Naturally occurring IgM antibodies to oxidation-specific epitopes

Understanding the Specific Implications of Amino Acids in the Antibody Development

As the demand for immunotherapy to treat and manage cancers, infectious diseases and other disorders grows, a comprehensive understanding of amino acids and their intricate role in antibody engineering has become a prime requirement. Naturally produced antibodies may not have the most suitable amino acids at the complementarity determining regions (CDR) and framework regions, for therapeutic purposes. Therefore, to enhance the binding affinity and therapeutic properties of an antibody, the specific impact of certain amino acids on the antibody's architecture must be thoroughly studied. In antibody engineering, it is crucial to identify the key amino acid residues that significantly contribute to improving antibody properties. Therapeutic antibodies with higher binding affinity and improved functionality can be achieved through modifications or substitutions with highly suitable amino acid residues. Here, we have indicated the frequency of amino acids and their association with the binding free energy in CDRs. The review also analyzes the experimental outcome of two studies that reveal the frequency of amino acids in CDRs and provides their significant correlation between the outcomes. Additionally, it discusses the various bond interactions within the antibody structure and antigen binding. A detailed understanding of these amino acid properties should assist in the analysis of antibody sequences and structures needed for designing and enhancing the overall performance of therapeutic antibodies.

Natural Antibodies Alert the Adaptive Immune System of the Presence of Transformed Cells in Early Tumorigenesis

Recent studies have revealed a critical role for natural Abs (NAbs) in antitumor immune responses. However, the role of NAbs in cancer immunosurveillance remains unexplored, mainly because of the lack of in vivo models that mimic the early recognition and elimination of transforming cells. In this article, we propose a role for NAbs in alerting the immune system against precancerous neoantigen-expressing cells immediately after they escape intrinsic tumor suppression mechanisms. We identify four distinct reproducible, trackable, MHC-matched neoantigen-expressing cell models that do not form tumors as the end point. This amplified readout in the critical window prior to tumor formation allows investigation of new mediators of cancer immunosurveillance. We found that neoantigen-expressing cells adoptively transferred in NAb-deficient mice persisted, whereas they were eliminated in wild-type mice, indicating that the circulating NAb repertoire alerts the immune system to the presence of transformed cells. Moreover, immunity is mounted against immunogenic and nonimmunogenic neoantigens contained in the NAb-tagged cells, regardless of whether the NAb directly recognizes the neoantigens. Beyond these neoantigen-expressing model systems, we observed a significantly greater tumor burden in chemically and virally induced tumor models in NAb-deficient mice compared with wild-type mice. Restoration of the NAb repertoire in NAb-deficient mice elicited the recognition and elimination of neoantigen-expressing cells and cancer. These data show that NAbs are required and sufficient for elimination of transformed cells early in tumorigenesis. These models can now be used to investigate how NAbs stimulate immunity via recognition receptors to eliminate precancerous cells.

Current Understanding of Natural Antibodies and Exploring the Possibilities of Modulation Using Veterinary Models. A Review

Natural antibodies (NAb) are defined as germline encoded immunoglobulins found in individuals without (known) prior antigenic experience. NAb bind exogenous (e.g., bacterial) and self-components and have been found in every vertebrate species tested. NAb likely act as a first-line immune defense against infections. A large part of NAb, so called natural autoantibodies (NAAb) bind to and clear (self) neo-epitopes, apoptotic, and necrotic cells. Such self-binding antibodies cannot, however, be considered as pathogenic autoantibodies in the classical sense. IgM and IgG NAb and NAAb and their implications in health and disease are relatively well-described in humans and mice. NAb are present in veterinary (and wildlife) species, but their relation with diseases and disorders in veterinary species are much less known. Also, there is little known of IgA NAb. IgA is the most abundant immunoglobulin with essential pro-inflammatory and homeostatic properties urging for more research on the importance of IgA NAb. Since NAb in humans were indicated to fulfill important functions in health and disease, their role in health of veterinary species should be investigated more often. Furthermore, it is unknown whether levels of NAb-isotypes and/or idiotypes can and should be modulated. Veterinary species as models of choice fill in a niche between mice and (non-human) primates, and the study of NAb in veterinary species may provide valuable new insights that will likely improve health management. Below, examples of the involvement of NAb in several diseases in mostly humans are shown. Possibilities of intravenous immunoglobulin administration, targeted immunotherapy, immunization, diet, and genetic modulation are discussed, all of which could be well-studied using animal models. Arguments are given why veterinary immunology should obtain inspiration from human studies and why human immunology would benefit from veterinary models. Within the One Health concept, findings from veterinary (and wildlife) studies can be related to human studies and vice versa so that both fields will mutually benefit. This will lead to a better understanding of NAb: their origin, activation mechanisms, and their implications in health and disease, and will lead to novel health management strategies for both human and veterinary species.

Antiphospholipid antibodies and lower extremity peripheral artery disease: A systematic review and meta-analysis

AIM

To evaluate the clinical relevance of antiphospholipid antibodies (aPL) in patients with lower extremity peripheral artery disease (PAD).

DATA SOURCES

EMBASE and MEDLINE databases were searched from inception to March 2020 for clinical studies reporting on the association between of aPL [IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA)] and PAD.

METHODS

We determined the pooled prevalence (PP) of patients positive for aPL in PAD or the PP of PAD in patients positive for aPL; we employed Peto's odds ratio with random effect for the meta-analysis.

RESULTS

Twenty-one studies comprising 6,057 patients were evaluated: in patients with PAD, the PP of IgG aCL was 12% vs 4.1% in those without, IgM aCL was 13.2% vs 2.1%, and LA 13.3% vs 3.3%, respectively. The PP of patients with LA was greater in critical limb ischemia than in the control group (19.3% vs 4.2%). Also, the PP of patients with LA was greater in the failed than in the successful revascularisation group (35.8% vs 15.8%). The PP of post-procedural revascularisation failures was similar in the groups given or not given oral anticoagulation (59.2% vs 61.9%).

CONCLUSION

All the aPL related to PAD regardless of diagnostic definition used, whereas LA related also to critical limb ischaemia and failed revascularisation. Data expressed as percentage of participants positive for aPL limit the interpretation of these relationships.

Schizophrenia phenomenology comprises a bifactorial general severity and a single-group factor, which are differently associated with neurotoxic immune and immune-regulatory pathways

In schizophrenia, a single latent trait underlies psychosis, hostility, excitation, mannerism, negative (PHEMN) symptoms, formal thought disorders (FTD) and psychomotor retardation (PMR). Schizophrenia is accompanied by a breakdown of gut and blood-brain-barrier (BBB) pathways, increased tryptophan catabolite (TRYCAT) levels, bacterial translocation, and lowered natural IgM and paraoxonase (PON)1 activity. The aim of this study was to examine the factor structure of schizophrenia symptom domains and the biomarker correlates of these factors. We recruited 80 patients with schizophrenia and 40 healthy subjects and assessed the IgA/IgM responses to paracellular/transcellular (PARA/TRANS) ratios, IgA responses to TRYCATs, natural IgM to malondialdehyde and Gram-negative bacteria, and PON1 enzymatic activity. Direct Hierarchical Exploratory Factor Analysis showed a bifactorial oblique model with a) a general factor which loaded highly on all symptom domains, named overall severity of schizophrenia ("OSOS"); and b) a single-group factor (SGF) loading on negative symptoms and PMR. We found that 40% of the variance in OSOS score was explained by IgA/IgM to PARA/TRANS ratio, male sex and education while 36.9% of the variance in SGF score was explained by IgA to PARA/TRANS, IgM to Gram-negative bacteria, female sex (positively associated) and IgM to MDA, and PON1 activity (negatively associated). Schizophrenia phenomenology comprises two biologically-validated dimensions, namely a general OSOS dimension and a single-group negative symptom dimension, which are associated with a breakdown of gut/BBB barriers, increased bacterial translocation and lowered protection against oxidation, inflammation and bacterial infections through lowered PON1 and natural IgM.

Maternal Transfer of Natural (Auto-) Antibodies in Chickens

The presence and relative levels (titers) of IgM and IgG natural antibodies (NAb) binding keyhole limpet hemocyanin (KLH), and natural (auto-) antibodies (N(A)Ab) binding salmon double-stranded DNA (dsDNA), (oxidated-) phosphatidyl (phosphoryl) choline-conjugated bovine serum albumin (PC-BSA), PC-conjugated ovalbumin (PC-OVA), and OVA, respectively, were studied in adult hen plasma, egg yolk, egg albumen, plasma of their hatchlings, and in 8-day-old chick plasma. Birds and eggs were from 2 lines divergently selected for high or low NAb levels binding KLH. This study aimed to determine 1) correlated phenotypic responses of selection for NAb to KLH, 2) transfer of maternal NAb and N(A)Ab via egg compartments, 3) levels of likely maternal NAb and N(A)Ab in hatchlings and 8-day-old chicks, and 4) whether a composite trait: IgM anti-PC-BSA/IgG anti-dsDNA ratio in the compartments could be used as a parameter for health or immune status. NAb and N(A)Ab to all tested antigens were found in adult hens, but low or no levels were found for IgM in yolk and IgG in albumen. Depending on the antigen, NAb and N(A)Ab were found in hatchlings and day 8 birds. Divergent selection and breeding based on NAb binding KLH affected antibody titers of almost all antigens in almost all compartments, in a similar way. Maternal transfer of NAb and N(A)Ab from the adult hen to offspring was via specific routes for specific antigens and isotypes, especially for IgG as suggested by cluster analyses and significant correlations. There was little indication of production of new NAb and N(A)Ab to the studied antigens in either the egg compartments or the hatchlings. A composite trait of IgM PC-BSA/IgG dsDNA ratio was as yet not indicative for immune status, as no significant differences were found between the lines for all compartments. In conclusion, hens provide neonatal chickens with natural (self-) binding IgG antibodies that have been proposed to perform homeostatic functions during the period in which neonates do not produce these antibodies themselves.

Breakdown of the Paracellular Tight and Adherens Junctions in the Gut and Blood Brain Barrier and Damage to the Vascular Barrier in Patients with Deficit Schizophrenia

Deficit schizophrenia is characterized by leaky intestinal tight and adherens junctions and bacterial translocation. Here we examine whether (deficit) schizophrenia is accompanied by leaky paracellular, transcellular, and vascular barriers in the gut and blood-brain barriers. We measured IgA responses to occludin, claudin-5, E-cadherin, and β-catenin (paracellular pathway, PARA); talin, actin, vinculin, and epithelial intermediate filament (transcellular pathway, TRANS); and plasmalemma vesicle-associated protein (PLVAP, vascular pathway) in 78 schizophrenia patients and 40 controls. IgA responses to claudin-5, E-cadherin, and β-catenin, the sum of the four PARA proteins, and the ratio PARA/TRANS were significantly higher in deficit schizophrenia patients than in nondeficit schizophrenia patients and controls. A large part of the variance in PHEMN (psychosis, hostility, excitation, mannerism, and negative) symptoms, psychomotor retardation, formal thought disorders, verbal fluency, word list memory, word list recall, and executive functions was explained by the PARA/TRANS ratio coupled with plasma IgA responses to Gram-negative bacteria, IgM to malondialdehyde, CCL-11 (eotaxin), IgA levels of the ratio of noxious to more protective tryptophan catabolites (NOX/PRO TRYCATs), and a plasma immune activation index. Moreover, IgA levels to Gram-negative bacteria were significantly associated with IgA to E-cadherin, β-catenin, and PLVAP, while IgA levels to claudin-5 were significantly predicted by IgA to E-cadherin, NOX/PRO TRYCAT ratio, Gram-negative bacteria, and CCL11. The phenomenology of the deficit syndrome is to a large extent explained by the cumulative effects of lowered natural IgM, breakdown of the paracellular and vascular pathways, increased bacterial translocation, peripheral immune-inflammatory responses, and indices of BBB breakdown.

Upregulation of the Intestinal Paracellular Pathway with Breakdown of Tight and Adherens Junctions in Deficit Schizophrenia

In 2001, the first author of this paper reported that schizophrenia is associated with an increased frequency of the haptoglobin (Hp)-2 gene. The precursor of Hp-2 is zonulin, a molecule that affects intercellular tight junction integrity. Recently, we reported increased plasma IgA/IgM responses to Gram-negative bacteria in deficit schizophrenia indicating leaky gut and gut dysbiosis. The current study was performed to examine the integrity of the paracellular (tight and adherens junctions) and transcellular (cytoskeletal proteins) pathways in deficit versus non-deficit schizophrenia. We measured IgM responses to zonulin, occludin, E-cadherin, talin, actin, and vinculin in association with IgA responses to Gram-negative bacteria, CCL-11, IgA responses to tryptophan catabolites (TRYCATs), immune activation and IgM to malondialdehyde (MDA), and NO-cysteinyl in 78 schizophrenia patients and 40 controls. We found that the ratio of IgM to zonulin + occludin/talin + actin + viculin (PARA/TRANS) was significantly greater in deficit than those in non-deficit schizophrenia and higher in schizophrenia than those in controls and was significantly associated with increased IgA responses to Gram-negative bacteria. IgM responses to zonulin were positively associated with schizophrenia (versus controls), while IgM to occludin was significantly associated with deficit schizophrenia (versus non-deficit schizophrenia and controls). A large part of the variance (90.8%) in negative and PHEM (psychosis, hostility, excitation, and mannerism) symptoms was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, IgM to E-cadherin and MDA, and memory dysfunctions, while 53.3% of the variance in the latter was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, CCL-11, TRYCATs, and immune activation. The results show an upregulated paracellular pathway with breakdown of the tight and adherens junctions and increased bacterial translocation in deficit schizophrenia. These dysfunctions in the intestinal paracellular route together with lowered natural IgM, immune activation, and production of CCL-11 and TRYCATs contribute to the phenomenology of deficit schizophrenia.

Leukocyte Bim deficiency does not impact atherogenesis in ldlr -/- mice, despite a pronounced induction of autoimmune inflammation

Proapoptotic Bcl-2 family member Bim is particularly relevant for deletion of autoreactive and activated T and B cells, implicating Bim in autoimmunity. As atherosclerosis is a chronic inflammatory process with features of autoimmune disease, we investigated the impact of hematopoietic Bim deficiency on plaque formation and parameters of plaque stability. Bim -/- or wild type bone marrow transplanted ldlr -/- mice were fed a Western type diet (WTD) for 5 or 10 weeks, after which they were immunophenotyped and atherosclerotic lesions were analyzed. Bim -/- transplanted mice displayed splenomegaly and overt lymphocytosis. CD4+ and CD8+ T cells were more activated (increased CD69 and CD71 expression, increased interferon gamma production). B cells were elevated by 147%, with a shift towards the pro-atherogenic IgG-producing B2 cell phenotype, resulting in a doubling of anti-oxLDL IgG1 antibody titers in serum of bim -/- mice. Bim -/- mice displayed massive intraplaque accumulation of Ig complexes and of lesional T cells, although this did not translate in changes in plaque size or stability features (apoptotic cell and macrophage content). The surprising lack in plaque phenotype despite the profound pro-atherogenic immune effects may be attributable to the sharp reduction of serum cholesterol levels in WTD fed bim -/- mice.

Senescent cells expose and secrete an oxidized form of membrane-bound vimentin as revealed by a natural polyreactive antibody

Studying the phenomenon of cellular senescence has been hindered by the lack of senescence-specific markers. As such, detection of proteins informally associated with senescence accompanies the use of senescence-associated β-galactosidase as a collection of semiselective markers to monitor the presence of senescent cells. To identify novel biomarkers of senescence, we immunized BALB/c mice with senescent mouse lung fibroblasts and screened for antibodies that recognized senescence-associated cell-surface antigens by FACS analysis and a newly developed cell-based ELISA. The majority of antibodies that we isolated, cloned, and sequenced belonged to the IgM isotype of the innate immune system. In-depth characterization of one of these monoclonal, polyreactive natural antibodies, the IgM clone 9H4, revealed its ability to recognize the intermediate filament vimentin. By using 9H4, we observed that senescent primary human fibroblasts express vimentin on their cell surface, and MS analysis revealed a posttranslational modification on cysteine 328 (C328) by the oxidative adduct malondialdehyde (MDA). Moreover, elevated levels of secreted MDA-modified vimentin were detected in the plasma of aged senescence-accelerated mouse prone 8 mice, which are known to have deregulated reactive oxygen species metabolism and accelerated aging. Based on these findings, we hypothesize that humoral innate immunity may recognize senescent cells by the presence of membrane-bound MDA-vimentin, presumably as part of a senescence eradication mechanism that may become impaired with age and result in senescent cell accumulation.

Silencing Triggering Receptors Expressed on Myeloid Cells-1 Impaired the Inflammatory Response to Oxidized Low-Density Lipoprotein in Macrophages

Atherosclerosis is a chronic progressive inflammatory disease characterized by the accumulation of lipid contents in arterial walls. Previous studies suggest participation of Toll-like receptors (TLRs) in lipid deposition and inflammatory response in vascular wall. The triggering receptor expressed on myeloid cells 1 (TREM-1) is a cell surface receptor of the immunoglobulin superfamily, which amplifies signal transduction of TLR pathway and enhances immune response to microbial infections. The aim of the present study was to investigate the effect of the oxidized low-density lipoprotein (oxLDL) on the expression of the TREM-1, as well as its engagement in proinflammatory cytokine production and foam cell formation in RAW264.7 mice macrophages. oxLDL enhanced TREM-1 and TLR-4, but not TLR-2 gene expression in macrophages; furthermore, silencing TREM-1 expression by short hairpin interfering RNA inhibited lipid phagocytosis and proinflammatory tumor necrosis factor-α (TNF-α) as well as interleukin-6 (IL-6) production in macrophages; moreover, application of synthetic antagonist, LP-17 polypeptide, reduced IL-6 production upon oxLDL stimulation in vitro and in vivo. In conclusion, in macrophages, oxLDL enhanced expression of TREM-1, which amplifies the innate immune response of TLR pathway; activation of TREM-1 contributes to atherogenesis process by enhancing proinflammatory cytokine production and foam cell formation.

Transplantation and Damage-Associated Molecular Patterns (DAMPs)

Upon solid organ transplantation and during cancer immunotherapy, cellular stress responses result in the release of damage-associated molecular patterns (DAMPs). The various cellular stresses have been characterized in detail over the last decades, but a unifying classification based on clinically important aspects is lacking. Here, we provide an in-depth review of the most recent literature along with a unifying concept of the danger/injury model, suggest a classification of DAMPs, and review the recently elaborated mechanisms that result in the emission of such factors. We further point out the differences in DAMP responses including the release following a heat shock pattern, endoplasmic reticulum stress, DNA damage-mediated DAMP release, and discuss the diverse pathways of regulated necrosis in this respect. The understanding of various forms of DAMPs and the consequences of their different release patterns are prerequisite to associate serum markers of cellular stresses with clinical outcomes.

Immunological Outcomes of Antibody Binding to Glycans Shared between Microorganisms and Mammals

Glycans constitute basic cellular components of living organisms across biological kingdoms, and glycan-binding Abs participate in many cellular interactions during immune defense against pathogenic organisms. Glycan epitopes are expressed as carbohydrate-only entities or as oligomers or polymers on proteins and lipids. Such epitopes on glycoproteins may be formed by posttranslational modifications or neoepitopes resulting from metabolic-catabolic processes and can be altered during inflammation. Pathogenic organisms can display host-like glycans to evade the host immune response. However, Abs to glycans, shared between microorganisms and the host, exist naturally. These Abs are able to not only protect against infectious disease, but also are involved in host housekeeping functions and can suppress allergic disease. Despite the reactivity of these Abs to glycans shared between microorganisms and host, diverse tolerance-inducing mechanisms permit the B cell precursors of these Ab-secreting cells to exist within the normal B cell repertoire.

Apoptotic cell responses in the splenic marginal zone: a paradigm for immunologic reactions to apoptotic antigens with implications for autoimmunity

Apoptotic cells drive innate regulatory responses that result in tolerogenic immunity. This is a critical aspect of cell physiology as apoptotic cells expose potentially dangerous nuclear antigens on the surface in apoptotic blebs, and failure in their recognition, phagocytosis, or destruction can cause dramatic autoimmunity in experimental models and is linked to development and progression of systemic pathology in human. The marginal zone is a specialized splenic environment that serves as a transitional site from circulation to peripheral lymphoid structures. The marginal zone serves a key role in trapping of particulates and initiation of innate responses against systemic microbial pathogens. However in recent years, it has become clear the marginal zone is also important for initiation of immune tolerance to apoptotic cells, driving a coordinated response involving multiple phagocyte and lymphocyte subsets. Recent reports linking defects in splenic macrophage function to systemic lupus erythematosus in a manner analogous to marginal zone macrophages in lupus-prone mice provide an impetus to better understand the mechanistic basis of the apoptotic cell response in the marginal zone and its general applicability to apoptotic cell-driven tolerance at other tissue sites. In this review, we discuss immune responses to apoptotic cells in the spleen in general and the marginal zone in particular, the relationship of these responses to autoimmune disease, and comparisons to apoptotic cell immunity in humans.

Novel immune assay for quantification of plasma protective capacity against oxidized phospholipids

Aim: Oxidized phospholipids (OxPL) are the major pathogenic component of oxidized low-density lipoproteins (OxLDL). Endogenous anti-OxPL activity, defined as the ability to neutralize adverse effects of oxidized lipids, may have biomarker potential. Methods & results: Using two anti-OxPL monoclonal antibodies (commercial mAB-E06 and custom mAB-509) we developed a novel ELISA that measures the global capacity of plasma to inactivate OxPL. Preincubation of OxLDL with plasma inhibits its binding of anti-OxPL mABs. This phenomenon (‘masking’) reflects anti-OxPL plasma activity. A pilot clinical application of the assay revealed reduced anti-OxPL activity in hypertension, coronary artery disease, acute coronary syndrome and diabetes. Conclusion: Inadequate anti-OxPL protection may contribute to cardiovascular disease and have biomarker potential in conditions associated with abnormal lipid peroxidation.

Nanotechnology inspired tools for mitochondrial dysfunction related diseases

Mitochondrial dysfunctions are recognized as major factors for various diseases including cancer, cardiovascular diseases, diabetes, neurological disorders, and a group of diseases so called "mitochondrial dysfunction related diseases". One of the major hurdles to gain therapeutic efficiency in diseases where the targets are located in the mitochondria is the accessibility of the targets in this compartmentalized organelle that imposes barriers toward internalization of ions and molecules. Over the time, different tools and techniques were developed to improve therapeutic index for mitochondria acting drugs. Nanotechnology has unfolded as one of the logical and encouraging tools for delivery of therapeutics in controlled and targeted manner simultaneously reducing side effects from drug overdose. Tailor-made nanomedicine based therapeutics can be an excellent tool in the toolbox for diseases associated with mitochondrial dysfunctions. In this review, we present an extensive coverage of possible therapeutic targets in different compartments of mitochondria for cancer, cardiovascular, and mitochondrial dysfunction related diseases.

Specific autoantigens in experimental autoimmunity-associated atherosclerosis

Higher cardiovascular morbidity in patients with a wide range of autoimmune diseases highlights the importance of autoimmunity in promoting atherosclerosis. Our purpose was to investigate the mechanisms of accelerated atherosclerosis and identified vascular autoantigens targeted by autoimmunity. We created a mouse model of autoimmunity-associated atherosclerosis by transplanting bone marrow from FcγRIIB knockout (FcRIIB(-/-)) mice into LDL receptor knockout mice. We characterized the cellular and molecular mechanisms of atherogenesis and identified specific aortic autoantigens using serologic proteomic studies. En face lesion area analysis showed more aggressive atherosclerosis in autoimmune mice compared with control mice (0.64 ± 0.12 vs 0.32 ± 0.05 mm(2); P < 0.05, respectively). At the cellular level, FcRIIB(-/-) macrophages showed significant reduction (46-72%) in phagocytic capabilities. Proteomic analysis revealed circulating autoantibodies in autoimmune mice that targeted 25 atherosclerotic lesion proteins, including essential components of adhesion complex, cytoskeleton, and extracellular matrix, and proteins involved in critical functions and pathways. Microscopic examination of atherosclerotic plaques revealed essential colocalization of autoantibodies with endothelial cells, their adherence to basement membranes, the internal elastica lamina, and necrotic cores. The new vascular autoimmunosome may be a useful target for diagnostic and immunotherapeutic interventions in autoimmunity-associated diseases that have accelerated atherosclerosis.-Merched, A. J., Daret, D., Li, L., Franzl, N., Sauvage-Merched, M. Specific autoantigens in experimental autoimmunity-associated atherosclerosis.

Innate response activator B cells: origins and functions

Innate response activator (IRA) B cells are a subset of B-1a derived B cells that produce the growth factors granulocyte macrophage colony stimulating factor and IL-3. In mouse models of sepsis and pneumonia, B-1a B cells residing in serosal sites recognize bacteria, migrate to the spleen or lung, and differentiate to IRA B cells that then contribute to the host response by amplifying inflammation and producing polyreactive IgM. In atherosclerosis, IRA B cells accumulate in the spleen, where they promote extramedullary hematopoiesis and activate classical dendritic cells. In this review, we focus on the ontogeny and function of IRA B cells in acute and chronic inflammation.

The Role of Damage-Associated Molecular Patterns (DAMPs) in Human Diseases: Part II: DAMPs as diagnostics, prognostics and therapeutics in clinical medicine

This article is the second part of a review that addresses the role of damage-associated molecular patterns (DAMPs) in human diseases by presenting examples of traumatic (systemic inflammatory response syndrome), cardiovascular (myocardial infarction), metabolic (type 2 diabetes mellitus), neurodegenerative (Alzheimer's disease), malignant and infectious diseases. Various DAMPs are involved in the pathogenesis of all these diseases as they activate innate immune machineries including the unfolded protein response and inflammasomes. These subsequently promote sterile autoinflammation accompanied, at least in part, by subsequent adaptive autoimmune processes. This review article discusses the future role of DAMPs in routine practical medicine by highlighting the possibility of harnessing and deploying DAMPs either as biomarkers for the appropriate diagnosis and prognosis of diseases, as therapeutics in the treatment of tumours or as vaccine adjuncts for the prophylaxis of infections. In addition, this article examines the potential for developing strategies aimed at mitigating DAMPs-mediated hyperinflammatory responses, such as those seen in systemic inflammatory response syndrome associated with multiple organ failure.

The Role of Damage-Associated Molecular Patterns in Human Diseases: Part I - Promoting inflammation and immunity

There is increasing interest by physicians in the impact of the innate immune system on human diseases. In particular, the role of the molecules that initiate and amplify innate immune pathways, namely damage-associated molecular patterns (DAMPs), is of interest as these molecules are involved in the pathogenesis of many human disorders. The first part of this review identifies five classes of cell stress/tissue injury-induced DAMPs that are sensed by various recognition receptor-bearing cells of the innate immune system, thereby mounting inflammation, promoting apoptosis and shaping adaptive immune responses. The DAMPs activate and orchestrate several innate immune machineries, including inflammasomes and the unfolded protein response that synergistically operates to induce inflammatory, metabolic and adaptive immune pathologies. Two examples of autoimmune diseases are discussed as they represent a typical paradigm of the intimate interplay between innate and adaptive immune responses.

Oxidized lipids and lysophosphatidylcholine induce the chemotaxis, up-regulate the expression of CCR9 and CXCR4 and abrogate the release of IL-6 in human monocytes

Lipids through regulation of chronic inflammation play key roles in the development of various diseases. Here, we report that a mixed population of human primary monocytes migrated towards LPC, as well as oxidized linoleic acid isoforms 9-S-HODE, 9-R-HODE and 13-R-HODE. Incubation with 9-R-HODE, 13-R-HODE and LPC resulted in increased expression of CXCR4, the receptor for SDF-1α/CXCL12, correlated with increased monocyte migration towards SDF-1α/CXCL12. Further, we report increased expression of CCR9, the receptor for TECK/CCL25, after stimulation with these lipids. Upon examining the migratory response towards TECK/CCL25, it was observed that an increase in CCR9 expression upon pre-treatment with 9-S-HODE, 9-R-HODE, 13-R-HODE and LPC resulted in increased migration of monocytes expressing CCR9. Only LPC but not any other lipid examined increased the influx of intracellular Ca²⁺ in monocytes. Finally, 9-S-HODE, 9-R-HODE, 13-R-HODE, or LPC inhibited the release of IL-6 from monocytes suggesting that these lipids may play important role in controlling inflammatory responses.

Advances in immune-modulating therapies to treat atherosclerotic cardiovascular diseases

In addition to hypercholesterolemia, innate and adaptive immune mechanisms play a critical role in atherogenesis, thus making immune-modulation therapy a potentially attractive way of managing atherosclerotic cardiovascular disease. These immune-modulation strategies include both active and passive immunization and confer beneficial reduction in atherosclerosis. Preclinical studies have demonstrated promising results and we review current knowledge on the complex role of the immune system and the potential for immunization as an immune-modulation therapy for atherosclerosis.

Danger signals - damaged-self recognition across the tree of life

Multicellular organisms suffer injury and serve as hosts for microorganisms. Therefore, they require mechanisms to detect injury and to distinguish the self from the non-self and the harmless non-self (microbial mutualists and commensals) from the detrimental non-self (pathogens). Danger signals are "damage-associated molecular patterns" (DAMPs) that are released from the disrupted host tissue or exposed on stressed cells. Seemingly ubiquitous DAMPs are extracellular ATP or extracellular DNA, fragmented cell walls or extracellular matrices, and many other types of delocalized molecules and fragments of macromolecules that are released when pre-existing precursors come into contact with enzymes from which they are separated in the intact cell. Any kind of these DAMPs enable damaged-self recognition, inform the host on tissue disruption, initiate processes aimed at restoring homeostasis, such as sealing the wound, and prepare the adjacent tissues for the perception of invaders. In mammals, antigen-processing and -presenting cells such as dendritic cells mature to immunostimulatory cells after the perception of DAMPs, prime naïve T-cells and elicit a specific adaptive T-/B-cell immune response. We discuss molecules that serve as DAMPs in multiple organisms and their perception by pattern recognition receptors (PRRs). Ca(2+)-fluxes, membrane depolarization, the liberation of reactive oxygen species and mitogen-activated protein kinase (MAPK) signaling cascades are the ubiquitous molecular mechanisms that act downstream of the PRRs in organisms across the tree of life. Damaged-self recognition contains both homologous and analogous elements and is likely to have evolved in all eukaryotic kingdoms, because all organisms found the same solutions for the same problem: damage must be recognized without depending on enemy-derived molecules and responses to the non-self must be directed specifically against detrimental invaders.

Alkoxyamines: a new family of pro-drugs against cancer. Concept for theranostics

Concept to apply alkoxyamines as a theranostic against cancer. The success relies on the highly biological generation of an unselective alkyl radical at the right time and at the right place.

Immune mechanisms in atherosclerosis, especially in diabetes type 2

Atherosclerosis and ensuing cardiovascular disease (CVD) are major complications of diabetes type 2. Atherosclerosis is a chronic inflammatory condition involving immunocompetent cells of different types present in the lesions. Even though inflammation and immune activation may be more pronounced in atherosclerosis in diabetes type 2, there does not appear to be any major differences between diabetics and non-diabetics. Similar factors are thus implicated in atherosclerosis-associated immune activation in both groups. The cause of immune activation is not known and different mutually non-exclusive possibilities exist. Oxidized and/or enzymatically modified forms of low-density lipoprotein (OxLDL) and dead cells are present in atherosclerotic plaques. OxLDL could play a role, being pro-inflammatory and immunostimulatory as it activates T-cells and is cytotoxic at higher concentrations. Inflammatory phospholipids in OxLDL are implicated, with phosphorylcholine (PC) as one of the exposed antigens. Antibodies against PC (anti-PC) are anti-atherogenic in mouse studies, and anti-PC is negatively associated with development of atherosclerosis and CVD in humans. Bacteria and virus have been discussed as potential causes of immune activation, but it has been difficult to find direct evidence supporting this hypothesis, and antibiotic trials in humans have been negative or inconclusive. Heat shock proteins (HSP) could be one major target for atherogenic immune reactions. More direct causes of plaque rupture include cytokines such as interleukin 1β (IL-1β), tumor necrosis factor (TNF), and also lipid mediators as leukotrienes. In addition, in diabetes, hyperglycemia and oxidative stress appear to accelerate the development of atherosclerosis, one mechanism could be via promotion of immune reactions. To prove that immune reactions are causative of atherosclerosis and CVD, further studies with immune-modulatory treatments are needed.

Antibody polyreactivity in health and disease: statu variabilis

An Ab molecule or a BCR that is able to bind multiple structurally unrelated Ags is defined as polyreactive. Polyreactive Abs and BCRs constitute an important part of immune repertoires under physiological conditions and may play essential roles in immune defense and in the maintenance of immune homeostasis. In this review, we integrate and discuss different findings that reveal the indispensable role of Ag-binding polyreactivity in the immune system. First, we describe the functional and molecular characteristics of polyreactive Abs. The following part of the review concentrates on the biological roles attributed to polyreactive Abs and to polyreactive BCRs. Finally, we discuss recent studies that link Ig polyreactivity with distinct pathological conditions.

Can proteomics yield insight into aging aorta?

The aging aorta exhibits structural and physiological changes that are reflected in the proteome of its component cells types. The advance in proteomic technologies has made it possible to analyze the quantity of proteins associated with the natural history of aortic aging. These alterations reflect the molecular and cellular mechanisms of aging and could provide an opportunity to predict vascular health. This paper focuses on whether discoveries stemming from the application of proteomic approaches of the intact aging aorta or vascular smooth muscle cells can provide useful insights. Although there have been limited studies to date, a number of interesting proteins have been identified that are closely associated with aging in the rat aorta. Such proteins, including milk fat globule-EGF factor 8, matrix metalloproteinase type-2, and vitronectin, could be used as indicators of vascular health, or even explored as therapeutic targets for aging-related vascular diseases.

Low levels of a natural IgM antibody are associated with vein graft stenosis and failure

BACKGROUND

All humans have natural, protective antibodies directed against phosphorylcholine (PC) epitopes, a common inflammatory danger signal appearing at sites of cell injury, oxidative stress, and on bacterial capsules. In large human cohorts, low levels of anti-PC IgM were associated with a significantly increased risk of stroke or myocardial infarction. However, it is not known if these antibodies protect against the premature closure of arterial reconstructions.

METHODS

A prospective, observational study of patients undergoing elective, infrainguinal, autogenous vein bypasses for atherosclerotic occlusive disease of the legs was conducted. Clinical data were recorded prospectively, and preoperative levels of anti-PC IgM measured with the CVDefine kit from Athera Biotechnologies (Solna, Sweden). The principal clinical end point was the loss of primary patency (loss of graft flow, or any intervention for stenosis). Patients were followed regularly by duplex ultrasound at 1, 3, 6, 12, 18 months, and yearly thereafter.

RESULTS

Fifty-six patients were studied, for an average of 1.3 years. Indications for surgery were claudication (33.9%), ischemic rest pain (17.9%), and ischemia with ulceration or gangrene (48.2%). Seventeen (30.4%) patients experienced loss of primary patency (10 graft occlusions, seven surgical or endovascular revisions of graft stenoses). Kaplan-Meier survival analysis showed that the quartile of patients with the lowest anti-PC IgM levels had significantly worse primary graft patency (log-rank test, P = .0085). Uni- and multivariate Cox proportional hazards analysis revealed that the preoperative anti-PC IgM level was an important predictor of graft failure. Patients with IgM values in the lowest quartile had a 3.6-fold increased risk of graft failure (95% confidence interval: 1.1-12.1), even after accounting for other significant clinical or technical factors such as indication for surgery, site of distal anastomosis, or vein graft diameter.

CONCLUSIONS

A naturally occurring IgM antibody directed against the proinflammatory epitope PC may be protective against vein graft stenosis and failure, through anti-inflammatory mechanisms. Measurement of this antibody may be a useful prognostic indicator, although larger studies of more diverse populations will be needed to confirm these results. The biological actions of anti-PC IgM suggest it may be useful in developing immunotherapies to improve bypass longevity.