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B cells, follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells are part of a circuit that may play a role in the development or progression of rheumatoid arthritis (RA). With the aim of providing further insight into this topic, here we evaluated the frequency of different subsets of Tfh and Tfr in untreated and long-term treated RA patients from a cohort of Argentina, and their potential association with particular human leukocyte antigen (HLA) class-II variants and disease activity. We observed that the frequency of total Tfh cells as well as of particular Tfh subsets and Tfr cells were increased in seropositive untreated RA patients. Interestingly, when analyzing paired samples, the frequency of Tfh cells was reduced in synovial fluid compared to peripheral blood, while Tfr cells levels were similar in both biological fluids. After treatment, a decrease in the CCR7 lo PD1 hi Tfh subset and an increase in the frequency of Tfr cells was observed in blood. In comparison to healthy donors, seropositive patients with moderate and high disease activity exhibited higher frequency of Tfh cells while seropositive patients with low disease activity presented higher Tfr cell frequency. Finally, we observed that HLA-DRB1*09 presence correlated with higher frequency of Tfh and Tfr cells, while HLA-DRB1*04 was associated with increased Tfr cell frequency. Together, our results increase our knowledge about the dynamics of Tfh and Tfr cell subsets in RA, showing that this is altered after treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ferrero, Onofrio, Acosta, Zacca, Ponce, Mussano, Onetti, Cadile, Costantino, Werner, Mas, Alvarellos, Montes, Acosta Rodríguez and Gruppi.)

Background: Parasitic infections by Trypanosoma cruzi (T. cruzi) are frequent in children from endemic areas. Specific therapies have been successfully used in pediatric populations to treat this disease. T. cruzi diagnosis should be optimized and become available for any clinical environment., Objective: To study T. cruzi prevalence in children from an area of active transmission and carry out a posttreatment follow-up. To verify the feasibility of detecting DNA of T. cruzi from dried blood spot., Methods: We analyzed presence of T. cruzi in 78 Aboriginal children (Toba community) that attended to a rural school of Chaco province, Argentina. Serum and whole blood (dried blood spot) were assessed by means of serological techniques and PCR. Positive children received Benznidazole. Diagnosis and post treatment follow-up of T. cruzi infection were performed., Results: The serology assay showed infection in 34 of 78 (43.5%) children studied; PCR was positive in 5/34, displaying parasitemia. Serology remained positive in 28/28 children 120 days post-treatment, while PCR was positive in 18/28 (6/34 children were lost in follow-up). No adverse effects during the treatment were reported., Conclusions: We were able to establish T. cruzi prevalence in the studied population and also to prove the usefulness of dried blood spot for T. cruzi detection using PCR in isolated areas. This method allowed us to verify early treatment failure. Possible causes of this failure are discussed below.

We report a case of Chagas disease reactivation in a patient with stage IIb follicular lymphoma in the cecum. He was admitted to the hospital with neutropenia and fever. He had a history of right hemicolectomy 6 months earlier and had received the sixth cycle of chemotherapy with cyclophosphamide/doxorubicin/vincristine/prednisone/rituximab. Blood and urine cultures were negative, but the fever persisted. Reactivation of Chagas disease was confirmed by means of quantitative real-time polymerase chain reaction (qRT-PCR). Parasitic load was 577 950 parasite equivalents/mL. The patient began treatment with benznidazole 5 mg/k per day every 12 hours. After 1 month, the qRT-PCR control was undetectable. The patient completed 60 days of treatment and is currently asymptomatic. Trypanosoma cruzi qRT-PCR may become a useful diagnostic method for reactivation of Chagas disease.

Chronic allograft nephropathy (CAN) represents an important cause of graft loss after kidney transplantation. TGF-beta1 is a key factor in fibrogenesis, and the angiotensin II receptor antagonist losartan may decrease the intra-graft synthesis of TGF-beta1. The aim of this study was to determine the clinical and molecular effect of losartan in kidney transplant patients (KTPs) with CAN. We studied nine KTPs, after the first year of transplantation, with proteinuria (more than 500 mg/24 h), stable renal function, and histological signs of CAN. Immunosuppression was cyclosporine, azathioprine, and corticoids. Kidney biopsy was performed in all patients at the beginning of the study and 12 weeks after treatment with 50 mg/day of losartan. Quantitation of intra-graft expression of TGF-beta1 was performed in all biopsies, by real-time PCR. After losartan treatment there were no differences in patients' BP and blood creatinine level. The proteinuria significantly dropped to 414.2+/-377 mg/24 h, P=0.001. Intra-graft expression of TGF-beta1 was decreased after treatment. In conclusion, losartan significantly decreases the intra-graft expression of TGF-beta1 and proteinuria in KTPs with CAN.

Previous studies have suggested a possible role for natural killer (NK) cells in resistance to some fungal infections, including Cryptococcus neoformans infections. The role of NK cells in early clearance of C neoformans from tissues and in long-term survival was studied in mice following intravenous inoculations of the organism. Mice treated with anti-asialo GM1 antiserum to temporarily reduce NK activity demonstrated an increase in colony-forming units (CFU) of C neoformans in the lung 24 hours after an intravenous inoculation of the organism. CFU in liver, spleen, kidney, and brain were not different in anti-asialo GM1 antiserum-treated versus control mice. An NK-specific reagent, anti-NK 1.1 monoclonal antibody, was used to deplete mice of NK cells in vivo for at least 14 days without affecting other natural defenses. The number of C neoformans retained in the lungs 24 hours after inoculation of the organism was significantly greater in NK cell-depleted mice than in controls, although CFU in other organs were unaffected. Following the intravenous inoculation of C neoformans, the survival of anti-NK 1.1-treated mice was not different from control mice. The effect of NK cell activity on resistance to C neoformans was also determined after an intratracheal inoculation of the organism. Mice pretreated with anti-NK 1.1 demonstrated no increases in CFU in the lungs, spleen, or brain as compared with controls. These data indicate that NK cells can play a role in vivo in early resistance against C neoformans if the organism is delivered via the intravenous route. However, NK cells do not play a role in either determining survival after an intravenous inoculation nor in resistance during an infection acquired via the respiratory tract.