David Boutboul’s research while affiliated with Université Paris Cité and other places

This case study presents the case of a 54-year-old human immunodeficiency virus (HIV)-positive male who developed type B insulin resistance syndrome (TBIRS) in conjunction with a relapse of human herpesvirus 8 (HHV8)-positive multicentric Castleman disease (MCD). This case is only the sixth reported instance of TBIRS associated with HHV8-associated MCD. The diagnosis was confirmed by the presence of anti-insulin receptor autoantibodies, and the patient was treated effectively with rituximab, with no relapse in follow-up. The cases described are discussed, along with the differences between them and our own case. Additionally, the potential for an autoimmune complication of MCD, even when HIV is well controlled, is addressed, as well as the available therapeutic approaches.

Topic Novel Genetic Etiologies of PIDs Preliminary data from this work were accepted and presented as an oral communication at the 21st biennial ESID meeting (October 2024). Background Epstein-Barr virus (EBV) is an oncogenic virus. Mostly asymptomatic, primary infection may be complicated by nonmalignant, malignant proliferations, and hemophagocytic lymphohistiocytosis. Infection resolution requires an appropriate cytotoxic T cell response, which depends on sustained T cell expansion. Several inherited EBV susceptibilities are associated with a high risk of complicated infection, which are often characterized by defective T cell expansion. Methods Four patients with EBV-related diseases and one with severe CMV were analyzed by whole-exome sequencing, in whom six deleterious biallelic compound heterozygous variants were identified in RECQL4. These mutations are predicted to be highly damaging and absent in exome public databases. RECQL4 is a DNA helicase involved in DNA replication initiation and DNA repair. Patients with RECQL4 variants have been previously reported with several autosomal recessive syndromes associated with poikiloderma and an increased risk of cancer. Few rare cases were also reported with immunodeficiency but no EBV-related diseases. An additional patient carrier of a homozygous null variant in RECQL4 presenting severe combined immunodeficiency and a severe RECQL4-related syndrome was studied. Results We showed that RECQL4 is upregulated in activated control T cells upon TCR-CD3 activation. In HEK cells, transiently overexpressed RECQL4 variants of the patients result in a reduced or absent RECQL4 expression. In activated T cells from patients, RECQL4 expression is strongly reduced or absent, and T cells exhibit a proliferation defect and an increased activation-induced apoptosis. In Jurkat T cell line, 3 different shRNA-targeting RECQL4 decrease its expression and induce a cell cycle blockade, proliferation arrest, and an increased apoptosis. Similarly in control T cells, silencing RECQL4 results in an expansion disadvantage and an increased apoptosis in the infected cells. Conclusion RECQL4 deficiency is associated with impaired T cell expansion that may underlie EBV susceptibility in patients.

This article reports a case of urogenital schistosomiasis mimicking IgG4-related disease (IgG4-RD) in a 47-year-old immunocompromised man with HIV. Initially diagnosed with IgG4-RD, further biopsies revealed schistosoma eggs. Elevated IgG4 levels indicated a Th2 immune response, highlighting its complex role in antischistosomal immunity and the need for careful differential diagnosis.

Cutaneous and mucosal manifestations associated with inflammatory bowel disease (IBD) are frequent. We report three cases of patients with ulcerative colitis who presented with extensive retiform purpura and/or cutaneous necrosis secondary to idiopathic thrombotic vasculopathy of the dermis. A review of the literature revealed six similar cases of thrombotic vasculopathy in the context of ulcerative colitis. Diagnosis requires skin biopsy and the exclusion of alternative diagnosis. Empiric treatment includes corticosteroids, anticoagulation and UC management, with a favorable prognosis and low recurrence risk. We believe that clinicians should be aware of this entity, which can sometimes serve as a revealing feature of ulcerative colitis.

Primary effusion lymphoma (PEL) is an HIV‐associated B‐cell non‐Hodgkin lymphoma (NHL) caused by Kaposi sarcoma herpesvirus (KSHV). There is no validated prognostic model in PEL, and prognosis is thought to be poor compared to other HIV‐associated NHL. We derived the PEL‐Prognostic score (PEL‐PS) from an international real‐world training set of 59 patients with HIV‐associated PEL who received first‐line anthracycline‐containing chemotherapy from the HIV and AIDS Malignancy Branch at the National Cancer Institute (NCI) in the United States and the National Center for HIV Malignancy at the Chelsea and Westminster Hospital (CWH) in England from 2000 to 2022. We identified prognostic factors associated with overall survival (OS). In a multivariable Cox model, ECOG ≥ 3 (p = 0.007; hazard ratio [HR] = 4.0 [95% CI: 1.5–11.1]) and hemoglobin < 8 g/dL (p = 0.006; HR = 3.8 [95% CI: 1.5–9.7]) were jointly associated with lower survival probability. The resulting PEL‐PS separated patients with no negative prognostic factors (score 0: hemoglobin ≥ 8 g/dL and ECOG ≤ 2, 48.1% of patients) with median OS of 10.6 years versus patients with 1–2 negative prognostic factors (score 1–2: hemoglobin < 8 g/dL and/or ECOG ≥ 3, 51.9% of patients) with median OS of 0.8 years (p < 0.0001). The PEL‐PS was then validated in 58 patients with HIV‐associated PEL treated with first‐line anthracycline‐containing chemotherapy at Hôpital Saint‐Louis in France over the same period: median OS in patients with PEL‐PS 0 was 16.9 years versus 0.6 years in patients with PEL‐PS score of 1–2 (p < 0.0001). The PEL‐PS identifies patients with good and poor prognosis. Patients with poor prognosis may benefit from novel therapies.

Background. Primary effusion lymphoma (PEL) is a rare form of Human Herpesvirus 8/Kaposi-Sarcoma Herpesvirus (HHV8/KSHV)-related B-cell lymphoma with an aggressive course, usually affecting immunocompromised individuals. Relapsed/refractory PEL has a very poor prognosis and therapeutic options are limited. Chimeric antigen receptor (CAR) T cells have revolutionized the treatment algorithm of diffuse large B-cell lymphoma (DLBCL) but their efficacy in rare lymphomas such as PEL is unknown. PEL usually lacks expression of pan-B-cell markers, such as CD19 and CD20. Conversely, several plasma cell markers, including CD38, are expressed at the surface of the majority of PEL and are currently under investigation as immunotherapy targets. Based on such immunophenotypic characteristics, in this work we tested the hypothesis that CD38-specific but not CD19-specific CAR T cells can exert antitumor effects against PEL. Methods. We employed two well established models of PEL (KSHV+EBV- ISI and BCP1 cell lines) as well as the DLBCL cell line DoHH2, showing a germinal genter phenotype, as reference. CD19 and CD38 expression was determined at protein level by extracellular flow cytometry. CD19 or CD38-specific CAR T cells with CD28 co-stimulatory domain were produced from healthy donors using retroviral vectors. Transduction efficacy was evaluated by CD19 or CD38 protein binding. Tumor cells were co-cultured with CAR T cells at an effector:target ratio of 1:1 after adjusting for transduction efficacy. Longitudinal cell growth was measured by bioluminescence in mCherry/Luciferase transduced cells after normalization to day 0. The percentage of live cells at day 3 was calculated after normalization to non-treated tumor cells. The t-test was used to determine statistical significance. Results. The PEL cell lines ISI and BCP1 expressed high levels of CD38 while CD19 expression was undetectable. As expected, the DLBCL cell line DoHH2 expressed high levels of both CD19 and CD38. Accordingly to such immunophenotype, CD19 CAR T cells could inhibit the tumor growth of DoHH2 cells while failed to exert any effect on ISI and BCP1 cells. Conversely, CD38-specific CAR T cells were able to control tumor growth of the three cell lines. An analysis conducted at day 3 on experiments performed with CAR T cells generated from 4 different donors showed that CD19 CAR T cells significantly reduced the percentage of DoHH2 live cells while did not affect PEL cell numbers. Conversely, CD38 CAR T cells led to a significant decrease in DoHH2, ISI and BCP-1 cells. Conclusions. CD38-specific CAR T cells showed in vitro tumor control in PEL models thus circumventing the tumor escape to CD19-specific CAR T cells due to lack of CD19 expression in PEL cells. Experiments to confirm these results in vivo are currently ongoing. Our data support the potential of CD38 CAR T cell development for the treatment of relapsed/refractory PEL.

Kaposi sarcoma-associated herpes virus (KSHV)/Human Herpesvirus 8 (HHV-8)-associated multicentric Castleman disease (MCD) is an inflammatory lymphoproliferative disorder mainly affecting immunocompromised hosts. Gold-standard diagnosis of KSHV/HHV-8 MCD currently relies on lymph node biopsy showing plasma-cell or mixed type Castleman disease associated to the pathognomonic presence of KSHV/HHV-8-infected cells located in the mantle zone. Hemophagocytic lympho-histiocytosis can complicate KSHV/HHV-8 MCD and lead to multiple organ failure and coagulopathy, delaying invasive sampling procedures. Our group previously reported the detection of circulating KSHV/HHV-8-infected cells (called KSHV/HHV-8-infected viroblasts, or KIVs) using standard flow cytometry in a small series of patients with KSHV/HHV-8-MCD flare. These cells had the same phenotype as those described in lymph node, were IgM, lambda and CD38 positive, and CD20 and CD24 negative. While specificity was high (100%) in this preliminary study, flow cytometry lacked sensitivity. The Flow-FISH technique, combining fluorescence in situ hybridization and flow cytometry, offers the advantage of viral transcripts direct and could improve the detection and characterization of KIVs during KSHV/HHV-8 MCD flares. Flow-FISH targeting Latent Nuclear Antigen (LNA) transcript of KSHV/HHV-8 was performed on peripheral blood mononuclear cells (PBMC) obtained from a large cohort of patients with KSHV/HHV-8 MCD flares and compared to standard flow cytometry. Fifty patients with KSHV/HHV-8 MCD flare were included in the study. All had histological confirmation of KSHV/HHV-8 MCD. Forty (80%) were male with a median age of 54. Thirty-two (64%) had a history of KSHV/HHV-8 MCD before the present flare, and 27 (54%) were living with HIV. Fifteen (30%) had a history of KS and none had history of PEL. Median C-reactive protein (CRP) levels and KSHV/HHV-8 whole blood viral load were 92 mg/L and 5.9 log copies/mL, respectively. Standard multiparametric flow cytometry was performed on PBMC in all patients. This technique was able to detect KIV, previously described as IgM+CD38highCD24-lambda+ cells, in 31 (62%) patients with KSHV/HHV-8 MCD flare (flow-cytometry positive group, or FC+). The percentage of IgM+CD38highCD24-lambda+ cells varied from 0.01% to 9.23% (median at 0.29%) among the CD3-CD14- population. Further extracellular characterization showed variable expression of CD19, CD20, CD27 and CD86 antigens. Flow-FISH was performed in 13 individuals in the FC+ group and showed the presence of LNA transcripts in all patients with LNA+ cells varying from 0.20% to 9% (median at 0.98%) of the CD3-CD14- population. All infected cells had a KIV phenotype and no other infected population was detected. Flow-FISH was performed on 11 samples from the 19 patients with KSHV/HHV-8-MCD flare but without detectable IgM+CD38highCD24-lambda+ population (FC- group). We were able to detect a significant LNA+ population in six additional cases (6/11, 54%, FC-FF+) with LNA+ cells varying from 0.01% to 0.1% (median at 0.04%) of the CD3-CD14- population. Once again, all infected cells had a KIV phenotype and no other infected population was detected. Two patients from the FC-FF- group received corticosteroids and/or etoposide before sampling. Overall, among the 42 patients for whom both standard flow cytometry and Flow-FISH could be performed, 37 (88%) had a detectable KIV population, supporting a role of Flow-FISH in enhancing sensitivity to detect these cells. We then compared the 31 patients from the FC+ group to the 19 patients from the FC- group. CRP level was significantly higher in the FC+ group (median at 108 mg/L vs 60 mg/L, p=0.03), as well as KSHV/HHV-8 DNA viral load (median at 6.3 copies/mL vs 5.2 copies/mL, p=0.012). The platelet count was significantly lower in the FC+ group (79 G/L vs 200 G/L, p=0.004). Combination of flow cytometry and Flow-FISH had a sensitivity of 88% to diagnose KSHV/HHV-8 MCD flare. Combination of flow cytometry and Flow-FISH emerges as a rapid and sensitive tool when suspecting KSHV/HHV-8 MCD flare, that might help the clinician to start an appropriate and urgent treatment without waiting for the result of lymph node biopsy that will further confirm the diagnosis.