Physiological and Pathological Inflammation Induced by Antibodies and Pentraxins

Intersecting Pathways: The Role of Metabolic Dysregulation, Gastrointestinal Microbiome, and Inflammation in Acute Ischemic Stroke Pathogenesis and Outcomes

Acute ischemic stroke (AIS) remains a major cause of mortality and long-term disability worldwide, driven by complex and multifaceted etiological factors. Metabolic dysregulation, gastrointestinal microbiome alterations, and systemic inflammation are emerging as significant contributors to AIS pathogenesis. This review addresses the critical need to understand how these factors interact to influence AIS risk and outcomes. We aim to elucidate the roles of dysregulated adipokines in obesity, the impact of gut microbiota disruptions, and the neuroinflammatory cascade initiated by lipopolysaccharides (LPS) in AIS. Dysregulated adipokines in obesity exacerbate inflammatory responses, increasing AIS risk and severity. Disruptions in the gut microbiota and subsequent LPS-induced neuroinflammation further link systemic inflammation to AIS. Advances in neuroimaging and biomarker development have improved diagnostic precision. Here, we highlight the need for a multifaceted approach to AIS management, integrating metabolic, microbiota, and inflammatory insights. Potential therapeutic strategies targeting these pathways could significantly improve AIS prevention and treatment. Future research should focus on further elucidating these pathways and developing targeted interventions to mitigate the impacts of metabolic dysregulation, microbiome imbalances, and inflammation on AIS.

The role of the oviduct environment in embryo survival

CONTEXT

Declining fertility is an issue in multiple mammalian species. As the site of fertilisation and early embryo development, the oviduct plays a critical role in embryo survival, yet there is a paucity of information on how the oviduct regulates this process.

AIMS

We hypothesised that differences in steroid hormone signalling and/or immune function would be observed in a model of poor embryo survival, the peripubertal ewe.

METHODS

We examined expression of steroid hormones in systemic circulation, oviductal expression of oestrogen receptorαand genes important in steroid hormone signalling, and immune function in pregnant and cyclic peripubertal and adult ewes on day 3 after oestrus.

KEY RESULTS

Concentrations of progesterone, but not oestradiol, were decreased in the peripubertal ewe compared to the adult ewe. Oestrogen receptorαprotein expression was increased in the peripubertal ewe, but pathway analysis of gene expression revealed downregulation of the oestrogen signalling pathway compared to the adult ewe. Differential expression of several genes involved in immune function between the peripubertal and adult ewe was consistent with an unfavourable oviductal environment in the peripubertal ewe lamb. Oestradiol concentration was positively correlated with the expression of multiple genes involved in the regulation of immune function.

CONCLUSIONS

Differences in the immune environment of the oviduct, potentially linked to differential modulation by steroid hormones, may partially underly the poor fertilisation and early embryo survival observed in the peripubertal ewe.

IMPLICATIONS

A unfavourable oviductal environment may play an important role in limiting reproductive success.

WR-PTXF, a novel short pentraxin, protects gut mucosal barrier and enhances the antibacterial activity in Carassius cuvieri × Carassius auratus red var

The pentraxin family is an evolutionarily conserved group that plays an important role in innate immunity. C-reactive protein (CRP) and serum amyloid P component (SAP) are classical members of the short pentraxins and are known to be the major acute phase proteins. In this work, we have cloned a novel pentraxin fusion protein, WR-PTXF, from Carassius cuvieri × Carassius auratus red var. In fish, the biological function of PTXF is essentially unknown. For this purpose, we report the identification and analysis of WR-PTXF and elucidate its role in the antibacterial innate immunity. WR-PTXF contains 224 amino acids and shares 79.8% and 23.0% sequence identities with crucian carp CRP and SAP, respectively. Blast analysis shows that WR-PTXF and goldfish PTXF had the highest similarity (97.3%). WR-PTXF is expressed in multiple tissues and is upregulated by Aeromonas hydrophila infection. WR-PTXF contains a short pentraxin domain and recombinant WR-PTXF protein (rWR-PTXF) can bind the A. hydrophila in a concentration-dependent manner. Further, rWR-PTXF displays apparent bacteriostatic activity against A. hydrophila in vitro by enhancing the uptake of the bound bacteria by host phagocytes. When introduced in vivo, rWR-PTXF not only protects the gut mucosa but also limits the colonization of A. hydrophila in systemic immune organs. Consistently, knockdown of WR-PTXF significantly promotes bacterial dissemination in the tissues of host. These results indicate that WR-PTXF is a classic pattern recognition molecule that exerts a protective effect against bacterial infection.

Two Polarity-Sensitive Fluorescent Probes Based on Curcumin Analogs for Visualizing Polarity Changes in Lipid Droplets

As a class of highly dynamic organelles, lipid droplets (LDs) are involved in numerous physiological functions, and the changes in polarity of LDs are closely related to a variety of diseases. In this work, we developed two polarity-sensitive fluorescent probes (CC-CH and CC-Cl) based on curcumin analogs. CC-CH and CC-Cl with a donor-acceptor-donor (D-A-D) structure exhibited the property of intramolecular charge transfer (ICT); thus, their fluorescence emissions were significantly attenuated with increasing ambient polarity. Cell experiments indicated that CC-CH and CC-Cl showed excellent photostability, a low cytotoxicity, and a superior targeting ability regarding LDs. After treatment with oleic acid (OA) and methyl-β-cyclodextrin (M-β-CD), the polarity changes of LDs in living cells could be visualized by using CC-CH and CC-Cl. In addition, CC-CH and CC-Cl could monitor polarity changes of LDs in different pathological processes, including inflammatory responses, nutrient deprivation, and H2O2-induced oxidative stress. Therefore, CC-CH and CC-Cl are promising potential fluorescent probes for tracking intracellular LD polarity changes.

Rituximab induced cytokine release with high serum IP-10 (CXCL10) concentrations is associated with infusion reactions

Monoclonal antibody induced infusion reactions (IRs) can be serious and even fatal. We used clinical data and blood samples from 37 treatment naïve patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) initiating therapy for progressive disease with a single 50 mg dose of intravenous (IV) rituximab at 25 mg/h. Twenty-four (65 %) patients had IRs at a median of 78 min (range 35-128) and rituximab dose of 32 mg (range 15-50). IR risk did not correlate with patient or CLL characteristics, CLL counts or CD20 levels, or serum rituximab or complement concentrations. Thirty-five (95 %) patients had cytokine release response with a ≥ 4-fold increase in serum concentration of ≥ 1 inflammatory cytokine. IRs were associated with significantly higher post-infusion serum concentrations of gamma interferon induced cytokines IP-10, IL-6 and IL-8. IP-10 concentrations increased ≥ 4-fold in all patients with an IR and were above the upper limit of detection (40,000 pg/ml) in 17 (71 %). In contrast, to only three (23 %) patients without an IR had an ≥ 4-fold increase in serum concentrations of IP-10 (highest 22,013 pg/ml). Our data suggest that cytokine release could be initiated by activation of effector cells responsible for clearance of circulating CLL cells with IRs occurring in those with higher levels of gamma interferon induced cytokines. These novel insights could inform future research to better understand and manage IRs and understand the role of cytokines in the control of cytotoxic immune responses to mAb.

Organokines in COVID-19: A Systematic Review

Coronavirus disease 2019 (COVID-19) is a viral infection caused by SARS-CoV-2 that induces a generalized inflammatory state. Organokines (adipokines, osteokines, myokines, hepatokines, and cardiokines) can produce beneficial or harmful effects in this condition. This study aimed to systematically review the role of organokines on COVID-19. PubMed, Embase, Google Scholar, and Cochrane databases were searched, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and 37 studies were selected, comprising more than 2700 individuals infected with the virus. Among COVID-19 patients, organokines have been associated with endothelial dysfunction and multiple organ failure due to augmented cytokines and increased SARS-CoV-2 viremia. Changes in the pattern of organokines secretion can directly or indirectly contribute to aggravating the infection, promoting immune response alterations, and predicting the disease progression. These molecules have the potential to be used as adjuvant biomarkers to predict the severity of the illness and severe outcomes.

IgA2 immune complexes selectively promote inflammation by human CD103+ dendritic cells

While immunoglobulin A (IgA) is well known for its neutralizing and anti-inflammatory function, it is becoming increasingly clear that IgA can also induce human inflammatory responses by various different immune cells. Yet, little is known about the relative role of induction of inflammation by the two IgA subclasses i.e. IgA1, most prominent subclass in circulation, and IgA2, most prominent subclass in the lower intestine. Here, we set out to study the inflammatory function of IgA subclasses on different human myeloid immune cell subsets, including monocytes, and in vitro differentiated macrophages and intestinal CD103+ dendritic cells (DCs). While individual stimulation with IgA immune complexes only induced limited inflammatory responses by human immune cells, both IgA subclasses strongly amplified pro-inflammatory cytokine production upon co-stimulation with Toll-like receptor (TLR) ligands such as Pam3CSK4, PGN, and LPS. Strikingly, while IgA1 induced slightly higher or similar levels of pro-inflammatory cytokines by monocytes and macrophages, respectively, IgA2 induced substantially more inflammation than IgA1 by CD103+ DCs. In addition to pro-inflammatory cytokine proteins, IgA2 also induced higher mRNA expression levels, indicating that amplification of pro-inflammatory cytokine production is at least partially regulated at the level of gene transcription. Interestingly, cytokine amplification by IgA1 was almost completely dependent on Fc alpha receptor I (FcαRI), whilst blocking this receptor only partially reduced cytokine induction by IgA2. In addition, IgA2-induced amplification of pro-inflammatory cytokines was less dependent on signaling through the kinases Syk, PI3K, and TBK1/IKKϵ. Combined, these findings indicate that IgA2 immune complexes, which are most abundantly expressed in the lower intestine, particularly promote inflammation by human CD103+ intestinal DCs. This may serve an important physiological function upon infection, by enabling inflammatory responses by this otherwise tolerogenic DC subset. Since various inflammatory disorders are characterized by disturbances in IgA subclass balance, this may also play a role in the induction or exacerbation of chronic intestinal inflammation.

The BNT162b2 mRNA SARS-CoV-2 vaccine induces transient afucosylated IgG1 in naive but not in antigen-experienced vaccinees

BACKGROUND

Afucosylated IgG1 responses have only been found against membrane-embedded epitopes, including anti-S in SARS-CoV-2 infections. These responses, intrinsically protective through enhanced FcγRIIIa binding, can also trigger exacerbated pro-inflammatory responses in severe COVID-19. We investigated if the BNT162b2 SARS-CoV-2 mRNA also induced afucosylated IgG responses.

METHODS

Blood from vaccinees during the first vaccination wave was collected. Liquid chromatography-Mass spectrometry (LC-MS) was used to study anti-S IgG1 Fc glycoprofiles. Responsiveness of alveolar-like macrophages to produce proinflammatory cytokines in presence of sera and antigen was tested. Antigen-specific B cells were characterized and glycosyltransferase levels were investigated by Fluorescence-Activated Cell Sorting (FACS).

FINDINGS

Initial transient afucosylated anti-S IgG1 responses were found in naive vaccinees, but not in antigen-experienced ones. All vaccinees had increased galactosylated and sialylated anti-S IgG1. Both naive and antigen-experienced vaccinees showed relatively low macrophage activation potential, as expected, due to the low antibody levels for naive individuals with afucosylated IgG1, and low afucosylation levels for antigen-experienced individuals with high levels of anti-S. Afucosylation levels correlated with FUT8 expression in antigen-specific plasma cells in naive individuals. Interestingly, low fucosylation of anti-S IgG1 upon seroconversion correlated with high anti-S IgG levels after the second dose.

INTERPRETATION

Here, we show that BNT162b2 mRNA vaccination induces transient afucosylated anti-S IgG1 responses in naive individuals. This observation warrants further studies to elucidate the clinical context in which potent afucosylated responses would be preferred.

FUNDING

LSBR1721, 1908; ZonMW10430012010021, 09150161910033, 10430012010008; DFG398859914, 400912066, 390884018; PMI; DOI4-Nr. 3; H2020-MSCA-ITN 721815.

C-Reactive Protein Controls IL-23 Production by Human Monocytes

C-reactive protein (CRP) is an acute-phase protein in humans that is produced in high quantities by the liver upon infection and under inflammatory conditions. Although CRP is commonly used as a marker of inflammation, CRP can also directly contribute to inflammation by eliciting pro-inflammatory cytokine production by immune cells. Since CRP is highly elevated in serum under inflammatory conditions, we have studied the CRP-induced cytokine profile of human monocytes, one of the main innate immune cell populations in blood. We identified that CRP is relatively unique in its capacity to induce production of the pro-inflammatory cytokine IL-23, which was in stark contrast to a wide panel of pattern recognition receptor (PRR) ligands. We show that CRP-induced IL-23 production was mediated at the level of gene transcription, since CRP particularly promoted gene transcription of IL23A (encoding IL-23p19) instead of IL12A (encoding IL-12p35), while PRR ligands induce the opposite response. Interestingly, when CRP stimulation was combined with PRR ligand stimulation, as for example, occurs in the context of sepsis, IL-23 production by monocytes was strongly reduced. Combined, these data identify CRP as a unique individual ligand to induce IL-23 production by monocytes, which may contribute to shaping systemic immune responses under inflammatory conditions.