Discussion:
In this study, 46 patients who developed kidney injury after COVID-19
infection or had an aggravation of the original kidney injury were
included.The patients with new-onset renal damage mainly present with
AKI and NS, while the patients withaggravated renal damage mainly
presents with CKD and NS. 20% of the patients presented with impaired
renal function.A previous international meta-analysis involving 49,048
patients found that the incidence of AKI among hospitalized patients
with COVID-19 in the United States and Europe was as high as 28.6%,
while the incidence in Asia was 5.5%[3]. In our
study, 19.6% of patients developed AKI, with a significantly lower
incidence and milder clinical symptoms. The reason might be that
compared with the Delta variant in the pandemic waves before 2022, the
Omicron variantis more transmissible but lessintrinsic
virulent[4].
Among 38 patients with renal biopsy in this study, IgAN was the most
common pathological type, other pathological diagnoses included MN,
FSGS, acute interstitial nephritis(AIN), mesangial proliferative
glomerulonephritis(MsGPN), EPGN, henoch-schonlein purpura
nephritis(HSPN), TMA, and LN.Currently, GC has been reported as the most
common pathological manifestation of COVID-19 associated nephropathy,
which is mostly seen in patients with African ancestry and is associated
with a high-risk APOL1 genotype[5]. The
differences of pathological type of COVID-19 associated kidney injury
may be related to race, region and strain variation. Compared with
European and American populations, the frequency and percentage of
population attributable risk (PAR%)of the risk alleles of
IgAN-susceptible genes were significantly higher in the Chinese
population[6].
Compared with the database of kidney biopsies over a 10-year period
prior to the pandemic in our center, IgAN accounted for a higher
proportion of COVAN patients. Ma Y et al. speculated that SARS-CoV-2
invaded respiratory tract and intestinal mucosa through the encoded S
protein, activated antigen presenting cells, stimulated B cells to
transform into Gd-IgA1λB cells and secreted Gd-IGa1through T-cell
dependent and independent pathways, and then formed immune complexes
deposited in the mesangium of the glomeruli, ultimately leading to the
occurrence of IgAN[7]. Among other pathological
types, a patient diagnosed with TMAhada more severe renal pathological
lesion and poorer prognosis.
80% of patients with COVID-19 associated kidney injury had normal serum
C3 complement level, a few patients had increased or decreased C3 level.
In renal tissues, C3 deposits were observed in 68.4% of patients. Some
scholars believe that low serum C3 level indicates overactivation and
depletion of the complement system, which is related to the severity of
the disease and poor prognosis[8-10]. It is
currently believed that complement is involved in the indirect mechanism
of COVID-19 kidney injury: SARS-CoV-2 binds to endothelial angiotensin
converting enzyme 2 (ACE2), activates the lectin pathway and classical
pathway of complement, recruits neutrophils and monocytes/macrophages,
releases proteases,cytokinesand reactive oxygen species, leads to
inflammation, subcutaneous matrix destructionand vasculitis-like
lesions[11].
Among the 17 patients of follow-up, 29% of them experienced
deterioration of renal function after treatment, but no patients
developed to ESRD. However, in a cohort study of AKI in hospitalized
patients with COVID-19 in 2020, 46% of hospitalized patients
experienced AKI, 19% of the AKI patients entered dialysis and 50%
died[12]. At present, there are few international
reports on the prognosis of patients with Omicron infection. The
possible reasons for the favorable prognosis of patients in this study
are as follows: Firstly, international guidelines for treatment of
SARS-CoV-2 infection have been developed. Antiviral drugs such as
Nematovir, Azfudine and Monoravir as well as neutralizing antibody drugs
such as ambavir/Romisivirwere available for targeted antiviral therapy.
Early detection and treatment can be achieved in most patients.
Secondly, the involved patients were mainly infected with Omicron
variant. Compared to the initial strain reported internationally,
Omicron variant was less virulent and less likely to cause severe cases.