Distinct blood and visceral adipose tissue regulatory T cell and innate lymphocyte profiles characterize obesity and colorectal cancer

Visceral adipose tissue (VAT) is a main site where metabolic and immunologic processes interplay to regulate, at local and systemic level, the inflammatory status and immune response. Obesity-associated inflammation and immune dysfunctions are inextricably linked to tumor but, in spite of intense efforts, the mechanisms underpinning this asso- ciation remain elusive. In this report, we characterized the profile of VAT-associated and circulating innate lymphocyte and regulatory T (T reg ) cell subsets underlying inflammatory conditions, such as obesity and colorectal cancer (CRC). Analysis of NK, NKT-like, γδ T, and T reg cell populations in VAT and blood of healthy lean subjects revealed that CD56 hi NK and OX40 + T reg cells are more abundant in VAT with respect to blood. Conversely, CD56 dim NK and total T reg cells are most present in the circulation, while γδ T lymphocytes are uniformly distributed in the two compartments. Interestingly, a reduced frequency of circulating activated T reg cells, and a concomitant preferential enrichment of OX40- expressing T reg cells in VAT, were selectively observed in obese (Ob) subjects, and directly correlated with body mass index. Likewise, CRC patients were characterized by a specific enrichment of VAT-associated NKT-like cells. In addition, Ob and CRC-affected individuals shared a significant reduction of the V γ 9V δ 2/ γδ T cell ratio at systemic level. The alterations in the relative proportions of T reg and NKT-like cells in VAT were found to correlate with the content of pro- and anti-inflammatory polyunsaturated fatty acids (PUFA), respectively. Overall, these results provide evidence for distinct alterations of the immune cell repertoire in the periphery with respect to the VAT microenvironment that uniquely characterize or are shared by different inflammatory conditions, such as obesity and CRC, and suggest that VAT PUFA composition may represent one of the factors that contribute to shape the immune phenotypes

Protein Isoaspartate Methyltransferase Prevents Apoptosis Induced by Oxidative Stress in Endothelial Cells: Role of Bcl-Xl Deamidation and Methylation

BACKGROUND:Natural proteins undergo in vivo spontaneous post-biosynthetic deamidation of specific asparagine residues with isoaspartyl formation. Deamidated-isomerized molecules are both structurally and functionally altered. The enzyme isoaspartyl protein carboxyl-O-methyltransferase (PCMT; EC 2.1.1.77) has peculiar substrate specificity towards these deamidated proteins. It catalyzes methyl esterification of the free alpha-carboxyl group at the isoaspartyl site, thus initiating the repair of these abnormal proteins through the conversion of the isopeptide bond into a normal alpha-peptide bond. Deamidation occurs slowly during cellular and molecular aging, being accelerated by physical-chemical stresses brought to the living cells. Previous evidence supports a role of protein deamidation in the acquisition of susceptibility to apoptosis. Aim of this work was to shed a light on the role of PCMT in apoptosis clarifying the relevant mechanism(s). METHODOLOGY/PRINCIPAL FINDINGS:Endothelial cells transiently transfected with various constructs of PCMT, i.e. overexpressing wild type PCMT or negative dominants, were used to investigate the role of protein methylation during apoptosis induced by oxidative stress (H(2)O(2); 0.1-0.5 mM range). Results show that A) Cells overexpressing "wild type" human PCMT were resistant to apoptosis, whereas overexpression of antisense PCMT induces high sensitivity to apoptosis even at low H(2)O(2) concentrations. B) PCMT protective effect is specifically due to its methyltransferase activity rather than to any other non-enzymatic interactions. In fact negative dominants, overexpressing PCMT mutants devoid of catalytic activity do not prevent apoptosis. C) Cells transfected with antisense PCMT, or overexpressing a PCMT mutant, accumulate isoaspartyl-containing damaged proteins upon H(2)O(2) treatment. Proteomics allowed the identification of proteins, which are both PCMT substrates and apoptosis effectors, whose deamidation occurs under oxidative stress conditions leading to programmed cell death. These proteins, including Hsp70, Hsp90, actin, and Bcl-xL, are recognized and methylated by PCMT, according to the general repair mechanism of this methyltransferase. CONCLUSION/SIGNIFICANCE:Apoptosis can be modulated by "on/off" switch partitioning the amount of specific protein effectors, which are either in their active (native) or inactive (deamidated) molecular forms. Deamidated proteins can also be functionally restored through methylation. Bcl-xL provides a case for the role of PCMT in the maintenance of functional stability of this antiapoptotic protein

Dietary Fatty Acids at the Crossroad between Obesity and Colorectal Cancer: Fine Regulators of Adipose Tissue Homeostasis and Immune Response

Colorectal cancer (CRC) is among the major threatening diseases worldwide, being the third most common cancer, and a leading cause of death, with a global incidence expected to increase in the coming years. Enhanced adiposity, particularly visceral fat, is a major risk factor for the development of several tumours, including CRC, and represents an important indicator of incidence, survival, prognosis, recurrence rates, and response to therapy. The obesity-associated low-grade chronic inflammation is thought to be a key determinant in CRC development, with the adipocytes and the adipose tissue (AT) playing a significant role in the integration of diet-related endocrine, metabolic, and inflammatory signals. Furthermore, AT infiltrating immune cells contribute to local and systemic inflammation by affecting immune and cancer cell functions through the release of soluble mediators. Among the factors introduced with diet and enriched in AT, fatty acids (FA) represent major players in inflammation and are able to deeply regulate AT homeostasis and immune cell function through gene expression regulation and by modulating the activity of several transcription factors (TF). This review summarizes human studies on the effects of dietary FA on AT homeostasis and immune cell functions, highlighting the molecular pathways and TF involved. The relevance of FA balance in linking diet, AT inflammation, and CRC is also discussed. Original and review articles were searched in PubMed without temporal limitation up to March 2021, by using fatty acid as a keyword in combination with diet, obesity, colorectal cancer, inflammation, adipose tissue, immune cells, and transcription factors

Dietary fatty acids and adipose tissue inflammation at the crossroad between obesity and colorectal cancer

Excess adiposity, a worldwide-growing pathological condition, is now recognized as a main risk factor for most chronic diseases including colorectal cancer (CRC). Obese subjects show an increased cancer incidence with obesity representing an important indicator of survival, prognosis, recurrence and response to therapy. A low-grade chronic inflammation of metabolically active tissues including the adipose tissue (AT), defined as meta-inflammation, is a main feature of obesity. Fatty acids (FA), the main AT components, are important modulators of inflammation, and the type of FA stored in AT critically affects tissue functions. Their profile within AT mirrors FA dietary intake but also depends on a metabolic control. Obesity, changes in the habitual diet, weight loss or pathological conditions like CRC influence FA profile of AT pointing to these molecules as important actors in AT dysfunction and meta-inflammation, that characterize metabolic diseases and may favor cancer development. Worth of note, diet is receiving growing attention as a main determinant in cancer prevention due to its capacity to modulate immune response and inflammation. Alterations in the balance between different families of FA may contribute to generate a pro-inflammatory profile with deleterious effects on metabolic and immune homeostasis at both local and systemic levels. This review focuses on FA as regulators of human AT inflammation discussing the role of obesity-, diet-, and weight loss-associated changes in FA profile in this process. The relevance of FA composition of AT in linking diet, obesity and CRC will be also reviewed

New method for bacterial load measurement during hydro-debridement of cutaneous ulcer

New method for bacterial load measurement during hydro-debridement of cutaneous ulcer. Apperti M, Di Lucia A, Goffredi L, Federico P, Mattera E, Masella A, Della Rocca MD, Apperti S. SourceSeconda Università degli Studi di Napoli, Dipartimento di Scienze Anestesiologiche, Chirurgiche e dell'Emergenza. Abstract AIM OF THE STUDY: Based on their experience using Versajet for debridement of chronic wounds, the Authors set up a study protocol to verify whether the hydro-surgical cleansing could offer the possibility of taking tissue specimens suitable for diagnostic microbiological evaluation. The aims of the study were the following: MAIN PURPOSE: To evaluate the efficacy of hydro-surgery in detecting the presence of microorganisms and measuring their load, as an alternative to conventional tissue sampling methods; SECONDARY PURPOSE: To set up an easier and less invasive diagnostic modality than surgical biopsy, even though likewise significant. RESULTS: The results of this study show that tissue specimen collection by hydro-aspiration using Versajet is comparable to biopsy sampling (and in some cases it can be even more reliable); moreover, it is not more time-consuming and is certainly less invasive. Compared to surgical biopsy, with such a method a greater amount of tissue may be collected; moreover, tissue specimens can be taken from a broader surface or, depending on the needs, from a more focused area on the margin or at the bottom of the woun

Visceral fat adipocytes from obese and colorectal cancer subjects exhibit distinct secretory and ω6 polyunsaturated fatty acid profiles and deliver immunosuppressive signals to innate immunity cells

Obesity is a low-grade chronic inflammatory state representing an important risk factor for colorectal cancer (CRC). Adipocytes strongly contribute to inflammation by producing inflammatory mediators. In this study we investigated the role of human visceral fat adipocytes in regulating the functions of innate immunity cells. Adipocyte-conditioned media (ACM) from obese (n = 14) and CRC (lean, n = 14; obese, n = 13) subjects released higher levels of pro-inflammatory/immunoregulatory factors as compared to ACM from healthy lean subjects (n = 13). Dendritic cells (DC), differentiated in the presence of ACM from obese and CRC subjects, expressed elevated levels of the inhibitory molecules PD-L1 and PD-L2, and showed a reduced IL-12/IL-10 ratio in response to both TLR ligand- and γδ T lymphocyte-induced maturation. Furthermore, CRC patient-derived ACM inhibited DC-mediated γδ T cell activation. The immunosuppressive signals delivered by ACM from obese and CRC individuals were associated with a pro-inflammatory secretory and ω6 polyunsaturated fatty acid profile of adipocytes. Interestingly, STAT3 activation in adipocytes correlated with dihomo-γlinolenic acid content and was further induced by arachidonic acid, which conversely down-modulated PPARγ. These results provide novel evidence for a cross-talk between human adipocytes and innate immunity cells whose alteration in obesity and CRC may lead to immune dysfunctions, thus setting the basis for cancer development

Mechanism for deamidation of asparaginyl residues in peptides.

<p>(Step 1): the nitrogen of the Asn+1 residue (a Gly in the example) attacks the β-carbonyl carbon of the Asn, thus forming the succinimidyl derivative of the peptide (ASU) with the ammonia elimination. The ASU ring can open spontaneously on either side of the nitrogen atom. In one case the α-aspartyl peptide is formed (Step 2). In the other case the β-isoaspartyl peptide does occur (Step 3).</p

Proposed role of Bcl-x_L deamidation and methylation in apoptosis.

<p>Deamidation-isomerization of two critical Asn residues of Bcl-x_L abolishes its antiapoptotic function. Methylation of the same residues can restore the functional integrity of Bcl-x_L through repair of the isopeptide bonds. Regulation of apoptosis toward antiapoptosis is gained through fine balancing of Bcl-x_L deamidation and methylation.</p

Quantitation of the extent of protein deamidation in cells lysates after oxidative stress.

<p>Cells transfected with <i>PCMT</i> wild type (sense), antisense <i>PCMT</i> (anti), PCMT mutants [Asp₈₃ →Phe₈₃ (Phe) and Asp₈₃→Val₈₃ (Val)] and endothelial cells transfected with void plasmid (PAE) were stressed with 0.3 mM of H₂O₂. Deamidated proteins were quantitated in each lysate preparation using recombinant PCMT. Standard deviation error bars are included for each analysis.</p