Intraepithelial neutrophils in mammary, urinary and gall bladder infections

Identification and validation of immune and diagnostic biomarkers for interstitial cystitis/painful bladder syndrome by integrating bioinformatics and machine-learning

Background

The etiology of interstitial cystitis/painful bladder syndrome (IC/BPS) remains elusive, presenting significant challenges in both diagnosis and treatment. To address these challenges, we employed a comprehensive approach aimed at identifying diagnostic biomarkers that could facilitate the assessment of immune status in individuals with IC/BPS.

Methods

Transcriptome data from IC/BPS patients were sourced from the Gene Expression Omnibus (GEO) database. We identified differentially expressed genes (DEGs) crucial for gene set enrichment analysis. Key genes within the module were revealed using weighted gene co-expression network analysis (WGCNA). Hub genes in IC/BPS patients were identified through the application of three distinct machine-learning algorithms. Additionally, the inflammatory status and immune landscape of IC/BPS patients were evaluated using the ssGSEA algorithm. The expression and biological functions of key genes in IC/BPS were further validated through in vitro experiments.

Results

A total of 87 DEGs were identified, comprising 43 up-regulated and 44 down-regulated genes. The integration of predictions from the three machine-learning algorithms highlighted three pivotal genes: PLAC8 (AUC: 0.887), S100A8 (AUC: 0.818), and PPBP (AUC: 0.871). Analysis of IC/BPS tissue samples confirmed elevated PLAC8 expression and the presence of immune cell markers in the validation cohorts. Moreover, PLAC8 overexpression was found to promote the proliferation of urothelial cells without affecting their migratory ability by inhibiting the Akt/mTOR/PI3K signaling pathway.

Conclusions

Our study identifies potential diagnostic candidate genes and reveals the complex immune landscape associated with IC/BPS. Among them, PLAC8 is a promising diagnostic biomarker that modulates the immune response in patients with IC/BPS, which provides new insights into the future diagnosis of IC/BPS.

A Dynamic Interplay of Innate Immune Responses During Urinary Tract Infection

Urinary tract infections (UTIs) represent one of the most prevalent bacterial infections globally, manifesting in diverse clinical phenotypes with varying degrees of severity and complications. The mechanisms underlying UTIs are gradually being elucidated, leading to an enhanced understanding of the immune responses involved. Innate immune cells play a crucial defensive role against uropathogenic bacteria through various mechanisms. Despite their significant contributions to host defense, these cells often fail to achieve complete clearance of uropathogens, necessitating the frequent prescription of antibiotics for UTI patients. However, the persistence of infections and related pathological symptoms in the absence of innate immune cells in animal models underscore the importance of innate immunity in UTIs. Therefore, the host protective functions of innate immune cells, including neutrophils, macrophages, mast cells, NK cells, innate lymphoid cells, and γδ T cells, are delicately coordinated and timely regulated by a variety of cytokines to ensure successful pathogen clearance.

Altered microbiome of serum exosomes in patients with acute and chronic cholecystitis

BACKGROUND

This study aimed to investigate the differences in the microbiota composition of serum exosomes from patients with acute and chronic cholecystitis.

METHOD

Exosomes were isolated from the serum of cholecystitis patients through centrifugation and identified and characterized using transmission electron microscopy and nano-flow cytometry. Microbiota analysis was performed using 16S rRNA sequencing.

RESULTS

Compared to patients with chronic cholecystitis, those with acute cholecystitis exhibited lower richness and diversity. Beta diversity analysis revealed significant differences in the microbiota composition between patients with acute and chronic cholecystitis. The relative abundance of Proteobacteria was significantly higher in exosomes from patients with acute cholecystitis, whereas Actinobacteria, Bacteroidetes, and Firmicutes were significantly more abundant in exosomes from patients with chronic cholecystitis. Furthermore, functional predictions of microbial communities using Tax4Fun analysis revealed significant differences in metabolic pathways such as amino acid metabolism, carbohydrate metabolism, and membrane transport between the two patient groups.

CONCLUSIONS

This study confirmed the differences in the microbiota composition within serum exosomes of patients with acute and chronic cholecystitis. Serum exosomes could serve as diagnostic indicators for distinguishing acute and chronic cholecystitis.

Mesenchymal stromal cells modulate infection and inflammation in the uterus and mammary gland

The use of mesenchymal stromal cells (MSCs) is emerging as an efficacious and safe treatment for many infectious and non-infectious inflammatory diseases in human and veterinary medicine. Such use could be done to treat mastitis and metritis, which are the most common disease conditions affecting dairy cows leading to considerable economic losses and reduced animal welfare. Currently, both disease conditions are commonly treated using local and systemic administration of antibiotics. However, this strategy has many disadvantages including low cure rates and the public health hazards. Looking for alternative approaches, we investigated the properties of MSCs using in-vitro mammary and endometrial cell systems and in-vivo mastitis and metritis murine model systems. In-vitro, co-culture of mammary and uterus epithelial cells constructed with NF-kB reporter system, the master regulator of inflammation, demonstrated their anti-inflammatory effects in response to.LPS. In vivo, we challenge animals with field strains of mammary and utero pathogenic Escherichia coli and evaluated the effects of local and systemic application of MSC in the animal models. Disease outcome was evaluated using histological analysis, bacterial counts and gene expression of inflammatory markers. We show that MSC treatment reduced bacterial load in metritis and significantly modulated the inflammatory response of the uterus and mammary gland to bacterial infection. Most notably are the immune modulatory effects of remotely engrafted intravenous MSCs, which open new avenues to the development of MSC-based cell-free therapies.

Sialylation regulates neutrophil transepithelial migration, CD11b/CD18 activation, and intestinal mucosal inflammatory function

Polymorphonuclear neutrophils (PMNs) play a critical role in clearing invading microbes and promoting tissue repair following infection/injury. However, dysregulated PMN trafficking and associated tissue damage is pathognomonic of numerous inflammatory mucosal diseases. The final step in PMN influx into mucosal lined organs (including the lungs, kidneys, skin, and gut) involves transepithelial migration (TEpM). The β2-integrin CD11b/CD18 plays an important role in mediating PMN intestinal trafficking, with recent studies highlighting that terminal fucose and GlcNAc glycans on CD11b/CD18 can be targeted to reduce TEpM. However, the role of the most abundant terminal glycan, sialic acid (Sia), in regulating PMN epithelial influx and mucosal inflammatory function is not well understood. Here we demonstrate that inhibiting sialidase-mediated removal of α2-3-linked Sia from CD11b/CD18 inhibits PMN migration across intestinal epithelium in vitro and in vivo. Sialylation was also found to regulate critical PMN inflammatory effector functions, including degranulation and superoxide release. Finally, we demonstrate that sialidase inhibition reduces bacterial peptide-mediated CD11b/CD18 activation in PMN and blocks downstream intracellular signaling mediated by spleen tyrosine kinase (Syk) and p38 MAPK. These findings suggest that sialylated glycans on CD11b/CD18 represent potentially novel targets for ameliorating PMN-mediated tissue destruction in inflammatory mucosal diseases.

Immune profiling of experimental murine mastitis reveals conserved response to mammary pathogenic Escherichia coli, Mycoplasma bovis, and Streptococcus uberis

Mastitis is one of the most prevalent and economically important diseases of dairy animals. The disease is caused by ascending bacterial infection through the teat canal. Among the most common mastitis-causing bacteria are Gram-negative coliforms, Gram-positive streptococci and staphylococci, and mycoplasma. The most prominent cellular hallmark of acute mammary infection is a massive recruitment of blood neutrophils into the tubular and alveolar milk spaces. The complex biological processes of leukocyte recruitment, activation, adhesion, and migration in the mammary gland remain largely elusive to date. While field research of mastitis in dairy animals contributed a lot to the development of mitigation, control, and even eradication programs, little progress was made toward understanding the molecular mechanisms underlying the pathogenesis of the disease. We report here experimental mastitis model systems in lactating mice challenged with field strains of common udder pathogens in dairy cows. We used these model systems to apply recently developed multiplex gene expression technology (Nanostring nCounter), which enabled us to study the expression of over 700 immune genes. Our analysis revealed a core of 100 genes that are similarly regulated and functionally or physically interacting in E. coli, M. bovis, and Strep uberis murine mastitis. Common significantly enriched gene sets include TNFɑ signaling via NFkB, Interferon gamma and alpha response, and IL6-JAK-STAT3 signaling. In addition, we show a significantly enriched expression of genes associated with neutrophil extracellular traps (NET) in glands challenged by the three pathogens. Ligand-receptor analysis revealed interactions shared by the three pathogens, including the interaction of the cytokines IL1β, IL1ɑ, and TNFɑ with their receptors, and proteins involved in immune cell recruitment such as complement C3 and ICAM1 (with CD11b), chemokines CCL3 and CCL4 (with CCR1), and CSF3 (with CSF3R). Taken together, our results show that mammary infection with E. coli, M. bovis, and Strep uberis culminated in the activation of a conserved core of immune genes and pathways including NET formation.

Pustular diseases and keratinocyte-myeloid synergy

Pustules are among the most common lesions produced in human skin. Infections by pathogens and drug-induced reactions are frequent causes of pustule formation. In recent years immune-mediated pustular diseases have drawn attention. It is proposed to classify pustular diseases according to the initiating events and sites: purely epidermal pustules, follicular pustules or pustules noted in autoinflammatory syndromes. The unifying pathology in all of the three categories is a microinvasion of activated neutrophils into epidermal or adnexal epithelia. Formation of pustules involves established IL-17 / IL-23, IL-36 / IL-36RN driven pathology, or IL-1 /caspase-activated autoinflammation. Pathophysiology demonstrates an intriguing synergy of keratinocytes with neutrophils. This is called keratinocyte-myeloid synergy (KMS). Non-infectious pustules are formed by IFNα controlling the production of chemoattractants (IL-8, LTB4) or induced by IL-1-regulated inflammasomes and caspase/ IFNβ-induced chemotaxins. The presence of physical barriers, for example, cornified cell layers (str. corneum), is instrumental in establishing chemotactic gradients and blocking migrating neutrophils. In follicular KMS-driven pustular disorders, in contrast to epidermal pustules, neutrophil-mediated toxicity propagates lasting and expanding ulcerating diseases with increased levels of circulating immunoglobulin A (IgA). Complexed IgA is suggested to propagate ongoing pustular diseases. These are prerequisites essential for developing pustules in burdensome human skin diseases.

Cell-in-cell phenomenon in urinary sediment: a case report

The internalization of apoptotic cells by non-phagocytic cells has been observed in different tissues and could be an important mechanism for the elimination of dying cells. Here, we describe a probable event of phagocytosis of apoptotic cells mediated by urothelial cells in urinary sediment. A 90-years-old male patient was admitted unconscious to the hospital, visible signs included: pale skin and dry mucous membranes, presumptively diagnosed as dehydration. Blood test revealed anaemia (haemoglobin 130 g/L) and hyperglycaemia (glucose 7.8 mmol/L), urinalysis showed a picture of urinary tract infection (leukocyturia and bacteriuria). The microscopic analysis of urinary sediment revealed the presence of urothelial cells and leukocytes internalized in urothelial cells. Anti-CD68 (membrane marker of macrophages) was tested by immunocytochemistry and a negative result was observed. Based on the findings phagocytosis of apoptotic cells mediated by urothelial cells was identified. This phenomenon can be observed in urinary sediment and should not be confused with a neoplastic process since it is a physiological event of cell elimination.

LEUKOCYTE-EPITHELIAL INTERACTIONS: A DOUBLE-EDGED SWORD THAT PROTECTS AND INJURES DURING HEALTH AND DISEASE

Neutrophils (PMNs) play a critical role in innate immunity, yet many pathologic conditions are associated with dysregulated infiltration of PMNs into tissues. In the gut, robust PMN accumulation and migration across the intestinal epithelium closely correlates with clinical symptoms in conditions such as ulcerative colitis. While much is known about how PMNs migrate out of blood vessels, far less is understood about how PMNs traverse epithelial barriers. Until fairly recently, in vitro models of PMN transepithelial migration (TEpM) across cultured intestinal epithelial cell lines provided many of the insights into the molecular basis of TEpM. However, innovative animal models have provided new avenues for investigating in vivo mechanisms regulating PMN TEpM. This report will highlight molecular insights gained from studies on PMN TEpM and provide a rationale for developing tissue targeted strategies directed at reducing pathologic consequences of dysregulated PMN trafficking in the gut.

The role of O-polysaccharide chain and complement resistance of Escherichia coli in mammary virulence

Mastitis, inflammation of the mammary gland, is a common disease of dairy animals. The disease is caused by bacterial infection ascending through the teat canal and mammary pathogenic Escherichia coli (MPEC) are common etiology. In the first phase of infection, virulence mechanisms, designated as niche factors, enable MPEC bacteria to resist innate antimicrobial mechanisms, replicate in milk, and to colonize the mammary gland. Next, massive replication of colonizing bacteria culminates in a large biomass of microbe-associated molecular patterns (MAMPs) recognized by pattern recognition receptors (PRRs) such as toll-like receptors (TLRs) mediating inflammatory signaling in mammary alveolar epithelial cells (MAEs) and macrophages. Bacterial lipopolysaccharides (LPSs), the prototypical class of MAMPs are sufficient to elicit mammary inflammation mediated by TLR4 signaling and activation of nuclear factor kB (NF-kB), the master regulator of inflammation. Using in vivo mastitis model, in low and high complements mice, and in vitro NF-kB luminescence reporter system in MAEs, we have found that the smooth configuration of LPS O-polysaccharides in MPEC enables the colonizing organisms to evade the host immune response by reducing inflammatory response and conferring resistance to complement. Screening a collection of MPEC field strains, we also found that all strains were complement resistant and 94% (45/48) were smooth. These results indicate that the structure of LPS O-polysaccharides chain is important for the pathogenesis of MPEC mastitis and provides protection against complement-mediated killing. Furthermore, we demonstrate a role for complement, a key component of innate immunity, in host-microbe interactions of the mammary gland.

Three-dimensional reconstruction of leukocyte internalisation in the luminal uterine epithelium following mating

Following mating, leukocytes are recruited to the uterine epithelium where they phagocytose spermatozoa and mediate maternal immune tolerance as well as a mild inflammatory response. In this ultrastructural study we utilised array tomography, a high-resolution volume scanning electron microscopy approach to 3D reconstruct the cellular relationships formed by leukocytes recruited to the luminal uterine epithelium 12 h post-mating in the rat. We report that following mating, neutrophils and macrophages are internalised by the luminal uterine epithelium, with multiple leukocytes internalised via contortion through a small tunnel in the apical membrane into a large membrane-bound vacuole within the cytoplasm of luminal uterine epithelial cells (UECs). Once internalised within the UECs, recruited leukocytes appear to phagocytose material within the membrane-bound vacuole and most ultimately undergo a specialised cell death, including vacuolisation and loss of membrane integrity. As these observations involve ultrastructurally normal leukocytic cells internalised within non-phagocytic epithelial cells, these observations are consistent with the formation of cell-in-cell structures via entosis, rather than phagocytic engulfment by UECs. Although cell-in-cell structures have been reported in normal and pathological conditions elsewhere, the data collected herein represents the first evidence of the formation of cell-in-cell structures within the uterine epithelium as a novel component of the maternal inflammatory response to mating.