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A KIM-1–AIM interaction promotes clearance of cellular debris in renal tubules after acute kidney injury to improve disease outcome. Acute kidney injury (AKI) is associated with prolonged hospitalization and high mortality, and it predisposes individuals to chronic kidney disease. To date, no effective AKI treatments have been established. Here we show that the apoptosis inhibitor of macrophage (AIM) protein on intraluminal debris interacts with kidney injury molecule (KIM)-1 and promotes recovery from AKI. During AKI, the concentration of AIM increases in the urine, and AIM accumulates on necrotic cell debris within the kidney proximal tubules. The AIM present in this cellular debris binds to KIM-1, which is expressed on injured tubular epithelial cells, and enhances the phagocytic removal of the debris by the epithelial cells, thus contributing to kidney tissue repair. When subjected to ischemia-reperfusion (IR)-induced AKI, AIM-deficient mice exhibited abrogated debris clearance and persistent renal inflammation, resulting in higher mortality than wild-type (WT) mice due to progressive renal dysfunction. Treatment of mice with IR-induced AKI using recombinant AIM resulted in the removal of the debris, thereby ameliorating renal pathology. We observed this effect in both AIM-deficient and WT mice, but not in KIM-1–deficient mice. Our findings provide a basis for the development of potentially novel therapies for AKI.

Wnt5a, a representative Wnt ligand that activates the β-catenin-independent pathway, has been shown to promote tumorigenesis. However, it is unclear where Wnt5a is produced and how it affects colon cancer aggressiveness. In this study, we demonstrate that Wnt5a is expressed in fibroblasts near the luminal side of the tumor, and its depletion suppresses mouse colon cancer formation. To characterize the specific fibroblast subtype, a meta-analysis of human and mouse colon fibroblast single-cell RNA-seq data is performed. The results show that Wnt5a is expressed in hypoxia-induced inflammatory fibroblast (InfFib), accompanied by the activation of HIF2. Moreover, Wnt5a maintains InfFib through the suppression of angiogenesis mediated by soluble VEGF receptor1 (Flt1) secretion from endothelial cells, thereby inducing further hypoxia. InfFib also produces epiregulin, which promotes colon cancer growth. Here, we show that Wnt5a acts on endothelial cells, inducing a hypoxic environment that maintains InfFib, thereby contributing to colon cancer progression through InfFib. Wnt5a is a member of the Wnt family of proteins that mainly activates the noncanonical Wnt signaling pathway. Here, the authors discover that inflammatory fibroblasts expressing Wnt5a, which are induced by hypoxia, contribute to colon cancer progression.

Reperfusion injury following cold and warm ischemia (IRI) is unavoidable during kidney transplantation and contributes to delayed graft function (DGF) and premature graft loss. Death of tubular epithelial cells (TECs) by necrosis during IRI releases pro-inflammatory mediators (e.g. HMGB1), propagating further inflammation (necroinflammation) and tissue damage. Kidney Injury Molecule-1 (KIM-1) is a phagocytic receptor upregulated on proximal TECs during acute kidney injury. We have previously shown that renal KIM-1 protects the graft against transplant associated IRI by enabling TECs to clear apoptotic and necrotic cells, and that recognition of necrotic cells by KIM-1 is augmented in the presence of the opsonin, apoptosis inhibitor of macrophages (AIM). Here, we tested whether recombinant AIM (rAIM) could be used to mitigate transplant associated IRI. We administered rAIM or vehicle control to nephrectomised B6 mice transplanted with a single B6 donor kidney. Compared to grafts in vehicle-treated recipients, grafts from rAIM-treated mice exhibited significantly less renal dysfunction, tubular cell death, tissue damage, tubular obstruction, as well as local and systemic inflammation. Both mouse and human rAIM enhanced the clearance of necrotic cells by murine and human TECs, respectively in vitro . These data support testing of rAIM as a potential therapeutic agent to reduce DGF following kidney transplantation.

Chronic kidney disease (CKD) encompasses multiple pathogenic mechanisms manifested by inflammation, fibrosis, oxidative stress and cell death. We previously showed that circulating protein CD5L (or AIM) ameliorates acute kidney injury, so we explored its effect in a mouse model of unilateral ureteral obstruction (UUO)-induced renal fibrosis. Here, we show a unique kidney-protective pathway mediated by CD5L. CD5L is endocytosed into renal epithelial cells, where it reduces oxidative stress, decreasing cell injury and death. This effect is supported by both a cysteine-dependent direct antioxidant activity of CD5L and enhancement of Nrf2-associated antioxidant responses. In addition, our data suggest that suppression of sphingomyelinase activity and reduction of cellular ceramide may contribute, at least in part, to CD5L-associated augmentation of Nrf2 nuclear transport. These effects depend on the reactive cysteine residue on the CD5L surface. Consistent with these findings, recombinant CD5L treatment in UUO mice reduces sphingomyelinase activity, activates Nrf2, and lowers oxidative stress, alleviating inflammation, fibrosis, and kidney injury. Our findings uncover a novel antioxidant pathway mediated by CD5L with potential implications for CKD-associated fibrotic mechanisms.

The prevalence of kidney stones is increasing and its recurrence rate within the first 5 years is over 50%. No treatments that prevent the occurrence/recurrence of stones have reached the clinic. Here, we show that AIM (also called CD5L) suppresses stone development and improves stone-associated physical damages. The N-terminal domain of AIM associates with calcium oxalate crystals via charge-based interaction to impede the development of stones, whereas the 2nd and C-terminal domains capture the inflammatory DAMPs to promote their phagocytic removal. Accordingly, when stones were induced by glyoxylate in mice, recombinant AIM (rAIM) injection dramatically reduced stone development. Expression of injury molecules and inflammatory cytokines in the kidney and overall renal dysfunction were abrogated by rAIM. Among various negatively charged substances, rAIM was most effective in stone prevention due to its high binding affinity to crystals. Furthermore, only AIM was effective in improving the physical complaints including bodyweight-loss through its DAMPs removal effect. We also found that tubular KIM-1 may remove developed stones. Our results could be the basis for the development of a comprehensive therapy against kidney stone disease. The circulating protein apoptosis inhibitor of macrophage (AIM) reduces kidney stone development and prevents build up, providing the basis for kidney stone disease therapy.

Ataxia is a condition characterized by impaired coordination of movements due to dysfunction of the cerebellum or related neural circuits. Here, we describe a mouse colony exhibiting progressive ataxia that arose spontaneously, which we have designated td. Whole genome sequencing and gene mapping revealed a 0.2 Mb tandem duplication involving exons 3 and 4 of the Grid2 gene, leading to premature termination of translation and reduced mRNA expression. Consistent with previous reports, our findings indicate that both structural and transcriptional abnormalities of Grid2 contribute to the observed phenotype. Notably, this type of variant in the Grid2 gene has not been identified. We observed atrophy of the granular and molecular layers and neuroinflammation in the granular layer of the td cerebellum, consistent with the role of Grid2 in Purkinje cell dendrites. Together, these findings establish td as a novel Grid2 mutant mouse model exhibiting cerebellar neurodegeneration.

Our previous studies revealed that REIC/Dkk-3 was expressed various tissues, including skin keratinocytes. The aim of the present study was to identify the factors that regulate the expression of the dickkopf Wnt signaling pathway inhibitor 3 (REIC/Dkk-3) tumor suppressor gene in normal human skin keratinocytes (NHKs). Several growth factors and cytokines that have previously been reported to be involved in the growth and differentiation of keratinocytes were screened as potential regulators. Western blot analysis was performed using protein from NHKs cultured with/without various factors including the epidermal growth factor, tumor necrosis factor-[alpha], transforming growth factor-[beta], interleukin (IL)-1F9, IL-6, IL-8 and [Ca.sup.2+]. The results indicated that only TNF-[alpha] downregulated REIC/Dkk-3 expression in NHKs. Subsequently, TNF-[alpha] was confirmed to reduce the expression levels of REIC/Dkk-3 in mouse skin tissue and hair culture models. TNF-[alpha]-mediated downregulation of REIC/Dkk-3 expression in NHKs was abrogated by the addition of a TNF-[alpha]-specific antibody. In conclusion, the results indicate that TNF-[alpha] downregulates REIC/Dkk-3 expression in normal skin keratinocytes.

Our previous studies revealed that REIC/Dkk-3 was expressed various tissues, including skin keratinocytes. The aim of the present study was to identify the factors that regulate the expression of the dickkopf Wnt signaling pathway inhibitor 3 (REIC/Dkk-3) tumor suppressor gene in normal human skin keratinocytes (NHKs). Several growth factors and cytokines that have previously been reported to be involved in the growth and differentiation of keratinocytes were screened as potential regulators. Western blot analysis was performed using protein from NHKs cultured with/without various factors including the epidermal growth factor, tumor necrosis factor-α, transforming growth factor-β, interleukin (IL)-1F9, IL-6, IL-8 and Ca2+. The results indicated that only TNF-α downregulated REIC/Dkk-3 expression in NHKs. Subsequently, TNF-α was confirmed to reduce the expression levels of REIC/Dkk-3 in mouse skin tissue and hair culture models. TNF-α-mediated downregulation of REIC/Dkk-3 expression in NHKs was abrogated by the addition of a TNF-α-specific antibody. In conclusion, the results indicate that TNF-α downregulates REIC/Dkk-3 expression in normal skin keratinocytes.

To show the importance of vector switching of nematodes in the evolution of the Bursaphelenchus xylophilus group, we tested a hypothesis that “Bursaphelenchus doui (or its ancestor) was transferred by Acalolepta fraudatrix, Acalolepta sejuncta, and/or Monochamus subfasciatus (or their ancestral species) from broad‐leaved trees to conifers, switched vectors from these cerambycid beetles to Monochamus beetles in conifers, and then evolved into the common ancestor of Bursaphelenchus mucronatus and B. xylophilus.” We used a simple nematode‐loading method to beetles and produced 20 binary combinations of five B. xylophilus group species and four cerambycid beetle species in the tribe Lamiini. The affinity of the nematodes for the beetles was examined based on phoretic stage formation of the nematodes. Phoretic stages of B. doui appeared in all beetle species examined, namely Acalolepta luxuriosa, Psacothea hilaris, A. fraudatrix, and Monochamus alternatus, although the affinity of the nematode for M. alternatus was weak. This finding indicates that B. doui could switch vectors to conifer‐using Monochamus beetles after transfer by A. fraudatrix from broad‐leaved trees to conifers. We conclude that vector switching of nematodes could have potentially happened during the evolutionary history of the B. xylophilus group. To clarify the role of vector switching of nematodes in the evolution of the Bursaphelenchus xylophilus group, we used a simple nematode‐loading method to beetles and produced 20 binary combinations of five B. xylophilus group species and four cerambycid beetle species in the tribe Lamiini. The affinity of the nematodes for the beetles was examined based on phoretic stage formation of the nematodes. The results showed that vector switching of nematodes could have potentially happened during the evolutionary history of the B. xylophilus group.

Objectives To evaluate the feasibility and safety of endoscopic ultrasound‐guided choledochoduodenostomy (EUS‐CDS) without fistula dilation using a novel self‐expandable metal stent (SEMS). Methods This retrospective study examined patients who underwent EUS‐CDS for malignant distal biliary obstruction between October 2017 and May 2021 at the National Cancer Center, Japan. The primary outcome was a technical success without fistula dilation. Secondary outcomes were the overall technical success, clinical success, adverse events (AEs), procedure time, recurrent biliary obstruction (RBO), and time to RBO (TRBO). Results Forty‐one patients were enrolled; 31 patients underwent EUS‐CDS with fistula dilation using a conventional SEMS with 7.5–8.5‐Fr delivery system (conventional SEMS group), and 10 patients underwent EUS‐CDS without fistula dilation using the novel SEMS with a 5.9‐Fr delivery system (novel SEMS group). In the novel SEMS group, the rate of technical success without fistula dilation was 90%. There were no differences in overall technical success (100% vs. 97%, p = 1.00), clinical success (80% vs. 90%, p = 0.58), and overall AEs (10% vs. 23%, p = 0.65) rates between the novel and conventional SEMS groups. In the novel SEMS group, no early AEs were observed and no bile leakage into the abdominal cavity was observed on the computed tomography scan after the procedure. The median procedure time was significantly shorter in the novel SEMS group (17 min vs. 24 min, p = 0.03). RBO and median TRBO did not differ between the 2 groups. Conclusions EUS‐CDS without fistula dilation using the novel SEMS with a 5.9‐Fr delivery system is technically feasible, straightforward, quick, and safe.