Glioblastoma (GBM) is an aggressive and highly therapy-resistant brain tumour ^1,2 . Although advanced disease has been intensely investigated, the mechanisms that underpin the earlier, likely more tractable, stages of GBM development remain poorly understood. Here we identify axonal injury as a key driver of GBM progression, which we find is induced in white matter by early tumour cells preferentially expanding in this region. Mechanistically, axonal injury promotes gliomagenesis by triggering Wallerian degeneration, a targetable active programme of axonal death ³ , which we show increases neuroinflammation and tumour proliferation. Inactivation of SARM1, the key enzyme activated in response to injury that mediates Wallerian degeneration ⁴ , was sufficient to break this tumour-promoting feedforward loop, leading to the development of less advanced terminal tumours and prolonged survival in mice. Thus, targeting the tumour-induced injury microenvironment may supress progression from latent to advanced disease, thereby providing a potential strategy for GBM interception and control.

Renal failure is one of the most important social problems for its incurability and high costs for patients’ health care. Through clarification of the underlying mechanism for the high susceptibility of cats to renal disease, we here demonstrates that the effective dissociation of serum AIM protein from IgM is necessary for the recovery from acute kidney injury (AKI). In cats, the AIM-IgM binding affinity is 1000-fold higher than that in mice, which is caused by the unique positively-charged amino-acid cluster present in feline AIM. Hence, feline AIM does not dissociate from IgM during AKI, abolishing its translocation into urine. This results in inefficient clearance of lumen-obstructing necrotic cell debris at proximal tubules, thereby impairing AKI recovery. Accordingly, mice whose AIM is replaced by feline AIM exhibit higher mortality by AKI than in wild-type mice. Recombinant AIM administration into the mice improves their renal function and survival. As insufficient recovery from AKI predisposes patients to chronic, end-stage renal disease, feline AIM may be involved crucially in the high mortality of cats due to renal disease. Our findings could be the basis of the development of novel AKI therapies targeting AIM-IgM dissociation, and may support renal function in cats and prolong their lives.

SARM1 is a toll/interleukin-1 receptor -domain containing protein, with roles proposed in both innate immunity and neuronal degeneration. Murine SARM1 has been reported to regulate the transcription of chemokines in both neurons and macrophages; however, the extent to which SARM1 contributes to transcription regulation remains to be fully understood. Here, we identify differential gene expression in bone-marrow-derived macrophages (BMDMs) from C57BL/6 congenic 129 ES cell-derived Sarm1^−/− mice compared with wild type (WT). However, we found that passenger genes, which are derived from the 129 donor strain of mice that flank the Sarm1 locus, confound interpretation of the results, since many of the identified differentially regulated genes come from this region. To re-examine the transcriptional role of SARM1 in the absence of passenger genes, here we generated three Sarm1^−/− mice using CRISPR/Cas9. Treatment of neurons from these mice with vincristine, a chemotherapeutic drug causing axonal degeneration, confirmed SARM1's function in that process; however, these mice also showed that lack of SARM1 has no impact on transcription of genes previously shown to be affected such as chemokines. To gain further insight into SARM1 function, we generated an epitope-tagged SARM1 mouse. In these mice, we observed high SARM1 protein expression in the brain and brainstem and lower but detectable levels in macrophages. Overall, the generation of these SARM1 knockout and epitope-tagged mice has clarified that SARM1 is expressed in mouse macrophages yet has no general role in macrophage transcriptional regulation and has provided important new models to further explore SARM1 function.