%, 95.00% and 100.00% for COX-2, 76.00%, 96.00%, 100.00%, and 100.00 for Ki-67, respectively. There were significant correlations between survivin and P16(INK4a), COX-2, Ki-67, as well as P16(INK4a) and Ki-67.

CONCLUSION

Survivin, P16(INK4a), COX-2 and Ki-67 play critical roles for development and progression of cervical cancer.

Theoretical studies on alkyne addition to molybdenum alkylidenes: the preference of alpha- and beta-additions

The addition of alkynes HC=CR to Mo(NH)(CH(2))(OR')(2) (R = H, Me, Ph; R' = CH(3), CF(3)) has been studied with both ab initio molecular orbital and density functional calculations. Geometry optimizations were carried out with the HF/3-21G, HF/HW3, and B3LYP/HW3 methods. The transition structures for these addition reactions are in distorted trigonal bipyramidal geometries, similar to those of alkene additions. The calculated activation enthalpy for HC=CH addition to Mo(NH)(CH(2))(OR')(2) is about 10.3 kcal/mol for R' = CH(3) and about 2.3 kcal/mol for R' = CF(3), indicating a significant preference for acetylene addition to Mo(NH)(CH(2))(OCF(3))(2) over Mo(NH)(CH(2))(OCH(3))(2). These barriers are higher than those of the corresponding ethylene addition by about 2-4 kcal/mol, even though the reaction of acetylene is much more exothermic. The alpha-addition of HC=CR (R = Me, Ph) is found to be considerably more favorable than the beta-addition to Mo(NH)(CH(2))(OR')(2). Interestingly, the alpha-addition has a lower activation energy, while the beta-addition has a higher activation energy, compared to that of the parent acetylene addition. Thus, alpha-addition is intrinsically favored over beta-addition by over 4 kcal/mol. This preference is reduced by solvent effect. All these can be explained by a destabilizing interaction between the nonreacting pi-orbital of alkyne and one of the lone pairs on the imido nitrogen. The steric effect of the bulky ligands in the real catalysts is also investigated qualitatively by the PM3 method. These studies give results in good accord with the experimentally observed regioselectivity.

Epitope studies with anti-beta 2-glycoprotein I antibodies from autoantibody and immunized sources

This paper examines the methodology of anti-beta(2)-glycoprotein I (beta(2)-GPI) epitope determination and provides further epitope studies using human sera containing anti-beta(2)-GPI autoantibodies. Studies in this field may be misleading as the antigen coating density using mutant forms of beta(2)-GPI may be below the threshold required for monogamous divalent binding by low affinity anti-beta(2)-GPI autoantibodies, while being easily detected by high affinity anti-beta(2)-GPI from immunized animals. The antigen density threshold effect is found in anti-beta(2)-GPI autoantibodies from humans and from monoclonal anti-beta(2)-GPI derived from mice with models of autoimmune disease. Anti-beta(2)-GPI from an autoimmune mouse and from 18/21 human sera did not bind above background levels to a domain-I-deleted mutant. In addition, single point mutations in domain I result in dramatic changes in the binding of many human sera containing anti-beta(2)-GPI. These findings support a conclusion that domain I of beta(2)-GPI contains significant epitopes for the anti-beta(2)-GPI antibodies found in the antiphospholipid syndrome.

Human beta 2-glycoprotein I binds to endothelial cells through a cluster of lysine residues that are critical for anionic phospholipid binding and offers epitopes for anti-beta 2-glycoprotein I antibodies

Beta 2-Glycoprotein I (beta 2GPI) is a phospholipid-binding protein recognized by serum autoantibodies from the anti-phospholipid syndrome both in cardiolipin- and beta 2GPI-coated plates. We found that: 1) recombinant wild-type beta 2GPI bound to HUVEC and was recognized by both human monoclonal IgM and affinity-purified polyclonal IgG anti-beta 2GPI anti-phospholipid syndrome Abs; and 2) a single amino acid change from Lys286 to Glu significantly reduced endothelial adhesion. Double and triple mutants (from Lys284,287 to Glu284,287, from Lys286,287 to Glu286,287, and from Lys284,286,287 to Glu284,286,287) completely abolished endothelial binding. A synthetic peptide (P1) spanning the sequence Glu274-Cys288 of the beta 2GPI fifth domain still displayed endothelial adhesion. Another peptide (P8), identical with P1 except that Cys281 and Cys288 were substituted with serine residues, did not bind to HUVEC. Anti-beta 2GPI Abs, once bound to P1 adhered to HUVEC, induced E-selectin expression and up-regulated IL-6 secretion. Control experiments conducted with irrelevant Abs as well as with the P8 peptide did not show any endothelial Ab binding nor E-selectin and IL-6 modulation. Our results suggest that: 1) beta 2GPI binds to endothelial cells through its fifth domain; 2) the major phospholipid-binding site that mediates the binding to anionic phospholipids is also involved in endothelial binding; 3) HUVEC provide a suitable surface for beta 2GPI binding comparable to that displayed by anionic phospholipids dried on microtiter wells; and 4) the formation of the complex between beta 2GPI and the specific Abs leads to endothelial activation in vitro.

beta 2-Glycoprotein I: target antigen for autoantibodies in the 'antiphospholipid syndrome'

Antiphospholipid' (aPL) antibodies are of important clinical significance because of their association with thrombosis both arterial and venous, recurrent foetal loss, specific neurological sequelae like seizures and chorea, cardiac valvular abnormalities and thrombocytopenia. Traditionally these autoantibodies have been assayed using phospholipid (PL) dependent tests and are classified as lupus anticoagulants (LA) and anticardiolipin (aCL) antibodies based on the method of detection. The antibodies thus, had been thought to bind PLs but it has now become clear that the true antigens are PL-binding proteins. The major protein consistently found as the target antigen for these autoantibodies is beta 2-glycoprotein I (beta 2-GPI). Other candidate PL-binding proteins have also been investigated including prothrombin, protein C and protein S but thus far appear to play less important roles in the binding of these antibodies.

The role of beta 2-glycoprotein I in the antiphospholipid syndrome

Antiphospholipid antibodies were originally thought to bind negatively-charged (anionic) phospholipids. Current evidence suggest that the target antigen is considerably more complex and includes beta 2-glycoprotein I, a phospholipid-binding plasma protein. Our understanding of the pathophysiology of the antiphospholipid syndrome has increased exponentially with a number of studies into the interactions of antiphospholipid antibodies and beta 2-glycoprotein I.

[Vitreous prolapse during cataract surgery]

Clinical data of 427 cases (458 eyes) of extracapsular cataract extraction and IOL implantation gave the impression that vitreous prolapse due to disruption of the zonula and the posterior capsule was a malpractical complication. Forcible capsulotomy too large or deep and uneven irrigating pressure were the common causes of zonular disruption. Obstructed passage and insufficient separation of the nucleus from the posterior cortical bed leading to difficult nuclear delivery, aspiration of cortex in the posterior chamber, poorly filled anterior chamber, insufficient room for the IOL, improper insertion of the posterior haptics and traumatic dialing were risk factors for posterior capsular rupture and vitreous prolapse.