Protective function and differentiation cues of brain-resident CD8+ T cells during surveillance of latent Toxoplasma gondii infection.

Chronic Toxoplasma gondii infection induces brain-resident CD8+ T cells (bTr), but the protective functions and differentiation cues of these cells remain undefined. Here, we used a mouse model of latent infection by T. gondii leading to effective CD8+ T cell-mediated parasite control. Thanks to antibody depletion approaches, we found that peripheral circulating CD8+ T cells are dispensable for brain parasite control during chronic stage, indicating that CD8+ bTr are able to prevent brain parasite reactivation. We observed that the retention markers CD69, CD49a, and CD103 are sequentially acquired by brain parasite-specific CD8+ T cells throughout infection and that a majority of CD69/CD49a/CD103 triple-positive (TP) CD8+ T cells also express Hobit, a transcription factor associated with tissue residency. This TP subset develops in a CD4+ T cell-dependent manner and is associated with effective parasite control during chronic stage. Conditional invalidation of Transporter associated with Antigen Processing (TAP)-mediated major histocompatibility complex (MHC) class I presentation showed that presentation of parasite antigens by glutamatergic neurons and microglia regulates the differentiation of CD8+ bTr into TP cells. Single-cell transcriptomic analyses revealed that resistance to encephalitis is associated with the expansion of stem-like subsets of CD8+ bTr. In summary, parasite-specific brain-resident CD8+ T cells are a functionally heterogeneous compartment which autonomously ensure parasite control during T. gondii latent infection and which differentiation is shaped by neuronal and microglial MHC I presentation. A more detailed understanding of local T cell-mediated immune surveillance of this common parasite is needed for harnessing brain-resident CD8+ T cells in order to enhance control of chronic brain infections.

Characteristics and incidence of infections in patients with multiple myeloma treated by bispecific antibodies: a national retrospective study.

OBJECTIVES: Bispecific antibodies (BsAbs) are an effective treatment used in relapsed or refractory multiple myeloma. Despite a well-tolerated safety profile, infectious events appear to be frequent in clinical trials. Real-world data on epidemiology, characteristics, risk factors, and outcomes of infections in patients treated with BsAb are still needed. METHODS: A retrospective, multicentre study in BsAb-treated patients with multiple myeloma was performed in 14 French centres from December 2020 to February 2023. The primary objective was to describe the incidence of infections that required hospitalization, specific treatment, or adaptation in BsAb administration. RESULTS: Among 229 patients with multiple myeloma treated with BsAb, 153 (67%) received teclistamab, 47 (20%) received elranatamab, and 29 (13%) talquetamab. We reported a total of 234 infections, including 123 (53%) of grade of ≥3. Predominant infections affected the respiratory tract (n = 116, 50%) followed by bacteraemias (n = 36, 15%). The hospitalization rate was 56% (n = 131), and 20 (9%) infections resulted in death. Global cumulative incidence of the first infection was 70% in all patients, 73% in patients treated with B-cell maturation antigen-targeting, and 51% with GPRC5D-targeting BsAb. In univariate analyses, corticosteroids for cytokine release syndrome (CRS)/immune effector cell-associated neurotoxicity syndrome (ICANS) were associated with a higher risk of first infection (HR = 2.13; 95% CI, 1.38-3.28), whereas GPRC5D-targeting BsAb and anti-bacterial prophylaxis were associated with a lower risk (HR = 0.53; 95% CI, 0.3-0.94 and HR = 0.65; 95% CI, 0.46-0.9). Fine and Gray multivariate model found that only corticosteroids for CRS/ICANS were correlated with a higher risk of first infection (HR = 2.01; 95% CI, 1.27-3.19). DISCUSSIONS: The implementation of preventive measures that aim to mitigate the risk of infection under BsAb is pivotal, notably in patients who received corticosteroids for CRS/ICANS.

Ceftriaxone compared with benzylpenicillin in the treatment of neurosyphilis in France: a retrospective multicentre study.

BACKGROUND: Intravenous benzylpenicillin is the gold-standard treatment for neurosyphilis, but it requires prolonged hospitalisation. Ceftriaxone is a possible alternative treatment, the effectiveness of which remains unclear. We aimed to assess the effectiveness of ceftriaxone compared with benzylpenicillin in the treatment of neurosyphilis. METHODS: We did a retrospective multicentre study including patients with neurosyphilis who were treated at one of eight tertiary care centres in France, from Jan 1, 1997, to Dec 31, 2017. We defined neurosyphilis as positive treponemal and non-treponemal tests and at least one of otic syphilis, ocular syphilis, either neurological symptom with a positive result on cerebrospinal fluid (CSF)-VDRL or CSF-PCR tests, or more than five leukocytes in a CSF cell count. Patients with neurosyphilis were identified from the medical information department database of each centre and assigned to one of two groups on the basis of the initial treatment received (ie, benzylpenicillin group or ceftriaxone group). The primary outcome was the overall clinical response (ie, proportion of patients with a complete or partial response) 1 month after treatment initiation. The secondary endpoints were proportions of patients with a complete response at 1 month and serological response at 6 months, and length of hospital stay. FINDINGS: Of 365 patients with a coded diagnosis of neurosyphilis in one of the eight care centres during 1997-2017, 208 were included in this study (42 in the ceftriaxone group and 166 in the benzylpenicillin group). The mean age of patients was 44·4 years (SD 13·4), and 193 (93%) were men. We observed 41 instances of overall clinical response (98%) in the ceftriaxone group versus 125 (76%) in the benzylpenicillin group (crude odds ratio [OR] 13·02 [95% CI 1·73-97·66], p=0·017). After propensity score weighting, overall clinical response rates remained different between the groups (OR 1·22 [95% CI 1·12-1·33], p<0·0001). 22 (52%) patients in the ceftriaxone group and 55 (33%) in the benzylpenicillin group had a complete response (crude OR 2·26 [95% CI 1·12-4·41], p=0·031), with no significant difference after propensity score weighting (OR 1·08 [95% CI 0·94-1·24], p=0·269). Serological response at 6 months did not differ between the groups (21 [88%] of 24 in the ceftriaxone group vs 76 [82%] of 93 in the benzylpenicillin group; crude OR 1·56 [95% CI 0·42-5·86], p=0·50), whereas hospital stay was shorter for patients in the ceftriaxone group than for those in the benzylpenicillin group (mean 13·8 days [95% CI 12·8-14·8] vs 8·9 days [5·7-12·0], p<0·0001). No major adverse effects were reported in either group. INTERPRETATION: Our results suggest that ceftriaxone is similarly effective to benzylpenicillin for the treatment of neurosyphilis, potentially decreasing the length of hospital stay. Randomised, controlled trials should be done to confirm these results. FUNDING: None.