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Glycation is vital in terms of its damaging effect on macromolecules resulting in the formation of end products, which are highly reactive and cross‐linked irreversible structures, known as advanced glycation end products (AGEs). The continuous accumulation of AGEs is associated with severe diabetes and its associated ailments. Saccharides with their reducing ends can glycate amino acid side chains of proteins, among them glucose is well‐known for its potent glycating capability. However, other reducing sugars can be more reactive glycating agents than glucose. The D‐ribose is a pentose sugar‐containing an active aldehyde group in its open form and is responsible for affecting the biological processes of the cellular system. D‐ribose, a key component of many biological molecules, is more reactive than most reducing sugars. Protein glycation by reducing monosaccharides such as D‐ribose promotes the accelerated formation of AGEs that could lead to cellular impairments and dysfunctions. Also, under a physiological cellular state, the bioavailability rate of D‐ribose is much higher than that of glucose in diabetes, which makes this species much more active in protein glycation as compared with D‐glucose. Due to the abnormal level of D‐ribose in the biological system, the glycation of proteins with D‐ribose needs to be analyzed and addressed carefully. In the present study, human immunoglobulin G (IgG) was isolated and purified via affinity column chromatography. D‐ribose at 10 and 100 mM concentrations was used as glycating agent, for 1–12 days of incubation at 37°C. The postglycation changes in IgG molecule were characterized by UV‐visible and fluorescence spectroscopy, nitroblue tetrazolium assay, and various other physicochemical analyses for the confirmation of D‐ribose mediated IgG glycation. Significance statement: 1.D‐ribose‐induced glycation leads to structural perturbations in immunoglobulin G (IgG), the formation of IgG‐advanced glycation end products, and the generation of oxidative stress. 2.UV‐visible spectroscopy revealed the hyperchromicity of glycated IgG increases with the increase in the concentration of D‐ribose and time interval. 3.The early glycation products that is, Amadori products or ketoamines formed during D‐ribose mediated glycation of IgG were assessed by nitroblue tetrazolium assay and found to be increased initially in the first 5 days. 4.Hydroxymethylfurfural, carbonyl content, thiobarbituric acid reactive substances, and fluorescence intensity were found to be increased in glycated IgG as compared to the native analog. 5.Free lysine and arginine were found to be decreased in glycated IgG in comparison to the native conformer of the protein. [ABSTRACT FROM AUTHOR]

Macrophages (Mϕs) play a central role in mucosal immunity by pathogen sensing and instruction of adaptive immune responses. Prior challenge to endotoxin can render Mφs refractory to secondary exposure, suppressing the inflammatory response. Previous studies demonstrated a differential subset-specific sensitivity to endotoxin tolerance (ET), mediated by LPS from the oral pathogen, Porphyromonas gingivalis (PG). The aim of this study was to investigate ET mechanisms associated with Mφ subsets responding to entropathogenic E. coli K12-LPS. M1- and M2-like Mφs were generated in vitro from the THP-1 cell line by differentiation with PMA and Vitamin D3, respectively. This study investigated ET mechanisms induced in M1 and M2 Mφ subsets, by measuring modulation of expression by RT-PCR, secretion of cytokines by sandwich ELISA, LPS receptor, TLR4, as well as endogenous TLR inhibitors, IRAK-M and Tollip by Western blotting. In contrast to PG-LPS tolerisation, E. coli K12-LPS induced ET failed to exhibit a subset-specific response with respect to the pro-inflammatory cytokine, TNFα, whereas exhibited a differential response for IL-10 and IL-6. TNFα expression and secretion was significantly suppressed in both M1- and M2-like Mφs. IL-10 and IL-6, on the other hand, were suppressed in M1s and refractory to suppression in M2s. ET suppressed TLR4 mRNA, but not TLR4 protein, yet induced differential augmentation of the negative regulatory molecules, Tollip in M1 and IRAK-M in M2 Mφs. In conclusion, E. coli K12-LPS differentially tolerises Mφ subsets at the level of anti-inflammatory cytokines, associated with a subset-specific divergence in negative regulators and independent of TLR4 down-regulation. [ABSTRACT FROM AUTHOR]

Objectives: Oral mucosal macrophages (MØs) determine immune responses; maintaining tolerance whilst retaining the capacity to activate defences against pathogens. MØ responses are determined by two distinct subsets; pro-inflammatory M1- and anti-inflammatory/regulatory M2-MØs. Tolerance induction is driven by M2 MØs, whereas M1-like MØs predominate in inflammation, such as that exhibited in chronic Porphyromonas gingivalis (PG) periodontal infection. MØ responses can be suppressed to benefit either the host or the pathogen. Chronic stimulation by pathogen associated molecular patterns (PAMPs), such as LPS, is well established to induce tolerance. The aim of this study was to investigate the P. gingivalis-driven induction of and responsiveness to the suppressive, antiinflammatory cytokine, IL-10, by MØ subsets. Methods: M1- and M2-like MØs were generated in vitro from the THP-1 monocyte cell line by differentiation with PMA and Vitamin D3, respectively. MØ subsets were stimulated by PG-LPS in the presence or absence of IL-10. Results: PG-LPS differentially induced IL-10 secretion and endogenous IL-10 activity in M1- and M2-like subsets. In addition, these subsets exhibited differential sensitivity to IL-10-mediated suppression of TNFα, where M2 MØs where sensitive to IL-10 and M1 MØs were refractory to suppression. In addition, this differential responsiveness to IL-10 was independent of IL-10-binding and expression of the IL-10 receptor signal transducing subunit, IL-10Rβ, but was in fact dependent on activation of STAT-3. Conclusion: P.gingivalis selectively tolerises regulatory M2 MØs with little effect on pro-inflammatory M1 MØs; differential suppression facilitating immunopathology at the expense of immunity. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA), a chronic inflammatory disease, and its exact aetiology is not defined clearly. The free radicals produced in large amount in RA are associated with alteration in molecular structure resulting in glycation of proteins. As a result of glycation, advanced glycation end products (AGEs) produced. In this study, collagen type II suspension was injected into Wistar rats to make RA model of rats. Simultaneously, hesperidin 50 mg kg−1 body weight was orally administrated to the rats for 21 days. X‐rays of the rat hind paws were analyzed and found to be significantly effective against bone loss after treatment with hesperindin. Nε‐(carboxymethyl)lysine (CML) and pentosidine (PTD) concentrations in collagen‐induced RA plasma were determined as 565.29 ± 30.15 and 37.23 ± 1.02 ng ml−1, respectively, while CML and PTD in IgG were 6.63 ± 0.44 ng mg−1 IgG and 425.33 ± 37.26 ng g−1 IgG, respectively. After treatment with hesperidin, the elevated levels of CML in plasma and in IgG were significantly (p < 0.001) lowered to 450.95 ± 15.05 mg ml−1 and 5.23 ± 0.27 ng mg−1 IgG, respectively. Similarly, concentrations of PTD in plasma and IgG of rats treated with hesperidin were 28.46 ± 1.20 ng ml−1 and 359.35 ± 31.11 ng g−1 IgG, respectively. Thus, after treatment with drug, plasma CML and IgG PTD levels were restored as 93% and 16%, respectively, through free radical scavenging activity of hesperidin resulting in alleviation of RA disease by decreasing the AGEs concentrations. Therefore, use of hesperidin may be useful to alleviate severity of RA disease. Significance statement: Collagen type II suspension was used to make a rheumatoid arthritis model of rat.Hesperidin treatment was effective against bone loss.Hesperidin effectively reduced the concentrations of advanced glycation end products like Nε‐(carboxymethyl)lysine and pentosidine.Treatment with hesperidin resulted in the alleviation of rheumatoid arthritis disease through free radical scavenging and antiglycation activities.Hesperidin may be useful to alleviate the severity of rheumatoid arthritis disease. [ABSTRACT FROM AUTHOR]