Expression of TIM-3, Human β-defensin-2, and FOXP3 and Correlation with Disease Activity in Pediatric Crohn's Disease with Infliximab Therapy

Macrophage Tim-3 maintains intestinal homeostasis in DSS-induced colitis by suppressing neutrophil necroptosis

T-cell immunoglobulin domain and mucin domain-3 (Tim-3) is a versatile immunomodulator that protects against intestinal inflammation. Necroptosis is a type of cell death that regulates intestinal homeostasis and inflammation. The mechanism(s) underlying the protective role of macrophage Tim-3 in intestinal inflammation is unclear; thus, we investigated whether specific Tim-3 knockdown in macrophages drives intestinal inflammation via necroptosis. Tim-3 protein and mRNA expression were assessed via double immunofluorescence staining and single-cell RNA sequencing (sc-RNA seq), respectively, in the colonic tissues of patients with inflammatory bowel disease (IBD) and healthy controls. Macrophage-specific Tim3-knockout (Tim-3M-KO) mice were generated to explore the function and mechanism of Tim-3 in dextran sodium sulfate (DSS)-induced colitis. Necroptosis was blocked by pharmacological inhibitors of receptor-interacting protein kinase (RIP)1, RIP3, and reactive oxygen species (ROS). Additionally, in vitro experiments were performed to assess the mechanisms of neutrophil necroptosis induced by Tim-3 knockdown macrophages. Although Tim-3 is relatively inactive in macrophages during colon homeostasis, it is highly active during colitis. Compared to those in controls, Tim-3M-KO mice showed increased susceptibility to colitis, higher colitis scores, and increased pro-inflammatory mediator expression. Following the administration of RIP1/RIP3 or ROS inhibitors, a significant reduction in intestinal inflammation symptoms was observed in DSS-treated Tim-3M-KO mice. Further analysis indicated the TLR4/NF-κB pathway in Tim-3 knockdown macrophages mediates the TNF-α-induced necroptosis pathway in neutrophils. Macrophage Tim-3 regulates neutrophil necroptosis via intracellular ROS signaling. Tim-3 knockdown macrophages can recruit neutrophils and induce neutrophil necroptosis, thereby damaging the intestinal mucosal barrier and triggering a vicious cycle in the development of colitis. Our results demonstrate a protective role of macrophage Tim-3 in maintaining gut homeostasis by inhibiting neutrophil necroptosis and provide novel insights into the pathogenesis of IBD.

Values of serum intestinal fatty acid-binding protein, fecal calprotectin, and fecal human β-defensin 2 for predicting necrotizing enterocolitis

BACKGROUND

This study aimed to assess the diagnostic potential of serum intestinal fatty acid-binding protein (I-FABP), fecal calprotectin (FC), and fecal human β-defensin 2 (hBD2) in predicting necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A prospective cohort of neonates with a gestational age < 32 weeks, suspected of NEC, was enrolled between June 2021 and December 2022. Serum I-FABP, FC, and fecal hBD2 levels were measured upon NEC suspicion, and diagnosis was confirmed through radiological examination or surgical intervention. Diagnostic precision of serum I-FABP, FC, and fecal hBD2 was assessed using a logistic regression model with multiple variables.

RESULTS

The study included 70 neonates (45 males, 25 females), with 30 developing NEC (40% Stage III, n = 12; 60% Stage II, n = 18) and 40 in the control group. NEC patients exhibited significantly higher serum I-FABP and FC levels (4.76 ng/mL and 521.56 µg/g feces, respectively) than those with other diagnoses (1.38 ng/mL and 213.34 µg/g feces, respectively; p ˂ 0.05 for both biomarkers). Stage II NEC neonates showed elevated fecal hBD2 levels (376.44 ng/g feces) than Stage III NEC neonates and controls (336.87 ng/g and 339.86 ng/g feces, respectively; p ˂ 0.05). No such increase was observed in infants progressing to Stage III NEC. Using a serum I-FABP threshold of > 2.54 ng/mL yielded 76.7% sensitivity, 87.5% specificity, 82.1% positive predictive value (PPV), and 83.3% negative predictive value (NPV). For FC (cutoff > 428.99 µg/g feces), corresponding values were 76.7% sensitivity, 67.5% specificity, 63.9% PPV, and 79.4% NPV.

CONCLUSION

Serum I-FABP and FC levels are valuable for early NEC detection and provide insights into disease severity. Low fecal hBD2 levels suggest an inadequate response to luminal bacteria, potentially rendering these infants more susceptible to NEC development or exacerbation.

Post-transplant Inflammatory Bowel Disease Associated with Donor-Derived TIM-3 Deficiency

Inflammatory bowel disease (IBD) occurring following allogeneic stem cell transplantation (aSCT) is a very rare condition. The underlying pathogenesis needs to be better defined. There is currently no systematic effort to exclude loss- or gain-of-function mutations in immune-related genes in stem cell donors. This is despite the fact that more than 100 inborn errors of immunity may cause or contribute to IBD. We have molecularly characterized a patient who developed fulminant inflammatory bowel disease following aSCT with stable 100% donor-derived hematopoiesis. A pathogenic c.A291G; p.I97M HAVCR2 mutation encoding the immune checkpoint protein TIM-3 was identified in the patient's blood-derived DNA, while being absent in DNA derived from the skin. TIM-3 expression was much decreased in the patient's serum, and in vitro-activated patient-derived T cells expressed reduced TIM-3 levels. In contrast, T cell-intrinsic CD25 expression and production of inflammatory cytokines were preserved. TIM-3 expression was barely detectable in the immune cells of the patient's intestinal mucosa, while being detected unambiguously in the inflamed and non-inflamed colon from unrelated individuals. In conclusion, we report the first case of acquired, "transplanted" insufficiency of the regulatory TIM-3 checkpoint linked to post-aSCT IBD.

Association of TIM-3 with anterior uveitis and associated systemic immune diseases: a Mendelian randomization analysis

Background

We aimed to investigate the causal association between TIM-3, an immune checkpoint inhibitor, and anterior uveitis (AU), as well as associated systemic immune diseases.

Materials and methods

We performed two-sample Mendelian randomization (MR) analyses to estimate the causal effects of TIM-3 on AU and three associated systemic diseases, namely ankylosing spondylitis (AS), Crohn's disease (CD), and ulcerative colitis (UC). Single-nucleotide polymorphisms (SNPs) associated with AU, AS, CD, and UC were selected as the outcomes: AU GWAS with 2,752 patients with acute AU accompanied with AS (cases) and 3,836 AS patients (controls), AS GWAS with 968 cases and 336,191 controls, CD GWAS with 1,032 cases and 336,127 controls, and UC GWAS with 2,439 cases and 460,494 controls. The TIM-3 dataset was used as the exposure (n = 31,684). Four MR methods, namely, inverse-variance weighting (IVW), MR-Egger regression, weighted median, and weighted mode, were used in this study. Comprehensive sensitivity analyses were conducted to estimate the robustness of identified associations and the potential impact of horizontal pleiotropy.

Results

Our studies show that TIM-3 is significantly associated with CD using the IVW method (OR = 1.001, 95% CI = 1.0002-1.0018, P-value = 0.011). We also found that TIM-3 may be a protective factor for AU although these results lacked significance (OR = 0.889, 95% CI = 0.631-1.252, P-value = 0.5). No association was observed between the genetic predisposition to particular TIM-3 and susceptibility to AS or UC in this study. No potential heterogeneities or directional pleiotropies were observed in our analyses.

Conclusion

According to our study, a small correlation was observed between TIM-3 expression and CD susceptibility. Additional studies in different ethnic backgrounds will be necessary to further explore the potential roles and mechanisms of TIM-3 in CD.

Tim-3 is upregulated in human colorectal carcinoma and associated with tumor progression

T cell immunoglobulin mucin-3 (Tim-3) has previously been implicated in the immune response and tumor biology. Colorectal carcinoma (CRC) is a malignancy, which is closely associated with inflammation. However, the role of Tim-3 in the progression of CRC remains to be fully elucidated. The present study aimed to investigate the role of Tim-3 in the progressive activities of human CRC. A total of 30 clinical CRC tissues and their adjacent tissues were collected. Slides from another 112 cases that underwent CRC surgical resection were also obtained. The protein and mRNA levels of Tim-3 in the clinical tissues and in CRC cell lines were initially examined using western blot and reverse transcription-quantitative polymerase chain reaction analyses, respectively. Immunohistochemical staining was performed to detect Tim-3 in the CRC samples. Specific small interfering (si)RNA against Tim-3 (siTim-3) was synthesized to knock down the expression of Tim-3, and the subsequent effects of Tim-3 knockdown on cell proliferation, migration and invasion were assessed. The data obtained showed that Tim-3 was expressed at high levels in the CRC tissues, compared with the non-cancerous tissues. The expression of Tim-3 in the clinical tissues was significantly associated with tumor size (P=0.007), tumor-node-metastasis staging (P<0.0001) and distant metastasis (P<0.0001). Knockdown of Tim-3 significantly reduced the cell proliferative rate of HCT116 and HT-29 cells. Wound closure activity was also inhibited by knockdown of Tim-3 in these two cell lines, and the migration and invasive abilities of these two cell lines were consistently decreased following knockdown of Tim-3. Taken together, Tim-3 was found to be a critical mediator in the progression of CRC and may serve as a potential therapeutic target for the treatment of CRC.

Fecal Human β-Defensin 2 in Children with Cystic Fibrosis: Is There a Diminished Intestinal Innate Immune Response?

BACKGROUND

Defects in bacterial host defenses in the cystic fibrosis (CF) airways have been extensively investigated, but the role of the intestinal innate immune system in CF is unknown. Human β-defensin 2 (HBD-2) is an antimicrobial protein produced by epithelial surfaces and upregulated by inflammation. Its expression in the CF intestine is unknown.

AIM

To determine whether HBD-2 was present in the feces of patients with CF, and to compare fecal HBD-2 levels between CF and healthy controls (HC). To compare fecal HBD-2 levels in inflamed and noninflamed states, as measured by fecal calprotectin, as a secondary aim.

METHODS

Feces from children with CF and HC were collected for analysis.

RESULTS

Thirty-three CF patients and 33 HC were recruited. All CF patients had detectable fecal HBD-2. There was no difference between fecal HBD-2 in CF and HC (median (IQR) 49.1 (19.7-77.2) versus 43.4 (26.5-71.9) ng/g; P = 0.7). Fecal calprotectin was significantly higher in the CF cohort than in HC (median (IQR) 61.3 (43.8-143.8) versus 19.5 (19.5-35.1) mg/kg; P < 0.0001). There was no difference in fecal HBD-2 levels between CF subjects with fecal calprotectin ≥50 mg/kg and <50 mg/kg (50.5 (19.6-80.2) versus 43.0 (19.0-70.4); P = 0.7). There was no correlation between fecal HBD-2 and calprotectin in CF (r = 0.14; P = 0.4).

CONCLUSION

Fecal HBD-2 levels were not increased in children with CF, in inflamed or noninflamed states. The lack of HBD-2 induction and upregulation under inflammatory conditions may suggest a diminished intestinal innate immune response in CF.